Ulnar Tunnel Syndrome

Ovid: 5-Minute Sports Medicine Consult, The

Ulnar Tunnel Syndrome
Richard A. Okragly
Scott Fister Johnson
  • Compression of the distal ulnar nerve as it passes through Guyon's canal:
    • Guyon's canal or the ulnar canal is located at the base of the hand.
  • The superficial sensory branch and/or the deep motor branch of the ulnar nerve can be involved.
  • Synonym(s): Handlebar palsy; Guyon's canal syndrome
  • Types (based on the Shea and McClain classification):
    • I—Combined sensory and motor deficit
    • II—Motor deficit only
    • III—Sensory deficit only
Risk Factors
  • Environmental trigger factors:
    • Repetitive occupational wrist trauma (occupational neuritis)
    • Baseball catchers
    • Cyclists
    • Hockey goalies
    • Golf and racquet sports
    • Martial arts
  • Anatomical
  • Ganglion cyst
  • Hamate fracture
  • Lipoma
  • Ulnar artery thrombosis
General Prevention
  • Avoid excessive pressure to ulnovolar aspect of palm.
  • Avoid repetitive wrist trauma.
  • Guyon's canal is located in the base of the hand on the ulnar side:
    • The borders of Guyon's canal are:
      • Pisiform (medially)
      • Hook of the hamate (laterally)
      • Volar carpal ligament/pisohamate ligament (roof)
      • Transverse retinacular ligament (floor)
  • Injury to the nerve is caused by trauma to wrist and pressure over the hypothenar eminence.
  • A true motor, true sensory, or mixed injury pattern can be seen, depending on the location of the compression.
  • The mixed (motor and sensory) type is due to compression in the proximal aspect of Guyon's canal before the division of the ulnar nerve into superficial and deep branches (type I).
  • True motor type is due to compression of the ulnar nerve at the level of the lower wrist (type II).
  • True sensory type is due to compression of the superficial branch of the ulnar nerve at the distal aspect of Guyon's canal (type III).
Commonly Associated Conditions
  • Ulnar cubital syndrome
  • Carpal tunnel syndrome
  • Radial nerve compression
  • Hook of hamate fractures
  • Martin-Gruber ulnar-median anastomosis (15% of population)
  • Riche-Cannieu deep ulnar-median anastomosis
  • Ring (4th) and small (5th) finger paresthesias with variable weakness of grip
  • Localized pain and tenderness over Guyon's canal
  • Paresthesias or vascular symptoms (coldness and pallor of the 4th and 5th digits, cyanosis, and pain) if the ulnar artery is involved
  • Coincident involvement of the median nerve is common (tingling or numbness or weakness or pain in the 2nd and 3rd digits and the lateral aspect of the 4th digit) (1,2,3)[C].
Physical Exam
  • Depending on the location of the lesion, motor, sensory, or mixed signs may be elicited.
  • Sensory (1,2,3)[C]:
    • Positive Tinnel's sign at the pisiform, affecting the medial aspect of the 4th digit and all of the 5th digit
    • Sensory loss at tip of little finger
    • Hypoesthesia on volar sensory branch without involvement of dorsal sensory branch
  • Motor (1,2,3)[C]:
    • Weakness with resistance of adductor pollicis and all interossei muscles
    • Late atrophy of the 1st dorsal interosseus muscle
    • Positive Wartenberg sign: Abduction of the small finger due to interosseous and lumbrical compromise
    • Positive Froment sign: Activation of flexor pollicis longus to substitute for adductor pollicis
    • Decreased grip strength (40% due to ulnar-innervated muscles)
    • Ulnar claw hand with paralysis of the deep motor branch


Diagnostic Tests & Interpretation
Generally, imaging is not need to make the diagnosis, but can be used to establish the etiology or rule out other diagnoses (1,2,3,4)[C]:
  • Radiographs to exclude carpal instability
  • CT scan to exclude hook of the hamate fractures
  • Doppler US to exclude thrombosis
  • MRI to exclude ganglion cyst or lipoma
Diagnostic Procedures/Surgery
Electromyogram (EMG) studies to document ulnar nerve pathology (1,2,3,4)[C]
Differential Diagnosis
  • Proximal ulnar entrapment (elbow, cervicothoracic spine)
  • Calcific tendonitis of flexor carpi ulnaris tendon
  • Carpal instability
  • Arthropathy of pisotriquetral joint
  • Ligamentous wrist injury
  • Ulnar artery thrombosis
  • Hypoesthesia on dorsal sensory branch does NOT involve compression in Guyon's canal.
Ongoing Care
Follow-Up Recommendations
  • Following surgery, proper wound care and pain control are essential.
  • Return to full activity 4–8 wks following surgical decompression (3)[C]
1. Anto C, Aradhya P. Clinical diagnosis of peripheral nerve compression in the upper extremity. Orthop Clin North Am. 1996;27:227–236.
2. Plancher KD, ed. The athletic elbow and wrist, part II: common overuse injuries. Clin Sports Med. 1996;15:347–353.
3. Baker CL Jr, ed. Overuse injuries in the upper extremity. Clin Sports Med. 2001;20:603–605.
4. Beltran J, Rosenberg ZS. Diagnosis of compressive and entrapment neuropathies of the upper extremity: value of MR imaging. AJR Am J Roentgenol. 1994;163:525–531.
5. Green DP. Operative hand surgery, 2nd Ed., Vol. 2. Churchill Livingstone Publishing, 1988:1452–1454.
354.2 Lesion of ulnar nerve

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