Lumbar spinal stenosis: Assessment of cauda equina involvement by electrophysiological recordings

Electrodiagnostic testing in dogs with disorders of the spinal cord or cauda equina

Electrodiagnostic (EDX) testing is uncommonly utilized in dogs other than for investigation of disorders of the neuromuscular system. In dogs with diseases affecting the spinal cord or cauda equina, EDX testing can provide functional data complementary to imaging information that together can guide therapeutic and management approaches. Additionally, in some clinical scenarios, EDX testing prior to advanced imaging is integral to identifying if there is spinal cord or cauda equina involvement and can aid in determining the appropriate diagnostic path. This review will outline EDX testing methods that have been reported in dogs relating to the diagnosis, monitoring or prognosis of various conditions affecting the spinal cord and cauda equina. The various tests will be briefly outlined regarding how they are performed and what information is provided. The main focus will be on clinical applications including highlighting situations where EDX testing is useful for differentiating between neurologic and non-neurologic presentations. Additional ways these EDX techniques could be incorporated in the management of diseases of the spinal cord and cauda equina in dogs will be presented.

Tibial nerve SEPs in diagnosing lumbar spinal stenosis: The utility of segmental evaluation using P15 and N21

Objective

To establish the utility of the additional evaluation of the P15 potential generated at the greater sciatic foramen in the tibial nerve somatosensory evoked potentials (SEPs) in diagnosing lumbar spinal stenosis (LSS).

Methods

We retrospectively reviewed tibial nerve SEP findings in patients having MRI-confirmed LSS at the cauda equina or conus/epiconus region. P15 and N21 potentials were recorded and the following findings were defined as localizing abnormalities: 1) normal P15 latency either with prolonged P15-N21 interval or with absent N21; 2) decreased ratio of the N21 amplitude to P15 amplitude. As non-localizing abnormalities, N21 and P38 latencies were also evaluated. Tibial nerve F-wave findings were also investigated.

Results

According to the entry criteria, 18 patients were included, 15 with cauda equina lesions and 3 with conus/epiconus lesions. Localizing abnormalities in SEPs were found in 67% of patients, achieving significantly higher sensitivity than delayed P38 latency (28%), and higher sensitivity than N21 abnormalities (39%), though this was not significant. Localizing abnormalities were observed even in 6 out of 11 patients lacking both sensory symptoms and signs. Tibial nerve F-wave was abnormal in 36% of 14 patients with F-wave examinations, whereas the localizing abnormalities in SEPs were found in 64% of the same patient population. P15 amplitude was depressed in 4 patients (22%), which may indicate the involvement of the dorsal root ganglion in LSS, although its latency was normal even for these patients.

Conclusions

Tibial nerve SEPs with the recording of P15 and N21 potentials achieved sufficiently high sensitivity in diagnosing LSS. They have the advantage over F-wave in that they can localize the lesion at the cauda equina or conus/epiconus level.

Significance

Tibial nerve SEPs are promising in evaluating LSS, especially in documenting sensory tract involvement in cases lacking sensory symptoms/signs.

Findings of Electrodiagnostic Studies in Moderate to Severe Lumbar Central Spinal Stenosis-Electrodiagnostic Studies in Lumbar Central Spinal Stenosis

Purpose: The purpose of this study was to investigate the findings of electrodiagnostic studies (nerve conduction study (NCS) and electromyography (EMG)) in patients with moderate and severe lumbar central spinal stenosis (LCSS). Methods: We retrospectively reviewed the medical records of Ulsan University Hospital and identified 32 consecutive patients (mean age = 66.9 ± 7.4 years; male:female = 8:24) with LCSS. Based on the results of T2 axial magnetic resonance imaging at the level of L4–5, patients were categorized as having severe (n = 14) or moderate LCSS (n = 18). Results from NCS and EMG were retrieved. Additionally, we included 15 age- and sex-matched volunteers without LCSS (mean age = 65.2 ± 8.0 years; male:female = 4:11) to serve as a control group. Results of NCS and EMG were compared between the three groups. Results: We found that, compared to normal subjects, patients with moderate or severe LCSS presented significantly lower distal amplitudes of the compound motor action potential of both peroneal and tibial nerves. Regarding EMG, positive sharp waves and fibrillation potentials were exclusively observed in patients with severe LCSS group (28.6%). Conclusion: Electrodiagnostic studies were significantly altered in patients with moderate and severe LCSS. Our results may be helpful to diagnose LCSS-induced radiculopathy and to differentiate it from other causes of peripheral nerve pathologies.

Association Between Latency of Dermatomal Sensory-Evoked Potentials and Quantitative Radiologic Findings of Narrowing in Lumbar Spinal Stenosis

OBJECTIVE

To identify the difference of quantitative radiologic stenosis between a normal latency group and an abnormal latency group, and to investigate the association of dermatomal somatosensory-evoked potential (DSEP) with magnetic resonance imaging (MRI) findings of narrowing in patients with lumbar spinal stenosis (LSS).

METHODS

We retrospectively reviewed the clinical records and P40 latencies of L5 DSEP of 40 patients with unilateral symptoms of LSS at the L4-5 disc level. Quantitative assessments of stenosis in lumbar spine MRI were performed with measurements of the anteroposterior diameter (APD), cross-sectional area (CSA) of the dural sac, ligamentous interfacet distance (LID), CSA of the neural foramen (CSA-NF), and subarticular zone width. Analyses were conducted through comparisons of radiologic severity between the normal and abnormal latency groups and correlation between radiologic severity of stenosis and latency of DSEP in absolute (APD <10 mm) and relative (APD <13 mm) stenosis.

RESULTS

The radiologic severities of lumbar stenosis were not significantly different between the normal and abnormal latency groups. In absolute and relative stenosis, latency showed a significant negative correlation with APD (r=-0.539, r=-0.426) and LID (r=-0.459, r=-0.494). In patients with relative stenosis, a weak significant positive correlation was found between latency and CSA-NF (r=0.371, p=0.048). LID was the only significant factor for latency (β=-0.930, p=0.011).

CONCLUSION

The normal and abnormal DSEP groups showed no significant differences inradiologic severity. The latency of DSEP had a negative correlation with the severity of central stenosis, and LID was an influencing factor.

Can the severity of central lumbar stenosis affect the results of nerve conduction study?

To evaluate the effect of the severity of spinal stenosis on the peripheral nerves of lower extremities by nerve conduction study (NCS).One hundred fifteen patients with lumbar spinal stenosis were recruited retrospectively in this study. The grading system for lumbar stenosis was used based on the degree of separation of the cauda equina. The degree of cauda equina damage caused by lumbar central stenosis was assessed by NCS of peripheral nerves. Multiple regression analysis was used to estimate which factors affect peripheral nerve injury, according to the presence of DM, total grading of lumbar central stenosis, and age.Only age was associated with low amplitude in the tibial and peroneal motor NCS in the multiple regression analysis. The severity of the compression of the cauda equina, caused by spinal stenosis, did not statistically significantly affect the NCS values of nerves on the lower extremities.In conclusion, the cauda equina is resilient against degenerative lumbar central stenosis. Unlike changes caused by peripheral nerve entrapment, lumbar central stenosis did not affect the findings of NCS on the peripheral nerve of lower extremities.

Natural Course and Diagnosis of Lumbar Spinal Stenosis: WFNS Spine Committee Recommendations

Lumbar spinal stenosis (LSS) is defined as a degenerative disorder showing a narrowing of the spinal canal. The diagnosis is straightforward in cases with typical neurogenic claudication symptoms and unequivocal imaging findings. However, not all patients present with typical symptoms, and there is obviously no correlation between the severity of stenosis and clinical complaint. The radiologic diagnosis of LSS is widely discussed in the literature. The best diagnostic test for the diagnosis of LSS is magnetic resonance imaging (MRI). However, canal diameter measurements have not gained much consensus from radiologists, whereas qualitative measures, such as cerebrospinal fluid space obliteration, have achieved greater consensus. Instability can best be defined by standing lateral radiograms and flexion-extension radiograms. For cases showing typical neurogenic claudication symptoms and unequivocal imaging findings, the diagnosis is straightforward. However, not all patients present with typical symptoms, and there is obviously no correlation between the severity of stenosis (computed tomography and MRI) and clinical complaint. In fact, recent MRI studies have shown that mild-to-moderate stenosis can also be found in asymptomatic individuals. Routine electrophysiological tests such as lower extremity electromyography, nerve conduction studies, F-wave, and H-reflex are not helpful in the diagnosis and outcome prediction of LSS. The electrophysiological recordings are complementary to the neurologic examination and can provide confirmatory information in less obvious clinical complaints. However, in the absence of reliable evidence, imaging studies should be considered as a first-line diagnostic test in the diagnosis of degenerative LSS.

[Classification and diagnosis of lumbar spinal stenosis]

BACKGROUND

Lumbar spinal stenosis is caused by various pathological conditions. With the diagnostic tools available, a precise classification of the condition should be made, which enables a consistent and appropriate therapeutic approach.

OBJECTIVES

In the present article, the currently used classifications of lumbar spinal stenosis are discussed and the diagnostic tools are presented, focussing on the imaging descriptions of morphological changes.

MATERIALS AND METHODS

This article is based on a PubMed literature search of the past 60 years and our own experiences.

RESULTS

Lumbar spinal stenosis is caused mainly by degenerative changes to the spine. MR tomographic imaging can result in precise anatomical illustration and classification of the stenosis.

CONCLUSIONS

Although modern imaging procedures deliver a very precise illustration of lumbar spinal stenosis, clinical symptoms make a considerable contribution to therapeutic decision-making. With the anatomical classification, differentiated surgical decompression of the spinal canal can be planned.

[Diagnostics and conservative treatment of cervical and lumbar spinal stenosis]

BACKGROUND

Degenerative stenotic spondylosis is not an uncommon cause of cervical spondylotic myelopathy (CSM) and cauda equina lesions in the aged population. Limited standardization exists with respect to diagnostic and therapeutic procedures.

OBJECTIVE

Literature review with respect to diagnostic and therapeutic procedures for neurologically relevant cervical and lumbar spinals stenosis.

MATERIAL AND METHODS

Comprehensive literature review.

RESULTS AND CONCLUSION

Clinical neurological examination and diagnostic imaging are fundamental for the diagnosis of neurologically relevant cervical and lumbar spinal stenosis. Additional laboratory blood and cerebrospinal fluid testing might be required for a differential diagnosis. Neurophysiological testing is reserved for specific clinical problems. The clinical evidence for the efficacy of conservative therapeutic strategies is limited.

Dermatomal Versus Mixed Somatosensory Evoked Potentials in the Diagnosis of Lumbosacral Spinal Canal Stenosis

PURPOSE

The existing literature on the use of dermatomal somatosensory evoked potentials in lumbosacral spinal canal stenosis is limited. The goal of this study was to evaluate the role of dermatomal against mixed tibial somatosensory evoked potential (SEP) as a complementary procedure to imaging studies in the diagnosis of lumbosacral stenosis.

METHODS

Thirty patients with clinically and radiologically diagnosed lumbosacral stenosis and 20 normal individuals were enrolled in the study. The study was ethically approved, and informed consent for participation was provided. All participants underwent bilateral mixed tibial and dermatomal SEP study of the third (L3), fourth (L4), fifth lumbar (L5), and first sacral (S1) dermatomes. N45, N25, N20, and N10 tibial SEP waves were measured from four channels, whereas dermatomal waves were measured from cortical recording. Peak latency and amplitude of each wave were calculated.

RESULTS

The cutoff value of the dermatomal S1 latency showed the highest sensitivity and specificity percentages (81.7 and 82.5, respectively), followed by L5 and N25. N25-N45 interpeak latency showed the lowest sensitivity and specificity. All L5, S1, L4, and N25 latency cutoff values presented highly significant differences between affected sides and controls (P < 0.0001), followed by N45 and N20. The amplitude cutoff values of SEP waves showed equivocal sensitivity and specificity percentages.

CONCLUSIONS

Somatosensory evoked potential studies can be used as a supplementary test for the diagnosis of lumbosacral stenosis, with the dermatomal studies being more valuable expressing multiple root abnormalities. S1 dermatomal wave latency has the highest diagnostic value, followed by L5, N25, and then L4 latencies.

Cauda Equina Conduction Time Determined by F-Waves in Normal Subjects and Patients With Neurogenic Intermittent Claudication Caused by Lumbar Spinal Stenosis

PURPOSE

Lumbar spinal stenosis typically presents with neurogenic intermittent claudication. The aim of this study was to investigate cauda equina conduction time (CECT) in patients with neurogenic intermittent claudication caused by lumbar spinal stenosis and its relationship with age and body height in normal subjects.

METHODS

The study included 172 normal subjects (group C) (mean age 44.1 ± 16.6 years; mean height 163.7 ± 8.9 cm). Forty-seven patients (group L) (mean age 71.3 ± 8.7 years; mean height 158.8 ± 11.2 cm) underwent surgery because of neurogenic intermittent claudication in cauda equina type of lumbar spinal stenosis. Motor-evoked potentials from the abductor hallucis were recorded. Magnetic stimulation was delivered at the S1 spinous process. Compound muscle action potentials (CMAPs) and F-waves were also recorded after supramaximal electric stimulation of tibial nerves. The peripheral motor conduction time (PMCT) was calculated from the latencies of CMAPs and F-waves as follows: (CMAPs + F-waves - 1)/2. The CECT was calculated by subtracting the onset latency of the motor-evoked potentials from PMCT.

RESULTS

The mean values for F-wave latencies, motor-evoked potential latencies, and CECT were 44.5 ± 3.3, 20.6 ± 1.8, and 3.4 ± 0.8 milliseconds, respectively. F-wave and motor-evoked potential latencies showed significant positive linear correlations with age and body height. However, no significant correlation was found between CECT and age (P = 0.43) or body height (P = 0.26). Mean CECT was 5.7 ± 1.5 in group L. There was a significant difference between groups C and L (P < 0.05).

CONCLUSIONS

The CECT value of normal subjects was 3.4 ± 0.8 milliseconds regardless of age and body height. We suggest that CECT may be a useful factor to consider when evaluating patients with neurogenic intermittent claudication.

Change in onset times of the abdominal muscles following functional task in lumbar spinal stenosis

The purpose of this study was to investigate the difference in the onset times of the abdominal muscle following a rapid arm task in lumbar spinal stenosis (LSS). In total, 32 patients with LSS were recruited from W oriental hospital. Muscle activity onset of the internal oblique (IO) and external oblique (EO) muscles was measured by electromyography (EMG) activity with a rapid arm movement and during the performance of a walking task. The LSS group demonstrated a significantly later onset of the IO, EO, and rectus abdominal (RA) muscles than the normal group. The deltoid reaction time of the normal group demonstrated significantly earlier activations of IO and EO, while the deltoid reaction time of the LSS group demonstrated significantly delayed activations of IO and RA. The EMG measurements of the IO, EO, and RA muscles while standing and walking were reliable and they offer empirical information about the trunk muscle activation of LSS patients.

Spinal stenosis

Narrowing of the spinal canal or foramina is a common finding in spine imaging of the elderly. Only when symptoms of neurogenic claudication and/or cervical myelopathy are present is a spinal stenosis diagnosis made, either of the lumbar spine, cervical spine or both (only very rarely is the thoracic spine involved). Epidemiological data suggest an incidence of 1 case per 100 000 for cervical spine stenosis and 5 cases per 100 000 for lumbar spine stenosis. Cervical myelopathy in patients over 50 years of age is most commonly due to cervical spine stenosis. Symptomatic spinal narrowing can be congenital, or, more frequently, acquired. The latter may be the result of systemic illneses, namely endocrinopathies (such as Cushing disease or acromegaly), calcium metabolism disorders (including hyporarthyroidism and Paget disease), inflammatory diseases (such as rheumathoid arthritis) and infectious diseases. Physical examination is more often abnormal in cervical spondylotic myeloptahy whereas in lumbar spinal stenosis it is typically normal. Therefore spinal stenosis diagnosis relies on the clinical picture corresponding to conspicuous causative changes identified by imaging techniques, most importantly CT and MRI. Other ancillary diagnostic tests are more likely to be yielding for establishing a differential diagnosis, namely vascular claudication. Most patients have a progressive presentation and are offered non operative management as first treatment strategy. Surgery is indicated for progressive intolerable symptoms or, more rarely, for the neurologically catastrophic initial presentations. Surgical strategy consists mainly of decompression (depending on the anatomical level and type of narrowing: laminectomy, foraminotomy, discectomy, corporectomy) with additional instrumentation should spinal stability and sagittal balance be at risk. For cervical spine stenosis the main objective of surgery is to halt disease progression. There is class 1b evidence that surgery is of benefit for lumbar stenosis at least in the short term.

Does the presence of the nerve root sedimentation sign on MRI correlate with the operative level in patients undergoing posterior lumbar decompression for lumbar stenosis?

BACKGROUND CONTEXT

Recent research describes the use of a nerve root sedimentation sign to diagnose lumbar spinal stenosis (LSS). The lack of sedimentation of the nerve roots (positive sedimentation sign) to the dorsal part of the dural sac is the characteristic feature of this new radiological parameter.

PURPOSE

To demonstrate how the nerve root sedimentation sign compares with other more traditional radiological parameters in patients who have been operated for LSS.

STUDY DESIGN/SETTING

A retrospective chart and image review.

PATIENT SAMPLE

Preoperative magnetic resonance images (MRIs) were reviewed from 71 consecutive operative patients who presented with LSS and received spinal decompression surgery from 2006 to 2010.

OUTCOME MEASURES

Preoperative T2-weighted MRIs were reviewed for each patient.

METHODS

One hundred thirty-four vertebral levels from L1 to L5 were measured for: sedimentation sign, cross-sectional area (CSA) and anterior/posterior (A/P) diameter of the dural sac, thickness of the ligamentum flavum, and Fujiwara grade of facet hypertrophy. Radiological measurements were made using Surgimap 1.1.2.169 software (Nemaris, Inc., New York, NY, USA). Statistical analyses were performed using the SPSS 17.0 statistical software (SPSS Inc., Chicago, IL, USA). Significance was demonstrated using unpaired t tests and chi-squared tests. Study funding was departmental. There were no study-specific conflicts of interest-associated biases.

RESULTS

A positive sedimentation sign was determined in 120 operated levels (89.5%), whereas 14 levels (10.5%) had no sign (negative sedimentation sign). The mean CSA and A/P diameter were 140.62 mm(2) (standard deviation [SD]=53) and 11.76 mm (SD=3), respectively, for the no-sign group; the mean CSA and A/P diameter were 81.87 mm(2) (SD=35) and 8.76 mm (SD=2.2), respectively, for the sedimentation sign group (p<.001). We found that 60% of levels with Fujiwara Grade A facet hypertrophy did not have a sedimentation sign, whereas 86.3% of levels with Grade B, 93.2% of levels with Grade C, and 100.0% of levels with Grade D did have a sedimentation sign (p<.001).

CONCLUSIONS

The sedimentation sign is a new measurement tool that can enable physicians to objectively assess and quantify spinal stenosis. The sign is most often present in patients who have clinically significant lumbar stenosis and require surgery.

An evidence-based clinical guideline for the diagnosis and treatment of degenerative lumbar spinal stenosis (update)

BACKGROUND CONTEXT

The evidence-based clinical guideline on the diagnosis and treatment of degenerative lumbar spinal stenosis by the North American Spine Society (NASS) provides evidence-based recommendations to address key clinical questions surrounding the diagnosis and treatment of degenerative lumbar spinal stenosis. The guideline is intended to reflect contemporary treatment concepts for symptomatic degenerative lumbar spinal stenosis as reflected in the highest quality clinical literature available on this subject as of July 2010. The goals of the guideline recommendations are to assist in delivering optimum efficacious treatment and functional recovery from this spinal disorder.

PURPOSE

Provide an evidence-based educational tool to assist spine care providers in improving quality and efficiency of care delivered to patients with degenerative lumbar spinal stenosis.

STUDY DESIGN

Systematic review and evidence-based clinical guideline.

METHODS

This report is from the Degenerative Lumbar Spinal Stenosis Work Group of the NASS's Evidence-Based Clinical Guideline Development Committee. The work group consisted of multidisciplinary spine care specialists trained in the principles of evidence-based analysis. The original guideline, published in 2006, was carefully reviewed. A literature search addressing each question and using a specific search protocol was performed on English language references found in MEDLINE, EMBASE (Drugs and Pharmacology), and four additional, evidence-based, databases to identify articles published since the search performed for the original guideline. The relevant literature was then independently rated by a minimum of three physician reviewers using the NASS-adopted standardized levels of evidence. An evidentiary table was created for each of the questions. Final recommendations to answer each clinical question were arrived at via work group discussion, and grades were assigned to the recommendations using standardized grades of recommendation. In the absence of Levels I to IV evidence, work group consensus statements have been developed using a modified nominal group technique, and these statements are clearly identified as such in the guideline.

RESULTS

Sixteen key clinical questions were assessed, addressing issues of natural history, diagnosis, and treatment of degenerative lumbar spinal stenosis. The answers are summarized in this document. The respective recommendations were graded by the strength of the supporting literature that was stratified by levels of evidence.

CONCLUSIONS

A clinical guideline for degenerative lumbar spinal stenosis has been updated using the techniques of evidence-based medicine and using the best available clinical evidence to aid both practitioners and patients involved with the care of this condition. The entire guideline document, including the evidentiary tables, suggestions for future research, and all references, will be available electronically at the NASS Web site (www.spine.org) and will remain updated on a timely schedule.

Prediction of long-term clinical outcome in patients with lumbar spinal stenosis

PURPOSE

The natural course of lumbar spinal stenosis (LSS) fluctuates and is not necessarily progressive. The aim of this study was to explore the predictors of clinical outcome in patients with LSS that might eventually help to optimise the therapeutic choices.

METHODS

A group of 56 patients (27 men, 29 women, median age 55; range 31-72 years) with clinically symptomatic mild-to-moderate LSS were re-examined after a median period of 88 months and their clinical outcomes classified as satisfactory (34 patients, 60.7 % with stable or improved clinical status) or unsatisfactory (22 patients, 39.3 % for whom clinical status deteriorated). A wide range of demographical, clinical, imaging and electrophysiological entry parameters were evaluated as possible predictors of clinical outcome.

RESULTS

Unlike the demographical, clinical and imaging variables, certain electrophysiological parameters were significantly associated with unsatisfactory outcomes. There was a significantly higher prevalence of pluriradicular involvement detected by EMG in patients with unsatisfactory outcome than those with satisfactory outcome (68.2 vs. 32.3 %; p = 0.035). Patients with unsatisfactory outcome had more frequent bilateral abnormalities of the soleus H-reflex (50.0 vs. 14.7 %; p = 0.015) and lower mean H-reflex amplitude. Multivariate logistic regression proposed two variables as mutually independent predictors of unsatisfactory outcome: EMG signs of pluriradicular involvement (OR = 3.72) and averaged soleus H-reflex amplitude ≤ 2.8 mV (OR = 2.87).

CONCLUSIONS

Satisfactory outcomes were disclosed in about 61 % of the patients with mild-to-moderate LSS in a 7-year follow-up. Electrophysiological abnormalities, namely the presence of pluriradicular involvement and abnormalities of the soleus H-reflex, were predictive of deterioration of clinical status in these patients.

Hip-spine syndrome

The incidence of symptomatic osteoarthritis of the hip and degenerative lumbar spinal stenosis is increasing in our aging population. Because the subjective complaints can be similar, it is often difficult to differentiate intra- and extra-articular hip pathology from degenerative lumbar spinal stenosis. These conditions can present concurrently, which makes it challenging to determine the predominant underlying pain generator. A thorough history and physical examination, coupled with selective diagnostic testing, can be performed to differentiate between these clinical entities and help prioritize management. Determining the potential benefit from surgical intervention and the order in which to address these conditions are of utmost importance for patient satisfaction and adequate relief of symptoms.

Diagnostic pitfalls in spine surgery: masqueraders of surgical spine disease

Disorders of the spine are common in clinical medicine, and spine surgery is being performed with increasing frequency in the US. Although many patients with an established diagnosis of a true surgically treatable lesion are referred to a neurosurgeon, the evaluation of patients with spinal disorders can be complex and fraught with diagnostic pitfalls. While “common conditions are common,” astute clinical acumen and vigilance are necessary to identify lesions that masquerade as surgically treatable spine disease that can lead to erroneous diagnosis and treatment. In this review, the authors discuss musculoskeletal, peripheral nerve, metabolic, infectious, inflammatory, and vascular conditions that mimic the syndromes produced by surgical lesions. It is possible that nonsurgical and surgical conditions coexist at times, complicating treatment plans and natural histories. Awareness of these diagnoses can help reduce diagnostic error, thereby avoiding the morbidity and expense associated with an unnecessary operation.

Leg weakness in a patient with lumbar stenosis and adrenal insufficiency

Lumbar spinal stenosis (LSS) is a common spinal disease in the elderly. The cardinal symptom of LSS is neurogenic claudication, but not all patients present with such typical symptom. The clinical symptoms are often confused with symptoms of peripheral neuropathy, musculo-skeletal disease and other medical conditions in elderly patients. In particular, LSS presenting with rapid progression of leg weakness must be distinguished from other combined diseases. We report a case of rapid progressive leg weakness in a patient with LSS and iatrogenic adrenal insufficiency that was induced by obscure health supplement.

Clinical classification of cauda equina syndrome for proper treatment

BACKGROUND AND PURPOSE

Cauda equina syndrome (CES) is a severe complication of lumbar spinal disorders; it results from compression of the nerve roots of the cauda equina. The purpose of this study was to evaluate the clinical usefulness of a classification scheme of CES based on factors including clinical symptoms, imaging signs, and electrophysiological findings.

METHODS

The records of 39 patients with CES were divided into 4 groups based on clinical features as follows. Group 1 (preclinical): low back pain with only bulbocavernosus reflex and ischiocavernosus reflex abnormalities. Group 2 (early): saddle sensory disturbance and bilateral sciatica. Group 3 (middle): saddle sensory disturbance, bowel or bladder dysfunction, motor weakness of the lower extremity, and reduced sexual function. Group 4 (late): absence of saddle sensation and sexual function in addition to uncontrolled bowel function. The outcome including radiographic and electrophysiological findings was compared between groups.

RESULTS

The main clinical manifestations of CES included bilateral saddle sensory disturbance, and bowel, bladder, and sexual dysfunction. The clinical symptoms of patients with multiple-segment canal stenosis identified radiographically were more severe than those of patients with single-segment stenosis. BCR and ICR improved in groups 1 and 2 after surgery, but no change was noted for groups 3 and 4.

INTERPRETATION

We conclude that bilateral radiculopathy or sciatica are early stages of CES and indicate a high risk of development of advanced CES. Electrophysiological abnormalities and reduced saddle sensation are indices of early diagnosis. Patients at the preclinical and early stages have better functional recovery than patients in later stages after surgical decompression.

Nerve root sedimentation sign: evaluation of a new radiological sign in lumbar spinal stenosis

STUDY DESIGN

Retrospective case-referent study.

OBJECTIVE

To assess whether the new sedimentation sign discriminates between nonspecific low back pain (LBP) and symptomatic lumbar spinal stenosis (LSS).

SUMMARY OF BACKGROUND DATA

In the diagnosis of LSS, radiologic findings do not always correlate with clinical symptoms, and additional diagnostic signs are needed. In patients without LSS, we observe the sedimentation of lumbar nerve roots to the dorsal part of the dural sac on supine magnetic resonance image scans. In patients with symptomatic and morphologic central LSS, this sedimentation is rarely seen. We named this phenomenon "sedimentation sign" and defined the absence of sedimenting nerve roots as positive sedimentation sign for the diagnosis of LSS.

METHODS

This study included 200 patients. Patients in the LSS group (n = 100) showed claudication with or without LBP and leg pain, a cross-sectional area <80 mm, and a walking distance <200 m; patients in the LBP group (n = 100) had LBP, no leg pain, no claudication, a cross-sectional area of the dural sac >120 mm, and a walking distance >1000 m. The frequency of a positive sedimentation sign was compared between the 2 groups, and intraobserver and interobserver reliability were assessed in a random subsample (n = 20).

RESULTS

A positive sedimentation sign was identified in 94 patients in the LSS group (94%; 95% confidence interval, 90%-99%) but none in the LBP group (0%; 95% confidence interval, 0%-4%). Reliability was kappa = 1.0 (intraobserver) and kappa = 0.93 (interobserver), respectively. There was no difference in the detection of the sign between segmental levels L1-L5 in the LSS group.

CONCLUSION

A positive sedimentation sign exclusively and reliably occurs in patients with LSS, suggesting its usefulness in clinical practice. Future accuracy studies will address its sensitivity and specificity. If they confirm the sign's high specificity, a positive sedimentation sign can rule in LSS, and, with a high sensitivity, a negative sedimentation sign can rule out LSS.

Clinical usefulness of assessing lumbar somatosensory evoked potentials in lumbar spinal stenosis

Object

The aim of this retrospective study was to evaluate the clinical usefulness of assessing lumbar somatosensory evoked potentials (SSEPs) in central lumbar spinal stenosis (LSS).

Methods

The latencies of lumbar SSEPs were recorded in 40 patients with central LSS, including 16 men and 24 women. The mean age of the patients was 67.3 ± 7.4 years. The diagnosis was LSS in 23 cases and LSS associated with degenerative spondylolisthesis in 17 cases. The average duration of symptoms was 43.8 ± 51.2 months. Twenty-two cases had bilateral and 18 cases had unilateral leg symptoms. Thirty-seven cases were associated with neurogenic intermittent claudication and the mean walking distance of patients with this condition was 246.8 ± 232.7 m. The mean Japanese Orthopedic Association scale score, as well as the visual analog scale (VAS) scores of low-back pain, leg pain, and numbness, were 16.5 ± 3.5, 6.0 ± 2.5, 6.9 ± 2.1, and 7.8 ± 2.2, respectively. The minimal cross-sectional area of the dural sac on MR imaging was 0.44 ± 0.21 cm2. Thirty-nine cases of cervical spondylotic myelopathy without lumbar and peripheral neuropathy were chosen as the control group.

Results

The latencies of lumbar SSEPs in patients with LSS and in the control group were 23.0 ± 2.0 ms and 21.6 ± 1.9 ms, respectively. There was a statistically significant difference between the LSS and control groups (p < 0.05). The latency of lumbar SSEPs was significant correlated with the VAS score of leg numbness (p < 0.05). The latency of lumbar SSEPs in LSS was clearly delayed when the VAS score of leg numbness was ≥ 8 (p < 0.05).

Conclusions

Lumbar SSEPs are able to detect neurological deficit in the lumbar area effectively, and they can reflect part of the subjective severity of sensory disturbance (numbness) in LSS. Both lumbar SSEPs and VAS scores of leg numbness may be useful for clinical evaluation in patients with LSS.

Thoracic disc herniation in a patient with tethered cord and lumbar syringomyelia and diastematomyelia: magnetic resonance imaging and neurophysiological findings

STUDY DESIGN

Case report.

OBJECTIVE

To describe the diagnostic challenges in a patient suffering from thoracic disc herniation (TDH) and spina bifida complicated by multiple lumbar spinal cord abnormalities, i.e., tethered cord, lumbar syringomyelia, and diastematomyelia.

SUMMARY OF BACKGROUND DATA

Advances in neuroimaging, i.e., magnetic resonance imaging, increase the sensitivity to disclose both clinically relevant but also other spine and spinal cord abnormalities. TDH accounts for less than 1% of all surgically treated disc herniations. Syringomyelia and diastematomyelia are comparably rare and present with varying degrees of spinal cord dysfunction.

METHODS

A 54-year-old women presented with progressive pain and sensorimotor symptoms in the lower back and limbs. Neurologic examination revealed lower limb spastic motor deficits and spinal ataxia. Magnetic resonance imaging revealed a T6-T7 disc herniation, with spinal cord signal change in addition to a spina bifida with sacral tethered cord, lumbar syringomyelia, and diastematomyelia. Combined neurophysiological testing identified a neurologic lesion in the mid thoracic cord, with normal lower limb nerve conduction and reflex recordings, but pathologic somatosensory-evoked potential and T6 paravertebral electromyography.

RESULTS

The patient was diagnosed with a clinically relevant T6-T7 disc herniation and underwent successful surgical decompression resulting in electrophysiological improvements.

CONCLUSION

This unique case highlights the value of electrophysiology in the evaluation of a complex spinal disorder in a patient suffering from acquired TDH in the presence of extensive congenital spine and spinal cord abnormalities. Clinical symptoms and signs can be complemented by neurophysiological techniques to improve diagnostic accuracy and improve the basis for treatment recommendations. In cases involving multiple spinal abnormalities, a comprehensive neurophysiological assessment beyond paravertebral electromyography studies, including nerve conduction and somatosensory-evoked potential recordings, is recommended to assist in confirming the diagnosis.

Motor conduction time along the cauda equina in patients with lumbar spinal stenosis

STUDY DESIGN

Magnetic lumbar stimulation was used to detect spinal nerve degeneration in patients with lumbar spinal stenosis (LSS).

OBJECTIVE

To evaluate delays in the motor conduction time in the cauda equina of patients with LSS.

SUMMARY OF BACKGROUND DATA

Previous studies suggested a bilateral slowing of motor conduction in the cauda equina in LSS. Among several methods, only magnetic stimulation is sufficiently sensitive for detecting potential degeneration in LSS. A recent study demonstrated the direct calculation of the cauda equina motor conduction time using magnetic stimulation at proximal and distal sites of the cauda equina. We used this technique to determine potential degeneration in patients with LSS.

METHODS

Twenty adult subjects and 15 patients with LSS were investigated. Lumbosacral roots were stimulated at intervertebral levels L1-L2 and L5-S1 by magnetic coil stimulation. The muscle responses to stimulation were recorded from the gastrocnemius-soleus, and anterior tibialis muscles on both sides with bipolar surface electrodes. The response latency from stimulations at the L5 spine level were subtracted from those at the L1 level on the same side. This value represented the conduction time from the proximal to distal ends of the cauda equina.

RESULTS

The mean conduction time along the cauda equina was significantly prolonged in patients with LSS compared with controls. The mean cauda equina motor conduction time was 1.97 +/- 0.67 milliseconds in controls and 3.57 +/- 2.22 milliseconds in patients with LSS (P = 0.00).

CONCLUSION

Determining the motor conduction time along the cauda equina using L1 and L5 magnetic stimulation provides an effective alternative method for evaluating the lumbar motor roots in patients with LSS.

Clinical value of motor evoked potentials with transcranial magnetic stimulation in the assessment of lumbar spinal stenosis

The objective of this study was to evaluate the clinical usefulness of assessing motor evoked potentials (MEP) in lumbar spinal stenosis (LSS). Twenty-three LSS patients were enrolled. The preoperative data of MEP latency (MEPLT), clinical symptoms, Japanese Orthopaedic Association (JOA) scores for low back pain, visual analogue scale (VAS) for back pain, leg pain and numbness, walking distance and the minimal cross-sectional area (mCSA) of the dural sac were evaluated. The mean MEPLT was 42.1 +/- 2.8 ms. Fourteen patients had bilateral leg symptoms. The mean walking distance and mCSA were 302.1 +/- 302.8 m and 0.4 +/- 0.2 cm(2), respectively. The mean JOA score and VAS scores for back pain, leg pain and numbness were 15.9 +/- 4.8, 6.0 +/- 2.9, 7.7 +/- 1.9 and 7.3 +/- 3.0, respectively. MEPLT was related to the walking distance, limb symptoms and the VAS for numbness. MEPLT was significantly delayed in patients who showed a walking distance less than 500 m. MEP is useful in LSS assessment. It can reflect the subjective severity of motor disturbance and predict the neurological deficit prior to appearance.