F wave study in children with birth brachial plexus paralysis
Kwast, O.
Electromyography and Clinical Neurophysiology 24(6): 457-467
1984
ISSN/ISBN: 0301-150X PMID: 6489251 Document Number: 221898
F wave parameters in the paralyzed and intact hand were analyzed in 26 children, of different ages, with birth brachial plexus (BP] paralysis. In 7 children with lesions of the upper and middle trunks of BP, F waves were analyzed in the median nerve; in 19 children with widespread lesion, F waves were analyzed in the median and ulnar nerves. The shortest F wave latencies, in addition to motor nerve conduction velocity in the distal segment (axilla to wrist), allowed detection of reduced conduction in the proximal segment (spinal cord to axilla) in 8 children of different ages with widespread lesion of BP. F chronodispersion (Fch) and maximal amplitudes of F waves (Fa) were normal in children with slight degree of lesion, who had other electromyographical signs of lesion in abductor pollicis brevis and abductor digiti quinti muscles. Normal values of Fch and Fa were explained by the mechanism of F wave forming in sprouting and regenerating nerve fibers. For that reason, the Fch method was less sensitive in indicating the lesion in pure regeneration (post-traumatic) processes than in possible demyelination ones. Increased Fa in 4 cases was explained by increased excitability of motor neurons or motor nerve fibers than by collateral innervation.