Effect of Heating on Nerve Conduction in Carpal Tunnel Syndrome

Abstract

The effect of temperature on normal nerves is well known, i.e., an increase in conduction velocity and a decrease in amplitude with an elevation in temperature. There are few reports examining the effect of temperature on abnormal nerves, e.g., in demyelination. To study the effect of increased temperature on demyelinating nerves in entrapment syndromes, the authors investigated 55 median and 48 ulnar nerves of 48 patients with carpal tunnel syndrome, and 48 median and 48 ulnar nerves of 26 healthy subjects. All measurements were obtained at 32 degrees C and 37 degrees C. Mean reductions in median sensory amplitude occurring with heating were significantly greater in the patient group than in the control group (P = 0.000). For median sensory response amplitude, the mean decrease was 32.1% in patients with carpal tunnel syndrome and 10.7% in the control subjects. The difference between median and ulnar nerves in the latency was significantly decreased (P = 0.027) after the nerves had heated to 37 degrees C. It is concluded that the elevation in temperature leads to conduction block in demyelinated sensory nerves, and that temperature provocation may be useful in the diagnosis of nerve disorders. The effect may be different in axonal and demyelinating disorders.

A handheld nerve conduction measuring device in carpal tunnel syndrome

“…In the present study the used index, the latency difference, was not temperature dependent. However, according to some earlier reports in some cases temperature does not always affect normal and pathological nerves in the same manner (27, 28). Also this might have caused the variance somewhat of because warming of the hands was not systematically performed.…”

The Relative Contributions of the Medial Sural and Peroneal Communicating Nerves to the Sural Nerve

“…Temperature has been known to be one of the most profound factors influencing nerve conduction studies 10,19,20,22,23. With surface recording electrodes within physiological temperature ranges (21-31℃), the SNAP showed a progressive linear increase in latency, amplitude, duration, and area with decreasing temperature 20,22.…”

Does hot pack application change the morphology of the median and ulnar nerves?

“…In another study, increased temperature decreased the median sensory amplitude by 32.1% in patients with CTS and by 10.7% in healthy individuals. [ 8 ] As a result, increased temperature changes EDX parameters in healthy individuals, particularly in pathological nerves. [ 21 , 22 ] Therefore, we consider that the effect of heat on morphological changes in nerves should be investigated in different anatomical localizations (such as carpal tunnel level and forearm) in USG studies.…”

“…[ 7 ] In a previous study, hot pack application increased the median and ulnar nerve conduction velocity and decreased the amplitude in both patients with carpal tunnel syndrome (CTS) and healthy individuals. [ 8 ]…”