A 55 Year Old Male Mechanic with Right Hand Weakness
A 50-year-old right-hand dominant male mechanic presents with a 9-month history of progressive difficulty with performing his job due to weakness in the right hand. He states that he has been dropping objects with his dominant hand and has started performing tasks with his left hand more frequently since he does not have any symptoms on the left. He does endorse long-standing neck pain and waking at night due to hand numbness. He also describes an aching sensation in his forearm. He denies any trauma.
Cranial nerves II-XII are intact
DTRs – 2+ upper and lower extremities
Strength- 5/5 upper extremities except for 4/5 right hand intrinsic muscles
Decreased sensation to pinprick in the right fifth digit
The clinical history and exam is suggestive of ulnar neuropathy at the elbow, or cubital tunnel syndrome. The MRI demonstrates degenerative cervical spine disease that does not explain the patient’s clinical picture. In most cases, the diagnosis of cubital tunnel syndrome is based on a careful history and physical examination. MRI is useful to rule out C8 or T1 radiculopathy. EMG/NCS can help confirm the diagnosis and help characterize the severity of disease.
Questions 1. Ulnar nerve entrapment at the elbow most commonly presents with numbness and tingling in the fourth and fifth digits. Other symptoms inclde elbow pain, nocturnal awakening, pain radiating from the elbow to the medial aspect of the forearm. Motor symptoms are less common but can range from mild hand intrinsic weakness to severe hypothenar wasting and clawhand deformity. Weakness of the palmar interosseous muscles is sometimes demonstrated as an inability to fully adduct the fifth digit (Wartenberg sign). Froment sign occurs when a patient compensates for a weak adductor pollicis muscle when holding a piece of paper between the thumb and index finger by using the median-innervated flexor pollicis longus muscle instead, resulting in flexion of the interphalangeal joint of the thumb.
Question 2. Conservative management of ulnar neuropathy is the preferred initial treatment strategy in mild cases of cubital tunnel syndrome. More severe cases require surgery. Based on randomized studies, in situ decompression is favored over transposition as the initial procedure. In situ decompression of the ulnar nerve is accomplished by transection of the arcuate ligament and flexor carpi ulnaris fascia to decompress the ulnar nerve.
Question 3. Entrapment of the ulnar nerve can also occur within the Guyon canal. Here, entrapment of the ulnar nerve results in hand weakness and atrophy, loss of dexterity, and variable sensory involvement, depending on the site of entrapment within the canal. Sparing of sensation in the dorsal aspect of the hand is typical of ulnar nerve entrapment at the wrist due to sparing of the dorsal cutaneous branch of the ulnar nerve. This can be an important finding to help distinguish ulnar nerve entrapment at the elbow versus the wrist.
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