Patient Safety: Importance of Temperature in Nerve Conduction Studies

Published June 08, 2026

From the Quality and Patient Safety Committee

A 45-year-old right-handed woman presented for evaluation of bilateral hand numbness. EDX studies demonstrated median sensory responses with prolonged latencies (3.7 ms and 3.6 ms) and slowed conduction velocities (37 m/s and 39 m/s). Median motor studies were largely normal, aside from mildly slowed conduction velocities across the forearms (42 m/s and 43 m/s) and slightly prolonged distal motor latencies. She was diagnosed with bilateral carpal tunnel syndrome. Further evaluation later revealed cervical myelopathy. A repeat EMG 1 month later showed normalization of conduction velocities and reduced amplitudes. 

Question:  What could have been done to ensure accuracy during the initial testing? 

1. Having the patient’s arm at a 90-degree angle 
2. Supramaximal stimulation 
3. Ensuring that the patient’s upper extremity temperature is at least 32–34°C 
4. Increasing the distance between recording electrodes 

Explanation:
The correct answer is 3. Temperature is a critical technical factor in nerve conduction studies and can significantly impact results. Reduced limb temperature can increase sensorimotor amplitudes, prolong distal latencies, slow conduction velocities, and increase temporal dispersion and response duration. Failure to recognize temperature-related artifact may lead to incorrect diagnostic conclusions, including misdiagnosis of conditions such as polyneuropathy or focal entrapment neuropathies. 

 It is essential to measure and monitor limb temperature throughout the study, as extremities may cool during testing. For accurate results, limb temperatures should generally be maintained above 31 C° for lower and 32° C for upper, with many references recommending a range of 32–34°C for distal extremities. When temperatures fall below this range, active warming techniques should be used. 

While correction factors for temperature have been described, they are based primarily on normal nerve data and may not reliably apply in abnormal conditions. Therefore, it is preferable to warm or rewarm the limb rather than attempt mathematical correction. Ensuring appropriate temperature control is a simple but essential step in maintaining diagnostic accuracy and preventing clinically significant errors. 

Authors: Vanessa Tiongson, MD and Kara Stavros, MD

 Supporting References:

  1. Preston DC and Shapiro BE. Electromyography and Neuromuscular Disorders (2021). 

  1. Denys EH. The influence of temperature in clinical neurophysiology. Muscle Nerve. 1991. 

  1. Rutkove SB. Effects of temperature on neuromuscular electrophysiology. Muscle Nerve. 2001. 

  1. Tilki HE et al. Effect of heating on nerve conduction in carpal tunnel syndrome. J Clin Neurophysiol. 2004