Tests
1st tests to order
electromyogram (EMG)
Test
EMG is the diagnostic test of choice.[28][29][30]
EMG is useful for diagnosing CTS, excluding or identifying other neurologic diagnoses, assessing the severity of median nerve damage, helping with choice of management, judging the success of interventions, determining prognosis, and as a baseline that can be followed over time.
Result
focal slowing of conduction velocity in the median sensory nerves across the carpal tunnel; prolongation of the median distal motor latency; possible decreased amplitude of median sensory and/or motor nerves
Tests to consider
ultrasound of the wrist
Test
Complementary to EMG; useful if space-occupying lesion is suspected, such as a ganglion cyst. Does have some diagnostic use (but less than EMG) by determining if the median nerve is swollen.[32][33][34][36] However, do not use ultrasound to assess severity of CTS because its effectiveness in determining severity is uncertain.[35]
Result
space-occupying lesion may be identified
MRI of the wrist
Test
Useful if space-occupying lesion suspected, especially preoperatively.[32] MRI is more accurate than ultrasound in delineating the carpal tunnel but is not superior to EMG and is resource-intensive.
Result
space-occupying lesion may be identified
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