Value of homonymous and heteronymous monosynaptic reflexes in the diagnosis and follow-up of cervical spinal injuries.

Needle electromyographic examination constitutes the only neurophysiological test used routinely to assess the integrity of proximal nerve pathways. A heteronymous reflex, with a latency consistent with a monosynaptic pathway, can be evoked in the contracting biceps brachii muscle by stimulation of the median nerve at the elbow. This reflex response provides a complementary technique to the biceps and supinator jerks for accessing the C(5)/C(6)motoneuron pool because its afferent limb involves the median nerve and the C(5)/C(6)posterior roots. Three cases are described to illustrate the clinical value of this heteronymous monosynaptic reflex of biceps brachii and of conventional H reflexes in the diagnosis and follow-up of lesions involving the C(5)/C(6)segments. Reflex function can be assessed for most spinal segments innervating the upper and lower limbs, thus allowing both objective confirmation of the clinical findings and documentation of changes over time. Copyright 1999 Harcourt Publishers Ltd.