Article

OBJECTIVES: To evaluate the effects of hand warming on electrodiagnostic (EDX)
parameters of carpal tunnel syndrome (CTS). Specifically, to evaluate the type
and magnitude of change in EDX values; to determine whether warming can change
the EDX diagnosis of CTS and, if so, to determine whether specific EDX tests are
more vulnerable to the effects of warming. DESIGN: Interventional before-after
trial. SETTING: Community EDX laboratory. PARTICIPANTS: Consecutive patients
(N=33) referred for EDX evaluation of suspected CTS. INTERVENTION: Each upper
limb was tested at room temperature (average hand temperature, 31.9 degrees C)
and retested after 20 minutes of heating pad warming (average hand temperature,
33.5 degrees C). MAIN OUTCOME MEASURES: Median and ulnar nerve motor and sensory
latency, conduction velocity, and amplitude. RESULTS: Warming resulted in
significantly faster transcarpal tunnel sensory and motor conduction (6%-10%),
reduced median: ulnar sensory latency to digit 4 difference (23%), and reduced
sensory nerve and compound motor action potential amplitude (10% and 13%,
respectively). The changes resulted in 15% fewer limbs meeting the EDX conduction
velocity criteria of CTS and 9% fewer by median: ulnar sensory latency to digit 4
difference. Waveform amplitudes became abnormally low after warming in 12% of limbs. CONCLUSIONS: Hand warming using a heating pad for 20 minutes increases
median nerve transcarpal tunnel conduction velocity and reduces amplitude. These
phenomena introduce potential sources of diagnostic error, particularly in
borderline cases. Generally, within hand, between nerve, and within nerve
comparison techniques are less susceptible to the conduction velocity effects of
warming.

Langue : ANGLAIS