Ulna Tunnel Syndrome

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