Electrophysiological recording of deep tendon reflexes: normative data in children and in adults.

OBJECTIVE: Latency measurement of myoelectric deep tendon (T) reflex responses is not usually performed in EMG laboratories. We investigated the optimal conditions of reliable recording of T reflex in children and adults. METHODS: Two hundred and sixty-eight normal subjects (139 males, 129 females, age rank 2 days-80 years) were studied. T reflexes were recorded from soleus and rectus femoris muscles (children and adults) and from triceps brachialis, biceps brachialis and flexor carpi radialis (adults). Specially devised hammers were used. They were fitted with a spring switch system in order to trigger the trace display on the EMG machine. Distinct technical options for the synchronisation delay assessment were tested. The nerve conduction velocities along reflex pathways were computed by referring the T wave latencies to subject's height. RESULTS: Reliable recordings could be obtained in all cases, with a strong linear correlation of the response latency with height. T reflex conduction velocities increased as the log value of subject age. Normative data from birth to 80 years are provided. CONCLUSION: T reflex recording represents a painless and easily performed technique. It may be helpful for the assessment of proximal conduction velocities, especially in children during maturation of the peripheral nervous system.