Ulnar Nerve Injury After Carpal Tunnel Release: Symptoms, Causes, and Recovery

Understanding Ulnar Nerve Injury Following Carpal Tunnel Surgery

Carpal tunnel release (CTR) is a common procedure to relieve median nerve compression. However, the ulnar nerve—which runs near the surgical site—can occasionally be injured during or after the operation, leading to distinct neurological symptoms.

Anatomy and Function of the Ulnar Nerve

The ulnar nerve provides sensation to the little finger and the ulnar half of the ring finger. It also controls most intrinsic hand muscles responsible for fine motor movements such as finger abduction, adduction, and thumb adduction.

Symptoms of Ulnar Nerve Injury

• Sensory loss: Numbness, tingling, or reduced sensation in the little finger and medial ring finger.
• Motor weakness: Difficulty spreading fingers, pinching, gripping, or making a fist due to intrinsic muscle weakness.
• Claw hand deformity: In severe or chronic cases, unopposed action of extrinsic extensors and flexors causes hyperextension at the metacarpophalangeal joints and flexion at the interphalangeal joints.
• Pain: Wrist, hand, or elbow pain, sometimes radiating along the ulnar nerve distribution.

Causes and Risk Factors

• Direct trauma during surgery (laceration, compression, or stretch)
• Postoperative hematoma or swelling compressing the nerve
• Improper positioning during surgery
• Preexisting ulnar neuropathy (cubital tunnel syndrome)
• Anatomical variations (e.g., Martin-Gruber anastomosis)

Diagnosis and Treatment

Early recognition is critical. Diagnosis involves clinical examination, nerve conduction studies, and sometimes imaging. Treatment depends on severity:

• Conservative: Splinting, activity modification, physical/occupational therapy, NSAIDs.
• Surgical: Neurolysis, nerve decompression, or nerve repair/grafting for severe transection.

Prognosis

Most neuropraxic injuries recover within weeks to months. Axonotmesis may take 6–12 months. Neurotmesis (complete transection) requires surgical intervention and has a guarded prognosis. Prompt evaluation by a hand surgeon or neurologist optimizes outcomes.