A 29-year-old worker in a warehouse comes to the Rheumatology Clonic for review

A 29-year-old worker in a warehouse comes to the Rheumatology Clonic for review. He complains of sensory loss affecting part of his nght hand, and some weakness when it comes to grasping heavy articles in the workplace. He notes that he IS tall (190cm in height), and has to lean on a low counter to sort /pick items for buyers. There is no past medical history of note and he takes no regular medication. There is dec1·eased sensation over the palmar aspect of the 4th and 5th f1ngers and the ulnar aspect of the hancl. You note minor weakness of the intrinsic muscles of the hand.
What is the most likely underlying diagnosis?

A C81esion
B Early motor neurone disease
C Median nerve lesion
D Radial nerve lesion
Ulnar nerve lesion

C8 lesion, (Option A), is incorrect. This is unlikely as in CB I Tl lesions sensory loss usually extends proximally to the wrist because of involvement of the medial cutaneous nerve of the forearm.
Ear1y motor neurone disease. (Option B), is ~ncorrect. The sensory loss effectively rules this out as the underlying d1agnos1s.
Median nerve lesion, (Option C) is incorrect. Med1an nerve lesions at the elbow lead to weakness of flexion of the index fmger, defective thumb opposition, and sensory loss over the palm of the hand, but over the thumb, index and middle f10gers, rather than the 4th and 5th fmgers.
Radial nerve lesion, (Option D), is incorrect. These lead to sensory loss over the lateral aspect of the hand, includ1ng the thumb