L5 Root Research Articles

Lumbar Epidural Steroid Injection for Painful Spasticity in Cervical Spinal Cord Injury: A Case Report.

We report a case of a 53-year-old male with traumatic cervical spinal cord injury (SCI). He could not maintain a standing position because of painful spasticity in his lower limbs. A magnetic resonance imaging and electromyography indicated chronic lumbosacral radiculopathy, explaining his chronic low back pain before the injury. For diagnostic as well as therapeutic purposes, transforaminal epidural steroid injection (ESI) to the right L5 root was performed. After the intervention, the spasticity decreased and his ambulatory function improved. This case illustrates that lumbar radiculopathy concomitant with a cervical SCI can produce severe spasticity and it can be dramatically improved by ESI.

Pathophysiology of knee jerk reflex abnormalities in L5 root injury.

Although the knee jerk reflex is mediated by the L3 and L4 nerve roots, evidence exists that altered knee jerk expression may occur with exclusively L5 radiculopathy. The present study set out to identify the factors responsible for knee jerk reflex abnormalities in L5 monoradiculopathy. We analyzed clinical and electrophysiological data in 56 subjects affected by L5 monoradiculopathy. Seventeen patients (30.3%) showed an abnormal knee reflex. L5 patients with an abnormal knee reflex differed significantly, in severity of pretibial muscle damage, from those with a normal knee reflex. On the basis of evidence, in humans, of a specific spinal pathway linking the pretibial and quadriceps muscles, we infer that an impairment of the proprioceptive drive from the pretibial muscles to spinal premotor excitatory interneurons contacting quadriceps motor neurons is the main causative factor responsible for reducing knee jerk expression. This mechanism should be considered to avoid misinterpretation of knee jerk reflex changes in lumbar radiculopathies.

A Rare Complication of Lumbar Spine Surgery: Pneumocephalus

Purpose: Pneumocephalus is an uncommon but serious complication of spinal surgery and its management and pathophysiology is not widely recognized. Incidence of symptomatic tension pneumocephalus secondary to posterior spinal arthrodesis is unknown. We describe a case of symptomatic tension pneumocephalus in the postoperative period of lumbar arthrodesis surgery, causes, risk factors, treatment and a review of the literature about this uncommon complication. Methods: The clinical findings, radiological studies (Magnetic resonance imaging and CT scan), and treatment were presented. Results: We report a rare case of a 41 year old woman with diagnosis of L3-L4, L4- L5 discopathy and left discal herniation L4-L5. A posterior spinal arthrodesis L3-L5, L3-L4 and L4-L5 discectomies and release of the left L5 root, was performed without apparent complications. 24 hours after surgery the patient developed generalized headache, neck stiffness, and dysarthria. MRI and CT scan revealed a huge pneumocephalus in the subarachnoid space, predominantly in the left frontal lobe without midline shift, which originates in the lumbar spinal canal. Treatment: The patient was treated conservatively, featuring 72 hours from progressive neurological improvement, up to clinical and radiological normalization after 7 days. Conclusions: Pneumocephalus is a rare but potentially serious complication of spine surgery related in most cases with inadvertent dural tear during surgery. Most collections are small, behave benign, and respond to conservative therapy. In the majority of patients with pneumocephalus, a conservative approach consisting of bedrest, hyperhydration, analgesics, sedatives, and antiemetics is adequate, and symptoms resolve in a few weeks. In the present case with inadvartent CSF fistula, the vacuum drainage system predisposed the patient to pneumocephalus. A high degree of suspicion is needed to make the diagnosis, prompt treatment, and remedy of the source of air to prevent unwanted morbidity and mortality.

Hitchhiker's Toe and Lumbar Disc Lesion: A Strange Coincidence in a Patient with Idiopathic Dystonia Treated with Botulinum Toxin Injection

Abstract A 40 years old female with generalised dystonia and chronic low back pain was injected with botulinum toxin injection to extensor hallucis longus(EHL) for management of Hitchhiker's toe. The patient benefited functionally but later developed EHL and extensor digitorum (ED) weakness. Further workup revealed degenerative L4/5 disc lesion causing L5 root affection as the cause for the weakness. This coincidental occurrence of EHL and ED weakness due to L4/5 disc lesion in a patient with generalised dystonia, following botox injection to EHL for management of Hitch hiker's toe, has not been reported before.

Saignement péridural suite à une analgésie péridurale obstétricale

Anaesthetists often stand in the front line to manage postpartum neurological deficits, although epidural analgesia is rarely responsible for these complications. An epidural analgesia was performed to relieve pain during spontaneous labor in a 34-year-old parturient. An emergency C-section was subsequently required due to fetal heart rate abnormalities. Twelve hours after catheter removal, the parturient developed a severe right leg motor and sensory neurological deficit, predominant on L5 and S1 roots and diagnosed by a neurologist as a central nerve root injury. Lumbar MRI identified a non-compressive epidural bleeding in front of the L5 vertebral body. Epidural bleeding after labor epidural analgesia is a rare complication that may jeopardize the functional prognosis. It may be difficult in some cases to differentiate an upper plexus injury due to labor and delivery from a central epidural analgesia-related nerve root lesion. Fetal head compression at the pelvic brim may induce neurological deficits in several well-differentiated nervous territories, thus mimicking an anaesthetic-induced perimedullar radiculopathy.

Pre- and Postoperative Evaluation of Patients With Lumbosacral Disc Herniation by Neurophysiological and Clinical Assessment

The application of complex neurophysiological examination including motor evoked potentials (MEP) for pre- and postoperative evaluation of patients experiencing acute sciatica. The assessment of sensitivity and specificity of needle electromyography, MEP, and H-reflex examinations. The comparative analysis of preoperative and postoperative neurophysiological examination. In spite of the fact that complex neurophysiological diagnostic tools seem to be important for interpretation of incompatible results of neuroimaging and clinical examination, especially in the patients qualified for surgical treatment, their application has never been completely analyzed and documented. Pre- and postoperative electromyography, electroneurography, F-waves, H-reflex, and MEP examination were performed in 23 patients with confirmed disc-root conflict at lumbosacral spine. Clinical evaluation included examination of sensory perception for L5-S1 dermatomes, muscles strength with Lovett's scale, deep tendon reflexes, pain intensity with visual analogue scale, and straight leg raising test. Sensitivity of electromyography at rest and MEP examination for evaluation of L5-S1 roots injury was 22% to 63% and 31% to 56% whereas specificity was 71% to 83% and 57% to 86%, respectively. H-reflex sensitivity and specificity for evaluation of S1 root injury were 56% and 67%, respectively. A significant improvement of root latency parameter in postoperative MEP studies as compared with preoperative was recorded for L5 (P = 0.039) and S1 root's levels (P = 0.05). The analysis of the results from neurophysiological tests together with neuroimaging and clinical examination allow for a precise preoperative indication of the lumbosacral roots injury and accurate postoperative evaluation of patients experiencing sciatica. 3.

Diffusion-weighted magnetic resonance (DW-MR) neurography of the lumbar plexus in the preoperative planning of lateral access lumbar surgery.

Magnetic resonance (MR) neurography has been used to evaluate entire nerves and nerve bundles by providing better contrast between the nerves and the surrounding tissues. The purpose of the study was to validate diffusion-weighted MR (DW-MR) neurography in visualizing the lumbar plexus during preoperative planning of lateral transpsoas surgery. Ninety-four (188 lumbar plexuses) spine patients underwent a DW-MR examination of the lumbar plexus in relation to the L3-4 and L4-5 disc spaces and superior third of the L5 vertebral body. Images were reconstructed in the axial plane using high-resolution Maximum Intensity projection (MIP) overlay templates at the disc space and L3-4 and L4-5 interspaces. 10 and 22 mm MIP templates were chosen to mimic the working zone of standard lateral access retractors. The positions of the L4 nerve root and femoral nerve were analyzed relative to the L4-5 disc in axial and sagittal planes. Third-party radiologists and a senior spine surgeon performed the evaluations, with inter- and intraobserver testing performed. In all subjects, the plexus was successfully mapped. At L3-4, in all but one case, the components of the plexus (except the genitofemoral nerve) were located in the most posterior quadrant (zone IV). The L3 and L4 roots coalesced into the femoral nerve below the L4-5 disc space in all subjects. Side-to-side variation was noted, with the plexus occurring in zone IV in 86.2 % right and only 78.7 % of left sides. At the superior third of L5, the plexus was found in zone III in 27.7 % of right and 36.2 % of left sides; and in zone II in 4.3 % right and 2.1 % left sides. Significant inter- and intraobserver agreement was found. By providing the surgeon with a preoperative roadmap of the lumbar plexus, DW-MR may improve the safety profile of lateral access procedures.

Comparison between bipolar and tetrapolar of the interferential current in nociceptive threshold, accommodation and pleasantness in healthy individuals

The study compared the effects between bipolar (BI) and tetrapolar (TT) forms of the interferential current (IC), on intensity and pain threshold to cold and pressure, accommodation and pleasantness of the current in healthy subjects. For this, a random, double-blind crossover study with 24 healthy subjects, of both genders, who were equally distributed in two groups, was conducted. The first evaluated item was the pain threshold to cold. The volunteers immersed the dominant foot in iced water (5°C) for 30 s, and recorded the pain threshold to cold. At the end, they graded the pain intensity by a visual analog scale (VAS). Soon after the pain threshold to pressure was evaluated with the use of a pressure algometer between the first and second metatarsal and L3 spinous process. Then the volunteers were submitted to the application of the IC, with the following parameters: 4000 Hz base frequency, amplitude modulated frequency (AMF) 50 Hz, for 20 min. Volunteers were re-evaluated straight away, 20 and 60 min after the IC usage. The last part of the analysis consisted of, after application of BI and TT, knowing which was the most enjoyable. The results revealed that in the evaluation of the pain threshold to pressure on the metatarsal, there was significant difference when comparing all evaluations of BI with only the last of TT; there was also difference on the accommodation threshold. We concluded that the IC usage, on nerve roots L4 and S3, on the proposed parameters, produced a higher accommodation threshold in the TT form, and it was more effective than BI on the metatarsal. However, the pain threshold to pressure (on the spine), to cold and its intensity did not suffer any change.

2014 Young Investigator Award Winner

Controlled radiological study.To investigate noninvasively in vivo spinal cord displacement in the vertebral canal during the passive straight leg raise (SLR) in asymptomatic subjects. The basic assumption is that the cord follows L5 and S1 nerve roots displacement by similar magnitude and direction (principle of linear dependence).It is generally accepted that the SLR produces some caudal movement mainly of L5 and S1 nerve roots, but the magnitude of this displacement is still a matter of debate.Sixteen asymptomatic volunteers were scanned with 1.5-T magnetic resonance scanner (Siemens Avanto, Erlangen, Germany) using T2-weighted turbo spin-echo fat-saturation sequence. The displacement of the medullar cone relative to the vertebral endplate of the adjacent vertebra during the passive SLR was quantified and compared with the position of the conus in the neutral (anatomic) position. Each movement was performed twice for evaluation of reproducibility. The measurements were repeated by 2 observers. Four practitioners performed the maneuvers in a random sequence to avoid series effects.Compared with the neutral (anatomic) position, the medullar cone displaced caudally in the spinal canal by 2.31 ± 1.2 mm with right (P ≤ 0.001) and 2.35 ± 1.2 mm with left SLR (P ≤ 0.001). Spearman correlations proved higher than 0.99 for intra and interobserver reliability, as well as results reproducibility testing for each maneuver.The data show that the spinal cord in the thoracolumbar region slides distally in response to the clinically applied SLR test. The high correlation values in this study show that these movements are consistent and reproducible. Because of the neural continuum, the authors speculate that this movement might be directly proportional to the sliding of the L5 and S1 neural roots. This study offers baseline measurements on which further studies in diagnosis of lumbar disc protrusion and radiculopathy may be developed.

Quantitative evaluation of normal lumbosacral plexus nerve by using diffusion tensor imaging

Objective To observe the lumbosacral plexus nerves by diffusion tensor tractography (DTT) and quantitatively evaluate them by using diffusion tensor imaging (DTI) in healthy volunteers.Methods A total of 60 healthy volunteers (30 males and 30 females) underwent DTI scanning.Mean FA values of the lumbosacral plexus nerves (both sides of lumbar roots L3 to S1,proximal and distal to the lumbar foraminal zone) were quantified.Differences among various segments of lumbar nerve roots were compared with ANOVA test and SNK test.Differences between two sides of the lumbar nerve roots at the same lumbar segment were compared with paired-samples t test.Differences between the proximal and the distal nerve to the the lumbar foraminal zone at the same lumbar segment were compared with paired-samples t test.The lumbosacral plexus nerve was visualized with tractography.Results (1) The lumbosacral plexus nerve was clearly visualized with tractography.(2) Mean FA values of the lumbar nerve roots L3 to S1 were as followings:proximal to the left lumbar foraminal zone 0.202 ± 0.021,0.201 ± 0.026,0.201 ± 0.027,0.191 ±0.016,distal to the left lumbar foraminal zone 0.222 ± 0.034,0.250 ± 0.028,0.203 ± 0.026,0.183 ± 0.020,proximal to the right lumbar foraminal zone 0.200 ± 0.023,0.202 ± 0.023,0.205 ± 0.027,0.191 ±0.017,distal to the right lumbar foraminal zone 0.225 ±0.032,0.247 ±0.027,0.205 ± 0.033,0.183 ±0.021.Mean FA values were significantly different between the proximal nerve to the distal nerve in lumbar nerve roots L3,L4,S1 (t =-9.114-2.366,P ＜ 0.05),but not significantly different in L5 (P ＞ 0.05).Differences were not found between the right and left side nerves at the same lumbar segment (P ＞ 0.05).(3) The whole length of the lumbar roots nerve L3 to S1 can be visualized clearly by using DTT.Conclusions Diffusion tensor imaging and tractography can show and provide quantitative information of human lumbosacral plexus nerves.DTI is a potential tool for the diagnosis of lumbosacral plexus nerve disease. Key words: Diffusion magnetic resonance imaging; Lumbosacral plexus; Spinal nerve roots

Electromyography and Nerve Conduction Studies in Patients with Lumbar Spinal Stenosis: Is Neurophysiological Examination an Important Tool?

Background: There is no single test that defines properly lumbar spinal stenosis (LSS) diagnosis, and diagnosis of the syndrome continues to rely on clinical judgment. LSS symptoms may be broad and may be seen in multiple disorders in elderly. Hypothesis: To identify the role of electromyography and nerve-conduction studies on LSS diagnosis. Materials and Methods: A cross-sectional study with prospective data collection was conducted. 31 symptomatic patients with LSS confirmed by MRI were evaluated with neurophysiology tests. We compared symptoms and neurophysiologic findings. Results: All patients reported pain, 83.9% of patients reported it to be moderate or severe and 90% of patients took pain medication. LSS did not affect NCS or SSR. Electromyography confirmed high frequency of radiculopathy, particularly multiradiculopathy. L5 and S1 roots were the most susceptible to injuries. We also found a higher prevalence of L4 radiculopathy. Discussion: Correlating electromyography with clinical findings, we found that the clinical presentation, the most important starting point of an evaluation, is poor in terms of identifying radiculopathy, a frequent consequence of LSS. For this reason, we suggest that electromyography may play an important role as a diagnostic tool, being useful in determining when symptoms are neurogenic in nature. In addition, it may serve to focus treatment only in the area where it is really necessary

Increased dietary salt intake enhances the exercise pressor reflex

Increased dietary salt in rats has been shown to sensitize central sympathetic circuits and enhance sympathetic responses to several stressors, including hyperinsulinemia, intracerebroventricular injection of angiotensin, and electrical stimulation of sciatic nerve afferents. These findings prompted us to test the hypothesis that increased dietary salt enhanced the exercise pressor reflex. Male Sprague-Dawley rats were fed 0.1% (low) or 4.0% (high) NaCl chow for 2 to 3 wk. On the day of the experiment, the rats were decerebrated, and the hind limb muscles were statically contracted for 30 s by electrically stimulating the cut peripheral ends of the L4 and L5 ventral roots. We found that contraction produced a significantly greater increase in mean arterial pressure of rats fed 4.0% (n = 26) vs. 0.1% (n = 22) NaCl (24 ± 2 vs. 15 ± 2 mmHg, respectively; P < 0.05). Baseline mean arterial pressure was not different between groups (0.1%, 77 ± 4 vs. 4.0% NaCl, 80 ± 3 mmHg). Likewise, the tension time indexes were not different between the two groups (P = 0.42). Section of the L4 and L5 dorsal roots greatly attenuated both the pressor and cardioaccelerator responses to contraction in both groups of rats, an effect showing that the responses were reflex in origin. Finally, electrical stimulation of the lumbar sympathetic chain produced similar increases in mean arterial pressure and decreases in femoral arterial blood flow and conductance between rats fed 0.1% vs. 4.0% NaCl diets. We conclude that increased dietary salt enhances the exercise pressor reflex.

Technical note: Resolution of spontaneous electromyographic discharge following disk-space distraction during lateral transpsoas interbody fusion

PurposeThe lateral transpsoas interbody fusion (LTIF) is an increasingly popular minimally invasive technique for lumbar interbody fusion. Although a posterior approach to the lumbar spine has traditionally been favored for the treatment of canal stenosis and neural foraminal stenosis, a growing body of evidence suggests that indirect decompression of the spinal canal and neural foramen can be achieved using a lateral transpsoas approach to the lumbar spine. We present 2 cases that may suggest a role for spontaneous electromyography (s-EMG) monitoring in assessing the adequacy of decompression during LTIF. MethodsThe 2 cases presented in this technical note illustrate resolution of s-EMG firing during LTIF, following distraction across the disk space. Removal of the distracting device produced the return of s-EMG firing. Both of these cases were operated at the L2-3 level. ResultsIn the first case, s-EMG firing was noted in the bilateral tibialis anterior leads. Resolution of EMG firing may suggest indirect decompression of the canal via ligamentotaxis as the L5 root traverses the L2-3 disk space. In the second case, s-EMG firing was noted in the left abductor hallucis and resolved with distraction of the L2-3 disk space. Again, this may be explained by canal decompression via ligamentotaxis as the S1 root traverses the L2-3 disk space. ConclusionIn both cases, distraction across the disk space resulted in resolution of s-EMG discharges—this correlated with an improvement in symptoms. These findings may suggest a role for s-EMG as a marker for adequacy of decompression in a select subset of patients undergoing LTIF. Further study is needed to determine if resolution of s-EMG is a useful measure of indirect decompression during LTIF.

Abstract 434: Increased Dietary Salt Intake Enhances the Exercise Pressor Reflex

Increased dietary salt in rats has been shown to sensitize central sympathetic circuits and enhance sympathetic responses to several stressors, including hyperinsulinemia, intracerebroventricular injection of angiotensin and electrical stimulation of sciatic nerve afferents. These findings prompted us to test the hypothesis that increased dietary salt enhanced the exercise pressor reflex.Male Sprague-Dawley rats were fed 0.1% (n=16) or 4.0% (n=18) NaCl chow for 14-21 days. Then, rats were decerebrated and the exercise pressor reflex was produced by static contraction of the hindlimb muscles through electrical stimulation of the cut peripheral ends of the L4 and L5 ventral roots. We found that contraction produced a significantly greater increase in mean arterial pressure of rats fed 4.0% NaCl (24±2 mmHg) versus 0.1% NaCl (15±2 mmHg). Baseline mean arterial pressure was not different between 0.1% versus 4.0% NaCl diets (79±5 vs 83±4 mmHg). The tension time indices were not different between the 0.1% (17±1 kg per s) versus 4.0% (18.2±2 kg s) NaCl groups (P = 0.422). The enhanced responsiveness to contraction appeared to be attributable to sensitized group III mechanoreceptors because the renal and lumbar sympathetic responses to contraction were augmented within 200 ms of the onset of contraction. Section of the L4 and L5 dorsal roots abolished the pressor responses to contraction in both groups of rats, an effect showing that the responses were reflex in origin. We conclude that increased dietary salt can enhance the reflex sympathetic responses to static exercise.

High-grade lumbosacral spondylolisthesis reduction and fusion in children using transsacral rod fixation

There is no consensus on how to treat surgically high-dysplastic developmental spondylolisthesis in children and adolescents. Although reducing spinal deformity seems mandatory, the issue of surgical reduction versus in situ fusion remains controversial. The files of 12 consecutive patients surgically treated for a grade 3 or 4 spondylolisthesis were reviewed. The treatment consisted in L4 to sacrum reduction and fusion by posterior approach. The reduction of lumbopelvic imbalance was made intraoperatively using a trans-sacral rod fixation technique. Mean preoperative L5 anterior slippage was 72.3 % (60 to 95 %). The mean preoperative lumbosacral tilt angle was 70.5° (43 to 92°). Mean final lumbosacral tilt angle was 102° (91 to 114°). Mean final L5 anterior slippage was 19 % (7 to 63 %). Neurological complications (radicular L5 or S1 deficits) were noted in five patients. At final follow-up L4 to S1 fusion was achieved in all patients. No patient had persistent deficit or radicular pain. The fusion rate in our series proved to be optimal. Thanks to the trans-sacral rod fixation, lumbosacral kyphosis correction was very good. The intrasacral positioning of the screws reduces the risk of implant prominence especially in such pediatric patients. We stress the importance to avoid complete slip reduction in such patients to minimize stretching on L5 and S1 roots. No additional immobilization is needed due to solid posterior instrumentation. Doing such procedure only by posterior approach avoids anterior approach-related complications.

Spinal nociceptive hyperexcitability induced by experimental disc herniation is associated with enhanced local expression of Csf1 and FasL

Sciatica after disc herniation may be associated with compression of spinal nerves, but also inflammatory substances released from the nucleus pulposus (NP) leaking into the spinal canal. Here, in an animal model mimicking clinical intervertebral disc herniation, we investigate the effect of NP on neuronal activity. In anaesthetized Lewis rats, extracellular single-unit recordings of spinal dorsal horn neurons were performed, and the C-fibre responses were examined. Moreover, quantitative polymerase chain reaction was used to explore the gene expression of proinflammatory cytokines in the NP tissue exposed to the spinal dorsal nerve roots L3–L5. In accordance with earlier studies, we showed a significant increase in the C-fibre response and an upregulation of the gene expression of interleukin 1β and tumour necrosis factor 180minutes after application of NP onto the nerve roots. Moreover, based on a polymerase chain reaction array of 84 common inflammatory cytokines at the same time point, we demonstrated a highly significant upregulation of colony-stimulating factor 1 also termed macrophage colony-stimulating factor and Fas ligand. The pronounced upregulation of Csf1 and Fas ligand 180minutes after application of NP onto the nerve roots suggests that macrophage activation and apoptosis may be involved in pain hypersensitivity and other sensory abnormalities after disc herniation.

Surgical treatment of high-grade dysplastic spondylolisthesis using intraoperative electrophysiological monitoring: report of two cases and review of the literature

Treatment of high-grade dysplastic spondylolisthesis in adolescents remains challenging. Surgical treatment of spondylolisthesis has been recommended in adolescents with pain refractory to conservative treatment, slippage progression, or severe slippage on presentation. Controversy exists as to the optimal surgical approach for high-grade spondylolisthesis. Moreover, some authors reported the incidence of L5 root palsy during the reduction procedure. We performed 2 cases of surgical treatment using intraoperative electrophysiological monitoring for patients with high-grade dysplastic spondylolisthesis in adolescence. Each patient received treatment consisting of decompression of nerve with surgical microscope, reduction, and circumferential fusion with transpedicular and monosegmental fixation surgery with intraoperative neurological monitoring with transcranial electric motor evoked potentials and continuous spontaneous electromyography recording. Intraoperative monitoring did not show any abnormal changes. The patients got well after surgery, and they showed no postoperative motor paralysis of the extremities. A postoperative radiogram showed reduction of the slippage, and computed tomogram showed bone union between L5 and S1 vertebral body. This report describes 2 cases of surgical treatment using intraoperative electrophysiological monitoring with transcranial electric motor evoked potentials and continuous spontaneous electromyography for patients with high-grade dysplastic spondylolisthesis in adolescence. We successfully perform the surgery without any neurological deficit using intraoperative electrophysiological monitoring.

Neuroprotection and axonal regeneration after lumbar ventral root avulsion by re-implantation and mesenchymal stem cells transplant combined therapy.

Ventral spinal root avulsion causes complete denervation of muscles in the limb and also progressive death of segmental motoneurons (MN) leading to permanent paralysis. The chances for functional recovery after ventral root avulsion are very poor owing to the loss of avulsed neurons and the long distance that surviving neurons have to re-grow axons from the spinal cord to the corresponding targets. Following unilateral avulsion of L4, L5 and L6 spinal roots in adult rats, we performed an intraspinal transplant of mesenchymal stem cells (MSC) and surgical re-implantation of the avulsed roots. Four weeks after avulsion the survival of MN in the MSC-treated animals was significantly higher than in vehicle-injected rats (45% vs. 28%). Re-implantation of the avulsed roots in the injured spinal cord allowed the regeneration of motor axons. By combining root re-implantation and MSC transplant the number of surviving MN at 28 days post-injury was higher (60%) than in re-implantation alone animals (46%). Electromyographic tests showed evidence of functional re-innervation of anterior tibialis and gastrocnemius muscles by the regenerated motor axons only in rats with the combined treatment. These results indicate that MSC are helpful in enhancing neuronal survival and increased the regenerative growth of injured axons. Surgical re-implantation and MSC grafting combined had a synergic neuroprotective effect on MN and on axonal regeneration and muscle re-innervation after spinal root avulsion.

L5/S1椎間孔外狭窄についての検討

Extraforaminal stenosis at the lumbosacral junction is less common than intraspinal canal lesions, and the radiological diagnosis is less established. We present 10 cases that presented with neurological deficits compatible with a diagnosis of L5 radiculopathy, such as sensory disturbance in the L5 area associated with neurogenic claudication. Radiography demonstrated lumbar scoliosis and wedging of the L5-S1 intervertebral space in 6 patients, and transitional vertebra (Castellvi types IB, IIA, and IIB) in 6 patients. Computed tomography demonstrated marked osteophyte formation at the posterolateral margin of the L5-S1 vertebral bodies in all 10 patients. Coronal constructive interference in steady-state magnetic resonance imaging showed extraforaminal entrapment of the L5 root. Decompression procedures included partial resection of the L5 pars interarticularis, sacral ala, and L5 transverse process along the L5 spinal nerve. Osteophytes of the L5-S1 vertebral bodies were also resected in 6 patients because they limited mobility of the nerve roots. Complete decompression was achieved with posterior bone resection in the other 4 patients. Pain relief was achieved in all patients. Our results demonstrate that simple decompression surgery using a surgical microscope is an effective and less invasive surgical option for patients with extraforaminal compression of the fifth lumbar spinal nerve at the lumbosacral junction.

L5 spinal nerve injury caused by misplacement of outwardly-inserted S1 pedicle screws

To evaluate L5 nerve root injuries caused by outwardly misplaced S1 pedicle screws. Pedicle screws remain the criterion standard for fixation of L5-S1 to correct lumbosacral instability. When inserting S1 pedicle screws, it is possible to injure the L5 nerve root if screws are inserted outwardly and the tip of the screw perforates the anterior cortex of the sacrum. Despite this risk, to our knowledge this type of injury has never been reported as a case series. We experienced 2 cases of L5 nerve root injury caused by outwardly-inserted S1 pedicle screws. In both cases, bilateral S1 pedicle screws were inserted outwardly using a free-hand technique, and on one side, screws induced severe pain by impinging on an L5 root. Computed tomography after the selective rootgraphy of the injured nerve showed the nerve compressed laterally by screw threads in Case 1 and crushed between the screw threads and the sacral body in Case 2. In both cases, leg pain disappeared immediately after the infiltration of the nerve with lidocaine, but symptoms recurred within a few days in Case 1 and within an hour in Case 2. Conservative treatment of three spinal nerve infiltrations was effective in Case 1, but reinsertion of the rogue screw was necessary in Case 2. Surgeons should recognize that lateral inclination of S1 pedicle screws can cause L5 nerve root injury, which may require reinsertion of the screw, especially in cases where insertion is difficult because of overlapping surrounding muscle or bony tissue.