Focal cooling improves neuronal conduction in peroneal neuropathy at the fibular neck

Heat can induce conduction block (CB) in demyelinated neurons; whether cool ing can reverse CB and increase strength is uncertain. In six patients with electrophysiologic evidence of peroneal neuropathy at the fibular neck wit h definite motor CB, standard motor nerve conduction studies were performed at 32 degreesC and then after the fibular neck region was cooled with an i ce pack to 8 degrees -12 degreesC. In all patients, cooling increased the a mplitude and area of the compound motor action potential obtained with popl iteal fossa stimulation, decreasing the relative amplitude drop across the fibular neck from a mean of 78% to 55%. A concomitant increase in foot dors iflexor strength was clearly observed in three of the six patients. Both th e electrophysiologic and clinical changes readily reversed upon rewarming. These data support the belief that, in compressive neuropathies, cooling re lieves conduction block in selected motor neurons, improving strength. (C) 2001 John Wiley & Sons, Inc.