Median nerve neuropathy

The median nerve is the most important nerve in the upper extremity, as it is responsible for most of the sensation of the hand, the fine motor functions of the thumb, and finger grasping. Median neuropathies most commonly occur as compressive neuropathy or entrapment neuropathy, but sometimes as neuritis without any compressive lesion. Carpal tunnel syndrome (CTS), anterior interosseous nerve syndrome, and pronator teres syndrome are the subtypes of median nerve neuropathies, of which CTS is the most common. Median neuropathies can be diagnosed clinically by careful history-taking and a physical examination. Typical symptoms of CTS include night pain (crying), a tingling sensation of the radial digits, numbness or paresthesia, clumsiness, and atrophy of the thenar muscles. Electrophysiologic testing can be used for confirmation of the diagnosis and for documentation before surgical treatment. Imaging modalities including ultrasonography or magnetic resonance imaging can be used to ensure diagnostic accuracy and to detect unusual causes of compression. Conservative treatments include rest, bracing, nerve stretching, non-steroidal anti-inflammatory drugs, and steroid injections. If nonsurgical approaches are unsatisfactory or the nerve damage is severe, surgical treatment should be considered. Carpal tunnel release for CTS is a relatively simple procedure that involves division of the transverse carpal ligament and decompression of the median nerve. Early diagnosis and proper management are important, as muscle atrophy and sensory loss may persist when surgical release is delayed in patients with advanced disease.

Resolution of Isolated Unilateral Hypoglossal Nerve Palsy Following Microvascular Decompression of the Intracranial Vertebral Artery

Isolated hypoglossal nerve paresis due to mechanical compression from a vascular lesion is very rare. We present a case of a 32-year-old man who presented with spontaneous abrupt-onset dysarthria, swallowing difficulty and left-sided tongue atrophy. Brain computed tomographic angiography and magnetic resonance imaging of the brainstem demonstrated an abnormal course of the left vertebral artery compressing the medulla oblongata at the exit zone of the hypoglossal rootlets that was relieved by microvascular decompression of the offending intracranial vertebral artery. This case supports the hypothesis that hypoglossal nerve palsy can be due to nerve stretching and compression by a pulsating normal vertebral artery. Microvascular decompression of the intracranial nerve and careful evaluation of the imaging studies can resolve unexpected isolated hypoglossal nerve palsy.

Distraction-Neural Lengthening of Rabbit Sciatic Nerve by Tissue Expansion Technique / 대한정형외과연구학회지

PURPOSE: To determine the upper limit of peripheral nerve lengthening without loss of function, the recovery time of peripheral nerve palsy due to nerve lengthening and their histological changes. MATERIALS AND METHODS: Twelve adult New Zealand rabbits weighing about 2.5 kg were assigned to the following groups. Group 1 (n=6) was subjected to slow tissue expansion with 30% of nerve lengthening while group 2 (n=6) was rapid expansion with 40% lengthening of nerve. The expanders were refilled every 2 times during the 2nd and 4th weeks making a total four times of expansion. The rabbits were assessed in terms of affected leg paralysis, neural length gain, EMG with nerve conduction velocity and histological changes. RESULTS: In group 1 (n=6), paralysis on affected leg was found in one rabbit and was recovered spontaneously on the 4th weeks after expander removal. In Group 2 (n=6), paralysis was found in four rabbits, and three of them were recovered on 4, 5 and 9 weeks after removal of the expander. EMG study showed increase in distal latency of 2.50+/- 0.20 m/sec, and decrease in nerve conduction velocity of 62.49+/- 5.30 m/sec compared to normal side with 1.89+/- 0.14 m/sec and 75.39+/- 7.82 m/sec. The mean neural length gain was 6 mm (30% of 20 mm of initial pre-experimental nerve length) in group 1 and 8 mm (40% of 20 mm) in group 2. Light microscopic examination revealed the loss of segmental myelination, decrease of myelination, and vacuolation. Electron microscopic examination showed that the normal ring shaped contour of axon was changed to convoluted shape.

Facilitation of Motor Evoked Potential by Stretching of Peripheral Nerve

OBJECTIVE: To investigate the effect of peripheral nerve stretching on motor evoked potentials (MEP) as a method of facilitation. METHODS: Twenty three normal healthy volunteers were enrolled. Transcranial magnetic stimu lation (TMS) was applied to the contralateral scalp at 7 cm lateral to Cz using 90 cm round coil. Intensity of stimulation was adjusted to 90% of maximal stimulation intensity. Recording was done on the abductor pollicis brevis muscle in three different conditions; firstly resting state, secondly voluntary contraction of abductor pollicis brevis muscle, and lastly with stretching of median nerve. The onset latency and amplitude were obtained and compared between three conditions. RESULT: The amplitude of MEP was significantly increased in the condition with muscle contraction and peripheal nerve stretching compared with resting state. The latency was shortened in the condition with muscle contraction with statistical significance and with peripheral nerve stretching without significance. CONCLUSION: We concluded that stretching of peripheral nerve can be used as a method of facilitation of MEP. This method is considered to be useful especially for the patients with motor paralysis or poor cooperarion for voluntary contraction.