105 Ulnar Nerve Compression at the Elbow

Case 105 Ulnar Nerve Compression at the Elbow

Stephen M. Russell

Fig. 105.1 A patient with severe left ulnar nerve entrapment at the elbow with clinical signs shown in (A–C). See Answer section for further description.

Clinical Presentation

A 50-year-old woman presents with 6 weeks of elbow pain localized to the left medial epicondyle.

It began after a prolonged period of holding the telephone with the affected hand.

A few days later she woke one morning with complete numbness in the small finger.

Then over the ensuing weeks, she developed progressive hand atrophy, weakness, and incoordination.

Her examination reveals dense numbness to light touch and pinprick on the hypothenar eminence (including the dorsum of the hand in this area), as well as the small finger and adjacent half of the ring finger.

Severe atrophy of most hand intrinsic muscles is noted.

Tapping in the retrocondylar groove causes paresthesias to occur in the small finger. Figure 105.1 illustrates the patient’s hands.
She has no neck pain and no Spurling sign.

Questions

What is your differential diagnosis?

In Fig. 105.1A, what atrophic muscle is labeled with the white arrow?
In Fig. 105.1B, what atrophic muscle is labeled with the black arrow?
In Fig. 105.1B, the white arrow indicates an examination finding that is commonly encountered with her diagnosis, what is it?
In Fig. 105.1C, the white arrow indicates another examination finding that is commonly encountered with her diagnosis; what is it?
Describe the McGowan classification of ulnar nerve entrapment.
What are the nonoperative treatment options available?
What are the indications for surgery?
What are her surgical options for ulnar nerve decompression and/or transposition?
Describe the efficacy and common complications of ulnar nerve decompression and/or transposition.

Answers

What is your differential diagnosis?

Her history and examination are classic for an ulnar nerve entrapment at the elbow, including her reporting a period of prolonged flexion that may have instigated her somewhat rapid progression of symptoms, a clear sensory loss in an ulnar nerve distribution, and the evidence of ulnar innervated hand intrinsic atrophy.1

Other less likely diagnoses would include a C8 radiculopathy, an ulnar nerve entrapment at the wrist, and rarely, neurogenic thoracic outlet syndrome.
In Fig. 105.1A, what atrophic muscle is labeled with the white arrow?
- There is marked atrophy of the first dorsal interosseous muscle.
- Atrophy of this muscle is usually the most obvious with moderate to severe ulnar nerve injury/entrapment.
In Fig. 105.1B, what atrophic muscle is labeled with the black arrow?
- Although most muscles of the thenar eminence are innervated by the median nerve, the largest one, the adductor pollicis, is innervated by the ulnar nerve; therefore, patients with ulnar neuropathy can also have atrophy of their thenar eminence.
In Fig. 105.1B, the white arrow indicates an examination finding that is commonly encountered with her diagnosis; what is it?
- When the patient opens her aff ected hand, an “ulnar claw hand” is revealed. This consists of ring and small finger hyperextension at the knuckles (metacarpal-phalangeal joints) with superimposed interphalangeal joint flexion secondary to a tenodesis effect.
In Fig. 105.1C, the white arrow indicates another examination finding that is commonly encountered with her diagnosis; what is it?
- A positive Froment sign
- In patients with severe ulnar neuropathy, the adductor pollicis cannot adduct a straight thumb.
- Instead, the patient flexes the distal interphalangeal joint (median innervated flexor pollicis longus) to oppose the thumb against the hand.
Describe the McGowan classification of ulnar nerve entrapment.
- Dr. McGowan classified ulnar nerve entrapment at the elbow as follows²:
  - Grade 1: purely subjective symptoms with mild hypesthesia
  - Grade 2: sensory loss with slight wasting and weakness of the hand intrinsic muscles
  - Grade 3: severe sensorimotor deficits
What are the nonoperative treatment options available?
- Very few nonoperative treatments are available.
- Some include wearing an elbow pad or an elbow splint; however, compliance with these is poor.
- Physical and occupational therapy may be effective in resolving mild cases.
What are the indications for surgery?
- Surgery is usually recommended for McGowan grade 2 and 3 ulnar nerve entrapments.
- As a general rule, if there are not periods during the day where the hand is normal, then nerve damage is likely occurring and surgery should be an option.
- Some patients with McGowan grade 1 entrapments request surgery when other conservative measures have failed.
What are her surgical options for ulnar nerve decompression and/or transposition?
- There are many surgical options for decompressing the ulnar nerve at the elbow (Fig. 105.2).
- One should use a technique they have personal experience with because, in general, most techniques are equally efficacious.
- Simple in situ decompression of the ulnar nerve has become more popular as of late because of a few recent randomized trials concluding that a simple decompression is as effective as a transposition.^3–5
Describe the efficacy and common complications of ulnar nerve decompression and/or transposition.
- The results of ulnar nerve decompression and/or transposition are that 60–80% of patients improve, while the rest are the same, or occasionally are worse over time.^3–5
- Complications include wound pain, elbow numbness, and neuroma formation from injury to the posterior division of the medial antebrachial cutaneous nerve (Fig. 105.2A).