Sciatic and tibial neuropathies.

The sciatic nerve is the body's largest peripheral nerve. Along with their two terminal divisions (tibial and fibular), their anatomic location makes them particularly vulnerable to trauma and iatrogenic injuries. A thorough understanding of the functional anatomy is required to adequately localize lesions in this lengthy neural pathway. Proximal disorders of the nerve can be challenging to precisely localize among a range of possibilities including lumbosacral pathology, radiculopathy, or piriformis syndrome. A correct diagnosis is based upon a thorough history and physical examination, which will then appropriately direct adjunctive investigations such as imaging and electrodiagnostic testing. Disorders of the sciatic nerve and its terminal branches are disabling for patients, and expert assessment by rehabilitation professionals is important in limiting their impact. Applying techniques established in the upper extremity, surgical reconstruction of lower extremity nerve dysfunction is rapidly improving and evolving. These new techniques, such as nerve transfers, require electrodiagnostic assessment of both the injured nerve(s) as well as healthy, potential donor nerves as part of a complete neurophysiological examination.

Validity of the Tinel Sign and Prevalence of Tibial Nerve Entrapment at the Tarsal Tunnel in Both Diabetic and Nondiabetic Subjects: A Cross-Sectional Study.

BACKGROUND: Nerve entrapments like carpal tunnel syndrome are more prevalent in patients with diabetes, especially in those with diabetic polyneuropathy. Our study aims were to investigate the validity of the Tinel sign in diagnosing tibial neuropathy and determine the prevalence of tibial nerve entrapment in both a diabetic and nondiabetic population. METHODS: Two hundred forty nonneuropathic subjects with diabetes and 176 diabetic subjects with neuropathy participating in the prospective Rotterdam Diabetic Foot Study and 196 reference subjects without diabetes and without neuropathy complaints were evaluated. All subjects underwent sensory testing of the feet, and complaints were assessed using the Michigan Neuropathy Screening Instrument. The Tinel sign was defined as discriminative and valid for diagnosing tibial nerve entrapment when the nerve-related Michigan Neuropathy Screening Instrument subscore of neuropathic symptoms differed at least 5 percent between the Tinel-positive and Tinel-negative subjects. When the sign was valid, prevalence estimates of tibial nerve entrapment at the tarsal tunnel were calculated. RESULTS: Significantly more neuropathic symptoms (p < 0.002) and higher sensory thresholds (p < 0.0005) were observed in (compressed) tibial nerve-innervated areas, indicating that a positive Tinel sign at the tarsal tunnel is a valid measure of tibial nerve abnormality. The prevalence of tibial nerve entrapment in diabetic patients was 44.9 percent (95 percent CI, 40.1 to 49.7 percent) versus 26.5 percent (95 percent CI, 20.3 to 32.7 percent) in healthy controls (p < 0.0001). CONCLUSIONS: Tibial nerve entrapment is more prevalent in diabetic subjects than in controls. The significantly more frequently reported neuropathic complaints and concomitant sensory disturbances provide evidence for the role of superimposed entrapment neuropathy in diabetes-related neuropathy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Diagnostic, IV.

Squatting-induced bilateral peroneal nerve palsy in a sewer pipe worker.

Compression neuropathy of the common peroneal nerve (CPN) at the fibula head is a common condition, but it has not attracted attention in working environments. Here, we report a 38-year-old sewer pipe worker who presented with bilateral CPN palsy following 6h working with a squatting posture in a narrow sewer pipe. During the work, he could not stretch his legs sufficiently because of the confined space. His symptoms deteriorated with repetition of the same work for 1 week. Motor nerve conduction study showed conduction block at the fibula head of bilateral CPNs, compatible with compression neuropathy at this lesion. Three months after cessation of work requiring the causative posture, his symptoms and neurophysiological abnormalities had resolved completely. Almost all seven of his co-workers presented transiently with similar and milder symptoms, although one showed CPN palsy for 6 months. Prolonged squatting posture in a confined space causes acute compression neuropathy at the fibula head in the CPN. More attention should be paid to 'confined space worker's compression neuropathy'.

Lower extremity nerve entrapments in athletes.

Nerve entrapments are a potential cause of lower extremity pain in athletes. Signs and symptoms suggestive of nerve entrapment include anesthesia, dysesthesias, paresthesias, or weakness in the distribution of a peripheral nerve. The physical examination may reveal an abnormal neurologic examination finding in the distribution of a peripheral nerve, positive nerve provocative testing, and positive Tinel sign over the area of entrapment. Electrodiagnostic studies, radiographs, magnetic resonance imaging studies, and sonographic evaluation may assist with the diagnosis of these disorders. Initial treatment usually involves conservative measures, but surgical intervention may be required if conservative treatment fails. This article discusses the diagnosis and treatment of common lower extremity nerve entrapments in athletes. A high index of suspicion for nerve entrapments enables the clinician to identify these conditions in a timely manner and institute an appropriate management program, thus improving patient outcomes.

Associated lateral process and posteromedial tubercle talus fractures with entrapment of the medial neurovascular bundle: a case report.

This paper describes a case of an isolated fracture of the lateral process of the talus associated with a fracture in the posteromedial tubercle of the talus with entrapment of the medial neurovascular bundle. Currently no similar cases have been published describing this type of neurovascular bundle injury. Furthermore, in contrast to previously published cases, both fractures were treated surgically despite the absence of posteromedial tubercle fracture displacement. This article reviews the literature and provides useful recommendations for the clinical management of similar cases in the future.

An unusual case of aneurysmal tibial nerve compression detected in ED.

We present an unusual case of tibial nerve compression caused by a true tibial posterior artery aneurysm. A 61-year-old man was admitted to the emergency department due to suspected muscle rupture. He had experienced a sudden, intense right calf pain and swelling that had begun during walking. He had a 6-month-long history of symptoms suggestive to the tibial nerve dysfunction and a month-long history of neurologic finding consistent with the right tibial nerve paresis. An examination of the legs revealed a painful mass in the posterior-medial compartment of the right calf. Emergency ultrasound scanning of the right lower leg vascularization showed an expansive saccular aneurysm of the proximal segment posterior tibial artery with mural thrombus and splitting of the aneurysmal wall. An angiography confirmed the diagnosis. Under spinal anesthesia, we performed aneurysmectomy and decompressed the tibial nerve. The histologic examination was compatible with a true aneurysm of the right posterior tibial artery.

Somatosensory evoked potential from S1 nerve root stimulation.

The objective of this study was to detect cerebral potentials elicited by proximal stimulation of the first sacral (S1) nerve root at the S1 dorsal foramen and to investigate latency and amplitude of the first cerebral potential. Tibial nerve SEP and S1 nerve root SEP were obtained from 20 healthy subjects and 5 patients with unilateral sciatic nerve or tibial nerve injury. Stimulation of the S1 nerve root was performed by a needle electrode via the S1 dorsal foramen. Cerebral potentials were recorded twice to document reproducibility. Latencies and amplitudes of the first cerebral potentials were recorded. Reproducible cerebral evoked potentials were recorded and P20s were identified in 36 of 40 limbs in the healthy subjects. The mean latency of P20 was 19.8 ± 1.6 ms. The mean amplitude of P20-N30 was 1.2 ± 0.9 µV. In the five patients, P40 of tibial nerve SEP was absent, while well-defined cerebral potentials of S1 nerve root SEP were recorded and P20 was identified from the involved side. This method may be useful in detecting S1 nerve root lesion and other disorders affecting the proximal portions of somatosensory pathway. Combined with tibial nerve SEP, it may provide useful information for diagnosis of lesions affecting the peripheral nerve versus the central portion of somatosensory pathway.

Electrodiagnostic evaluation of lower extremity neurogenic problems.

Electrodiagnosis is a powerful tool for evaluating lower extremity disorders that stem from the peripheral nervous system. Electrodiagnostic testing can help differentiate neurogenic versus non-neurogenic causes of complaints such as pain, weakness, and paresthesias. It can help practitioners pinpoint the anatomic location and reveal the underlying pathology in peripheral nerve lesions. This article focuses on the electrodiagnostic evaluation of neurogenic processes that present as foot and ankle symptoms.

Peroneal and tibial intraneural ganglion cysts in the knee region: a technical note.

BACKGROUND: Recent research has resulted in an improved understanding of the pathogenesis and treatment of intraneural ganglia, particularly with respect to the most common form, the peroneal nerve at the fibular neck region. OBJECTIVE: To outline the mechanism for the development and propagation of intraneural ganglia located in the knee region, along with their treatment, as well as highlight how shared principles can be exploited for successful treatment of the more commonly occurring peroneal intraneural ganglia. METHODS: A surgical approach has been developed for peroneal intraneural cysts based on the pathogenesis. The treatment of the less common tibial intraneural cysts is designed along the same principles. RESULTS: A strategy consisting of (1) disarticulation (resection) of the superior tibiofibular joint (ie, the source), (2) disconnection of the articular branch connection (ie, the conduit), and (3) decompression (rather than resection) of the cyst has improved outcomes and eliminated intraneural recurrences in peroneal intraneural cysts. These same principles and techniques can be applied to the rarer tibial intraneural ganglia derived from the same joint. The mechanism of development and propagation for intraneural cysts in the knee region as well as a surgical technique and its rational are described and illustrated. CONCLUSION: Understanding the joint-related basis of intraneural cysts leads to simple targeted surgery that addresses the joint, its articular branch, and the cyst. The success of the shared surgical strategy for both peroneal and tibial intraneural ganglia confirms the principles of the unifying articular theory.

Common peroneal and posterior tibial ischemic nerve damage, a rare cause.

A 56-year old gentleman presented to our orthopaedic foot and ankle clinic, with unusual symptoms in his left foot. He described a tight sensation over his toes, "like sandpaper under his skin". The pain had started post operatively following a bilateral aorto-femoral bypass. He was subsequently investigated and found to have an ischemic lesion Identified in his common peroneal and posterior tibial nerve with associated muscle atrophy on EMG. This represents a previously unreported complication of aorto-femoral bypass surgery.

Common peroneal and tibial nerve paralysis secondary to herpes zoster infection: a case report.

BACKGROUND: The usual presentation of herpes zoster (HZ) is a self-limiting vesicular rash, often accompanied by post-herpetic neuralgia. However, HZ can give rise to other complications, that have unusual presentations and serious sequelae like segmental motor paralysis of the limbs that is a relatively rare complication. CASE: A 68-year-old man presented with foot drop on the right side had a history of HZ infection on and around the knee and the popliteal fossa. He was treated with acyclovir by a dermatologist and 10 days after the inital symptoms he developed weakness on the right ankle and on the muscles distal to the knee. In a few days foot drop has developed and he was unable to walk without help. Three months later he was admitted to the neurology out patient clinic. On his electrophysiological examination common peroneal nerve could not be stimulated on the right side. The distal latency of the tibial nerve has prolonged, CMAP amplitude has diminished and the nerve conduction velocity has slowed down. Latency of the sural nerve has prolonged with a small SNAP amplitude and a slow nerve conduction velocity on the right side. Electromyography revealed denervation on the muscles inervated by tibialis anterior and common peroneal nerves distal to the knee. CONCLUSION: The double mononeuropathy of the tibial and common peroneal nerves secondary to HZ was not found in the published data. HZ should be considered as a possible cause of the paralysis of peripheral nerves and more attention should be paid to it.