Deep tendon reflex in Eaton-Lambert syndrome.

The mechanism of absent or decreased deep tendon reflex in Eaton-Lambert syndrome was studied. There was no evidence suggestive of the presence of a neuropathy. On the other hand, a brief (about 10 seconds) maximal voluntary contraction made the absent deep tendon reflexes elicitable, which suggests that the block of neuromuscular transmission in Eaton-Lambert syndrome is responsible for the absent or decreased deep tendon reflex. Such enhancement of the decreased deep tendon reflex in Eaton-Lambert syndrome might be helpful in differentiating neuropathy and Eaton-Lambert syndrome.