Definition
Symptoms & signs from compression of ulnar nerve in guyon's canal
May be purely sensory, purely motor or combination
Anatomy Guyon's Canal
4cm long ulnar tunnel
Floor - transverse carpal ligament
Roof - volar carpal ligament and pisohamate ligament
Walls - pisiform (ulna) & hook of hamate (radial)
Contents
Ulna nerve and artery
- nerve ulnar to artery
Within canal at distal margin ulna nerve divides into 2
- superficial sensory
- deep motor branch
- separated by common tendinous origin of hypothenar muscles
3 zones
1. Proximal to bifurcation ulnar nerve - motor and sensory branches
2. Medial & distal to bifurcation - motor branch
3. Lateral & distal to bifurcation - sensory branch
Aetiology
Intrinsic
Soft tissue masses (including ganglia) 46%
Anomalous Muscles 16%
Extrinsic
Repeated blunt trauma
Can also get
- thrombosis of ulnar artery / hypothenar hammer syndrome
- fracture of hamate (Golfer)
- aneurysm ulnar artery
History
Pain & paraesthesia in ulnar hand & fingers
Weakness hand
- difficulty fine motor skills
Examination
Look
- hypothenar wasting / intrinsic wasting / ulna claw hand
Feel
- decreased sensation in LF
- decreased sensation hypothenar eminence / dorsal branch suggest higher lesion
Motor
- intrinsic weakness / abd digiti minimi / adductor pollicis / 1st dorsal interossei
Special
- Tinel's over Guyon
- Allen's test
Cervical spine
DDx
Cubital Tunnel Syndrome
TOS
Cervical root compression
NCS / EMG
Confirm Guyon's canal site of compression
X-ray
Tunnel view
- hamate fracture / pisiform OA
MRI
Ganglion
Management
Non-operative Management
Restrict exacerbating activities
Splint in neutral
NSAIDs
Operative
Release
Incision
- radial border of FCU
- 3 cm proximal to wrist crease
- across crease and along line of ring finger
Superficial dissection
- ulnar nerve isolated proximal to wrist
- followed into Guyon's canal
Deep dissection
- divide volar carpal ligament
- divide pisohamate ligament
- resect hook hamate or pisiform if needed
Dangers
- injury palmar branch ulna nerve