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Age / Sex : 44 / F
Chief complaint: discomfort of left 1-4th fingers & web spaces
1) What is your impression?
Two weeks later, you can see the final diagnosis with a brief discussion of this case.
(Quiz는 quiz일 뿐이오니 답안은 한개만 보내주시기 바라오며, 복수의 답안을 보내주시는 분은 정답이 포함되어 있더라도 부득이 semi-correct answer로 처리토록 하겠습니다.)
Courtesy: 이상용(Sang Yong Lee), 전북대병원(Chonbuk National University Hospital)
Diagnosis: Guyon canal syndrome
Discussion
Findings:
Swelling of motor
branch of the Lt ulnar in Guyon’s canal level on ultrasonographic images
Interosseous
muscle atrophy in 1st – 4th web space
Fig. 1. Transverse
US shows marked swelling of the motor branch of the left ulnar nerve (arrows)
in the Guyon canal. On the right side the motor branch of the ulnar nerve is
normal in size.
Fig. 2. On transverse image of 1st web space volume of
interosseous muscle was decreased on the left side.
Differential Diagnosis:
Abnormalities of the ulnar artery
More proximal ulnar neuropathies (eg, cubital tunnel
syndrome, thoracic outlet syndrome, cervical radiculopathy)
Amyotrophic lateral sclerosis
Focal motor neuron myelopathy,
Syringomyelia,
Pancoast tumor
Diagnosis:
Guyon canal syndrome
Discussion:
Unlike CTS, Guyon canal syndrome is uncommon to
rare. In Guyon canal syndrome, the ulnar nerve is compressed, leading to
initial patient complaints of paresthesia and later complaints of motor
abnormalities in the distribution of the fourth and fifth digits as well as weakness
in the midpalmar muscles.
Guyon canal syndrome is the result of compression
of the nerve within the canal by a space-occupying lesion, such as a mass, varix,
ulnar artery pseudoaneurysm, or ganglion cyst. It can also be caused by
extrinsic compression on the canal, such as by handlebars in avid bicyclists,
leading to cyclist’s palsy or in golf and racquet sports. Another form of
extrinsic compression is the hypothenar hammer syndrome. Hypothenar hammer
syndrome is thrombosis or aneurysm of the superficial palmar branch of the ulnar
artery due to repetitive compression against the tip of the hook of the hamate,
usually in people who use the base of their hand to hammer objects into place.
To diagnose the Guyon canal syndrome,
radiologist have to knee the exact anatomy of the ulnar nerve and it’s branches
in Guyon canal and distal area to the canal. Ulnar nerve is divided into the
motor and sensory branches in the Guyon canal. Motor branch is going down
medial to the sensory branch. Both MRI and ultrasound may show swelling of the
ulnar nerve or masses in Guyon canal or aneurysmal dilatation of the ulnar
artery.
References:
1. Theodore TM, William RR. Nerve entrapment syndromes of the
elbow, forearm, and wrist. AJR 2010; 195:585-594
2. Gustav A, David WC, Doris B, Borut M, Dominik W. Peripheral neuropathies of the median,
radial, and ulnar nerves: MR imaging features. RadioGraphics 2006; 26:1267–1287
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