Ulnar tunnel syndrome

Ulnar tunnel syndrome
Ulnar tunnel syndrome
Other names	Guyon's canal syndrome
	Depiction of classic ulnar sensory distribution, including ulnar-4th and 5th fingers. Note that this diagram does not portray hand muscles affected by ulnar neuropathy.
Specialty	Orthopedic surgery

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Ulnar tunnel syndrome, also known as Guyon's canal syndrome or Handlebar palsy, is ulnar neuropathy at the wrist where it passes through the ulnar tunnel (Guyon's canal).^[1] The most common presentation is a palsy of the deep motor branch of the ulnar nerve causing weakness of the interosseous muscles. Ulnar tunnel syndrome is usually caused by a ganglion cyst pressing on the ulnar nerve, other causes include traumas to the wrist and repetitive movements, but often the cause is unknown (idiopathic).^[2] Long distance bicycle rides are associated with transient alterations in ulnar nerve function.^[3] Sensory loss in the ring and small fingers is usually due to ulnar nerve entrapment at the cubital tunnel near the elbow, which is known as cubital tunnel syndrome, although it can uncommonly be due to compression at the wrist.

Causes

Ulnar neuropathy at the wrist is often associated with a mass such as a ganglion cyst or thrombosis or an aneurysm of the ulnar artery.^[4] The role of activities and exposure is less certain.

Diagnosis

Classification

Ulnar tunnel syndrome may be characterized by the location or zone within the Guyon's canal at which the ulnar nerve is compressed. The nerve divides into a superficial sensory branch and a deeper motor branch in this area. Thus, Guyon's canal can be separated into three zones based on which portion of the ulnar nerve are involved. The resulting syndrome results in either muscle weakness or impaired sensation in the ulnar distribution.^[1]

Zone	Location	Symptoms	Associations
1	Proximal (prior to ulnar nerve bifurcation)	Mixed motor & sensory	Ganglia & hook of hamate fractures
2	Surrounding deep motor branch ulnar nerve	Motor only	Ganglia & hook of hamate fractures
3	Surrounding superficial sensory branch of ulnar nerve	Sensory only	Ulnar artery pathology

Zone 2 type syndromes are most common, while Zone 3 are least common.

Treatment

The role of gloves which help protect the ulnar nerve from compression is unclear. Palsy of the ulnar motor nerve isolated to the wrist is treated with operative decompression, often with concomitant ganglion excision. The surgery is to divide the volar carpal ligament which forms the roof of Guyon's canal, thereby reducing compression on the ulnar nerve.^[5]^[6]

References

^ ^a ^b Hatch, Daniel (August 20, 2014). "Ulnar Tunnel Syndrome". Orthobullets. Retrieved Sep 7, 2014.
^ Taylor, Michele. "What Is Ulnar Tunnel Syndrome? Causes, Symptoms, Treatment". WebMD. Retrieved 15 June 2024.
^ Akuthota, V.; Plastaras, C.; Lindberg, K.; Tobey, J.; Press, J.; Garvan, C. (2005). "The effect of long-distance bicycling on ulnar and median nerves: an electrophysiologic evaluation of cyclist palsy". The American Journal of Sports Medicine. 33 (8): 1224–30. doi:10.1177/0363546505275131. PMID 16000656.
^ Depukat, Paweł; Mizia, Ewa; Kuniewicz, Marcin; Bonczar, Tomasz; Mazur, Małgorzata; Pełka, Piotr; Mróz, Izabela; Lipski, Marcin; Tomaszewski, Krzysztof (2015). "Syndrome of canal of Guyon - definition, diagnosis, treatment and complication". Folia Medica Cracoviensia. 55 (1): 17–23. ISSN 0015-5616. PMID 26774628.
^ Okutsu I, Hamanaka I, Yoshida A (April 2009). "Pre- and postoperative Guyon's canal pressure change in endoscopic carpal tunnel release: correlation with transient postoperative Guyon's canal syndrome". J Hand Surg Eur Vol. 34 (2): 208–11. doi:10.1177/1753193408100122. PMID 19282410.
^ Assmus H, Antoniadis G, Bischoff C, Hoffmann R, Martini AK, Preissler P, Scheglmann K, Schwerdtfeger K, Wessels KD, Wüstner-Hofmann M (May 2011). "Cubital tunnel syndrome - a review and management guidelines". Cent Eur Neurosurg. 72 (2): 90–8. doi:10.1055/s-0031-1271800. PMID 21547883.