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.

Relationship Between Cauda Equina Conduction Time and Type of Neurogenic Intermittent Claudication due to Lumbar Spinal Stenosis.

INTRODUCTION: This study investigated whether the prolongation of the cauda equina conduction time (CECT) was related to the type of neurogenic intermittent claudication due to lumbar spinal stenosis. METHODS: In total, 149 patients who underwent surgery due to lumbar spinal stenosis with neurogenic intermittent claudication were classified into three groups as follows: cauda equina-type(n = 67), radicular-type(n = 29), and mixed-type(n = 53). Cauda equina conduction time was measured by placing disc electrodes on the abductor hallucis muscle, electrically stimulating the tibial nerve of the ankle and recording the compound muscle action potentials and F-waves. Motor evoked potentials from the abductor hallucis muscle were measured after magnetically stimulating the lumbosacral spine. Cauda equina conduction time was calculated from the latencies of compound muscle action potentials, F-waves, and motor evoked potentials. The measurement of the dural sac cross-sectional area were assessed using computed tomography myelography or MRI. RESULTS: The values of CECT were as follows: cauda equina-type, 5.6 ± 1.1 ms; mixed-type, 5.1 ± 0.9 ms; and radicular-type, 4.0 ± 0.9 ms. The values of dural sac cross-sectional area were as follows: cauda equina-type, 42.8 ± 18.7 mm; mixed-type, 49.6 ± 20.9 mm; and radicular-type, 75.3 ± 19.1 mm. In the cauda equina-type and mixed-type patients, CECT was significantly prolonged and there were negative correlations between CECT and dural sac cross-sectional area. CONCLUSIONS: Cauda equina conduction time differed according to the type of lumbar spinal stenosis. The prolongation of CECT may be caused by the demyelination of the CE. Cauda equina conduction time may be a useful measure for evaluating the dysfunction of the CE rather than radiculopathy for patients with lumbar spinal stenosis.

Assessment and management of cauda equina syndrome.

INTRODUCTION: Cauda equina syndrome (CES) is a rare condition that affects the nerves in the spine supplying the bladder, bowel and sexual function. Identification and subsequent urgent action is required to avoid permanent damage to these essential organs. Delays in diagnosis can have devastating and life changing consequences for patients and result in high cost negligence claims. PURPOSE: The purpose of this masterclass is to examine the current evidence and provide an evidence-based, clinically reasoned approach in the safe management of patients presenting with CES. It will include a focus on the importance of communication, documentation and a practical approach to safety netting those at risk. IMPLICATIONS FOR PRACTICE: CES has significant implications for patients and clinicians alike. Timely, effective diagnosis and management of patients with CES results in a better outcome.

Effect of Static Compression Loads on Intervertebral Disc: An in Vivo Bent Rat Tail Model.

OBJECTIVE: To evaluate how well different magnitudes of compression-induced degenerative changes using a bent rat tail model simulated human lumbar lordosis. It has been shown that compression plays an important role in intervertebral disc degeneration (IDD). METHODS: Sprague-Dawley rats (n = 25) were instrumented with a special compressive apparatus that was used to bend the intervertebral disc between the 8th and the 10th caudal vertebral bodies using two Kirschner wires inserted percutaneously into the middle of two tail vertebrae. Then, rats were divided into five different static compression loads (control, sham, 1.8 N, 4.5 N, and 7.2 N). The degeneration of the discs was evaluated by magnetic resonance imaging (MRI), histology, gene expression of anabolism and catabolism after 2 weeks. We used the signal characteristics of the disc in T2-weighted MRI to reflect the changes caused by degeneration as this is the most relevant and clinically recognized way to assess IDD. Pfirrmann classification was used to classify disc images. The tail discs from C8-9 and C9-10 with their two adjacent half vertebrae were carefully cut out and decalcified. Then the sections were paraffin-embedded and cut into 5-µm sections by histotome. Finally, they were stained with Safranin O-Fast Green and hematoxylin, and hematoxylin and eosin, respectively. Images were taken using a microscope and staining and compression-induced changes were assessed by a Masuda's grading scale. The relative expression levels of mRNA encoding rat anabolic genes and catabolic genes were evaluated by real-time reverse transcription (RT)-polymerase chain reaction (PCR). The mRNA expression fold change of the target gene was calculated using the 2-ΔΔCt method in the loaded and unloaded disc. RESULTS: As the loading magnitude increased, static compression produced a significantly progressive decrease in nucleus intensity on T2-weighted MRI, a decrease of aggrecan and Type II collagen, an increase in Matrix metallopeptidase-3 (MMP-3) and MMP-13 expressions, and a histomorphological degeneration. The sham group had a score of 1.4 ± 0.3, the 1.8 N group had a score of 2.4 ± 0.3, the 4.5 N group had a score of 3.2 ± 0.3, and the 7.2 N group had a score of 4.4 ± 0.3, which was based on the Pfirrmann classification score, in which the control group had a score of 1. These results demonstrated that the sham group was not significantly different from the control group. Histological analysis showed that in the loaded disc, the size of the nucleus was reduced and that the annular layer was disorganized. Based on the Masuda grading scale, scores were as follows: for the control group, 3.8 ± 0.35; sham, 4.2 ± 0.35; 1.8 N, 5.4 ± 0.35; 4.5 N, 7.6 ± 0.35; and 7.2 N, 10 ± 0.35. The gene expression was divided into the following: anabolic genes (aggrecan, collagen type1-α1, and collagen type2-α1) and catabolic genes (MMP-3 and MMP-13). Aggrecan and collagen type 2 were, respectively, downregulated from 0.42 ± 0.04 to 0.21 ± 0.04 and from 0.93 ± 0.06 to 0.17 ± 0.06 as the magnitude of compression increased, whereas collagen type 1 was significantly upregulated, from 2.49 ± 0.19 to 4.40 ± 0.19, when compared with the control group (from 1.8 to 7.2 N, P < 0.05). Catabolic genes MMP-3 and MMP-13 were significantly upregulated in all experimental groups (P < 0.05, MMP-3: from 1.46 ± 0.18 to 3.44 ± 0.18; MMP-13: from 1.19 ± 0.12 to 2.82 ± 0.13); however, MMP-13 exhibited no significant changes but tended to be upregulated when compared with the 1.8 N group with the 4.5 N group. CONCLUSIONS: Different stresses led to different processes of degenerative changes, the concave disc degenerating more severely as stress gradually increased.

Disorders of the Cauda Equina.

PURPOSE OF REVIEW: Conditions that affect the cauda equina are a diverse group of disorders that require timely recognition and management. This article reviews cauda equina anatomy, the diagnostic approach to disorders of the cauda equina, features of cauda equina syndrome, and diskogenic and nondiskogenic disorders of the cauda equina. RECENT FINDINGS: Establishing clinical criteria for cauda equina syndrome has been a focus of a number of reviews, although the clinician must maintain a low threshold for emergent imaging in cases of suspected cauda equina syndrome because of the suboptimal reliability of various signs and symptoms in identifying this condition clinically. The timing of surgical intervention for compressive causes of cauda equina dysfunction remains a point of contention, although urgent decompression remains standard practice. A recent review that focused on outcomes in patients with cauda equina compression who underwent surgical decompression identified significant residual deficits in patients despite appropriate and timely intervention. Autoimmune conditions targeting the cauda equina have been increasingly recognized, including chronic immune sensory polyradiculopathy and chronic immune sensorimotor polyradiculopathy. SUMMARY: Disorders that affect the cauda equina require thoughtful and timely clinical examination and diagnostic testing to establish a definitive cause and an appropriate treatment approach.

A significant correlation between cauda equina conduction time and cerebrospinal fluid protein in chronic inflammatory demyelinating polyradiculoneuropathy.

We investigated the relationship between the involvement of the cauda equina in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and the increment of cerebrospinal fluid (CSF) protein. We measured cauda equina conduction time (CECT) in 14 CIDP patients using magnetic stimulation with a MATS coil. Statistical analysis revealed that CECT and CSF protein had a significant positive linear correlation. Conduction time of the peripheral nerve trunk, in contrast, had no significant linear correlation with CSF protein. We revealed that the involvement of the cauda equina and increment of CSF protein are closely related. In CIDP cases with elevated CSF protein, spinal nerves including the cauda equina are very likely involved.

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.

Lesson of the month 2: Cauda equina in Cushing's syndrome.

We present the case of a 34-year old woman who initially presented with obesity and back pain. She was eventually diagnosed with Cushing's syndrome secondary to an adrenocortical carcinoma that had metastasised to her spine, causing cauda equina compression. The delays in reaching the correct diagnosis caused significant morbidity and exemplify the pitfalls of premature closing, a common cognitive error in diagnostic reasoning.

Lumbar Disc Herniation Causing Cauda Equina Syndrome in a Paediatric Patient. A Case Report.

Lumbar disc disease occurs mainly in the adult population. A disc prolapse in the paediatric population is very rare. Cauda equine syndrome resulting from compression of the cauda equina is a rare syndrome and is one of the few spinal surgical emergencies. Here we present a 13-year-old boy with pain in the lumbar region radiating bilaterally to the lower limbs, with asymmetrical weakness of lower the limbs, perianal hypoaesthesia and urinary retention. MRI of lumbar spine confirmed disc protrusion at the L3-L4 level with severe spinal canal stenosis. Patient was treated with microdiscectomy at the L3-L4 level. Postoperatively, his neurological deficit disappeared gradually. Although very rare, lumbar disc prolapse in the paediatric age group can lead to cauda equina syndrome. Early diagnosis and treatment can prevent life-long disability.

Neoplastic cauda equina syndrome: a neuroimaging-based review.

Cauda equina syndrome refers to dysfunction of the cauda equina, the collection of ventral and dorsal lumbar, sacral and coccygeal nerve roots that surround the filum terminale. This most commonly occurs as a result of compression by a herniated lumbosacral disc. However, the syndrome may also complicate metastatic cancer or a primary neoplasm within or infiltrating the spinal canal. An accurate and timely diagnosis is critical to avoid irreversible loss of neurological function. The clinician and radiologist must therefore be aware of the many possible causes to guide timely management. Here we review the diverse neoplastic causes affecting the cauda equina nerve roots from a neuroimaging-based perspective. We divide them by location into intramedullary neoplasms at the conus (such as astrocytoma), intradural-extramedullary neoplasms (such as schwannoma and leptomeningeal metastases) and extradural neoplasms (such as spinal metastases from systemic neoplasms). We also discuss the clinical features associated with cauda equina tumours, with special focus on cauda equina syndrome.

[ESTABLISHING AN ANIMAL MODEL OF DEFECATION RECONSTRUCTION AFTER SPINAL CORD INJURY IN RATS BY MECHANICAL POLISHING METHOD].

OBJECTIVE: To study the feasibility and advantages of preparing an animal model of defecation reconstruction after spinal cord injury in rats by mechanical polishing method. METHODS: Forty adult female Sprague Dawley rats (weighing, 250-300 g) were randomly divided into 2 groups (n=20). The lamina was opened by mechanical polishing method to expose the cauda equina in experimental group, then bilateral L5 and S1 nerve roots end-to-end anastomosis was done under 10 times microscope, and finally cauda equina between the L5 and L6 (except S1) was cut. The lamina was opened by traditional bites method in control group, and the other treatment methods were in agreement with the experimental group. The operative time, intra-operative blood loss, and situation of rats at postoperative 3 days were recorded. RESULTS: The operative time of experimental group[(93.05±7.60) minutes] was significantly shorter than that in control group[(131.30±11.68) minutes] (t=12.279, P=0.000); intra-operative blood loss in experimental group[(4.33±0.46) mL] was significantly lower than that in control group[(7.36±0.58) mL] (t=18.293, P=0.000). At 3 days after operation, 18 rats (90%) survived in experimental group, and 12 rats (60%) survived in control group; difference was significant in the survival rate between 2 groups (χ2=4.800, P=0.028). CONCLUSIONS: To establish an animal model of defecation reconstruction after spinal cord injury in rats by mechanical polishing method is feasible, and it has shorter operative time, less blood loss, and lower postoperative mortality than the traditional bites method. But there is a certain learning curve and requirement to master microsurgical techniques.

Fecal incontinence as a predominant symptom in a case of multiply recurrent tethered cord: diagnosis and operative strategies.

Recurrent manifestations of tethered spinal cord after an initial operative intervention for a simple fatty filum terminale is fairly uncommon. The authors present the case of an unusual clinical course in which there were 3 distinct episodes of recurrence, each time presenting predominantly as fecal incontinence and resolving with operative intervention. Typical signs of tethering were absent on radiological evaluation, and operative intervention was based on clinical grounds. Intraoperatively, sacral nerve roots to the anal sphincter were found tethered to the filar stump with electrophysiological evidence of regained activity on disentanglement. To the best of the authors' knowledge, a similar clinical course or operative findings have not been reported.

[Intraoperativ electrophysiological monitoring during neurosurgery on eloquent structures]. / Intraoperatív elektrofiziológia elokvens idegrendszeri struktúrákat erinto idegsebészeti beavatkozások során.

OBJECTIVE: We summarize our experiences on intraoperative electrophysiological monitoring during neurosurgical procedures on eloquent neuronal structures. PATIENTS, METHODS: Sixty patients were enrolled retrospectively in our study with pathologies involving eloquent neuronal structures. They were operated between May 2011. and March 2012. at the University of Debrecen, Department of Neurosurgery and at the National Institute of Neurosciences. Patients underwent standard preoperative examinations due to the primary pathology. In all cases we used intraoperative electrophysiological monitoring. We had 22 cases with cranial nerve monitoring, 10 cases with cauda monitoring, 16 cases with motor system monitoring, six cases with complex spinal cord monitoring, three degenerative spine reconstructions and 3 awake surgeries. RESULTS: We found that with the use of intraoperative electrophysiology we could make these neurosurgical procedures safer, and were able to optimize the extent of resection in the cases of oncological pathologies. CONCLUSIONS: Our experiences as well as the international literature suggests that in certain high risk neurosurgical procedures intraoperative electrophysiology is indispensible for safe and optimally extended operation.

Cauda equina conduction time in Guillain-Barré syndrome.

The proximal segment of peripheral nerves is assumed to be involved in both demyelinating and axonal types of Guillain-Barré syndrome (GBS). However, electrophysiological examinations have not yet clarified if this segment is involved. We measured cauda equina conduction time (CECT) in nine demyelinating GBS and seven axonal GBS patients. Compound muscle action potentials (CMAPs) were recorded from the abductor hallucis muscle. Electrical stimulation was given at the ankle and the knee, and magnetic stimulation was given over the first sacral (S1) and first lumbar (L1) spinous processes using a magnetic augmented translumbosacral stimulation (MATS) coil. CECT was obtained by subtracting S1-level latency from L1-level latency. CECT was prolonged in all the patients with demyelinating GBS who had leg symptoms, whereas motor conduction velocity (MCV) at the peripheral nerve trunk was normal in all the patients. In all the patients with axonal GBS having leg symptoms, CECT and MCV were normal and no conduction blocks were detected between the ankle and the neuro-foramina. The cauda equina is much more frequently involved than the peripheral nerve trunk in demyelinating GBS. In axonal GBS, usually, CECT is normal and segmental lesions are absent between the ankle and the neuro-foramina. Therefore, the CECT measurement should be very useful for directly detecting demyelinating lesions in GBS.

Changes in excursion and strain in the rat sciatic nerve under cauda equina compression induced by epidural balloon inflation.

BACKGROUND CONTEXT: Healthy nerves are able to stretch and glide as responses to normal physiological movement. Injury to the nerve may alter the nerve's mechanical properties and result in neuropathy. Whether cauda equina compression alters the mechanical properties of the sciatic nerve is still unclear. PURPOSE: The purpose of this study was to demonstrate the changes in excursions and strains of the sciatic nerve in vivo after acute cauda equina compression was induced by epidural balloon compression. STUDY DESIGN: An animal comparative study with induced cauda equina compression was designed for in situ measurements of nerve properties. METHODS: Twenty-six adult Sprague-Dawley rats were divided into three groups. The balloon group (n=10) underwent epidural compression induced by inflation of an embolectomy balloon catheter that was inserted through an L6 laminotomy. The control group (n=10) underwent laminotomy but without compression. The normal group (n=6) received no back surgery. This model of neuropathy was confirmed with electrophysiological examination. The excursions and strains of the sciatic nerve in response to the modified straight leg-raising (SLR) test were measured in situ and analyzed. RESULTS: The scales of the excursions were lower in the balloon group than in the other two groups, in both 90° flexion and extension of the knee. The balloon group was more sensitive to positional changes. The strain was significantly higher under the condition of epidural balloon compression. CONCLUSIONS: We concluded that cauda equina compression decreased the excursion and increased the strain of the sciatic nerve in response to a modified SLR test. These findings might indicate one of the mechanisms of the pain provoked by the SLR test and also possibly contribute to an understanding of the pathogenesis of the neuropathy in the lower limbs of patients with cauda equina compression.

Detrusor overactivity in patients with cauda equina syndrome.

STUDY DESIGN: Retrospective cross-sectional study. OBJECTIVE: To delineate the neurogenic bladder type in patients with cauda equina syndrome (CES) and to suggest, in light of the clinical, radiological, and electrophysiological findings, a possible cause of bladder dysfunction. SUMMARY OF BACKGROUND DATA: Many patients with CES experience bladder dysfunction, although the type of neurogenic bladder is quite variable in the clinical setting. Bladder dysfunction in patients with CES is usually areflexic or acontractile detrusor. However, detrusor overactivity (DOA) also reported the cases that cannot be explained by pure root injuries in the cauda equina region. METHODS: Patients with CES with neurogenic bladder were studied, all of whom (n = 61; mean age ± SD, 48.0 ± 15.9 yr) underwent urodynamic analysis, magnetic resonance imaging (MRI), and electrophysiology. According to the urodynamic findings, the neurogenic bladder was classified into 2 types: DOA and detrusor underactivity or acontractility. The highest level of injury (HLI) or level of injury was determined and analyzed on the basis of the clinical-urodynamic and electrophysiological findings, respectively. RESULTS: Twenty patients with CES (32.8%) showed DOA; in most of them (85.0%, 17/20 patients), the HLI on electrophysiological assessment was L2 or above. Forty-one patients with CES showed detrusor underactivity or acontractility; and most of the patients with CES whose HLI was L3 or below showed detrusor underactivity or acontractility (91.2%, 31/34 patients). None of the HLI or level of injury from the clinical or magnetic resonance imaging findings correlated with neurogenic bladder type. We also found that urodynamic findings including maximal detrusor pressure and bladder capacity was partially correlated with the HLI on electrophysiological assessment (r² = 0.244, P < 0.001 and r² = 0.330; P < 0.001, respectively). CONCLUSION: DOA was seen most often in patients with CES whose HLI was L2 or above, and might be associated with combined conus medullaris lesion. Electrophysiology might be the most useful assessment tool for prediction of neurogenic bladder type in patients with CES.

Clinical significance of imaging and histological characteristics of filum terminale in tethered cord syndrome.

OBJECT: The pathophysiology of tethered cord syndrome (TCS) is uncertain; however, it has been suggested that fibrous and fatty elements within the filum terminale (FT) play a role. The objective of this study was to describe the radiological and histological features of the FT in TCS and determine if there are associations between those features and clinical outcomes, complications, and urodynamics. METHODS: In this retrospective study, histological, MRI, and clinical data obtained in 293 patients with TCS who underwent FT transection were reviewed and analyzed in a multivariate analysis. RESULTS: The median patient age was 4.9 years (range 0.3-64.3 years). On MRI, a fatty filum was present in 65% of patients and a thickened filum (> 2 mm) was seen in 45%. Histologically, the FT contained prominent fibrous tissue in 95%, nerve twigs in 79%, adipose tissue in 59%, and vascular tissue in 36%. Histological features associated with a thickened filum on MR images were adipose tissue (OR 3.5, p < 0.001), nerve twigs (OR 2.2, p = 0.028), and vascular tissue (OR 0.5, p = 0.025). Adipose tissue was associated with a conus level below the L2-3 disc space (OR 2.3, p = 0.031) and with a fatty filum on imaging (OR 9.8, p < 0.001). Nerve twigs were associated with abnormal urodynamics (OR 10.9, p = 0.049). The only variable predictive of clinical improvement was conus level; patients with conus levels caudal to L-2 were less likely to improve postoperatively (OR 0.3, p = 0.042). CONCLUSIONS: Fibrous tissue was ubiquitous and may be important in the pathophysiology of TCS. Nerve twigs and adipose tissue were associated with abnormal urodynamics and low-lying coni, respectively. Although the majority of patients clinically improved, patients with normal conus levels had significantly better outcomes.

Differentiation of neonatal dorsal root ganglion-derived neural stem cells into oligodendrocytes after intrathecal transplantation into a cauda equina lesion model.

Cauda equina syndrome (CES) is characterized by varying patterns of low back pain, sciatica, lower extremity sensorimotor loss, and bowel and bladder dysfunction. The prognosis for complete recovery of CES is dependent on not only the time before surgical intervention with decompression but also the severity of the nerve damage. Delayed or severe nerve compression impairs the capability of nerve regeneration. Transplantation of neural stem cells (NSCs) may facilitate axon regeneration and functional recovery in a spectrum of neurological disorders. Our study shows that the NSCs derived from early postnatal dorsal root ganglion (DRG) are able to proliferate to form neurospheres and differentiate into O4(+) oligodendrocytes but not glial fibrillary acidic protein (GFAP(+)) astrocytes or ßIII-tubulin(+) neurons in vitro. After intrathecal transplantation into the lumbar spinal canal stenosis animal model, most of the GFP-expressing NSCs were induced to differentiate into oligodendrocytes in vivo. Although the recovery of sensorimotor function was not significantly improved in rats with transplantation therapy, our results implied that subarachnoid microinjection of NSCs may promote axon regeneration of DRG neurons in the cauda equina model after nerve injury.