You do a thorough neurological examination and find the following:
- Speech – normal
- HMF – normal
- Cranial nerves – normal
- UL – right arm – ShAb 5/5; EF 5/5; EE 5/5; WE 1/5; FE 2/5; F ab 5/5; APB 5/5
- Reflexes – normal
- Sensation – patch of numbness on back of right hand
- Rest – normal
So, we have evidence of focal neurological deficits, namely, weakness in wrist extension, finger extension, and decreased sensation to the back of the right hand. This doesn’t really fit with a stroke, there is motor and sensory loss, but in a very specific pattern. Additionally, the reflexes are normal which is not in keeping with an UMN lesion.
This case requires a bit of neuro-anatomy knowledge but the pattern of weakness fits with a radial nerve palsy. The radial nerve is basically responsible for extension of the arm so it will present with weakness on extension. The radial nerve is also responsible for sensation over the posterior aspect of the arm and the dosrum of the hand.
The history is also suggestive of this, radial mono-neuropathies are often caused by compression of the nerve when people fall asleep drunk (which is what gives this injury it’s colloquial name of Saturday night palsy!).
Here’s a good example in the flesh.
And a lovely short lecture that covers it in more detail.