Clinical and prognostic features in unilateral femoral neuropathies

Femoral and obturator neuropathies

The femoral and obturator nerves both arise from the L2, L3, and L4 spinal nerve roots and descend into the pelvis before emerging in the lower limbs. The femoral nerve's primary function is knee extension and hip flexion, along with some sensory innervation to the leg. The obturator nerve's primary function is thigh adduction and sensory innervation to a small area of the medial thigh. Each may be injured by a variety of potential causes, many of them iatrogenic. Here, we review the anatomy of the femoral and obturator nerves and the clinical features and potential etiologies of femoral and obturator neuropathies. Their necessary investigations, including electrodiagnostic studies and imaging, their prognosis, and potential treatments, are discussed in this chapter.

Iatrogenic femoral nerve injuries: Analysis of medico-legal issues through a scoping review approach

Purpose

Accidental femoral nerve injury is a well-known iatrogenic complication of orthopaedic, abdominal, and pelvic surgery. Because of the largely transitory nature of the symptoms associated with nerve damage, its true incidence is in all likelihood underestimated. This work aims to illustrate the surgical contexts within which this nerve injury is reported, based on the evidence obtained from a Scoping Review of the literature of the last 20 years, with specific reference to the underlying etiopathogenetic mechanisms and prognostic outcomes, to highlight the evaluation issues of medico-legal interest related to this pathology.

Methods

We conducted a Scoping Review of iatrogenic femoral nerve injuries reported between 2000 and 2021 by searching the electronic databases Pubmed, Scopus, Ovid Medline, Ovid Emcare, and Web of Science.We conducted the review according to the five-step methodology outlined by Arksey and O'Malley.

Results

The literature search identified 104 papers, including case reports, case series, and retrospective studies. Surgical contexts within which iatrogenic femoral nerve injuries were reported include orthopaedic, abdominal, gynaecological, urological, vascular, and plastic surgery, as well as locoregional anaesthesiological procedures. The long-term prognosis was generally favourable.

Conclusions

Because of its frequent iatrogenic genesis, femoral nerve injury is a topic of intense medico-legal interest. From the perspective of estimating the patient's disability, the mostly favourable nature of the prognosis makes the medico-legal assessment, in some respects, complex, thus requiring a precise evaluation methodology.

Electrodiagnostic Assessment of Uncommon Mononeuropathies

Carpal tunnel syndrome, ulnar neuropathy at the elbow, and peroneal neuropathy are the most common mononeuropathies; however, other individual nerves may also be injured by various processes. These uncommon mononeuropathies may be less readily diagnosed owing to unfamiliarity with the presentations and vague symptoms. Electrodiagnostic studies are essential in the evaluation of uncommon mononeuropathies and can assist in localization and prognostication. However, they can also be challenging; stimulation at the proximal sites is difficult and well-validated reference values are not available. This article reviews the electrodiagnostic assessment of several uncommon upper and lower extremities mononeuropathies.

Peripheral Neuropathy in the Lower Limbs of Individuals With Spinal Cord Injury or Disease: A Retrospective Study

PURPOSE

This study investigated the frequency and types of peripheral neuropathy in the lower limbs of patients undergoing rehabilitation after traumatic spinal cord injury or spinal cord disease.

METHODS

This study included consecutive patients with spinal cord injury/spinal cord disease who had electrophysiological assessments during their admission in a rehabilitation center from October 2015 to July 2019. Patients with traumatic spinal cord injury were compared with patients with nontraumatic spinal cord disease.

RESULTS

There were 67 patients (52 male patients, 15 female patients; mean age = 56.5 yrs) of whom 36 patients had spinal cord injury and 31 patients had spinal cord disease. Most of the patients were middle-aged men with at least one preexisting medical comorbidity, who were mostly admitted for rehabilitation of cervical, incomplete spinal cord injury/spinal cord disease. Most patients (86.6%) had abnormal electrophysiological studies representing 5.57% of all admissions. A length-dependent polyneuropathy was diagnosed in 0.77% of all admissions (n = 8). The group of patients with spinal cord injury was comparable with the group of patients with spinal cord disease regarding the other baseline data, clinical, and electrophysiological findings.

CONCLUSIONS

Diseases of the peripheral nervous system were similarly found among patients undergoing rehabilitation for either spinal cord injury or spinal cord disease. A length-dependent polyneuropathy was diagnosed in 0.77% of all admissions. Timely diagnosis and proper treatment of the cause of peripheral neuropathies in the lower limbs in these patients may potentially influence rehabilitation protocols and improve patient outcomes.

Iliopsoas hematoma presenting with sudden knee extensor weakness: A case report

RATIONALE

Hematoma of the iliopsoas muscle is a rare condition. Prolonged pressure conditions due to hematoma of the femoral nerve can cause severe pain in the affected groin, hip, and thigh, and quadriceps weakness. We report a rare case of a spontaneous iliopsoas muscle hematoma that caused sudden femoral neuropathy.

PATIENT CONCERNS

A 71-year-old woman presented sudden left hip pain and knee extensor weakness. The pain was aggravated with left hip extension. She had a bilateral total hip replacement surgery due to avascular necrosis. She was diagnosed as mild stenosis of the cerebral artery and took aspirin to prevent cerebral artery atherosclerosis.

DIAGNOSIS

A hip computed tomography scan demonstrated a suspicious fluid collection at the left iliopsoas bursa. We considered the possibility of lower limb weakness due to neuralgic amyotrophy and performed electromyography and enhanced lumbosacral magnetic resonance imaging (MRI). Electromyography finding showed left femoral neuropathy of moderate severity around the inguinal area was diagnosed. On MRI, left iliopsoas bursitis or hematoma, and displacement of the left femoral nerve due to the iliopsoas bursitis/hematoma were observed.

INTERVENTION

Ultrasonography (US)-guided aspiration of the left iliopsoas hematoma was performed. We started steroid pulse therapy for 8 days.

OUTCOMES

After US-guided aspiration and steroid pulse therapy, the patient's knee extension motor grade improved from grade 1 to 2, and the pain was slightly reduced. At 3 weeks after the aspiration procedure, her hip flexion motor grade had improved from grade 3+ to 4 at follow-up.

LESSONS

Imaging studies are fundamental to diagnose of iliopsoas hematoma. Electromyography examination plays an important role in determining the prognosis of patients and lesion site. Despite the negligible change in sitting position, hematoma can develop. Physicians should consider hematoma that cause femoral neuropathy.

A case of monofocal motor neuropathy with GM1 and GD1b antibodies improved with intravenous immunoglobulin

Multifocal motor neuropathy is a purely motor neuropathy with a probably dysimmune pathogenesis, supported by the presence of anti-GM1 IgM antibodies in about half of the cases. Single nerve involvement allows for diagnosis of possible multifocal motor neuropathy. We present the case of a middle age man presenting with progressive weakness and hypotrophy in the left leg and difficulty in walking, in which we have diagnosed a dysimmune mononeuropathy. Treatment with IVIg was performed with substantial improvement. Although only one nerve is involved, early diagnosis of dysimmune mononeuropathy is important to start IVIg treatment that is often decisive.

Lower extremity entrapment neuropathies

Entrapment neuropathies are frequently encountered by rheumatologists, not only because they are common but also because of their association with certain rheumatological and systemic disorders. Recognizing entrapment neuropathy early can help avoid progressive neurological deficits, as well as facilitate appropriate treatment measures, which can effectively minimize a patient's symptoms. Entrapment neuropathies may be distinguished from other musculoskeletal causes of lower extremity pain by identifying characteristic patterns of weakness and/or sensory loss, so a focused bedside neurological examination is key for diagnosis. In this chapter, we review the most common entrapment neuropathies that occur in the lower extremities, review the relevant neuroanatomy, outline a diagnostic approach to distinguish them from other mimics, and highlight appropriate management options.

Postpartum femoral neuropathy: managing the next pregnancy

A 34-year-old primiparous woman presented in spontaneous labour and had an unassisted vaginal birth of a 3.5 kg infant. Postnatally, the patient experienced lower limb weakness and was unable to mobilise unassisted. A diagnosis of postpartum femoral neuropathy was made. Full recovery of normal motor function was not achieved until 5 months postpartum. She returned in her next pregnancy, seeking advice on how to avoid this complication from reoccurring. It was decided that an elective caesarean section was an appropriate mode of delivery, which she underwent at 39 weeks without complication and without recurrence of the femoral neuropathy.

Entrapment Neuropathies of the Lower Extremity

Entrapment neuropathies in the lower limbs are a common neurologic problem and may present in any medical setting. Accurate identification and management of these nerve palsies can prevent pain, sensory loss, incoordination, and muscle weakness that may significantly affect a patient's functional mobility. In this article, the authors focus on the cause, signs and symptoms, diagnosis, and treatment of select entrapment neuropathies of the lower extremity, including palsies of the common peroneal, lateral femoral cutaneous, femoral, and posterior tibial nerves.

PERIPHERAL NERVE INJURY IN SPORTS

SUMMARY – Peripheral nerve injuries in sports are rare. Peripheral nerve injuries in sports are caused by pressure, stretching, or bone fracture. Peripheral nerve injuries are more frequent on upper limbs, and the type of injury is determined by the type of sport. According to Seddon, we distinguish 3 levels of injury: 1) neurapraxia; 2) axonotmesis; and 3) neurotmesis. Diagnosis must be reached as early as possible to enable timely initiation of appropriate treatment. The diagnostics of peripheral nerve injuries includes electromyography and nerve conduction studies, somatosensory evoked potentials, magnetic resonance imaging, and ultrasound. Proximal nerve injuries have a poorer prognosis for neurologic recovery.

NERVE ENTRAPMENT IN THE HIP REGION: CURRENT CONCEPTS REVIEW

The purpose of this clinical commentary is to review the anatomy, etiology, evaluation, and treatment techniques for nerve entrapments of the hip region. Nerve entrapment can occur around musculotendinous, osseous, and ligamentous structures because of the potential for increased strain and compression on the peripheral nerve at those sites. The sequela of localized trauma may also result in nerve entrapment if normal nerve gliding is prevented. Nerve entrapment can be difficult to diagnose because patient complaints may be similar to and coexist with other musculoskeletal conditions in the hip and pelvic region. However, a detailed description of symptom location and findings from a comprehensive physical examination can be used to determine if an entrapment has occurred, and if so where. The sciatic, pudendal, obturator, femoral, and lateral femoral cutaneous are nerves that can be entrapped and serve a source of hip pain in the athletic population. Manual therapy, stretching and strengthening exercises, aerobic conditioning, and cognitive-behavioral education are potential interventions. When conservative treatment is ineffective at relieving symptoms surgical treatment with neurolysis or neurectomy may be considered.

Level of Evidence

5.

Gastrointestinal Mucormycosis After Orthotopic Liver Transplantation Presenting as Femoral Nerve Palsy: A Case Report and Review of the Literature

Mucormycosis has emerged as a major threat to transplant recipients with high morbidity and mortality. This infection most commonly presents with rhino-sino-orbital localization. Gastrointestinal mucormycosis is uncommon, with presenting symptoms usually abdominal in nature. Here, we describe the case of a liver transplant recipient who developed gastrointestinal mucormycosis with an initial manifestation of femoral nerve palsy, ultimately resulting in fungal dissemination and patient demise. This case highlights the challenges in making a timely diagnosis of mucormycosis, particularly in immunocompromised patients.

Femoral nerve and lumbar plexus injury after minimally invasive lateral retroperitoneal transpsoas approach: electrodiagnostic prognostic indicators and a roadmap to recovery

Injury to the lumbosacral (LS) plexus is a well-described complication after lateral retroperitoneal transpsoas approaches to the spine. The prognosis for functional recovery after lumbosacral plexopathy or femoral/obturator neuropathy is unclear. We designed a retrospective case-control study with patients undergoing one-level lateral retroperitoneal transpsoas lumbar interbody fusion (LLIF) between January 2011 and June 2016 to correlate electrodiagnostic assessments (EDX) to physiologic concepts of nerve injury and reinnervation, and attempt to build a timeline for patient evaluation and recovery. Cases with post-operative obturator or femoral neuropathy were identified. Post-operative MRI, nerve conduction studies (NCS), electromyography (EMG), and physical examinations were performed at intervals to assess clinical and electrophysiologic recovery of function. Two hundred thirty patients underwent LLIF. Six patients (2.6%) suffered severe femoral or femoral/obturator neuropathy. Five patients (2.2%) had immediate post-operative weakness. One of the six patients developed delayed weakness due to a retroperitoneal hematoma. Five out of six patients (83%) demonstrated EDX findings at 6 weeks consistent with axonotmesis. All patients improved to at least MRC 4/5 within 12 months of injury. In conclusion, neurapraxia is the most common LS plexus injury, and complete recovery is expected after 3 months. Most severe nerve injuries are a combination of neurapraxia and variable degrees of axonotmesis. EDX performed at 6 weeks and 3, 6, and 9 months provides prognostic information for recovery. In severe injuries of proximal femoral and obturator nerves, observation of proximal to distal progression of small-amplitude, short-duration (SASD) motor unit potentials may be the most significant prognostic indicator.

Electrophysiological Study of Femoral Nerve Function After a Continuous Femoral Nerve Block for Anterior Cruciate Ligament Reconstruction: A Randomized, Controlled Single-Blind Trial

BACKGROUND

A continuous femoral nerve block (CFNB) is an effective analgesic treatment after anterior cruciate ligament (ACL) reconstruction but may result in transient femoral nerve injuries and quadriceps muscle weakness, which in turn contribute to worsened functional outcomes.

PURPOSE

To compare electrophysiological criteria of a femoral nerve injury as well as functional and pain-related outcomes after ACL reconstruction when analgesia was provided by a CFNB or intravenous patient-controlled analgesic of morphine (IV PCA).

STUDY DESIGN

Randomized controlled clinical trial; Level of evidence, 1.

METHODS

A total of 74 patients scheduled for ACL reconstruction were randomized to receive a CFNB before surgery, followed by a ropivacaine infusion for 2 days and oxycodone, or IV PCA. The primary outcome was the rate of femoral nerve injuries at 4 weeks postoperatively, defined as a reduction of the compound muscle action potential (CMAP) area from the vastus medialis muscle after supramaximal femoral nerve stimulation at the groin, associated with an absent H-reflex of the femoral nerve and signs of vastus medialis muscle denervation. Secondary functional outcomes were quadriceps muscle strength, active flexion range, and distance walked, as measured on postoperative days 1 and 2. Secondary pain-related outcomes were IV morphine consumption and pain scores at rest and on movement in phase 1 recovery and on postoperative days 1 and 2.

RESULTS

No patients met the electrophysiological criteria of a femoral nerve injury. The mean CMAP area at 4 weeks was equivalent in both the CFNB and IV PCA groups (47 ± 16 mV·ms and 51 ± 13 mV·ms, respectively; P = .50). While no differences were detected in functional outcomes or pain scores, the consumption of an IV morphine equivalent was reduced by the administration of a CFNB in phase 1 recovery (6 ± 5 mg and 13 ± 7 mg, respectively; P = .0003), on postoperative day 1 (6 ± 7 mg and 19 ± 17 mg, respectively; P = .0005), and on postoperative day 2 (11 ± 10 mg and 19 ± 17 mg, respectively; P = .03) compared with an IV PCA.

CONCLUSION

Despite prior contrary reports, a CFNB did not result in femoral nerve injuries or worsened functional outcomes after ACL reconstruction. The improvement of analgesia with a CFNB was only marginal and not clinically relevant beyond 24 hours. Registration: NCT01321138 ( ClinicalTrials.gov identifier).

"Anterior subcutaneous pelvic internal fixator (INFIX), Is it safe?" A cadaveric study

INTRODUCTION

Anterior pelvic internal fixator (INFIX) is used to treat unstable pelvic ring injuries. Nerve injury complications with this procedure have been reported.

OBJECTIVES

This anatomic study attempted to identify structures at risk after application of INFIX.

MATERIALS AND METHODS

INFIX was applied in fifteen fresh, frozen, anatomical specimens using polyaxial pedicular screws and subcutaneous rods. Surgical dissection was done to identify the structures at risk including the femoral nerve (FN), femoral artery (FA), femoral vein (FV) and the lateral femoral cutaneous nerve (LFCN) related to which are potentially affected by the implant.

RESULTS

All structures at risk were closer to the rod than to the pedicular screw. Measurements were made between the rod and the structures at risk. The LFCN was an average of 13.49±1.65mm (95% CI 12.871-14.103) from the lateral end of the rod. The FN was an average of 12.43±3.42mm (95% CI 11.151-13.709), the FA was an average of 12.80±3.67 (95% CI 11.430-14.173) and the FV was an average of 13.48±3.73 (95% CI 12.082-14.871) below the rod. No direct compression of the rod to the structure at risk was observed.

CONCLUSIONS

The femoral nerve is the structure most at risk of compression by the INFIX rod. Careful surgical technique is required in every step of this surgery. We suggest using polyaxial screws and recommend that during screw insertion the surgeon should leave some space between the screw and rectus fascia. The the rod should be trimmed as short as possible to reduce LFCN irritation.

Femoral nerve palsy after pelvic fracture treated with INFIX: a case series

OBJECTIVE

The treatment of some pelvic injuries has evolved recently to include the use of a subcutaneous anterior pelvic fixator (INFIX). We present 8 cases of femoral nerve palsy in 6 patients after application of an INFIX to highlight this potentially devastating complication to pelvic surgeons using this technique and discuss how it might be avoided in the future.

DESIGN

Retrospective chart review. Case series.

SETTING

Five level 1 and 2 trauma centers, tertiary referral hospitals.

PATIENTS/PARTICIPANTS

Six patients with anterior pelvic ring injury treated with an INFIX who experienced 8 femoral nerve palsies (2 bilateral).

INTERVENTION

Removal of internal fixator, treatment for femoral nerve palsy.

MAIN OUTCOME MEASUREMENTS

Clinical and electromyographic evaluation of patients.

RESULTS

All 6 patients with a total of 8 femoral nerve palsies had their INFIX removed. Variable resolution of the nerve injuries was observed.

CONCLUSIONS

Application of an INFIX for the treatment of pelvic ring injury carries a potentially devastating risk to the femoral nerve(s). Despite early implant removal after detection of nerve injury, some patients had residual quadriceps weakness, disturbance of the thigh's skin sensation, and/or gait disturbance attributable to femoral nerve palsy at the time of early final follow-up.

LEVEL OF EVIDENCE

Therapeutic level IV. See Instructions for Authors for a complete description of levels of evidence.

Outer electrospun polycaprolactone shell induces massive foreign body reaction and impairs axonal regeneration through 3D multichannel chitosan nerve guides

We report on the performance of composite nerve grafts with an inner 3D multichannel porous chitosan core and an outer electrospun polycaprolactone shell. The inner chitosan core provided multiple guidance channels for regrowing axons. To analyze the in vivo properties of the bare chitosan cores, we separately implanted them into an epineural sheath. The effects of both graft types on structural and functional regeneration across a 10 mm rat sciatic nerve gap were compared to autologous nerve transplantation (ANT). The mechanical biomaterial properties and the immunological impact of the grafts were assessed with histological techniques before and after transplantation in vivo. Furthermore during a 13-week examination period functional tests and electrophysiological recordings were performed and supplemented by nerve morphometry. The sheathing of the chitosan core with a polycaprolactone shell induced massive foreign body reaction and impairment of nerve regeneration. Although the isolated novel chitosan core did allow regeneration of axons in a similar size distribution as the ANT, the ANT was superior in terms of functional regeneration. We conclude that an outer polycaprolactone shell should not be used for the purpose of bioartificial nerve grafting, while 3D multichannel porous chitosan cores could be candidate scaffolds for structured nerve grafts.

Entrapment neuropathies of the lower extremity

Neuropathies that affect the lower limbs are often encountered after trauma or iatrogenic injury or by entrapment at areas of anatomic restriction. Symptoms may initially be masked by concomitant trauma or recovery from surgical procedures. The nerves that serve the lower extremities arise from the lumbosacral plexus, formed by the L2-S2 nerve roots. The major nerves that supply the lower extremities are the femoral, obturator, lateral femoral cutaneous, and the peroneal (fibular) and tibial, which arise from the sciatic nerve, and the superior and inferior gluteal nerves. An understanding of the motor and sensory functions of these nerves is critical in recognizing and localizing nerve injury. Electrodiagnostic studies are an important diagnostic tool. A well-designed electromyography study can help confirm and localize a nerve lesion, assess severity, and evaluate for other peripheral nerve lesions, such as plexopathy or radiculopathy.

Compression and entrapment neuropathies

Peripheral nerve entrapments are frequent. They usually appear in anatomical tunnels such as the carpal tunnel. Nerve compressions may be due to external pressure such as the fibular nerve at the fibular head. Malignant or benign tumors may also damage the nerve. For each nerve from the upper and lower limbs, detailed clinical, electrophysiological, imaging, and therapeutic aspects are described. In the upper limbs, carpal tunnel syndrome and ulnar neuropathy at the elbow are the most frequent manifestations; the radial nerve is less frequently involved. Other nerves may occasionally be damaged and these are described also. In the lower limbs, the fibular nerve is most frequently involved, usually at the fibular head by external compression. Other nerves may also be involved and are therefore described. The clinical and electrophysiological examination are very important for the diagnosis, but imaging is also of great use. Treatments available for each nerve disease are discussed.

Prediction of surgical outcome for proximal-type cervical spondylotic amyotrophy novel mode of assessment using compound action potentials of deltoid and biceps brachii and central motor conduction time

STUDY DESIGN

Case studies of patients with cervical spondylotic amyotrophy used compound muscle action potentials (CMAPs) of deltoid and biceps brachii muscles and central motor conduction time (CMCT).

OBJECTIVE

To discuss surgical outcome for proximal-type cervical spondylotic amyotrophy in the context of results obtained with CMAPs and CMCT.

SUMMARY OF BACKGROUND DATA

There have been no reports that correlate surgical outcome with CMAPs of deltoid and biceps brachii muscles or with CMCT.

METHODS

A retrospective study was performed for 24 patients with proximal-type cervical spondylotic amyotrophy who underwent surgical treatment of the cervical spine. Erb-point-stimulated CMAPs were recorded in the deltoid and biceps. The percent amplitude of CMAPs was calculated in comparison with the opposite side. Motor-evoked potentials were recorded from bilateral abductor digiti minimi. CMAPs and F waves were recorded after supramaximal electric stimulation of ulnar nerves. CMCT was calculated as follows: motor-evoked potentials latency - (CMAPs' latency + F latency - 1)/2 (ms). Muscle strength was evaluated using manual muscle testing. Improvements in strength were classified as excellent, good, or fair.

RESULTS

The improvement was graded as excellent in 12 cases, good in 2 cases, and fair in 10 cases. The average percentage for CMAPs' amplitude on the affected side compared with the normal side in deltoid and biceps brachii muscles was significantly different between the excellent and fair patient groups. The CMCT on the affected side was not significantly different between excellent and fair patient groups.

CONCLUSION

The average percentage range of deltoid and biceps brachii muscle CMAPs' amplitude determined at the onset of illness correlated significantly with postoperative recovery. Surgical intervention of the cervical spine should be performed in patients in whom the average percentage of CMAPs' amplitude in deltoid and biceps brachii muscles ranges from 30% to 50%.

Electrodiagnostic evaluation of lower extremity mononeuropathies

This article discusses the anatomy of lower limb mononeuropathies and reviews the general approach to evaluating patients in the electrodiagnostic laboratory with suspected mononeuropathies of the lower limb. Through illustrative cases of patients presenting with a floppy foot, buckling knee, or painful foot, the approaches using nerve conduction studies and needle electromyography are reviewed, and the pattern of findings of peroneal, tibial, sciatic, femoral, and obturator neuropathies is shown.

Duloxetine contributing to a successful multimodal treatment program for peripheral femoral neuropathy and comorbid 'reactive depression' in an adolescent

In the United States, duloxetine has been approved for the treatment of major depressive disorder, diabetic peripheral neuropathic pain and fibromyalgia in the adult population. Data regarding the use of duloxetine in the pediatric population, however, are very limited. Femoral nerve injury is a rare complication of cardiac catheterization. In the case described, duloxetine contributed to a successful multimodal treatment program for peripheral neuropathic pain due to femoral neuropathy in an adolescent with 'reactive depression' and conversion symptoms. To the best of the authors' knowledge, the present article is only the third such report on this dual use of duloxetine in children and adolescents, and the first report of such treatment following femoral neuropathy induced by cardiac catheterization.

Iatrogenic femoral neuropathy: two cases and literature update

Iatrogenic femoral neuropathy is an uncommon surgical or obstetric complication that may be underreported. It results from compression, stretch, ischemia, or direct trauma of the nerve during hip arthroplasty, self-retaining retractor use in pelvicoabdominal surgery, lithotomy positioning for anesthesia or labor, and other more rare causes. Decreasing incidence of this complication after abdominal and gynecologic surgery but increase in its absolute numbers after hip arthroplasty has emerged over the last decade. We describe two illustrative cases related respectively to lithotomy positioning and self-retaining retractor use. The variability in clinical presentation of iatrogenic femoral nerve lesions, some new insights in their diverse pathophysiology, and in the diagnostic and treatment options are discussed with an update from the literature.

Thyroid Hormone in Biodegradable Nerve Guides Stimulates Sciatic Nerve Regeneration: A Potential Therapeutic Approach for Human Peripheral Nerve Injuries

It has been already demonstrated that thyroid hormone (T3) is one of the most important stimulating factors in peripheral nerve regeneration. We have recently shown that local administration of T3 in silicon tubes at the level of the transected rat sciatic nerve enhanced axonal regeneration and improved functional recovery. Silicon, however, cannot be used in humans because it causes a chronic inflammatory reaction. Therefore, in order to provide future clinical applications of thyroid hormone in human peripheral nerve lesions, we carried out comparative studies on the regeneration of transected rat sciatic nerve bridged either by biodegradable P(DLLA-(-CL) or by silicon nerve guides, both guides filled with either T3 or phosphate buffer. Our macroscopic observation revealed that 85% of the biodegradable guides allowed the expected regeneration of the transected sciatic nerve. The morphological, morphometric and electrophysiological analysis showed that T3 in biodegradable guides induces a significant increase in the number of myelinated regenerated axons (6862 +/- 1831 in control vs. 11799 +/- 1163 in T3-treated). Also, T3 skewed the diameter of myelinated axons toward larger values than in controls. Moreover, T3 increases the compound muscle action potential amplitude of the flexor and extensor muscles of the treated rats. This T3 stimulation in biodegradable guides was equally well to that obtained by using silicone guides. In conclusion, the administration of T3 in biodegradable guides significantly improves sciatic nerve regeneration, confirming the feasibility of our technique to provide a serious step towards future clinical application of T3 in human peripheral nerve injuries.

Lumbosacral Magnetic Root Stimulation in Lumbar Plexopathy

We report a 76-yr-old man with left femoral nerve distribution weakness resulting from a nontraumatic retroperitoneal hematoma associated with coumadin anticoagulation. Although electric root stimulation was relatively contraindicated, magnetic lumbosacral root stimulation identified a proximal conduction block allowing more extensive assessment of the nerve damage. To our knowledge, this is the first report of magnetic root stimulation in assessment of lumbosacral plexus dysfunction in retroperitoneal hematoma.

Treatment Concepts for Idiopathic and Iatrogenic Femoral Nerve Mononeuropathy

Femoral mononeuropathy has many etiologies and is often quite disabling, causing lower extremity paresthesia, anesthesia, pain, or paresis. Despite its morbidity, few therapies have been described to treat the femoral nerve palsy that does not resolve with conservative management or that is refractory to physical therapy. In this report, we present 3 cases of femoral nerve palsy; one as a complication of local nerve block, one as a complication of laparotomy, and one of idiopathic origin. In each case, symptomatic and objective improvement was achieved with femoral neurolysis. We suggest guidelines for the management of those patients who fail to respond to conservative therapy and indications for surgical intervention.

A novel technique for recording from the serratus anterior

OBJECTIVE

To design an electrodiagnostic technique by which to accurately record the serratus anterior compound muscle action potential (CMAP).

DESIGN

Observational study.

SETTING

Academic electromyography laboratory.

PARTICIPANTS

Fifteen healthy volunteers.

INTERVENTIONS

The long thoracic nerve was stimulated by using a standard bipolar surface electrode in the axilla, just anterior to the midaxillary line. The serratus anterior CMAP was recorded by using a self-adhesive, 8.0 x 0.5 cm, ring electrode as the E1 placed across the serratus anterior interdigitations starting at the nipple level. A self-adhesive, motor (1 x 1 cm) electrode was used as E2 and placed over the seventh rib. A standard self-adhesive ground electrode was placed over the inferior region of the latissimus dorsi.

MAIN OUTCOME MEASURES

Distal motor latency (DML), and CMAP amplitude and duration.

RESULTS

After removing 2 outliers, the results are reported as the mean +/- 1.96 standard deviations. Right long thoracic DML was 2.2+/-1.0ms and the left was 2.3+/-0.9ms, with a side-to-side mean difference of 0.3+/-0.4ms. The right serratus CMAP amplitude was 3.8+/-3.9mV and the left was 3.9+/-3.7mV, with a side-to-side mean difference of 0.6+/-1.2mV. Statistical analysis did not reveal a significant side-to-side difference for DML or CMAP amplitude. Both sides were combined to form a single set of trials for DML and CMAP amplitude. The mean DML became 2.2+/-0.7ms, and the CMAP amplitude was 3.5+/-1.9mV. The CMAP duration was 14.5+/-4.3ms on the right and 14.5+/-4.1ms on the left. A significant, positive correlation existed between height and DML ( P <.02). The 95% confidence intervals for DML and CMAP amplitudes were 2.1 to 2.5ms and 1.5 to 3.1mV, respectively.

CONCLUSIONS

Our latency, side-to-side comparisons and amplitude data were consistent with other motor nerve conduction findings in the literature. Stimulating the long thoracic nerve in the axilla will provide a reliable technique to aid in the diagnosis and treatment of long thoracic neuropathy.

The role of knee immobilizers in cancer patients with femoral neuropathy

OBJECTIVE

To determine the utility of knee immobilizers for cancer patients with femoral neuropathy.

DESIGN

Retrospective case series with chart reviews and telephone interviews.

SETTING

Teaching hospital, inpatient setting, and 1-year follow-up as outpatients.

PARTICIPANTS

Five cancer patients with femoral neuropathy (4 men, 1 woman; age range, 51-76 y). Inclusion criteria were (1) diagnosis of femoral neuropathy, (2) receipt of knee immobilizer as an inpatient, and (3) ability to discuss opinions about knee orthotics at 1-year follow-up.

INTERVENTION

Knee immobilizer. Main outcome measures Number of falls with and without knee immobilizer, ambulatory distance with and without immobilizer, subjective rating of activity level, and feeling of stability with and without immobilizer.

RESULTS

Patients reported that the knee immobilizer reduced their number of falls by up to 10-fold, increased ambulatory distance between 105 and 420 ft (31.5 and 126 m), improved their feeling of stability, and increased overall activity levels.

CONCLUSIONS

Patients can benefit from knee immobilizers during their rehabilitation efforts: risk of falls decreased, ambulation distance increased, and relative peace of mind was achieved with the orthotic's use.

The motor-evoked potentials elicited from the deltoid muscle by transcranial magnetic stimulation with a standardized facilitation: the potential diagnostic utility for C5 radiculopathy

STUDY DESIGN

We investigated the effects of standardized facilitation on stability in amplitude of the motor-evoked potentials from the deltoid muscle after magnetic stimulation over the scalp in normal study participants.

OBJECTIVES

To test the potential of this technique in evaluating deltoid weakness and recovery after C5 radiculopathy.

SUMMARY OF BACKGROUND DATA

Most previous motor-evoked potential studies have emphasized the value of the latency rather than amplitude, probably because the amplitude varies much more than the latency, even in the same individual.

METHODS

Twenty right-handed healthy men underwent deltoid motor-evoked potential studies on three successive occasions at intervals of >2 weeks. A digital readout of the shoulder abduction force allowed the study participant to adjust voluntary contraction to 20% of the maximal force at the moment of stimulation. The deltoid motor-evoked potentials were compared with the M responses recorded from the relaxed deltoid after electrical stimulation of the brachial plexus.

RESULTS

Despite considerable individual variability in the amplitude of deltoid motor-evoked potentials, a standardized facilitation yielded a relatively small variation of amplitude between sessions in the same individual, showing an intersession variability index of 9.1 +/- 7.9%. The side-to-side amplitude ratio, averaging 82 +/- 12%, also provides a more reliable measure in evaluating unilateral deltoid weakness than the absolute value. The measures on the left showed significantly higher amplitude than on the right for the deltoid motor-evoked potentials but not for the M responses.

CONCLUSIONS

The changes of the motor-evoked potential amplitude exceeding 25% between sessions and side-to-side amplitude ratios <60% can be outside the normal limits. The asymmetry of deltoid motor-evoked potentials in favor of the nondominant side is of physiologic interest.

Electrophysiologic assessment of shoulder girdle weakness in patients with cervical spondylosis: prognostic value of supraclavicular stimulation

OBJECTIVES

We tested the use of supraclavicular stimulation as a prognostic measure of deltoid function after cervical spondylotic radiculopathy.

METHODS

Electrophysiological study consisted of supramaximally stimulating the brachial plexus and recording compound muscle action potentials (CMAPs) from the deltoid in 32 patients with unilateral weakness of 3 months or shorter duration as compared with 69 healthy subjects.

RESULTS

Despite considerable individual variability and age-related reduction in amplitude and area of deltoid CMAPs, the side-to-side ratios yielded useful, reproducible values. The measures recorded initially correlated significantly with the eventual recovery of deltoid strength but, interestingly, not with the initial degree of weakness. In particular, the CMAPs greater than 50%, even in the face of severe weakness, predicted a nearly complete return of function.

CONCLUSIONS

Supraclavicular stimulation provides a useful measure in monitoring deltoid weakness and predicting its recovery in patients with cervical spondylosis.

Electrodiagnostic approach to the patient with suspected mononeuropathy of the lower extremity

Lower extremity mononeuropathies are less common than those affecting the upper limb. Yet, they are often challenging and more difficult to diagnose. The electrodiagnostic (EDX) studies play a pivotal role in diagnosis. Well planned and executed studies are very useful, although limiting factors such as age, foot swelling or prior lumbar spine surgery may hinder making a definite diagnosis. In this section, the author emphasizes the EDX studies of most lower extremity mononeuropathies and discusses, briefly, their anatomical and clinical aspects.