Malformation of lumbar spinal roots and sheaths in the causation of low backache and sciatica

Conjoined nerve root in a patient with lumbar disc herniation accompanied by a lumbosacral spine anomaly: a case report

BACKGROUND

A nerve root anomaly, typified by a conjoined nerve root, is a rare finding. Conjoined nerve root anomalies are easily missed even in preoperative advanced imaging modalities, which can be potentially troublesome during and after surgery. In this report, we present a case of conjoined right L5-S1 nerve root in a patient with lumbar disc herniation, accompanied by spina bifida occulta, which was undiagnosed on preoperative imaging studies.

CASE REPORT

A 55-year-old Asian (Japanese) woman presented with low back pain and right leg radiating pain due to lumbar disc herniation at the right L5/S1. Physical examination revealed a positive Lasègue sign and the range of the straight leg raising test was 20° on the right side. The right patellar tendon reflex was normal; however, the right ankle jerk reflex disappeared. Although no obvious hypoesthesia was noted, mild muscle weakness (4/5) was observed in the right leg on the manual muscle test. We planned the lumbar discectomy under a microscope. During surgery, the conjoined right L5-S1 nerve root, which was compressed by herniated nucleus pulposus, was encountered. Although it was very thick and less mobile, some pieces of herniated nucleus pulposus could be removed piece by piece from the axillary part. After sequential decompressive procedures, the tightness of the conjoined right L5-S1 nerve root decreased but its mobility did not improve much. The laterality of the thickness and exit angle of the conjoined right L5-S1 nerve root was retrospectively confirmed on T2 coronal magnetic resonance images and magnetic resonance neurography. Postoperatively, right leg pain was immediately alleviated and complete improvement of muscle weakness was achieved 1 week later (5/5).

CONCLUSIONS

Magnetic resonance neurography is extremely useful for the accurate diagnosis of anomalous nerve roots because of clear visualization of the neural tissue. Discectomy under a microscope, which enables magnified three-dimensional observation of the surgical field, must provide a valid and safe procedure to achieve not only secure resection of herniated discs but also adequate exposure of anomalous nerve roots.

Relationship of segmental variations in the human lumbar plexus to the length of the 12th rib

BACKGROUND

Evaluating segmental variations in the lumbar plexus is crucial for neurological diagnosis. In the present study, we examined the relationship between the segmental composition of the lumbar plexus and length of the 12th rib.

PROCEDURES

To evaluate segmental variations in the lumbar plexus, the furcal nerve (Nf) which forms the boundary between the lumbar and sacral plexus, was used as an index of plexus arrangement.

MAIN FINDINGS

Segmental variations in the Nf were classified into four groups on the basis of whether the Nf originated from the ventral rami of L3 and L4 (Nf L3 + L4 group), L4 (Nf L4 group), L4 and L5 (Nf L4 + L5 group), or L5 (Nf L5 group). The Nf L3 + L4 group was associated with short 12th rib, and groups Nf L4 + L5 and Nf L5 were associated with long 12th rib. These findings suggest that the segmental variations in the lumbar plexus are related to the length of the 12th rib.

CONCLUSIONS

Therefore, the segmental variations in the lumbar plexus can be evaluated non-invasively and easily by measuring the length of the 12th rib. This may contribute to the diagnosis and treatment of various lumbar radiculopathies.

Intraspinal characteristics of thoracic spinal nerve roots anomalies

Purpose: The anomalous anatomical arrangement of the thoracic spinal nerve roots within the spinal canal can complicate the surgical treatment of several pathologies. The aim of this work was to reveal intraspinal anatomical variations of the thoracic spinal nerve roots.Methods: Anatomical study on 43 cadavers with a mean age of 53.7. After opening the spinal canal and dural sac, intradural and extradural anomalies of the thoracic spinal nerve roots were documented. Extradural communicating branches were excised, histologically processed and examined for the presence of nervous tissue.Results: We found 14 cases (32.6%) of intraspinal thoracic nerve root variations: intradural in 8 cases (18.6%), intradural communicating branches in 3 cases (6.97%), extradural anatomical variations occurred 6 cases (13.95%), 2 cases (4.65%) had extradural communicating branches between the nerve roots, 1 case had simultaneous occurrence of intradural and extradural communications (0.23%). All the results are differentiated according to the plexus type. In macroscopic extradural thoracic communicating branch had no nervous tissue on microscopy.Conclusions: This study describes intraspinal anatomical variations of thoracic spinal nerve roots. Knowledge of these variables should help prevent the failure of several medical procedures.

Nerve root anomalies detected intra-operatively technical nuances towards achieving a successful surgical outcome: our experience of three case reports at a tertiary level centre

OBJECTIVE

Analysis of three case reports of nerve root anomalies detected intra-operatively and its implications.

DESIGN

Data collected during one year prospective non-randomised study using hospital records.

SETTING

Single tertiary care centre.

SUBJECTS

3 patients in one year period.

Conjoint Lumbosacral Nerve Root-A Case Report

Introduction:

Conjoint nerve root is embryological nerve root anomaly mainly involving lumbosacral region. The anomalous roots present primarily as a bifid, conjoined structure arising from a wide area of the dura. Because of their size and attachment to surrounding structures, they are uniquely susceptible to trauma. The effects of compression and entrapment are amplified in the presence of stenosis of the lateral recesses where developmental changes and disc herniations deplete the available reserve space [1].

Case Report:

We report a case of conjoint lumbosacral nerve root which was missed on MRI and diagnosed intra-operatively.

Conclusion:

The importance of the case report lies in the fact that one must be aware of finding conjoint nerve root directly while operating and do appropriate level of surgery, misinterpretation can lead to devastating results.

Nerve root anomalies: implications for transforaminal lumbar interbody fusion surgery and a review of the Neidre and Macnab classification system

Lumbar nerve root anomalies are uncommon phenomena that must be recognized to avoid neural injury during surgery. The authors describe 2 cases of nerve root anomalies encountered during mini-open transforaminal lumbar interbody fusion (TLIF) surgery. One anomaly was a confluent variant not previously classified; the authors suggest that this variant be reflected in an amendment to the Neidre and Macnab classification system. They also propose strategies for identifying these anomalies and avoiding injury to anomalous nerve roots during TLIF surgery. Case 1 involved a 68-year-old woman with a 2-year history of neurogenic claudication. An MR image demonstrated L4–5 stenosis and spondylolisthesis and an L-4 nerve root that appeared unusually low in the neural foramen. During a mini-open TLIF procedure, a nerve root anomaly was seen. Six months after surgery this patient was free of neurogenic claudication. Case 2 involved a 60-year-old woman with a 1-year history of left L-4 radicular pain. Both MR and CT images demonstrated severe left L-4 foraminal stenosis and focal scoliosis. Before surgery, a nerve root anomaly was not detected, but during a unilateral mini-open TLIF procedure, a confluent nerve root was identified. Two years after surgery, this patient was free of radicular pain.

Intraoperative conjoined lumbosacral nerve roots associated with spondylolisthesis

Lumbosacral nerve roots anomalies may produce low back pain. These anomalies are reported to be a cause for failed back surgery. They are usually left undiagnosed, especially in endoscopic discectomy techniques. Any surgery for entrapment disorders, performed on a patient with undiagnosed lumbosacral nerve roots anomaly, may lead to serious neural injuries because of an improper surgical technique or decompression. In this report, we describe our experience with a case of L5-S1 spondylolisthesis and associated congenital lumbosacral nerve root anomalies discovered during the surgical intervention, and the difficulties raised by such a discovery. Careful examination of coronal and axial views obtained through high-quality Magnetic Resonance Imaging may lead to a proper diagnosis of this condition leading to an adequate surgical planning, minimizing the intraoperatory complications.

Intradural microanatomy of the nerve roots S1–S5 at their origin from the conus medullaris

Object

The conus medullaris and the nerve roots from S-1 to S-5 regulate bladder function as well as movement and sensation of the lower extremities. This most caudal region of the spinal cord has not been studied in great detail anatomically despite its important regulatory role. The goal of this analysis is to characterize the normal intradural microanatomy of the sacral nerve roots at their origin from the conus medullaris.

Methods

The thecal sacs from 20 cadavers were fixated in formaldehyde and dissected under the operative microscope.

Results

More than 50 rootlets originated from the conus medullaris over a distance of < 3 cm. The rootlets were loosely organized into bundles by the arachnoid membrane with decreasing diameters. These diameters were 1.7 mm (ventral)/2.4 mm (dorsal) at S-1, and 0.17 mm (ventral)/0.4 mm (dorsal) at S-5. The roots were separated by neither the dentate ligament nor interradicular gaps. The number of rootlets decreased in the rostrocaudal direction with 2 ventral and 5 dorsal rootlets at S-1, but only 1 ventral (inconsistently found) and 2 dorsal rootlets at S-5. Typically, 1 nerve anastomosis was present between adjacent dorsal roots from S-1 to S-4. Nerve anastomoses between ventral roots or rootlets of the same root were less frequent. The dorsal segment of origin (linea radicularis) decreased in length from 7.2 mm at S-1 to 4.8 mm at S-5.

Conclusions

The current study provides anatomical details and specific morphometric data of the intradural contents at the level of the conus medullaris. This information is valuable for intraoperative orientation, endoscopic navigation, and possible intradural nerve stimulation.

Conjoined lumbosacral nerve roots compromised by disk herniation: sagittal shoulder sign for the preoperative diagnosis

OBJECTIVE

The objective was to determine the importance of the "sagittal shoulder sign" on magnetic resonance (MR) images for the diagnosis of conjoined lumbosacral nerve roots (CLNR) that are compromised by herniated disks.

MATERIALS AND METHODS

Magnetic resonance images of 11 patients (6 men and 5 women; age range, 25-71 years; average age, 48.7 years) with surgically proven CLNR, which was compromised by herniated disks, were retrospectively evaluated by two musculoskeletal radiologists. MR images were evaluated for the presence or absence of the sagittal shoulder sign-a vertical structure connecting two consecutive nerve roots and overlying disk on the sagittal MR images. The radiologists noted the type of accompanying disk herniation and bony spinal canal changes, as well as other characteristic MR features of CLNR, the common passage of two consecutive nerve roots through the neural foramen on axial MR images.

RESULTS

The sagittal shoulder sign was identified with a mean frequency of 90.9% by the two observers (in 10 of 11 patients). The common passage of two consecutive nerve roots through the neural foramen on axial MR images was identified with a mean frequency of 59.1% (in 7 and 6 out of 11 patients, by observers 1 and 2, respectively). Good interobserver agreement for the sagittal shoulder sign was present (k = 0.621, p < 0.05).

CONCLUSION

Observation of the sagittal shoulder sign may prove helpful for diagnosing CLNR in patients with disk herniation. In particular, this sign appears to be useful when there is no evidence of CLNR on axial MR images.

Lumbosacral nerve root anomaly associated with spondylolisthesis in an adolescent: a case report and review of the literature

STUDY DESIGN

Case report.

OBJECTIVE

We describe the case of a lumbosacral nerve root anomaly in a 16-year-old male with spondylolisthesis and neurologic findings exceeding that that was expected of the underlying deformity. A complete review of clinical, radiologic, and operative records was performed.

SUMMARY OF BACKGROUND DATA

Spondylolisthesis is a relatively common cause of lower back pain in adolescents. Neurologic findings may occur, most commonly associated with higher grade spondylolisthesis and spondyloptosis. Lumbosacral nerve root anomalies have been reported and are typically associated with neurologic symptoms in excess of the underlying deformity.

METHODS

The 16-year-old male presented with lower back pain, difficulty walking, and sensory and motor symptoms in the L5 and S1 nerve root distributions. Radiographs revealed a Meyerding grade III spondylolisthesis, with a slip angle of 14 degrees and a lumbosacral angle of 76 degrees . Neither computerized tomography nor magnetic resonance imaging revealed the presence of lumbosacral nerve root anomalies.

RESULTS

Intraoperatively, an L5-S1 anastomotic nerve root on the left side was identified.

CONCLUSIONS

This case emphasizes the need to consider the presence of lumbosacral nerve root anomalies in cases in which neurologic findings exceed what would be anticipated. Preoperative identification of these anomalies allows for their existence to be considered in the surgical plan.

Conjoined lumbosacral nerve roots: observations on three cases and review of the literature

Lumbosacral nerve root anomalies are a rare group of congenital anatomical anomalies. Various types of anomalies of the lumbosacral nerve roots have been documented in the available international literature. Generally speaking, these anomalies may consist of a bifid, conjoined structure, of a transverse course or of a characteristic anastomized appearance. Firstly described as an incidental finding during autopsies or surgical procedures performed for lumbar disk herniations and often asymptomatic, lumbosacral nerve root anomalies have been more frequently described in the last years due to the advances made in radiological diagnosis (metrizamide myelography and CT, MRI). Our study comprised three patients with conjoined lumbosacral nerve roots, representing 0.25% of a total of 1200 patients who underwent lumbosacral CT/MRI procedures in the Addolorata Hospital and in the Service of Neuroradiology of the University of Rome "La Sapienza" during the last three years (March 2001-March 2004). We report our experience with three cases of conjoined lumbosacral nerve roots and analyze the most important literature on this topic. MR imaging is a better diagnostic procedure (in comparison to CT) for the differentiation of nerve root anomalies and, in particular, coronal sections furnish a precise definition of the profile of the conjoined/enlarged rootlets. In fact, the accurate information derived from MRI of multiple planes may be priceless for the preoperative and diagnostic evaluation of lumbosacral nerve root anomalies.

Conjoined lumbosacral nerve roots: current aspects of diagnosis

Conjoined lumbosacral nerve roots (CLNR) are the most common anomalies involving the lumbar nerve structures which can be one of the origins of failed back syndromes. They can cause sciatica even without the presence of a additional compressive impingement (such as disc herniation, spondylolisthesis or lateral recess stenosis), and often congenital lumbosacral spine anomalies (such as bony defects) are present at the "conjoined sheaths". This congenital anomaly has been reported in 14% of cadaver studies, but myelographic or computed tomographic studies have revealed an incidence of approximately 4% only. Diagnostic methods such as magnetic resonance imaging (MRI) are helpful for determination of the exact anatomical relations in this context. We present five typical cases of conjoined nerve roots observed during a 1 year period, equivalent to 6% of our out-patients without a history of surgical treatment on the lumbar spine. In all cases with suspicious radiological findings MRI or lumbar myelography combined with CT and multiplanar reconstructions is recommended.

Diagnosis of lumbosacral nerve root anomalies by magnetic resonance imaging

This study evaluates the use of magnetic resonance imaging (MRI) in the diagnosis of lumbosacral nerve root anomalies. Prevalence of anomalous nerve roots has been based on anatomic dissection or preoperative neuroradiologic investigations. Three hundred seventy-six patients with low back pain and/or radicular pain who underwent MRI of the lumbar spine were reviewed. Sixty-five cases of nerve root anomalies were found (an incidence of 17.3%) of which 1 case of cranial origin, 5 cases of caudal origin, 2 cases of conjoined nerve root, and 57 cases of furcal nerve roots (15.1%) were identified. Furcal nerve roots were most commonly found at L3 and L4 levels and were classified, according to their division, into intra-and extraforaminal. MRI provided accurate information on lumbosacral nerve root anomalies.

Conjoined lumbosacral nerve roots

Conjoined lumbosacral nerve roots is a congenital anomaly that may produce lumbosciatic pain. When symptomatic and undiagnosed, it may be one of the causes of failed back syndrome. Diagnosis with water-soluble contrast myelography has a frequency of 4%. Anatomical studies have shown to have an incidence of 14%. High quality Magnetic Resonance Imaging (MRI) with coronal views may reveal this condition without recurring to computed tomography (CT)-myelography. In this paper we describe our recent experience with five consecutive cases observed during a one year period.

The frequency of intradural conjoined lumbosacral dorsal nerve roots found during selective dorsal rhizotomy

The frequency of occurrence of conjoined nerve roots (CR) in the cauda equina has been reported to range from 0.3% to 2%. We found intradural conjoined nerve roots in 13 of 123 (10.6%) patients undergoing selective dorsal rhizotomy for spasticity due to cerebral palsy. The anomaly occurred most commonly at L5-S1 and S1-S2. There was no consistent relationship to other anomalies of segmental anatomy. Our finding of a significantly higher number of conjoined nerve roots in these patients is primarily due to the surgical exposure of the entire cauda equina. This anomaly is more common than previous reports have indicated.

Association of conjoined and anastomosed nerve roots in the lumbar region. A case report

Different types of anomalies of the lumbosacral nerve roots were documented in the literature. The present report is the first description of a combination of conjoined and anastomosed nerve roots, at the same level and unilaterally, in the lumbar region.

Conjoined lumbosacral nerve roots. Diagnosis with metrizamide myelography

The most common anomaly of the lumbosacral nerve roots consists of a composite root sleeve containing the roots for two spinal nerves. Before the advent of water-soluble myelography, this anomaly was rarely diagnosed except at operation. Metrizamide myelography readily demonstrates the anomaly because of improved filling of the root sleeves and greater definition of the nerve roots within the subarachnoid space. However, an underlying disk herniation may not be evident on the myelogram because of the unique anatomic configuration.

Developmental asymmetry of roots of the cauda equina at metrizamide myelography: report of seven cases with a review of the literature

The myelographic findings of developmental asymmetry of the lumbo-sacral nerve root sheaths are described in seven patients and details of the clinical presentation and management are presented. Six of the seven patients had referred pain to the leg on the side of the anomaly. There were no significant associated plain film findings. Adherence to recommended techniques of metrizamide myelography is stressed, with particular reference to horizontal beam decubitus oblique projections, which profile the root sheaths to best effect. Minimal signs in the frontal projection are also described, which may be the initial clue to diagnosis. The possibility of erroneous diagnosis of lateral disc protrusion is emphasised if this anatomical variant is not recognised.

Surgical treatment of 63 cases of conjoined nerve roots

The operative results of 63 cases of lumbar disc disease with surgically confirmed conjoined nerve roots are reviewed. The first 55 patients were treated by standard hemilaminectomy and discectomy, with only 30% reporting a good result. Of the last eight patients treated by hemilaminectomy, pediculectomy, and discectomy, seven patients returned to work. Te rationale for and the technique of pediculectomy are discussed in detail. Clinical, radiological, and surgical clues indicating the presence of the conjoined nerve root anomaly are reviewed.

Redundant nerve roots of the cauda equina

Four cases of redundant nerve roots of the cauda equina are reported, and the pertinent literature is reviewed. This disorder mainly affects males. The clinical history ranges from months to decades. The illness often starts with low back pain or sciatica, or both. Motor and sensory impairment of the legs dominate the further course of the disease. Serpentine filling defects in the column of contrast are a characteristic (but inconstant) feature on myelograms. Abatement of signs and symptoms occurs following adequate decompression of the redundant roots.

Conjoined lumbosacral nerve roots. Management of herniated discs and lateral recess stenosis in patients with this anomaly

Anomalous L-5 and S-1 nerve roots occur infrequently. If not properly recognized, surgery for entrapment disorders may result in serious neural injury because of an improper surgical approach in exposure and in removing the underlying herniated discs. The diagnosis has been made preoperatively since the introduction of water-soluble myelography because of improved filling of the nerve roots. A herniated disc beneath the bifid root causes extreme pain and disability with marked signs of entrapment because of firm fixation of the conjoined root in the lateral recess between the two pedicles. An underlying herniated disc may not be recognized because of the unique anatomical changes. To properly identify the nature of the lesion, wide exposure by hemilaminectomy is preferred, with unroofing of the lateral recesses and wide foraminal decompression. Eight such patients are reported: seven had herniated discs, and one had lateral recess stenosis with superior facet entrapment. With adequate decompression, all patients made a rapid, uneventful recovery.

[Anomalies of the pattern of lumbosacral nerve roots and its clinical significance (author's transl)]

Twenty personal observations and 18 cases collected from the literature are analysed. The most frequently encountered anomaly were: common dural origin of 2 nerve roots and common exit of 2 nerve roots through the intervertebral foramen. Other anomalies comprised: interradicular connections and Y-shaped or horizontla course of the nerve root. Multiple anomalies were not encountered. In 9 out of 20 patients in the own series and in 6 out of 18 patients reported in the literature, history and clinical findings suggested prolapsed intervertebral disc, operation revealed only nerve root anomalies. Decompression produced improvement or complete relieve of previously existing signs and plain X-rays is not possible. The diagnosis is based on myelographic findings. The pathogenesis of the anomalies is discussed. It is suggested that they should not be considered as a causative factor of low back pain or sciatica.