Magnetic resonance tractography of the lumbosacral plexus: Step-by-step

ABSTRACT

MR tractography of the lumbosacral plexus (LSP) is challenging due to the difficulty of acquiring high quality data and accurately estimating the neuronal tracts. We proposed an algorithm for an accurate visualization and assessment of the major LSP bundles using the segmentation of the cauda equina as seed points for the initial starting area for the fiber tracking algorithm.Twenty-six healthy volunteers underwent MRI examinations on a 3T MR scanner using the phased array coils with optimized measurement protocols for diffusion-weighted images and coronal T2 weighted 3D short-term inversion recovery sampling perfection with application optimized contrast using varying flip angle evaluation sequences used for LSP fiber reconstruction and MR neurography (MRN).The fiber bundles reconstruction was optimized in terms of eliminating the muscle fibers contamination using the segmentation of cauda equina, the effects of the normalized quantitative anisotropy (NQA) and angular threshold on reconstruction of the LSP. In this study, the NQA parameter has been used for fiber tracking instead of fractional anisotropy (FA) and the regions of interest positioning was precisely adjusted bilaterally and symmetrically in each individual subject.The diffusion data were processed in individual L3-S2 nerve fibers using the generalized Q-sampling imaging algorithm. Data (mean FA, mean diffusivity, axial diffusivity and radial diffusivity, and normalized quantitative anisotropy) were statistically analyzed using the linear mixed-effects model. The MR neurography was performed in MedINRIA and post-processed using the maximum intensity projection method to demonstrate LSP tracts in multiple planes.FA values significantly decreased towards the sacral region (P < .001); by contrast, mean diffusivity, axial diffusivity, radial diffusivity and NQA values significantly increased towards the sacral region (P < .001).Fiber tractography of the LSP was feasible in all examined subjects and closely corresponded with the nerves visible in the maximum intensity projection images of MR neurography. Usage of NQA instead of FA in the proposed algorithm enabled better separation of muscle and nerve fibers.The presented algorithm yields a high quality reconstruction of the LSP bundles that may be helpful both in research and clinical practice.

Lumbar Degenerative Disease Part 1: Anatomy and Pathophysiology of Intervertebral Discogenic Pain and Radiofrequency Ablation of Basivertebral and Sinuvertebral Nerve Treatment for Chronic Discogenic Back Pain: A Prospective Case Series and Review of Literature

Degenerative disc disease is a leading cause of chronic back pain in the aging population in the world. Sinuvertebral nerve and basivertebral nerve are postulated to be associated with the pain pathway as a result of neurotization. Our goal is to perform a prospective study using radiofrequency ablation on sinuvertebral nerve and basivertebral nerve; evaluating its short and long term effect on pain score, disability score and patients’ outcome. A review in literature is done on the pathoanatomy, pathophysiology and pain generation pathway in degenerative disc disease and chronic back pain. 30 patients with 38 levels of intervertebral disc presented with discogenic back pain with bulging degenerative intervertebral disc or spinal stenosis underwent Uniportal Full Endoscopic Radiofrequency Ablation application through either Transforaminal or Interlaminar Endoscopic Approaches. Their preoperative characteristics are recorded and prospective data was collected for Visualized Analogue Scale, Oswestry Disability Index and MacNab Criteria for pain were evaluated. There was statistically significant Visual Analogue Scale improvement from preoperative state at post-operative 1wk, 6 months and final follow up were 4.4 ± 1.0, 5.5 ± 1.2 and 5.7 ± 1.3, respectively, p < 0.0001. Oswestery Disability Index improvement from preoperative state at 1week, 6 months and final follow up were 45.8 ± 8.7, 50.4 ± 8.2 and 52.7 ± 10.3, p < 0.0001. MacNab criteria showed excellent outcomes in 17 cases, good outcomes in 11 cases and fair outcomes in 2 cases Sinuvertebral Nerve and Basivertebral Nerve Radiofrequency Ablation is effective in improving the patients’ pain, disability status and patient outcome in our study.

Erdheim-Chester disease mimicking lumbar nerve schwannoma: case report and literature review

Introduction

Erdheim-Chester disease (ECD) is a rare, non-Langerhans cell histiocytosis. The clinical spectrum of ECD is diverse, varying from asymptomatic focal lesion to life-threatening multisystem infiltration. Neurological manifestations of ECD are common, mostly due to the involvement of the central nerve system. However, spinal nerve or peripheral nerve involvement has rarely been mentioned.

Case presentation

Herein, we present a case of a 32-year-old female patient complaining about radiating pain on the front and lateral side of her left thigh for 2 months. Spinal MRI with contrast enhancement showed a space-occupying lesion on the left L3/L4 intervertebral foramen, indicating an initial diagnosis of lumbar nerve schwannoma. The patient underwent surgery to remove the mass and decompress the lumbar nerve. Postoperative histological examination revealed the diffuse infiltration of foamy histiocytes that were CD68+, CD163+, and CD1a- on immunostaining, which confirmed the diagnosis of Erdheim-Chester disease. The radiating pain was gradually alleviated and PET-CT was performed but showed no further involvement of ECD.

Discussion

To the best of our knowledge, this is the first case of ECD demonstrated as an infiltrative mass on the spinal nerve, with imaging manifestations and compression symptoms similar to those of peripheral nerve schwannoma.

Influence of injectate volume on paravertebral spread in erector spinae plane block: An endoscopic and anatomical evaluation

The paravertebral spread that occurs after erector spinae plane block may be volume-dependent. This cadaveric study was undertaken to compare the extent of paravertebral spread with erector spinae plane block using different dye volumes. After randomization, twelve erector spinae plane blocks were performed bilaterally with either 10 ml or 30 ml of dye at the level of T5 in seven unembalmed cadavers except for two cases of unexpected pleural puncture using the 10 ml injection. Direct visualization of the paravertebral space by endoscopy was performed immediately after the injections. The back regions were also dissected, and dye spread and nerve involvement were investigated. A total of five 10 ml injections and seven 30 ml injections were completed for both endoscopic and anatomical evaluations. No paravertebral spread was observed by endoscopy after any of the 10-ml injections. Dye spread to spinal nerves at the intervertebral foramen was identified by endoscopy at adjacent levels of T5 (median: three levels) in all 30 ml injections. In contrast, the cases with two, four, and three out of five were stained at only the T4, T5, and T6 levels, respectively, with the 10 ml injection. Upon anatomical dissection, all blocks were consistently associated with posterior and lateral spread to back muscles and fascial layers, especially with the 30 ml injections, which showed greater dye expansion. In one 30 ml injection, sympathetic nerve involvement and epidural spread were observed at the level of the injection site. Although paravertebral spread following erector spinae plane block increased in a volume-dependent manner, this increase was variable and not pronounced. As the injectate volume increased for the erector spinae blocks, the injectate spread to the back muscles and fascial layers seemed to be predominantly increased compared with, the extent of paravertebral spread.

Anatomical description of anaesthetic spread after deep erector spinae block at L-4

INTRODUCTION

Thoracic erector spinae plane (ESP) block is now used for postoperative analgesia. However, although reports of lumbar ESP have been published, the anesthetic spread and mechanism of action of this technique remains unclear. We describe the lumbar ESP block technique and evaluate the spread of 20ml of solution administered at the level of the transverse process of L4 in a cadaver model.

METHODS

Observational study after 12 lumbar ESP blocks at L4 on a fresh cadaver model (6 bilaterally). The spread of 20ml of injected contrast solution was assessed by computed tomography in all 6 samples. Four of the samples were evaluated by anatomical study, 2 by plane dissection, and 2 others were frozen and cut into 2-2.5cm axial slices.

RESULTS

The injected solution spread from L2 to L5 in a cranio-caudal direction in the erector spinae muscle, reaching the facet joints medially and the thoracolumbar fascia laterally. In 33% of cases the solution did not spread anterior to the transverse process; in 51%, spread was minimal and did not affect the corresponding spinal nerves, and in 2 samples (16%), spread was extensive and reached the corresponding spinal nerves.

CONCLUSIONS

Lumbar ESP at L4 always acts on the posterior branches of the spinal nerves, but seldom spreads to the paravertebral space to block the spinal nerve.

Multicenter reproducibility study of diffusion MRI and fiber tractography of the lumbosacral nerves

BACKGROUND

Diffusion tensor imaging (DTI) has been applied in the lumbar and sacral nerves in vivo, but information about the reproducibility of this method is needed before DTI can be used reliably in clinical practice across centers.

PURPOSE

In this multicenter study the reproducibility of DTI of the lumbosacral nerves in healthy volunteers was investigated.

STUDY TYPE

Prospective control series.

SUBJECTS

Twenty healthy subjects.

FIELD STRENGTH/SEQUENCE

3T MRI. 3D turbo spin echo, and 3.0 mm isotropic DTI scan.

ASSESSMENT

The DTI scan was performed three times (twice in the same session, intrascan reproducibility, and once after an hour, interscan reproducibility). At site 2, 1 week later, the protocol was repeated (interweek reproducibility). Fiber tractography (FT) of the lumbar and sacral nerves (L3-S2) was performed to obtain values for fractional anisotropy, mean, axial, and radial diffusivity.

STATISTICAL TESTS

Reproducibility was determined using the intraclass correlation coefficient (ICC), and power calculations were performed.

RESULTS

FT was successful and reproducible in all datasets. ICCs for all diffusion parameters were high for intrascan (ranging from 0.70-0.85), intermediate for interscan (ranging from 0.61-0.73), and interweek reliability (ranging from 0.58-0.62). There were small but significant differences between the interweek diffusivity values (P < 0.0005). Depending on the effect size, nerve location, and parameter of interest, power calculations showed that sample sizes between 10 and 232 subjects are needed for cross-sectional studies.

DATA CONCLUSION

We found that DTI and FT of the lumbosacral nerves have intermediate to high reproducibility within and between scans. Based on these results, 10-58 subjects are needed to find a 10% change in parameters in cross-sectional studies of the lumbar and sacral nerves. The small significant differences of the interweek comparison suggest that results from longitudinal studies need to be interpreted carefully, since small differences may also be caused by factors other than disease progression or therapeutic effects.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:951-963.

Nerve Ultrasound Predicts Treatment Response in Chronic Inflammatory Demyelinating Polyradiculoneuropathy-a Prospective Follow-Up

As reliable biomarkers of disease activity are lacking, monitoring of therapeutic response in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) remains a challenge. We sought to determine whether nerve ultrasound and electrophysiology scoring could close this gap. In CIDP patients (fulfilling EFNS/PNS criteria), we performed high-resolution nerve ultrasound to determine ultrasound pattern sum scores (UPSS) and predominant echotexture nerve conduction study scores (NCSS) as well as Medical Research Council sum scores (MRCSS) and inflammatory neuropathy cause and treatment disability scores (INCAT) at baseline and after 12 months of standard treatment. We retrospectively correlated ultrasound morphology with nerve histology when available. 72/80 CIDP patients featured multifocal nerve enlargement, and 35/80 were therapy-naïve. At baseline, clinical scores correlated with NCSS (r2 = 0.397 and r2 = 0.443, p < 0.01), but not or hardly with UPSS (Medical Research Council sum scores MRCSS r2 = 0.013, p = 0.332; inflammatory neuropathy cause and treatment disability scores INCAT r2 = 0.053, p = 0.048). Longitudinal changes in clinical scores, however, correlated significantly with changes in both UPSS and NCSS (r2 = 0.272-0.414, p < 0.0001). Combining nerve/fascicle size with echointensity and histology at baseline, we noted 3 distinct classes: 1) hypoechoic enlargement, reflecting active inflammation and onion bulbs; 2) nerve enlargement with additional hyperechogenic fascicles/perifascicular tissue in > 50% of measured segments, possibly reflecting axonal degeneration; and 3) almost no enlargement, reflecting "burned-out" or "cured" disease without active inflammation. Clinical improvement after 12 months was best in patients with pattern 1 (up to 75% vs up to 43% in pattern 2/3, Fisher's exact test p < 0.05). Nerve ultrasound has additional value not only for diagnosis, but also for classification of disease state and may predict treatment response.

Stereotactic topography of the greater and third occipital nerves and its clinical implication

This study aimed to provide topographic information of the greater occipital (GON) and third occipital (3ON) nerves, with the three-dimensional locations of their emerging points on the back muscles (60 sides, 30 cadavers) and their spatial relationship with muscle layers, using a 3D digitizer (Microscribe G2X, Immersion Corp, San Jose CA, USA). With reference to the external occipital protuberance (EOP), GON pierced the trapezius at a point 22.6 ± 7.4 mm lateral and 16.3 ± 5.9 mm inferior and the semispinalis capitis (SSC) at a point 13.1 ± 6.0 mm lateral and 27.7 ± 9.9 mm inferior. With the same reference, 3ON pierced, the trapezius at a point 12.9 ± 9.3 mm lateral and 44.2 ± 21.4 mm inferior, the splenius capitis at a point 10.0 ± 5.3 mm lateral and 59.2 ± 19.8 mm inferior, and SSC at a point 11.5 ± 9.9 mm lateral and 61.4 ± 15.3 mm inferior. Additionally, GON arose, winding up the obliquus capitis inferior, with the winding point located 52.3 ± 11.7 mm inferior to EOP and 30.2 ± 8.9 mm lateral to the midsagittal line. Knowing the course of GON and 3ON, from their emergence between vertebrae to the subcutaneous layer, is necessary for reliable nerve detection and precise analgesic injections. Moreover, stereotactic measurement using the 3D digitizer seems useful and accurate for neurovascular structure study.

Visualization of lumbar nerves using reduced field of view diffusion tensor imaging in healthy volunteers and patients with degenerative lumbar disorders

OBJECTIVE

We investigated high resolution diffusion tensor imaging (DTI) of lumbar nerves with reduced field of view (rFOV) using 3 T MRI.

METHODS

DTI measured with rFOV was compared with conventional FOV (cFOV) 3.0 T MRI in 5 healthy volunteers and 10 patients with degenerative lumbar disorders. The intracanal, foramina and extraforamina of the L5 nerve were established as the regions of interest and fractional anisotropy (FA) values and apparent diffusion coefficient (ADC) values were measured. Image quality for tractography and FA maps and ADC maps, interindividual and intraindividual reliability of FA and ADC, and signal-to-noise (SNR) were studied.

RESULTS

Both of image qualities with tractography, FA map and ADC map showed that lumbar nerves were more clearly imaged with the rFOV. Intraindividual reliability was higher with rFOV compared with the conventional method for ADC values, while interindividual reliability was higher for both FA values and ADC values with the rFOV method over the conventional method (p < 0.05). Significantly higher SNR was obtained with rFOV compared with cFOV in the spinal canal (p < 0.05).

CONCLUSION

rFOV enabled clearer imaging of the lumbar nerve, allowing for more accurate measurement of FA and ADC values. Significantly higher SNR was obtained with rFOV compared with cFOV in the spinal canal. To our knowledge, this research showed for the first time the usefulness of rFOV in patients with degenerative lumbar disorders. High resolution DTI using rFOV may become useful in clinical applications because visualization of nerve entrapments and quantification of DTI parameters may allow more accurate diagnoses of lumbar nerve dysfunction. Advances in knowledge: Compared with traditional methods, rFOV allows for clear imaging of the lumbar nerve and enables accurate measurements of the FA and ADC values. High-resolution DTI with rFOV may be used to visualize nerve entrapments and allow for more accurate diagnosis of DTI parameter quantification with opportunities for clinical applications.

Spinal nerve involvement in early Guillain-Barré syndrome: The Haymaker and Kernohan's legacy

Pathological studies of early Guillain-Barré syndrome (GBS), defined as of 10days of disease onset, are scanty making it difficult to interpret the physiopathology of clinical and electrophysiological features. In 1949, Webb Haymaker and James Kernohan reported 50 clinico-pathological studies of fatal GBS cases, 32 of them having died between days 2 and 10 after onset. They established that the brunt of initial lesions, consisting of endoneurial oedema interpreted as degenerative, relied on spinal nerves. That this oedema was inflammatory was soon thereafter recognized. Two decades later, however, the pathogenic role of endoneurial oedema was disputed. In experimental allergic neuritis, considered an animal model of GBS, the initial lesion appearing on day 4 post-inoculation is marked inflammatory oedema in the sciatic nerve and lumbosacral nerve roots. Additional detailed clinico-pathological studies corroborated that the appearance of epi-perineurium at the subarachnoid angle, where anterior and posterior roots join to form the spinal nerve, is a pathological hotspot in early GBS, there developing inflammatory oedema, incipient demyelination and endoneurial ischemic zones with axonal degeneration. Furthermore, nerve ultrasonography has demonstrated predominant spinal nerve changes in early GBS, either demyelinating or axonal. Other outstanding Haymaker and Kernohan's contributions were to clarify the complex nosology of the syndrome bringing under the same rubric Landry's paralysis, acute febrile polyneuritis and GBS, and critically analyzing GBS exclusion criteria by then prevailing. It is concluded that the authors' legacy remains as relevant as ever.

Survival Analysis of Occipital Nerve Stimulator Leads Placed under Fluoroscopic Guidance with and without Ultrasonography

BACKGROUND

Electrical stimulation of the greater occipital nerves is performed to treat pain secondary to chronic daily headaches and occipital neuralgia. The use of fluoroscopy alone to guide the surgical placement of electrodes near the greater occipital nerves disregards the impact of tissue planes on lead stability and stimulation efficacy.

OBJECTIVE

We hypothesized that occipital neurostimulator (ONS) leads placed with ultrasonography combined with fluoroscopy would demonstrate increased survival rates and times when compared to ONS leads placed with fluoroscopy alone.

STUDY DESIGN

A 2-arm retrospective chart review.

SETTING

A single academic medical center.

METHODS

This retrospective chart review analyzed the procedure notes and demographic data of patients who underwent the permanent implant of an ONS lead between July 2012 and August 2015. Patient data included the diagnosis (reason for implant), smoking tobacco use, disability, and age. ONS lead data included the date of permanent implant, the imaging modality used during permanent implant (fluoroscopy with or without ultrasonography), and, if applicable, the date and reason for lead removal. A total of 21 patients (53 leads) were included for the review. Chi-squared tests, Fishers exact tests, 2-sample t-tests, and Wilcoxon rank-sum tests were used to compare fluoroscopy against combined fluoroscopy and ultrasonography as implant methods with respect to patient demographics. These tests were also used to evaluate the primary aim of this study, which was to compare the survival rates and times of ONS leads placed with combined ultrasonography and fluoroscopy versus those placed with fluoroscopy alone. Survival analysis was used to assess the effect of implant method, adjusted for patient demographics (age, smoking tobacco use, and disability), on the risk of lead explant.

RESULTS

Data from 21 patients were collected, including a total of 53 ONS leads. There was no statistically significant difference in the lead survival rate or time, disability, or patient age with respect to the implant method with or without ultrasonography. There was a statistically significant negative effect on the risk of explant with regards to lead removal in smoking patients compared to non-smoking patients (hazard ratio 0.36). There was also a statistically significant difference in smoking tobacco use with respect to the implant method, such that a greater number of patients whose leads were placed with combined fluoroscopy and ultrasonography had a history of smoking (P = 0.048).

LIMITATIONS

This study is a retrospective chart review that had statistically significant differences in the patient groups and a small sample size.

CONCLUSION

This study assessed the survival rates and times of ONS leads placed with ultrasonography and fluoroscopy versus fluoroscopy alone. We did not observe an effect to suggest that the incremental addition of ultrasound guidance to fluoroscopy as the intraoperative imaging modality used during the permanent implant of ONS leads yields statistically significant differences in lead survival rate or time. Medical comorbidities, including age and smoking status, may play a role in determining the risk of surgical revision and should be considered in future studies.

KEY WORDS

Neuromodulation, peripheral nerve stimulation, occipital nerve stimulation, occipital neuralgia, chronic daily headaches, ultrasonography.

Nerve ultrasound in the differentiation of multifocal motor neuropathy (MMN) and amyotrophic lateral sclerosis with predominant lower motor neuron disease (ALS/LMND)

The objective of the study was to investigate nerve ultrasound (US) in comparison to nerve conduction studies (NCS) for differential diagnosis of amyotrophic lateral sclerosis with predominant lower motoneuron disease(ALS/LMND) and multifocal motor neuropathy(MMN). A single-center, prospective, examiner-blinded cross-sectional diagnostic study in two cohorts was carried out. Cohort I: convenience sample of subjects diagnosed with ALS/LMND or MMN (minimal diagnostic criteria:possible ALS (revised EL-Escorial criteria), possible MMN (European Federation of Neurosciences guidelines).Cohort II: consecutive subjects with suspected diagnosis of either ALS/LMND or MMN. Diagnostic US and NCS models were developed based on ROC analysis of 28 different US and 32 different NCS values measured in cohort I. Main outcome criterion was sensitivity/specificity of these models between ALS/LMND and MMN in cohort II.Cohort I consisted of 16 patients with ALS/LMND and 8 patients with MMN. For cohort II, 30 patients were recruited, 8 with ALS/LMND, 5 with MMN, and 17 with other diseases. In cohort I, the three best US measures showed higher mean ± SD areas under the curve than the respective NCS measures (0.99 ± 0.01 vs. 0.79 ± 0.03, p<0.001; two-sided t test). The US model with highest measurement efficacy (8 values) and diagnostic quality reached 100 % sensitivity and 92 % specificity for MMN in cohort II, while the respective NCS model (6 values, including presence of conduction blocks) reached 100 and 52 %. Nerve US is of high diagnostic accuracy for differential diagnosis of ALS/LMND and MMN. It might be superior to NCS in the diagnosis of MMN in hospital-admitted patients with this differential diagnosis.

Ultrasound-Guided Intermediate Site Greater Occipital Nerve Infiltration: A Technical Feasibility Study

BACKGROUND

Two studies recently reported that computed tomography (CT) guided infiltration of the greater occipital nerve at its intermediate site allows a high efficacy rate with long-lasting pain relief following procedure in occipital neuralgia and in various craniofacial pain syndromes.

OBJECTIVE

The purpose of our study was to evaluate the technical feasibility and safety of ultrasound-guided intermediate site greater occipital nerve infiltration.

STUDY DESIGN

Retrospective study.

SETTING

This study was conducted at the imaging department of a 1,409 bed university hospital.

METHODS

Local institutional review board approval was obtained and written consent was waived. In this retrospective study, 12 patients suffering from refractory occipital neuralgia or craniofacial pain syndromes were included between April and October 2014. They underwent a total of 21 ultrasound-guided infiltrations. Infiltration of the greater occipital nerve was performed at the intermediate site of the greater occipital nerve, at its first bend between obliqus capitis inferior and semispinalis capitis muscles with local anestetics and cortivazol. Technical success was defined as satisfactory diffusion of added iodinated contrast media in the fatty space between these muscles depicted on control CT scan. We also reported first data of immediate block test efficacy and initial clinical efficacy at 7 days, one month, and 3 months, defined by a decrease of at least 50% of visual analog scale (VAS) scores.

RESULTS

Technical success rate was 95.24%. Patients suffered from right unilateral occipital neuralgia in 3 cases, left unilateral occipital neuralgia in 2 cases, bilateral occipital neuralgia in 2 cases, migraine in one case, cervicogenic headache in one case, tension-type headache in 2 cases, and cluster headache in one case. Block test efficacy was found in 93.3% (14/15) cases. Clinical efficacy was found in 80% of cases at 7 days, in 66.7% of cases at one month and in 60% of cases at 3 months. No major complications were noted.

LIMITATIONS

Some of the limitations of our study include that it represents a single institution. The low number of infiltrations included in this study, for this guidance procedure, is another bias.

CONCLUSIONS

This ultrasound-guided infiltration technique appears to be feasible, safe, non-ionizing, and fast when targeting the greater occipital nerve in its intermediate portion. This imaging guidance modality should be used in routine clinical practice.

KEY WORDS

Greater occipital nerve, infiltration, ultrasound guidance, corticosteroids, occipital neuralgia, craniofacial pain syndrome.

In Vivo MRI Measurement of Spinal Cord Displacement in the Thoracolumbar Region of Asymptomatic Subjects with Unilateral and Sham Straight Leg Raise Tests

Background

Normal displacement of the conus medullaris with unilateral and bilateral SLR has been quantified and the "principle of linear dependence" has been described.

Purpose

Explore whether previously recorded movements of conus medullaris with SLRs are i) primarily due to transmission of tensile forces transmitted through the neural tissues during SLR or ii) the result of reciprocal movements between vertebrae and nerves.

Study design

Controlled radiologic study.

Methods

Ten asymptomatic volunteers were scanned with a 1.5T magnetic resonance (MR) scanner using T2 weighted spc 3D scanning sequences and a device that permits greater ranges of SLR. Displacement of the conus medullaris during the unilateral and sham SLR was quantified reliably with a randomized procedure. Conus displacement in response to unilateral and sham SLRs was quantified and the results compared.

Results

The conus displaced caudally in the spinal canal by 3.54±0.87 mm (mean±SD) with unilateral (p≤.001) and proximally by 0.32±1.6 mm with sham SLR (p≤.542). Pearson correlations were higher than 0.99 for both intra- and inter-observer reliability and the observed power was 1 for unilateral SLRs and 0.054 and 0.149 for left and right sham SLR respectively.

Conclusions

Four relevant points emerge from the presented data: i) reciprocal movements between the spinal cord and the surrounding vertebrae are likely to occur during SLR in asymptomatic subjects, ii) conus medullaris displacement in the vertebral canal with SLR is primarily due to transmission of tensile forces through the neural tissues, iii) when tensile forces are transmitted through the neural system as in the clinical SLR, the magnitude of conus medullaris displacement prevails over the amount of bone adjustment.

Giant Spinal Schwannoma in a 76-year-old Woman--A Case Report

A schwannoma is a benign nerve sheath tumor composed of Schwann cells. Spinal schwannoma originates from dorsal roots of the spinal cord, causing symptoms due to the compression of neighboring structures. We present a patient with a low back pain and left L2 and L3 radiculopathy. Neuroimaging techniques (CT, MRI) showed a large expansive mass in the left lumbar paraspinal area. The tumor was removed totally by the posterior approach and was verified to originate from the left L2 spinal nerve root. The histopathological examination revealed typical findings of a schwannoma. The pain was resolved promptly after the surgery, however the patient's neurological condition wasn't improved. Surgical treatment was a final treatment, and no additonal therapy was necessary.

Successful Identification and Assessment of the Superior Cluneal Nerves with High-Resolution Sonography

BACKGROUND

Low back pain is a disabling and common condition, whose etiology often remains unknown. A suggested, however rarely considered, cause is neuropathy of the medial branch of the superior cluneal nerves (mSCN)-either at the level of the originating roots or at the point where it crosses the iliac crest, where it is ensheathed by an osseo-ligamentous tunnel. Diagnosis and treatment have, to date, been restricted to clinical assessment and blind infiltration with local anesthetics.

OBJECTIVE

To determine whether visualization and assessment of the mSCN with high-resolution ultrasound (HRUS) is feasible.

STUDY DESIGN

Interventional cadaver study and case series.

METHODS

Visualization of the mSCN was assessed in 7 anatomic specimens, and findings were confirmed by HRUS-guided ink marking of the nerve and consecutive dissection. Further, a patient chart and image review was performed of patients assessed at our department with the diagnosis of mSCN neuropathy.

RESULTS

The mSCN could be visualized in 12 of 14 cases in anatomical specimens, as confirmed by dissection. Nine patients were diagnosed with mSCN syndrome of idiopathic or traumatic origin. Diagnosis was confirmed in all of them, with complete resolution of symptoms after HRUS-guided selective nerve block.

LIMITATIONS

These findings are first results that need to be evaluated in a systematic, prospective and controlled manner.

CONCLUSION

We hereby confirm that it is possible to visualize the mSCN in the majority of anatomical specimens. The patients described may indicate a higher incidence of mSCN syndrome than has been recognized. mSCN syndrome should be considered in patients with low back pain of unknown origin, and HRUS may be able to facilitate nerve detection and US-guided nerve block.

High-Resolution Ultrasound for Diagnostic Assessment of the Great Auricular Nerve--Normal and First Pathologic Findings

PURPOSE

The great auricular nerve (GAN) is a sensory branch of the superficial cervical plexus. While its blockade is an established procedure, little is known about the ultrasound appearance of pathologic conditions of the GAN itself. We, therefore, aimed to evaluate the possibility of the visualization and diagnostic assessment of the GAN along its entire course by means of high-resolution ultrasound (HRUS).

MATERIALS AND METHODS

To assess the feasibility of visualization, we performed HRUS with an 18 MHz probe, HRUS-guided, fine-needle ink markings and consecutive dissection in six anatomical specimens. Then, we measured the diameter of the GAN in healthy volunteers and finally performed a retrospective review of patients referred for HRUS examinations because of pain within GAN territory between August 1, 2012 and August 1, 2013.

RESULTS

The GAN was clearly visible with HRUS from its formation to the final branches, and was marked successfully on both sides in all anatomical specimens (n = 12). The mean average in-vivo was 0.14 cm ± 0.03 (range 0.08-0.2). Seven cases of patients with GAN pathologies of various origins (idiopathic, traumatic, tumorous and iatrogenic) were identified, of which 6 were visible on HRUS and all of which could be confirmed by complete resolution of symptoms after selective HRUS-guided GAN block.

CONCLUSION

This study confirms the reliable ability to visualize the GAN with HRUS throughout its course, both in anatomical specimens and in vivo. The provided cases show that pathologies of the GAN seem to have a variety of causes and may not be rare. We, therefore, encourage the use of HRUS in patients with unclear pain in the auricular, periauricular and posterior-lateral head.

ULTRASOUND GUIDED DORSAL RAMUS NERVE BLOCK FOR REDUCTION OF POSTOPERATIVE PAIN IN PATIENTS UNDERGOING LUMBAR SPINE SURGERY: A CASE SERIES IMAGING STUDY

In patients undergoing spine surgery postoperative pain management can often be complicated with side effects associated with high dose narcotic such as respiratory depression and those associated with non-steroidal anti-inflammatory drugs such as interference with bone healing process. Local anesthetics can help in both decreasing postoperative pain and minimizing side effects associated with systematically administered analgesics. This report describes the use of preoperative ultrasound guided dorsal ramus nerve block to reduce postoperative pain in six patients undergoing lumbar spine surgery under general anesthesia.

Ultrasound-guided greater occipital nerve block: an efficient technique in chronic refractory migraine without aura?

BACKGROUND

The effectiveness of greater occipital nerve block (GONB) in patients with primary headache syndromes is controversial. Few studies have been evaluated the usefulness of GONB in patients with migraine without aura (MWOA).

OBJECTIVE

To compare the effectiveness of ultrasound-guided GONB using bupivacaine 0.5% and placebo on clinical improvement in patients with refractory MWOA in a randomized, double-blinded clinical trial.

STUDY DESIGN

A prospective, randomized, placebo-controlled, double-blind pilot trial.

SETTING

Physical medicine and rehabilitation and neurology departments of a University Hospital.

METHODS

Thirty-two patients with a diagnosis of MWOA according to the International Classification of Headache Disorders-II criteria were included in the study. Twenty-three patients (2 men, 21 women) completed the study. They were randomly assigned to receive either GONB with local anesthetic (bupivacaine 0.5% 1.5 mL) or greater occipital nerve (GON) injection with normal saline (0.9% 1.5 mL). Ultrasound-guided GONB was performed to more accurately locate the nerve. All procedures were performed using a 7 - 13 MHz high-resolution linear ultrasound transducer. The treatment group was comprised of 11 patients and the placebo group was comprised of 12 patients. The primary outcome measure was the change in the headache severity score during the one-month post-intervention period. Headache severity was assessed with a visual analogue scale (VAS) from 0 (no pain) to 10 (intense pain).

RESULTS

In both groups, a decrease in headache intensity on the injection side was observed during the first post-injection week and continued until the second week. After the second week, the improvement continued in the treatment group, and the VAS score reached 0.97 at the end of the fourth week. In the placebo group after the second week, the VAS values increased again and nearly reached the pre-injection levels. The decrease in the monthly average pain intensity score on the injected side was statistically significant in the treatment group (P = 0.003), but not in the placebo group (P = 0.110). No statistically significant difference in the monthly average pain intensity score was observed on the uninjected side in either group (treatment group, P = 0.994; placebo group, P = 0.987). No serious side effect was observed after the treatment in either group. Only one patient had a self-limited vaso-vagal syncope during the procedure.

LIMITATIONS

This trial included a relatively small sample. This may have been the result of the inclusion of only those patients who correctly completed their pain diaries. Another major limitation is the short follow-up duration. Patients were followed for one month after the injection, thus relatively long-term effects of the injection have not been observed.

CONCLUSIONS

Ultrasound guided GONB with 1.5 mL of 0.5% bupivacaine for the treatment of migraine patients is a safe, simple, and effective technique without severe adverse effects. To increase the effectiveness of the injection, and to implement the isolated GONB, ultrasonography guidance could be suggested.

The anatomy of the sacrococcygeal cornual region and its clinical relevance

There has been no systematic study of the anatomy of the region between the sacral and coccygeal cornua. Reference texts describe an intercornual ligament connecting these structures. The aim of this study was to investigate the anatomy of this region, which may be relevant to unexplained cases of coccygeal pain (coccydynia) and local nerve blocks. The bony anatomy of the sacrococcygeal (SC) cornual region was analyzed in 33 CT scans obtained from supine adults of mostly European origin with no known SC pathology, 7 μCT scans of cadaver SC specimens, and 105 Asian Indian adult skeletons. A further five cadaver SC specimens were examined histologically. SC cornual fusion was seen in 45% of CT/μCT scans (mean age 67 years, 20 males) and in 20% of adult skeletons (78 males); there was no association with age or sex. In the absence of SC fusion, the mean intersacrococcygeal cornual gap was 7.1 ± 2.4 mm; this was bridged by an intercornual ligament composed of parallel vertical collagen fibers reinforced by elastin fibers on its anterior surface. Small nerve branches were observed adjacent to the ventral aspect of the intercornual ligament and, in one case, traversing the ligament. Ipsilateral sacral and coccygeal cornua are therefore normally bridged by an intercornual ligament that is probably innervated. The cornua are fused on one or both sides in 20-45% of adults. These findings may have implications for some cases of coccydynia and for anesthetists performing local nerve blocks.

Occipital neuromodulation for refractory headache in the Chiari malformation population

Chronic occipital and suboccipital headache is a common symptom in patients with Chiari I malformation (CMI). These headaches may persist despite appropriate surgical treatment of the underlying pathology via suboccipital decompression, duraplasty and related procedures. Occipital stimulation has been shown to be effective in the treatment of a variety of occipital headache/pain syndromes. We present our series of 18 patients with CMI and persistent occipital headaches who underwent occipital neurostimulator trials and, following successful trials, permanent stimulator placement. Seventy-two percent (13/18) of patients had a successful stimulator trial and proceeded to permanent implant. Of those implanted, 11/13 (85%) reported continued pain relief at a mean follow-up of 23 months. Device-related complications requiring additional surgeries occurred in 31% of patients. Occipital neuromodulation may provide significant long-term pain relief in selected CMI patients with persistent occipital pain. Larger and longer-term studies are needed to further define appropriate patient selection criteria as well as to refine the surgical technique to minimize device-related complications.

Occipital nerve stimulation: technical and surgical aspects of implantation

Occipital nerve stimulation may provide pain relief for patients with otherwise refractory primary headache disorders. While this treatment modality remains an off-label use of spinal cord stimulator technology, a growing body of literature documents surgical techniques, stimulation parameters, complications, and outcome of this novel form of neuromodulation. This chapter will review occipital nerve stimulation, including surgical techniques and complications noted in the literature. A discussion of stimulation parameters used for occipital stimulation will be included. Prospective, blinded studies of occipital nerve stimulation may clarify the role of occipital stimulation in chronic headache management.

Overall anatomical features and clinical value of the sacral nerve in high resolution computed tomography reconstruction

BACKGROUND

Sacral nerve injury is a common complication of pelvic or sacral fractures. As the sacral nerve courser within the sacrum and has a complex relationship with the surrounding tissues, different parts of the sacral plexus injury have similar clinical symptoms and signs. Since lack of specific imaging technique in the diagnosis of sacral nerve injury, especially on multi-segment, multi-site, how to determine the preoperative location and extent of the sacral nerve injury accurately becomes a concern of the general orthopaedic and images practitioners. This study was conducted to gain an insight into the overall anatomical features of the sacral nerve (SN) on the same slice in high resolution computed tomography (HRCT) reconstruction and to determine the value of this information for the clinical diagnosis of related diseases.

METHODS

Fifty healthy volunteers and 30 patients (40 sides) with SN lesions confirmed by surgery were scanned using a 16-slice helical CT scanner (Light Speed, GE, USA). Among the patients, 6 with intervertebral disk hernia (6 sides), 8 with spinal stenosis (12 sides), 11 with pelvic trauma (14 sides), 4 with pelvic malignancies (6 sides), and 1 with sacral vertebral tuberculosis (2 sides). The SN multiplanar reconstruction was performed using a UNIX-based SCD4.1 workstation where the image was set on the same slice. All images were stored in the Digital Imaging and Communications in Medicine format. The display of nerves in different sections was analyzed using a five-graded scale with coordinate curves of each individual score. The overall anatomic features visible on the slice were analyzed and the abnormalities of the lesions were studied.

RESULTS

The image of the same slice clearly revealed the shape, running direction, thickness, tension and adjacent anatomy of the S1-S4 nerves. The rank of display rates in different sections was: outward-rotated oblique sagittal > outward-rotated oblique coronal > oblique coronal plane > coronal > sagittal > transverse section. The S5 nerve was partially displayed from the starting point to the segment around the posterior sacral foramen. The overall anatomy of the triangular sacral plexus was only revealed in the oblique outward-rotated sagittal section, while 100% of its individual rami, as well as two or three of the adjacent rami, were displayed from their starting points to the anterior border of the piriformis. The abnormalities included 39 sides of morphological change (97.5%), 38 sides of compression (95.0%), 35 sides of adhesion (87.5%), 32 sides of displacement (80.0%), 34 sides of shrinkage (85.0%), 6 sides of thickening (15.0%), and 2 sides of abruption (5.0%).

CONCLUSIONS

The 16-slice CT multiplanar reconstruction was able to reveal the overall anatomic features of the SN on the same slice. The section of reconstruction was a crucial factor in determining the display capability of various sacral nerves. This technology was valuable in the diagnosis and management of related diseases.

[Compression syndromes in the disc-radicular conflict in patients with intervertebral disc lesion]

One thousand and thirty patients with proved L(5)/S(1)disc herniations were examined. The dynamics of disease in acute stage was studied using ultrasonography and electromyography in 3 groups of patients: 280 with lumboischialgia, 520 with the root syndrome and 230 controls without back pain. It has been shown that edematous epiduritis and venous stas in the superincumbent spinal movement segment is a main pathogenetic mechanism of acute phase of the disc-radicular conflict. Focal myelopathy is a pathogenetic mechanism of radiculopathy in the disc-recticular conflict. Compression and reflex syndromes are caused by the common mechanisms and their differentiation by clinical presentations has a conditional character.

Removal of an iliosacral screw entrapping the L5 nerve root after failed posterior pelvic ring fixation: a case report

We present a case of a pelvic ring fracture that was originally treated with anterior symphyseal plating and a misplaced percutaneous iliosacral screw. The anterior extraosseus portion of the misplaced 7.3-mm cannulated screw irritated the L5 nerve root, resulting in a radiculopathy. Subsequent surgery involved and mandated removing the bent screw after open identification and protection of the L5 nerve root to avoid further nerve damage; the sacroiliac joint was subsequently debrided and fused. This case represents a complication of acute percutaneous iliosacral screw fixation of pelvic ring injuries and the subsequent strategy for successful salvage.

The effect of posterior bridging of C-1 on craniovertebral junction surgery

Object

The groove for the vertebral artery (VA) may be bridged on C-1, forming a canal through which the artery passes. Because this variant may significantly affect the commonly performed C-1 posterior laminectomy, the authors studied the incidence and radiological appearance of this anatomical feature in surgical specimens.

Methods

Anatomical measurements were performed using a Vernier caliper (accurate to 0.1 mm) on 166 dry C-1 vertebrae. In addition, a convenience sample of 172 cervical x-ray films was evaluated. Partial osseous bridging was detected in eight (4.8%), and a complete osseous bridge, forming the canalis arteriae vertebralis (canal for the VA), was seen unilaterally (eight on the left and two on the right) in 10 (6%) and bilaterally in eight (4.8%) of the dry vertebrae. On lateral radiography, a complete bone bridge was observed on nine (5.2%) and a partial bridge on 10 (5.8%) of the 172 studies.

Conclusions

The discovery of a common variant may necessitate an immediate change in surgical management, and this anomaly could even increase the rate of surgery-related complications. The VA canal, present in the C-1 vertebra in approximately 5% of the specimens evaluated, was a variant that may be protective against VA injury. Knowledge of this variant may help the surgeon undertaking procedures in the C-1 region.

Symptomatic cervical disc herniation in a pediatric Klippel-Feil patient: the risk of neural injury associated with extensive congenitally fused vertebrae and a hypermobile segment

STUDY DESIGN

A case report.

OBJECTIVE

To report the occurrence of a herniated cervical disc following a high-impact activity in a pediatric Klippel-Feil patient who presented with spinal cord compression, myelopathy, and myelomalacia requiring posterior instrumented fusion followed by an anterior discectomy and fusion at the hypermobile nonfused segment.

SUMMARY OF BACKGROUND DATA

The primary hallmark of Klippel-Feil syndrome (KFS) is the presence of at least one congenitally fused cervical segment. Studies have reported the potential risk of cervical injury from hypermobility associated with the nonfused cervical segment in KFS. The manifestation of a cervical disc herniation in the pediatric KFS patient is rare. To the authors' knowledge, the development of a symptomatic cervical herniated disc attributed to mechanical fatigue following a high-impact activity has not been addressed in the literature with respect to the pediatric KFS patient having extensive cervical fusion and a hypermobile segment.

METHODS

A 16.8-year-old KFS boy with occipitalization of C1 and fusion of C2-C3 and C4-T1 presented with myelopathy, severe cord compression, and myelomalacia stemming from a left-sided herniated cervical disc at C3-C4 with onset following an 8-foot high rooftop jump. On radiographic evaluation, the patient's C3-C4 segment was hypermobile.

RESULTS

The patient was operatively managed via a same-day combined posterior-anterior procedure. The posterior aspect of the procedure entailed a posterior lateral mass plate-screw fixation at C3-C4 with autologous iliac crest bone fusion. Anteriorly, a discectomy was performed at C3-C4 with application of an interbody tricortical autograft. After surgery, the patient wore a halo vest for 3 months, followed by a soft collar for an additional 3 months. On final follow-up at 39 months, the patient was asymptomatic with no instrumentation-related complications, fusion of the posterior graft-bed and anterior interbody graft was noted, and cervical alignment was maintained.

CONCLUSIONS

A hypermobile segment in the pediatric KFS patient is a risk factor that may lead to cord compression. A symptomatic herniated cervical disc may develop from an excessive mechanical load stress in a pediatric KFS patient with multiple fused segments. In such a patient, a same-day combined posterior-anterior procedure provides cord decompression and stabilizes the spine with a favorable outcome.

Microendoscopic partial resection of the sacral ala to relieve extraforaminal entrapment of the L-5 spinal nerve at the lumbosacral tunnel

✓ The authors report the cases of three patients with L-5 radiculopathy caused by extraforaminal entrapment of the L-5 spinal nerve at the lumbosacral tunnel; this structure comprises the lumbosacral ligament, the sacral ala, and the L-5 and S-1 vertebral bodies. All three patients suffered severe leg pain and neurological deficits compatible with L-5 radiculopathy. Decompressive surgery involved the microendoscopic partial resection of the sacral ala along the L-5 spinal nerve. All patients experienced immediate pain relief postoperatively. Microendoscopic partial resection of the sacral ala is an effective and minimally invasive surgical option for patients with extraforaminal entrapment of the L-5 spinal nerve.

Sonographic visualization and ultrasound-guided block of the third occipital nerve: prospective for a new method to diagnose C2-C3 zygapophysial joint pain

BACKGROUND

Chronic neck pain after whiplash injury is caused by cervical zygapophysial joints in 50% of patients. Diagnostic blocks of nerves supplying the joints are performed using fluoroscopy. The authors' hypothesis was that the third occipital nerve can be visualized and blocked with use of an ultrasound-guided technique.

METHODS

In 14 volunteers, the authors placed a needle ultrasound-guided to the third occipital nerve on both sides of the neck. They punctured caudal and perpendicular to the 14-MHz transducer. In 11 volunteers, 0.9 ml of either local anesthetic or normal saline was applied in a randomized, double-blind, crossover manner. Anesthesia was controlled in the corresponding skin area by pinprick and cold testing. The position of the needle was controlled by fluoroscopy.

RESULTS

The third occipital nerve could be visualized in all subjects and showed a median diameter of 2.0 mm. Anesthesia was missing after local anesthetic in only one case. There was neither anesthesia nor hyposensitivity after any of the saline injections. The C2-C3 joint, in a transversal plane visualized as a convex density, was identified correctly by ultrasound in 27 of 28 cases, and 23 needles were placed correctly into the target zone.

CONCLUSIONS

The third occipital nerve can be visualized and blocked with use of an ultrasound-guided technique. The needles were positioned accurately in 82% of cases as confirmed by fluoroscopy; the nerve was blocked in 90% of cases. Because ultrasound is the only available technique today to visualize this nerve, it seems to be a promising new method for block guidance instead of fluoroscopy.

[Three-dimensional construction of the relation between the anterior branches of lumbar nerves 4, 5, lumbosacral trunk and sacroiliac joint]

OBJECTIVE

To construct a three-dimensional model to demonstrate the relation between the anterior branches of lumbosacral 4,5, lumbosacral trunk, and the pelvis.

METHODS

An formaldehyde-fixed adult cadaver was dissected to expose the anterior branches of the lumbar nerves 4 and 5, lumbosacral trunk and the sacroiliac. The mixture of titanium powder and adhesive was smeared on the surface of the major branches of L4 and L5 nerves, lumbosacral trunk, femoral nerves and obturator nerves. As soon as the mixture solidified, the specimen was scanned by spiral CT at 3 mm intervals to obtain 159 two-dimensional sectional images for three-dimensional model reconstruction on a personal computer using the software 3-D DOCTOR.

RESULTS AND CONCLUSION

The reconstructed model can well demonstrate the spatial relation between the nerves and the pelvis, and allows rotation in every direction, which at the same time can be conveniently applied for purpose of clinical teaching.

Thoracic Paravertebral Block for Percutaneous Transhepatic Biliary Drainage

Percutaneous transhepatic biliary drainage is a painful procedure most commonly performed after intravenous sedation. Despite systemic opiates and benzodiazepines, most patients experience significant pain during the procedure and in the recovery period. Paravertebral blocks allow the spinal nerve roots and sympathetic chain in the paravertebral space to be anesthetized, and their role in providing analgesia for thoracic and upper abdominal surgical procedures is well-established. Herein a case is described in which thoracic paravertebral blockade dramatically reduced standard intra- and postprocedural analgesic needs and provided superior pain control.

The posterior lumbar ramus: CT-anatomic correlation and propositions of new sites of infiltration

BACKGROUND AND PURPOSE

Lumbar zypapophyseal joints are innervated by the medial branch of the posterior lumbar ramus. The aim of this work was to describe the precise course of the medial ramus on axial CT scans and to define a precise location for its selective infiltration.

METHODS

Lumbar spines of two cadavers were first dissected to assess the route of the L1-L5 posterior ramus. Thirty lumbar spinal nerves of three cadavers were injected in the epineural space with a mixture of iodine contrast and stain to perform a correlation between anatomic gross sections and CT sections in the axial plane. A histologic study was also performed to ensure the neurologic nature of the structure identified.

RESULTS

The fibroosseous canal located between the mamillary and the accessory processes was a constant pathway for the medial branch of the L1-L4 posterior ramus. This former was always located closer to the accessory process. The L5 posterior ramus and its divisions could also be identified into a groove bounded laterally by the ala of the sacrum and medially by the base of the superior articular process of S1.

CONCLUSION

The accessory process and the groove bounded laterally by the ala of the sacrum and medially by the base of the superior articular process of S1 can be easily depicted on CT images and may allow a precise and selective infiltration of the medial branch of the posterior lumbar ramus.

Characterization of Hemangioblastomas of Spinal Nerves

OBJECTIVE:

Hemangioblastoma is classified as a benign tumor of the central nervous system. Peripheral nervous system hemangioblastomas to date have been described only in a few case reports. Experience in treating patients with these rare lesions, which harbor diagnostic and therapeutic pitfalls, is limited.

METHODS:

To characterize these lesions better, we reviewed our hemangioblastoma database for patients who underwent surgery for extradural hemangioblastoma of the spinal nerve.

RESULTS:

Between 1983 and 2003, six patients underwent surgery for spinal nerve hemangioblastomas at our institution. These tumors occurred in 2% of all patients with hemangioblastomas of the central nervous system, or 6% of all patients with spinal hemangioblastomas. The occurrence did not differ in von Hippel-Lindau disease cases versus sporadic cases. Radiographically, the tumors easily could be mistaken for schwannomas or metastases; however, they did have some typical features. If a hemangioblastoma was not suspected primarily, profuse bleeding could complicate surgery. Most of the tumors arose from the dorsal sensory fascicles. The vascular supply was from extradural circulation. In general, the surgical outcome of these lesions was good, and permanent neurological deficit was rare. However, local recurrence was observed in three of six patients.

CONCLUSION:

These tumors harbor diagnostic and therapeutic pitfalls. In general, the tumors are surgically more challenging, and clinically significant bleeding as well as local tumor recurrence is more common than in intradural hemangioblastomas, mostly because of the frequency of incorrect initial radiographic diagnosis. We suggest that because of the surgical consequences, hemangioblastoma should always be considered to be an important radiological differential diagnosis for nerve sheath tumors. Angiography can bring clarification to ambiguous cases.

Real-time sonographic imaging for periradicular injections in the lumbar spine: a sonographic anatomic study of a new technique

OBJECTIVE

We conducted this study to develop a sonographically guided approach to the spinal nerve of the lumbar spine and to assess its feasibility and accuracy by means of computed tomography (CT).

METHODS

Fifty sonographically guided approaches at 5 levels (L1-S1) were performed on 5 embalmed cadavers, which were positioned prone. The spinal nerves of the lumbar spine were shown under sonographic guidance. In 1 cadaver, the most lateral aspect of the roof of the intervertebral foramen was defined as a reference point. Its position was computed as a distance from the tip of the spinal process (A), the midline (B), and the intervertebral disk (C). Subsequently, axial transverse CT scans were made to verify these distances. In a second part of the experiment, a spinal needle was advanced under sonographic guidance to the spinal nerves for each lumbar spinal level on 1 embalmed cadaver. The exact placement of the needle tips was checked with the help of CT.

RESULTS

This technique for a sonographically guided approach to the periradicular area proved to be feasible and accurate. Sonography and CT provided the same mean measurements of 4.0, 2.5, and 1.4 cm for distances A, B, and C, respectively. The Pearson correlation coefficient was 0.99 (P < .001) between sonography and CT. In the experimental study, all 10 needle tips were placed periradicular to the spinal nerves.

CONCLUSIONS

Sonographic guidance is a useful adjunct to increase the safety and efficacy of periradicular injections in the lumbar spine.

Ultrasound-guided lumbar facet nerve block: a sonoanatomic study of a new methodologic approach

BACKGROUND

Lumbar facet nerve (medial branch) block for pain relief in facet syndrome is currently performed under fluoroscopic or computed tomography scan guidance. In this three-part study, the authors developed a new ultrasound-guided methodology, described the necessary landmarks and views, assessed ultrasound-derived distances, and tested the clinical feasibility.

METHODS

(1) A paravertebral cross-axis view and long-axis view were defined under high-resolution ultrasound (15 MHz). Three needles were guided to the target point at L3-L5 in a fresh, nonembalmed cadaver under ultrasound (2-6 MHz) and were subsequently traced by means of dissection. (2) The lumbar regions of 20 volunteers (9 women, 11 men; median age, 36 yr [23-67 yr]; median body mass index, 23 kg/m2 [19-36 kg/m2]) were studied with ultrasound (3.5 MHz) to assess visibility of landmarks and relevant distances at L3-L5 in a total of 240 views. (3) Twenty-eight ultrasound-guided blocks were performed in five patients (two women, three men; median age, 51 yr [31-68 yr]) and controlled under fluoroscopy.

RESULTS

In the cadaver, needle positions were correct as revealed by dissection at all three levels. In the volunteers, ultrasound landmarks were delineated as good in 19 and of sufficient quality in one (body mass index, 36 kg/m2). Skin-target distances increased from L3 to L5, reaching statistical significance (*, **P < 0.05) between these levels on both sides: L3r, 45+/-6 mm*; L4r, 48+/-7 mm; L5r, 50+/-6 mm*; L3l, 44+/-5 mm**; L4l, 47+/-6 mm; L5l, 50+/-6 mm**. In patients, 25 of 28 ultrasound-guided needles were placed accurately, with the remaining three closer than 5 mm to the radiologically defined target point.

CONCLUSION

Ultrasound guidance seems to be a promising new technique with clinical relevance and the potential to increase practicability while avoiding radiation in lumbar facet nerve block.

Extraforaminal entrapment of the fifth lumbar spinal nerve by osteophytes of the lumbosacral spine: anatomic study and a report of four cases

STUDY DESIGN

An anatomic study of the associations between the fifth lumbar spinal nerve (L5 spinal nerve) and a lumbosacral tunnel, consisting of the fifth lumbar vertebral body (L5 vertebral body), the lumbosacral ligament, and sacral ala, and clinical case reports of four patients with lumbar radiculopathy secondary to entrapment of the L5 spinal nerve in the lumbosacral tunnel.

OBJECTIVES

To delineate the anatomic, clinical, and radiologic features and surgical outcome of patients with entrapment of the L5 spinal nerve in the lumbosacral tunnel.

SUMMARY OF BACKGROUND DATA

Although several cadaveric studies on a lumbosacral tunnel as a possible cause of L5 radiculopathy have been reported, few studies had focused on osteophytes of the L5-S1 vertebral bodies as the major component of this compressive lesion, and clinical reports on patients with this disease have been rare.

METHODS

Lumbosacral spines from 29 geriatric cadavers were examined with special attention to the associations between osteophytes of the L5-S1 vertebral bodies and the L5 spinal nerve. Four patients with a diagnosis of the entrapment of the L5 spinal nerve by osteophytes at the lumbosacral tunnel were treated surgically, and their clinical manifestations and surgical results were reviewed retrospectively.

RESULTS

The anatomic study demonstrated osteophytes of the L5-S1 vertebral bodies in seven of the 29 cadavers. Entrapment of the L5 spinal nerve in the lumbosacral tunnel was observed in six of the seven cadavers with L5-S1 osteophytes but in only one of the 22 cadavers without such osteophytes (P < 0.05, chi2 test). All four patients had neurologic deficits in the L5 nerve root distribution. MRI and myelography showed no abnormal findings in the spinal canal, but CAT scans demonstrated prominent osteophytes on the lateral margins of L5-S1 vertebral bodies in all four. Selective L5 nerve block completely relieved all patients of pain but only temporarily. Three patients were treated via a posterior approach by resecting the sacral ala along the L5 spinal nerve, and the other patient was treated by laparoscopic anterior resection of the osteophytes. Pain relief was obtained in the four patients immediately after surgery, but one patient experienced recurrence of pain 1 year after the first surgery and was successfully treated by additional posterior decompression and fusion.

CONCLUSIONS

Extraforaminal entrapment of L5 spinal nerve in the lumbosacral tunnel can cause L5 radiculopathy, and osteophytes of L5-S1 vertebral bodies are a major cause of the entrapment.

Migration of pacemaker lead into the spinal venous plexus: case report with special reference to Batson's theory of spinal metastasis

OBJECTIVE AND IMPORTANCE

Migration of a foreign material via venous routes into the spinal canal is a very rare incidence. We report the second case in which a foreign body has migrated into the spinal canal via the venous route.

CLINICAL PRESENTATION

This 35-years-old man presented with sudden onset of severe low back pain and pain in the right leg four months after an unsuccessful attempt to remove a disconnected cardiac pacemaker lead via the femoral vein. Direct lumbar x-ray demonstrated the broken lead of the cardiac pacemaker at the entrance of the right L5 foramen which was also demonstrated by lumbar CT. SURGICAL INTERVENTION: After right L5 hemilaminotomy, the pacemaker lead was found in a vein of the anterior spinal venous plexus just beneath and lateral to the right L5 root. After dissecting it from the surrounding adipose tissue, the embolised pacemaker lead was taken out.

CONCLUSION

We present a case report and review of the literature on migration of foreign material into the spinal canal, factors effecting the flow directions in the spinal veins. This case may be the first evidence that proved Batson's theory of spinal metastases in man.

Fibrous adhesive entrapment of lumbosacral nerve roots as a cause of sciatica

STUDY DESIGN

Report of seven patients with fibrous adhesive entrapment of lumbosacral nerve roots as a cause of sciatica, whose radiographic findings were negative and who experienced relief from sciatica immediately after the entrapment was released.

OBJECTIVES

To describe a new clinical entity of fibrous adhesive entrapment of lumbosacral nerve roots with negative radiographic findings.

SETTING

Orthopaedic department, Japan.

METHODS

Clinical evaluation and post-operative outcome in seven patients with entrapment of lumbosacral nerve roots because of fibrous adhesion confirmed intraoperatively.

RESULTS

Radiographic examinations by magnetic resonance imaging (MRI), myelography, and computed tomographic (CT) myelography demonstrated neither disc herniations nor spinal stenosis in all seven patients, and differential nerve root block was effective for relieving sciatica and low back pain. We confirmed, intraoperatively, entrapment of the nerve root by fibrous adhesion, and all seven patients were relieved from sciatica and low back pain postoperatively.

CONCLUSION

This study presented seven patients with sciatica caused by fibrous adhesive entrapment of lumbosacral nerve roots who underwent decompression and release of fibrous adhesion. Radiographic examinations, such as MRI, myelography and CT myelography, showed no compressive shadows and also differential nerve root block was effective for its diagnosis. This study seems to be the first report of patients with entrapment of lumbosacral nerve roots caused by fibrous adhesion, whose radiographic findings were negative.

Sonographic measurement of needle insertion depth in paravertebral blocks in women

Single-injection paravertebral block offers adequate unilateral analgesia for thoracic and upper abdominal surgery. This technique is easy to learn but there is a risk, albeit low, of pleural puncture. The aim of the study was to determine whether sonographic measurements of the distances from the skin to the transverse process and to the parietal pleura are useful for calculating the required depth of needle insertion. Before puncture of the paravertebral space, the distances from the skin to the transverse process and to the parietal pleura were measured by sonography. The deviation of the needle from the horizontal plane was measured and an angle correction for the insertion depth was calculated. Twenty-two women undergoing elective unilateral breast surgery were studied. Sonographic visualization of the transverse process and the parietal pleura and measurement of their distances from the skin was successful in all women. Puncture of the paravertebral space failed in one obese woman. There was a very close correlation between needle insertion depth from the skin to the transverse process and the distance measured by ultrasound if angle correction was used (adjusted r2=0.95). Similarly, there was excellent correlation between the angle-corrected ultrasound distance from the skin to the parietal pleura and the distance from the skin to the paravertebral space (adjusted r2=0.92).

Specificity of lumbar medial branch and L5 dorsal ramus blocks. A computed tomography study

STUDY DESIGN

A cross-sectional study.

OBJECTIVES

To determine the face validity of lumbar medial branch blocks.

SUMMARY OF BACKGROUND DATA

Lumbar medial branch blocks have been used increasingly to diagnose zygapophysial joint pain. The course and relations of the medial branches of the dorsal rami have been demonstrated in previous anatomic studies. What is not known is whether blocks of the medial branches anesthetize these nerves exclusively or whether they anesthetize other structures that are potential sources of pain.

METHODS

In a cadaveric study, the branches of the dorsal rami were exposed. Spinal needles were placed over the nerves, and plain radiographs were taken to demonstrate the precise radiographic locations of the nerves. In the second phase of the study, healthy volunteers underwent injections of radiographic contrast over the nerves, and plain radiographs and computed tomographic images were taken. Injections were performed using different rates of injection and in two positions for each nerve.

RESULTS

Radiographic contrast incorporated the medial branches of the dorsal rami in every injection. When injections were performed using the upper position, aberrant flow of contrast medium was demonstrated with extension into the epidural space or intervertebral foramina. When a position lower on the transverse process was selected, aberrant flow was very uncommon. Eight percent of injections were found to be intravenous.

CONCLUSIONS

When the appropriate technique is used, medial branch blocks are target specific. To guard against false-negative responses due to intravenous up-take, contrast medium must be used before the injection of local anaesthetic.

Anterior decompression of foraminal stenosis below a lumbosacral transitional vertebra. A case report

STUDY DESIGN

A case of unilateral far-out foraminal entrapment of the L5 spinal nerve below a transitional vertebra is presented with a review of the literature.

OBJECTIVES

To describe management of a rare far-out foraminal stenosis below a transitional vertebra and to evaluate the surgical procedure and results.

SUMMARY OF BACKGROUND DATA

Far-out foraminal stenosis with radiculopathy caused by bony spur formation secondary to anomalous articulation between the transverse process and the sacral ala is rarely reported. Decompression at this point traditionally has been performed through a posterior approach, similar to that performed for the far-out syndrome. There are no previous reports describing anterior decompression through an extraperitoneal approach.

METHODS

The diagnosis was confirmed by computed tomography, magnetic resonance imaging, and selective radiculography. Anterior decompression was performed by resecting the bony spur using a wide muscle-splitting extraperitoneal approach.

RESULTS

Anterior decompression was performed with minimal intervention to the spine and the trunk muscles. Good relief of low back pain and sciatica was obtained.

CONCLUSIONS

Selective radiculography was the method of examination with the optimal diagnostic value for far-out foraminal stenosis. An anterior approach to the decompression of far-out foraminal stenosis below a lumbosacral transitional vertebra is a relatively simple and effective method.

[Three-dimensional recons-truction of lumbar-sacral canal and its contents: experimental study]

In order to suit the needs of studies in spinal column surgery on three-dimensional spatial structure and morphology of lumbar-sacral canal and the nervous tissue within it, an experimental model was applied by the authors using lumbosacral specimens from two fresh young adult cadavers. Successive 2mm thick CTM screening was carried out from L3 to S2 vertebral bodies with an interval of 1mm. The serial two-dimensional CT photographical pictures so obtained were inputted into a computer and the three-dimensional images were reconstructed through a VIDAS image analysis system. The experimental results indicated that the three-dimensional images of reconstructed vertebral canal and the nervous tissue within it were lifelike. These images could not only reveal their three-dimensional structure and morphology, but also be cut and composed together at any direction and section by turning and transpositioning along X, Y and Z axes. The authors hold that the visual effect expressed by three-dimensional images reconstructed from two-dimensional pictures can play important role in stereomorphologic, biomechanical, and other studies in fields of anatomy, image analysis, and clinical medicine.

Neural arch tuberculosis: a morbid disease. Radiographic and computed tomographic findings

We have reviewed the clinical features, together with the radiographs and computerised tomography, in 9 patients with tuberculosis of the vertebral body and neural arch. All presented with paraparesis or paraplegia. The morbidity associated with this disease is so serious that it is essential to have an accurate means of evaluating the lesion as early as possible. Routine radiographs can only indicate the level of the disease and the loss of disc space, but cannot define the full extent of the lesion. Computed tomography shows details of the tuberculous involvement of the neural arch, as well as the vertebral body and spinal canal; the site and extent of the soft tissue lesions can also be seen. This is essential for evaluation of the neural arch involvement which will enable the clinician to select the appropriate treatment, and so prevent neurological complications.

Evaluation of cervical diskography in pain origin and provocation

The purpose of this article is to analyze the role of cervical diskography as a diagnostic method via reproduced pain. A nonionic contrast medium (Iohexol) that does not harm normal tissue was used in this series to prevent false-positive provocative pain. One hundred forty-four patients (128 with cervical spondylotic myelopathy, eight with cervical spondylotic radiculopathy, and eight with cervical spondylotic amyotrophy) were studied. Among 72 patients in the symptomatic neck pain group who complained of neck pain before diskography, 65% showed reproduced pain. However, in the control group (neurologic symptoms only) 50% of the patients complained of provocative neck pain during dye injection. These results demonstrated that this provocation technique appeared unreliable for diagnosing symptomatic disk levels.

Evoked spinal cord potentials for diagnosis during brachial plexus surgery

We used evoked spinal cord potentials (ESCP) for intraoperative diagnosis in 17 cases of traumatic brachial plexus palsy. Forty spinal nerves were directly stimulated during exploration of the brachial plexus and ESCP recorded from the cervical epidural space were compared with simultaneously observed somatosensory evoked potentials (SEP) and myelographic findings. Both SEP and ESCP could be evoked in 21 spinal nerves but ESCP were always more distinct and five to ten times greater in amplitude than SEP. In four nerves, ESCP but no SEP were produced, suggesting that there was continuity from the nerves to the spinal cord. ESCP were obtained from two spinal nerves which appeared to be abnormal on the myelogram. The results show that intraoperative electrodiagnosis by epidural ESCP recordings can provide useful information on the lesions of traumatic brachial plexus palsy.

Proximal lumbar spinal nerves in axial MR imaging, CT, and anatomic sections

The proximal lumbar spinal nerve is composed of a group of small fascicles interspersed with fat. These fascicles converge into the ventral ramus. The authors studied the appearance of this portion of the spinal nerve through analysis of magnetic resonance (MR) images, computed tomographic (CT) scans, and exactly corresponding anatomic sections in cadavers. The fascicles can be identified at MR imaging or CT as poorly defined structures surrounded by the fat lateral to the neural foramen. The ventral ramus appears as a pair of oval, contiguous, small homogeneous structures. The evaluation of nerve compression may be aided by identification of the fascicles and ventral rami on CT and MR images.

Contralateral trigeminal dysaesthesias associated with second cervical nerve compression: a case report

This 70-year-old woman presented with a left C2 solitary metastatic lesion producing ipsilateral occipital pain associated with contralateral fronto-orbital dysaesthesias. Examination revealed analgesia in the left C2 dermatome and hyperaesthesia in the right forehead. These symptoms and findings resolved following a course of radiation therapy to the C2 metastasis. Ipsilateral trigeminal dysaesthesias produced by cervical lesions have been described, however, contralateral cervicogenic trigeminal dysaesthesias have not. Relevant experimental data are analysed; neural pathways are suggested by which a cervical lesion, especially at C2 or C3, may produce trigeminal dysaesthesias referred ipsilaterally or contralaterally.

Dimensions of the spinal canal in individuals symptomatic and non-symptomatic for sciatica: a CT study

Measurements obtained in 50 spinal CT studies of patients referred for suspected lumbo-sacral nerve root compression, were compared to those of a group of 30 individuals asymptomatic in this respect, who had been referred for abdominal pathology. Transverse ligamentous interfacet and transverse dural dimensions were significantly reduced in the sciatica group, with usually normal interpedicular and sagittal dimensions ruling out idiopathic developmental stenosis. The borderline value for ligamentous interfacet distance (ILD) at L4-5 appeared to be 11 mm.