NCS-MEDIAN NEUROPATHY (WRIST)

SUMMARY

1. Sensory fibers are usually affected first. Rarely, motor axons are preferentially affected, due to focal compression of the recurrent branch or selective effects on fascicles within the nerve.

2. The patient often does not localize the numbness to simply the median distribution but indicates the whole hand.

3. Detection of slowing of median nerve conduction at the wrist is the primary goal of investigation.

4. 3 sensory studies (add the latency differences to obtain the Combined Sensory Index score):
- Comparison of median-ulnar conduction to the ring finger
- Comparison of median-radial conduction to the thumb
- Comparison of median-ulnar conduction to the palm (8cm distance)

5. Motor conduction studies should be performed even if sensory studies are normal. Needle EMG is sometimes useful as well.

Reference(s)

Wilkinson, I., Furmedge, D. and Sinharay, R. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press. Get it on Amazon.
Feather, A., Randall, D. and Waterhouse, M. (2020). Kumar And Clark’s Clinical Medicine. 10th ed. S.L.: Elsevier Health Sciences. Get it on Amazon.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].