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Guyon's Canal Syndrome
Pathology
Ulnar nerve compression within Guyon's canal.
Anatomy
Essentials
- Guyon's canal lies within the medial wrist, superficial to the transverse carpal ligament.
- Within the canal, the ulnar nerve divides into deep (motor) and superficial (sensory) branches within the canal.
- The dorsal and palmar ulnar cutaneous branches takeoff proximal to Guyon's canal and are, therefore, unaffected in Guyon's canal syndrome.
Details
- The tunnel begins (proximally) at the volar carpal ligament.
- It extends (distally) to the fibrous connection between the hypothenar muscles (abductor digiti minimi and flexor digiti minimi).
- It's medial (ulnar) edge is at the pisiform bone.
- It's lateral (radial) edge is at the hook of the hamate.
Compression Zones
In Brief
- Zone 1 - Impacts the proximal ulnar nerve segment (from the volar carpal ligament to the bifurcation of the ulnar nerve).
- Zone 2 - Impacts the deep (motor) branch.
- Zone 3 - Impacts the superficial (sensory) branch.
Notable Causes
- Long-distance bicycle riding
- Ganglion cysts
Clinical Presentation
Varies based on site of compression (compression zone)
- Motor: Ulnar-distribution weakness with potential claw hand.
- Sensory: Superficial sensory branch numbness - 5th digit and medial half of the 4th digit.
- Positive Tinel sign at the wrist.
Treatment
- Splinting
- Surgical decompression