[The terminal latency quotient in patients with compressive syndromes]

In our investigation 119 patients suffering from carpal tunnel syndrome, and 45 suffering from cubital tunnel syndrome have been analyzed. The above mentioned syndromes belong to compressive mononeuropathies and are the result of the narrowing of the anatomical channel, through which the nerve passes, causing direct or indirect pressure on the nerve and difficulties in the flow of particles and nerve impulses towards the periphery. The aim of our work was to study the influence of the compressive lesion, primarily on the distal motor and sensory latencies. To achieve a better precision, the distal motor latency is expressed as a quotient of terminal latency. It is obtained by dividing the distance between the stimulation and the recording point in centimeters with the latency of response expressed in miliseconds. Sensory latencies are obtained by orthodromic stimulation of the finger and the detection of the neural potential at the wrist. According to our results, the proximal pathological process, besides causing the localized slowing down of conduction velocity, affects the conduction velocity of the distal sensory fibers in a higher degree than of the distal motor fibers. In any case the distal motor latencies are in a higher percentage prolonged by the distal lesion, such as carpal channel syndrome, in comparison with the proximal lesion (cubital tunnel syndrome). The less pronounced prolongation of the distal latencies, especially of sensory ones, must not be proclaimed as a consequence of a local compression without additional plurisegmental analysis.