An unusual presentation of tarsal tunnel syndrome caused by an inflatable ice hockey skate.

BACKGROUND: Tarsal tunnel syndrome is a rare form of entrapment neuropathy. In athletes, it is usually the result of repetitive activity, local injury or a space-occupying lesion. Rarely, athletic footwear has been described as the primary cause of this syndrome. METHODS: A 37-year-old male recreational hockey player was examined clinically and electrophysiologically because of spreading numbness in the toes of his left foot while playing hockey and wearing inflatable ice hockey skates designed to promote a better fit. RESULTS: Clinical and electrophysiological studies revealed evidence of left medial and lateral plantar nerve involvement. Reduced amplitudes of mixed and motor plantar nerve responses with fibrillation potentials and positive sharp waves and no evidence of conduction block suggest that the primary pathology was axonal loss. Follow-up examination showed significant clinical and electrophysiological improvement after the patient stopped wearing his inflatable ice hockey skates. CONCLUSION: We report an unusual case of tarsal tunnel syndrome caused by an inflatable ice hockey skate. The patient improved clinically and electrophysiologically when he stopped wearing the boot.

Isolated brachialis wasting: an unusual presentation of neuralgic amyotrophy.

Although neuralgic amyotrophy can selectively affect discrete components of the brachial plexus including individual peripheral nerves, involvement of an individual nerve fascicle is rare. Discrete fascicular musculocutaneous neuropathy as a manifestation of neuralgic amyotrophy has not previously been reported to our knowledge. We report two cases of otherwise typical neuralgic amyotrophy with isolated brachialis muscle wasting. Abnormal spontaneous activity, motor unit remodeling, or both, was observed only in the brachialis muscle. Lateral antebrachial cutaneous nerve conduction studies were normal. These cases serve to broaden the spectrum of the clinical presentation of neuralgic amyotrophy.

Wartenberg's migrant sensory neuritis.

We describe a patient with the sudden onset of a painful, purely sensory, mononeuritis multiplex. Investigations showed no evidence for any underlying systemic condition. A nerve biopsy showed fascicular wallerian degeneration with perineurial thickening, inflammatory cells, and immunoglobulin G (IgG) deposition. His painful sensory deficits persisted, with no improvement after treatment with prednisone. The clinical characteristics in this case were very similar to those originally described by Wartenberg, and subsequently by other investigators. The investigations in our case strongly suggest that there may be an underlying immune pathogenesis for cases of Wartenberg's migrant sensory neuritis.

Conduction block in neuralgic amyotrophy.

We describe two cases of neuralgic amyotrophy with electrophysiological evidence of conduction block across the lower trunk of the brachial plexus. Low-output impedance stimulation of the cervical spinal roots in combination with collision was used to accurately demonstrate the conduction block. Complete electrophysiological recovery of the conduction block occurred within 3 months. Early clinical and electrophysiological recovery in both patients suggests that, in some cases, demyelination may predominate early in the course of neuralgic amyotrophy.

Noninvasive ankle distraction: relationship between force, magnitude of distraction, and nerve conduction abnormalities.

Seven healthy volunteers (14 ankles; four males, 3 females) with no history of ankle or foot pathology were placed in a modified beach chair position on an operating table for ankle distraction using a noninvasive ankle distractor. In-line traction of 0 to 225 N (50 lb) in 22.5-N (5-lb) increments was applied to the ankle. A direct lateral radiograph was obtained at each distraction force. The joint space was measured on the lateral radiographs using electronic microcalipers. Surface recordings of the superficial peroneal, deep peroneal dorsal digital cutaneous, and sural nerves were obtained. The ankle joint space increased progressively from an average 3.1 mm with no force applied to an average 4.2 mm with 225 N (50 lb) distraction force applied. The maximum joint distraction averaged 1.3 mm (range, 0.35 to 2.35 mm). The sensory amplitudes were diminished or absent with increasing time and force of distraction. The decreased amplitudes were most marked after 1 hour of distraction with 135 N (30 lb) or greater distraction force. This correlated with symptoms of paresthesias. The superficial and deep peroneal cutaneous nerves were affected to a much greater extent than the sural nerve. The amplitudes quickly returned to normal values with the weight being released from the ankle. The noninvasive ankle distractor safely increased ankle joint space by more than 1 mm. Distraction with 135 N (30 lb) or more for 1 hour is associated with reversible nerve conduction changes. Based on these findings, we recommend using the noninvasive ankle distraction apparatus for ankle arthroscopy, with up to 135 N (30 lb) of traction applied to the foot for up to 1 hour. Greater force, applied for longer periods, is associated with increasing nerve conduction abnormalities.

AAEM case report #27: acute retrohumeral radial neuropathies.

Acute radial neuropathies localized to the retrohumeral course of the radial nerve are common. Most individuals fully recover within a matter of days or, at the most, a few weeks. In a few, recovery may take longer and occasionally remains incomplete. In almost all instances the site of injury to the radial nerve can be accurately localized to the region of the spiral groove and the relative contributions of conduction block and axonal degeneration assessed using electrophysiologic techniques.

Quantitation of axon loss and conduction block in acute radial nerve palsies.

Eleven acute radial nerve palsies were examined between 3 days and 14 weeks following the onset of the neuropathy. Our objective was to quantify the relative extent of axon loss and conduction block in radial motor fibers supplying the extensor and abductor pollicis longus (EPL/APL) muscles. In 10 of 11 cases, conduction block exceeded axon loss. Maximum motor and sensory conduction velocities were normal distal to the spiral groove, suggesting that the larger myelinated fibers were not selectively involved in this acute neuropathy. The localization of the conduction block and slowing was, in every case, across the spiral groove. This method provides a relatively simple way of assessing the approximate contributions of axon loss and conduction block, and fits well with the early and usually complete clinical recovery in these cases.

Early postoperative ulnar neuropathies following coronary artery bypass surgery.

Ulnar neuropathies following surgery are common. However, they often go undetected during the early postoperative period, because the patient may be unaware of symptoms related to the neuropathy. Nerve conduction studies are useful in localizing the lesion, but are usually employed only in cases developing signs and symptoms. We undertook this study to determine the incidence, time of onset, and outcome of clinical and subclinical ulnar neuropathies. Electrophysiological studies were carried out preoperatively, immediately following surgery, and 4 to 6 weeks postoperatively in 20 coronary artery bypass patients. Conduction velocity across the elbow was reduced in 3 limbs (8%) postoperatively, all of which were detected immediately following surgery. One patient developed conduction block and weakness in ulnar supplied intrinsic hand muscles. Denervation was seen in 2 cases and, in 1 case (5%), a right brachial plexus injury was clinically evident 5 days following surgery. All newly developing ulnar neuropathies were asymptomatic, with most recovering to their preoperative electrophysiological status at follow-up.

Influence of peripheral afferents on cortical and spinal motoneuron excitability.

The objective of this study was to establish to what extent muscle, cutaneous, and joint afferents alter the excitability of spinal and cortical motor neurons. This question was examined by studying the impact of electrical stimulation of the second and third digits, the median nerve at the wrist, and the recurrent thenar motor branch on the F/H and magneto-electrical cortical motor responses (MEPs) of the thenar muscles. The firing frequencies of single F/H motor unit action potentials were unaltered by the foregoing conditioning peripheral stimuli. MEPs conditioned by motor threshold stimulation of the median nerve at the wrist or the recurrent motor branch were significantly increased in size at conditioning to test intervals of 50 to 80 milliseconds. No significant change in MEP size resulted from conditioning stimulation of the digital nerves. We conclude that muscle afferents were primarily responsible for the increase in MEP size. Conditioning stimuli may allow examiners to assess central motor conduction where it would otherwise be impossible.

Quantitation of axon loss and conduction block in peroneal nerve palsies.

We compared conduction in motor fibers supplying the extensor digitorum brevis (EDB) and anterior lateral compartment (AL) muscles. The object was to determine whether there were any differences in the relative proportions of degenerated and blocked nerve fibers between the longer EDB and shorter AL fibers. In almost every case the percentage of motor fibers undergoing axonal degeneration was greatest in EDB fibers. Conversely, the percentage of conduction block was greatest in the AL motor fibers. As clinical recovery is dependent on AL muscles rather than EDB, electrophysiological study of the relative proportions of degenerated and blocked fibers in the former should provide a more reliable measure of outcome than similar studies of EDB. Conduction velocity distal to the fibular head was not slowed despite the large loss of EDB motor fibers. Evidence for selective involvement of the larger myelinated fibers is, therefore, lacking. The location of the major conduction abnormalities was in almost every case between the mid-fibular head and popliteal fossa.

Peripheral nerve injuries in cardiac anaesthesia.

Clinical nerve damage in patients undergoing CABG is frequent (15% of patients), while subclinical changes in ulnar nerve function are more common (40% here). Not all injuries develop in the early perioperative period. Most injuries are located at the elbow, and most recover without sequelae. Larger patients appear to be at most risk, but this study does not identify specific interventions which might decrease the risk of injury.