Radial Neuropathy

Fig. 10.38 a-c. Wartenberg syndrome. a,b Short-axis and c long-axis 15-7 MHz US images over the radial nerve at the wrist in a patient with symptoms of superficial radial neuropathy after intravenous infusion in the cephalic vein, a Proximal to the level of injury, a normal-appearing nerve (arrow) is seen adjacent to an occluded cephalic vein (arrowhead). b,c At the level of puncture, a fusiform hypoechoic thickening of the nerve (arrow) with loss of the fascicular echotexture can be appreciated as a result of trauma. Note the position of the nerve relative to the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendons... 

Differential diagnoses of peripheral neuropathy were entertained. Laboratory tests revealed that serum parameters for electrolytes and proteins were all within the normal range. Urine porphyrinogen and porphobilinogen levels were normal. Tests were negative for serum rheumatoid factor and antinuclear antibodies, the latter used in detection of connective tissue diseases such as systemic lupus erythematosus and polyarteritis nodosa that could present with features of peripheral neuropathy. Nerve conduction studies of the radial, ulnar, and median nerves revealed delayed conduction. Biopsies of the ulnar and radial nerves showed loss of nerve fibers and sudanophilic (indicating lipid) deposits in the Schwann cells of the neurons. Similarly, the yellowish plaques of the pharynx showed abundant macrophages filled with sudanophilic material. These deposits were not membrane-bound. 

Three cases of radial nerve palsy were reported in demented elderly patients confined to wheelchairs who were treated with haloperidol. The combination of extrapyra-midal and sedative adverse effects, added to wheelchair confinement, may have resulted in pressure on the upper arm with subsequent neuropathy (18). 

Peripheral neuropathy wrist drop, due to radial nerve involvement, is a classic manifestation of chronic lead neurotoxicity. Clinical and experimental studies support the view that lead induces peripheral nerve lesions. Central nervous system the manifestations of saturnine encephalopathy include headache, irritability, insomnia, apprehension, confusion, nightmares and fits. High exposure levels (at least 200/ig Pb/lOOml in children and 500)Ltg Pb/lOOml in adults) are usually found. Recovery from encephalopathy is often incomplete, and residual neurological damage is frequent. 

Supinator syndrome, also referred to as posterior interosseous syndrome or radial tunnel syndrome , is a rare compression neuropathy of the upper limb affecting the posterior interosseous nerve just near or behind the supinator muscle (Spinner 1968). This nerve is vulnerable to injury at the proximal edge of the superficial belly of the supinator muscle that forms a free, strong, fibrous arch, the arcade of Frohse . At this site, the posterior interosseous nerve may be tethered and entrapped by fibrous bands. 

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