J Korean Orthop Assoc.  2014 Jun;49(3):235-238.

Symptomatic Neural Loop of the Distal Ulnar Nerve

• Lee HI
• Park MJ
• Lee GJ
• Ha SH

Abstract

We found a unique anatomical variant of the distal ulnar nerve, a neural loop encompassing the flexor carpi ulnaris during Guyon's canal exploration. Compression by the flexor carpi ulnaris during active wrist movement was suspected as the cause of ulnar neuropathy. The symptom was relieved after neurolysis and release of surrounding tissue. With regard to the ulnar side wrist pain, which is suspicious for ulnar compression syndrome at the wrist level, the surgeon should always suspect anomalous nerve branch as source of compressive neuropathic pain.

Keyword

ulnar nerve; wrist; ulnar nerve compression syndromes; ulnar neuropathy

MeSH Terms

Neuralgia
Ulnar Nerve Compression Syndromes
Ulnar Nerve*
Ulnar Neuropathies
Wrist

Figure

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  Figure 1 A neural loop was encountered during Guyon's canal exploration. D: distal part, P: proximal part. (A) Distal portion of the neural loop was observed. Arrowhead: flexor carpi ulnaris, black arrow: a neural loop, white arrow: major branch of the ulnar nerve. (B) Proximal portion of the neural loop was observed.

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  Figure 2 Epineurolysis of the neural loop and decompression of adjacent soft tissue was performed. Arrowhead: flexor carpi ulnaris, black arrow: a neural loop, white arrow: major branch of the ulnar nerve, D: distal part, P: proximal part.

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  Figure 3 Several variations of the distal ulnar nerve are illustrated. (A) Normal anatomy. (B) Distal neural loop around hook of hamate. Dotted line is a neural loop. (C) Neural loop from the dorsal cutaneous branch to the superficial branch of the ulnar nerve. Dotted line is a neural loop. (D) Neural loop piercing flexor carpi ulnaris (FCU) is shown. (E) Neural loop encompassing FCU, which was presented in this case report, is shown.

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