Investigations

1st investigations to order

electromyogram (EMG)

Test
Result
Test

EMG is the diagnostic test of choice.[28][29][30]

EMG is useful for diagnosing CTS, excluding or identifying other neurological 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

Investigations to consider

ultrasound of the wrist

Test
Result
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][35]

Result

space-occupying lesion may be identified

MRI of the wrist

Test
Result
Test

Useful if space-occupying lesion suspected, especially pre-operatively.[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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