Segmental overlap: foot drop in S1 radiculopathy

Recent advances in neuroanatomy: the myotome update

The myotome of a muscle is the basis for diagnosing spinal and peripheral nerve disorders. Despite its critical importance in clinical neurology, myotome charts presented in many textbooks, surprisingly, show non-negligible discordances with each other. Many authors do not even clearly state the bases of their charts. Studies that have presented with raw data regarding myotome identification are rather rare. A classic study in the 19th century that pursued the nerve course in cadavers still has a substantial influence on existing charts, despite its definite limitations. Other scarce studies in humans include identification by root stimulation during surgery, clinical observations in root avulsion or spinal cord injury and clinical and electromyographical investigations in patients with single radiculopathies or certain plexopathies. A few recent studies have proposed new theories regarding the myotomes of some muscles. T1 innervation of the median intrinsic hand muscles is a typical example. We have added a number of new findings, such as T1 innervation of the forearm flexor muscles innervated by the median nerve except the pronator teres and flexor carpi radialis, C5 innervation of the brachioradialis, and two C6 indicator muscles, pronator teres and extensor carpi radialis brevis. Increased accuracy of the myotome charts will improve the localisation in neurology.

Dorsal root ganglion pulsed radiofrequency using bipolar technology in patients with lumbosacral radicular pain duration ≥ 2 years

BACKGROUND

Transforaminal epidural steroid injection (TFESI) or dorsal root ganglion pulsed radiofrequency (PRF) are alternative treatments for lumbosacral radicular pain (LSRP). This study aimed to investigate the clinical efficacy of TFESI combined with dorsal root ganglion PRF using bipolar technology to treat LSRP in patients with pain duration ≥ 2 years.

METHODS

This prospective single-armed cohort study included 20 patients with LSRP duration ≥ 2 years, who underwent treatment of TFESI combined with bipolar PRF. The primary outcomes included numerical rating scale (NRS) and successful treatment rate (pain relief ≥50%). The secondary outcomes included Oswestry Disability Index (ODI), patient satisfaction using the modified MacNab criteria, severe complications, hospital stay and total costs. The final follow-up was 6 months postoperatively.

RESULTS

The successful treatment rate and average pain relief at 6 months postoperatively were 80% and 73.0% ± 17.5%, respectively. The successful treatment rates in patients with and without prior intervention history at 6 months postoperatively were 77.8% and 81.8%, respectively. The mean NRS score significantly decreased from 6.5 ± 0.8 to 1.1 ± 0.7 at 2 weeks postoperatively, to 1.3 ± 0.7 at 3 months postoperatively, and to 1.7 ± 1.0 at 6 months postoperatively (all P < 0.001), while the mean ODI score significantly decreased from 43.5 ± 2.5 to 22.5 ± 4.3 at 2 weeks postoperatively, to 20.0 ± 3.5 at 3 months postoperatively, and to 19.5 ± 3.6 at 6 months postoperatively (all P < 0.001). The excellent and good patient satisfaction at 6 months postoperatively was 85%. No severe complications were observed in this cohort. The average hospital stay and total costs were 3.0 ± 0.5 days and 3.36 ± 0.77 thousand dollars, respectively.

CONCLUSION

The treatment of TFESI combined with PRF using bipolar technology might be an alternative option to treat chronic LSRP in patients with pain duration ≥ 2 years after a failure of conservative treatments, with a favorable 6-month efficacy and inexpensive total costs. However, long-term outcomes and superiority of bipolar procedure over monopolar procedure in patients with longer pain duration should be further investigated in future studies.

A national survey on the management of foot drop secondary to lumbar degenerative disease in the United Kingdom

PURPOSE

There is considerable variation in the management of foot drop secondary to lumbar degenerative disease (LDD) that occurs between centres and surgeons (spinal surgeons and neurosurgeons). The lack of standardised practice reflects the paucity in evidence base for management of this condition. In this survey, we aimed to assess current practice in the UK and identify the areas of variation.

METHODS

A case-based survey was distributed to members of the Society of British Neurological Surgeons and British Association of Spine Surgeons through an online questionnaire. The survey consisted of 10 questions designed to determine the management of foot drop secondary to LDD.

RESULTS

A total of 163 responses were collected among UK neurosurgeons and spinal surgeons with good geographical representation. 92% were Consultants. 86% of the respondents would offer surgery. The indication for offering surgery varied but 54% of respondents would offer surgery to patients who present with a painful foot drop. There was a huge variation in offering surgery dependent on the grade of weakness. The strongest prognostic indicator predicted was duration of weakness (92%). The timing of intervention was wide-ranging in the responses received. Almost all responded that they would be willing to participate in a prospective study in the future to determine best practice.

CONCLUSIONS

This survey highlights the significant variability in management of foot drop secondary to LDD amongst consultant surgeons within the UK. It is also suggestive of a weak evidence base and indicates an urgent need for a high quality national prospective study.

Prognostic indicators of surgical outcome in painful foot drop: a systematic review and meta-analysis

PURPOSE

Foot drop is a relatively uncommon presentation of lumbar degenerative disease and there is currently a paucity of evidence on management and outcomes which is reflective of the lack of standardised treatment provided to patients. The purpose of this systematic review and meta-analysis is to determine the effectiveness of surgical management and the factors that predict surgical outcome.

METHODS

A systematic database search of Cochrane Library, Ovid Medline, Pubmed, Embase and Google Scholar was undertaken from inception through August 2018. Only studies reporting on surgical outcome in adult patients who had a painful foot drop and underwent decompression were included. Case reports and studies with surgical fixation were excluded. Study quality was assessed using the Newcastle-Ottawa Scale. Data were pooled using a random-effects model.

RESULTS

797 studies were screened and 9 observational studies met the inclusion criteria. This resulted in a total of 431 patients who underwent decompression for foot drop. Pooled rates of outcome for improvement in foot drop MRC grade were 84.5% (range 67.9-96%). Sub-group meta-analyses of studies revealed a statistically significant association between duration of foot drop (pooled 4.95 [95% CI 1.13-21.74]), severity of preoperative weakness (pooled 0.38 [95% CI 0.15-0.93]) on post-operative outcome and age (pooled 6.28 [1.33-29.72]).

CONCLUSION

This is the first systematic review and meta-analysis to explore the outcome and prognostic indicators of lumbar decompression for foot drop. Findings indicate that age, duration of foot drop weakness and MRC grade of foot drop prior to intervention were strong predictors of surgical outcome.

Acute bilateral foot drop with or without cauda equina syndrome-a case series

Introduction

Isolated acute bilateral foot drop due to degenerative spine disease is an extremely rare neurosurgical presentation, whilst the literature is rich with accounts of chronic bilateral foot drop occurring as a sequela of systemic illnesses. We present, to our knowledge, the largest case series of acute bilateral foot drop, with trauma and relevant systemic illness excluded.

Methods

Data from three different centres had been collected at the time of historic treatment, and records were subsequently reviewed retrospectively, documenting the clinical presentation, radiological level of compression, timing of surgery, and degree of neurological recovery.

Results

Seven patients are presented. The mean age at presentation was 52.1 years (range 41–66). All patients but one were male. All had a painful radiculopathic presentation. Relevant discopathy was observed from L2/3 to L5/S1, the commonest level being L3/4. Five were treated within 24 h of presentation, and two within 48 h. Three had concomitant cauda equina syndrome; of these, the first two made a full motor recovery, one by 6 weeks follow-up and the second on the same-day post-op evaluation. Overall, five out of seven cases had full resolution of their ankle dorsiflexion pareses. One patient with 1/5 power has not improved. Another with 1/5 weakness improved to normal on the one side and to 3/5 on the other.

Conclusion

When bilateral foot drop occurs acutely, we encourage the consideration of degenerative spinal disease. Relevant discopathy was observed from L2/3 to L5/S1; aberrant innervation may be at play. Cauda equina syndrome is not necessarily associated with acute bilateral foot drop. The prognosis seems to be pretty good with respect to recovery of the foot drop, especially if partial at presentation and if treated within 48 h.

Muscle responses to radicular stimulation during lumbo-sacral dorsal rhizotomy for spastic diplegia: Insights to myotome innervation

OBJECTIVE

Most of knowledge on muscle radicular innervation was from explorations in root/spinal cord pathologies. Direct and individual access to each of the lumbar-sacral -ventral and dorsal- nerve roots during dorsal rhizotomy for spastic diplegia allows precise study of the corresponding muscle innervation. Authors report the lumbo-sacral segmental myotomal organization obtained from recordings of muscle responses to root stimulation in a 20-children prospective series.

METHODS

Seven key-muscles in each lower limb and anal sphincter were Electromyography (EMG)-recorded and clinically observed by physiotherapist during L2-to-S2 dorsal rhizotomy. Ventral roots (VR), for topographical mapping, and dorsal roots (DR), for segmental excitability testing, were stimulated, just above threshold for eliciting muscular response.

RESULTS

In 70% of the muscles studied, VR innervation was pluri-radicular, from 2-to-4 roots, with 1 or 2 roots being dominant at each level. Overlapping was important. Muscle responses to DR stimulation were 1.75 times more extended compared to VR stimulation. Inter-individual variability was important.

CONCLUSIONS

Accuracy of root identification and stimulation with the used method brings some more precise information to radicular functional anatomy.

SIGNIFICANCE

Those neurophysiological findings plead for performing Intra-Operative Neuromonitoring when dealing with surgery in the lumbar-sacral roots.

Accurate segmental motor innervation of human lower-extremity skeletal muscles

BACKGROUND

There is limited knowledge about accurate segmental motor innervation of the human lower extremity skeletal muscles. The aim of the present study was to explore the truth of segmental motor innervation of the lower extremity.

METHODS

Included in this study were 20 patients with unilateral fracture of the sacrum and sacral nerve injury, who underwent internal fixation and decompression of the sacral nerve in our hospital between June 2009 and January 2014. L4-S4 nerve roots of the uninjured side were stimulated during operation. Motor innervation was determined by stimulating the spinal nerves with supramaximal intensity.

RESULTS

We found the gluteus medius and the gluteus maximus were both mainly innervated by L5 and S1. In addition, the nerve fibres that innervated the extensor digitorum brevis, the abductor hallucis and the flexor digitorum brevis were mainly from S2 to S3.

CONCLUSIONS

Our study provides the electrophysiological mapping of the segmental anatomy of the human lower extremity muscles, which should be clinically useful in helping the diagnosis and treatment of nerve injury and neuropathies.

Foot drop caused by lumbar degenerative disease: clinical features, prognostic factors of surgical outcome and clinical stage

OBJECTIVE

The purpose of this study was to analyze the clinical features and prognostic factors of surgical outcome of foot drop caused by lumbar degenerative disease and put forward the clinical stage.

METHODS

We retrospectively reviewed 135 patients with foot drop due to lumbar degenerative disease. The clinical features and mechanism were analyzed. Age, sex, duration of palsy, preoperative muscle strength of tibialis anterior (TA), sensation defect of affected lower limb, affected foot, diagnosis and compressed nerve roots were recorded and compared with surgical outcome.

RESULTS

Foot drop was observed in 8.1% of all inpatients of lumbar degenerative disease. L5 nerve root compression was observed in 126 of all 135 patients (93.3%). Single, double and triple roots compression was observed respectively in 43, 83, and 9 patients (31.9%, 61.5%, and 6.6%). But there was no significant relationship between preoperative muscle strength of TA and the number of compressed roots. The muscle strength of TA was improved in 113 (83.7%) patients after surgery, but it reached to >=4 in only 21 (15.6%) patients. Improvement of the muscle strength of TA was almost stable at the 6-month follow-up. At the last follow-up, the muscle strength of TA was 1, 2, 3, 4, 5 respectively in 28, 24, 62, 13, 8 patients. Multivariate logistic regression showed duration of palsy (p=0.0360, OR=2.543), preoperative muscle strength of TA (p=0.0064, OR=5.528) and age (p=0.0309, OR=3.208) were factors that influenced recovery following an operation.

CONCLUSIONS

L5 nerve root was most frequently affected. The muscle strength of TA improved in most patients after surgery, but few patients can get a good recovery from foot drop. Patients of shorter duration of palsy, better preoperative muscle strength of TA and younger age showed a better surgical outcome.