Question

A 34-year-old male patient with a past medical history of diabetes mellitus and hypertension presents with unilateral numbness, weakness, and atrophy of the hypothenar muscles. The middle, ring, and small fingers are held in flexion, and there is weakness of abduction of the small finger. The patient cannot prevent paper from being pulled through the fingers, and there is decreased sensation to pinprick over the palmar aspect of the ring and small fingers. The deep tendon reflexes of the bracHIOradialis, biceps, and triceps on the affected side are 1+. What is the most likely cause?

1) Carpal tunnel syndrome
2) Ulnar nerve entrapment at the elbow
3) Radial nerve entrapment
4) Median nerve entrapment at the wrist

Answer 1

The patient's clinical presentation suggests ulnar nerve entrapment at the elbow due to marked symptoms in the ulnar nerve distribution, including hypothenar muscle involvement and sensory changes in the ring and small fingers.

Step-by-step explanation:

The patient's symptoms of unilateral numbness, weakness, and atrophy of the hypothenar muscles, along with the clawing of the middle, ring, and small fingers and decreased sensation over the palmar aspect of the ring and small fingers, are indicative of ulnar nerve entrapment at the elbow. The ulnar nerve is responsible for the motor innervation of most of the intrinsic muscles of the hand, including the hypothenar muscles (the abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi), which are involved in the movement of the small finger. The ulnar nerve also provides sensory innervation to the palmar and dorsal aspects of the medial one and a half fingers. Therefore, the most likely cause of the patient's symptoms is ulnar nerve entrapment at the elbow (Option 2).

Carpal tunnel syndrome is caused by compression of the median nerve in the wrist and generally manifests with symptoms in the thumb, index, and middle fingers rather than the ring and small fingers. The patient's issue being localized to the ring and small fingers, along with the hypothenar atrophy, does not align with carpal tunnel syndrome. Radial nerve entrapment primarily affects the extensor muscles of the forearm and would not typically present with the patient's symptoms. Median nerve entrapment at the wrist leads to carpal tunnel syndrome, which, as stated before, affects different fingers.

The weakness of abduction of the small finger and inability to prevent paper from being pulled through the fingers, combined with the described sensory deficits, supports the diagnosis of ulnar nerve entrapment at the elbow. The final answer is ulnar nerve entrapment at the elbow, which can be summarized in two line explanation: The patient exhibits symptoms corresponding to the distribution and functions of the ulnar nerve, and ulnar nerve entrapment at the elbow is the most consistent with the clinical presentation.