Ulnar Tunnel Syndrome

By admin Last updated Nov 12, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Richard A. Okragly

Scott Fister Johnson

Basics

Description

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.

Etiology

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

Diagnosis

History

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

P.619

Diagnostic Tests & Interpretation

Imaging

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.

Treatment

Pre-Hospital

Avoid aggravating activities, including but not limited to (2,3)[C]:

Repetitive hand motions
Heavy grasping
Resting the palm against hard surfaces

Medication

First Line

NSAIDs (2,3)[C]

Second Line

Local injection of corticosteroids (2,3)[C]

Additional Treatment

General Measures

Conservative treatment to include (2,3)[C]:
- Splinting
- Physical therapy
- Rest
Adjust handlebar positions or increase padding with gloves (2,3)[C].
Avoid repetitive wrist trauma (2,3)[C].

Surgery/Other Procedures

Fascial release to free the aponeurosis around Guyon's canal (2,3,5)[C]
Surgery to remove compressive ganglion (2,3,5)[C]

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]

References

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.

Codes

ICD9

354.2 Lesion of ulnar nerve