Guyon's Canal Syndrome
Guyon's Canal is a small tunnel that lies within the wrist (between the Hamate and Pisiform bones of the hand, the roof of the canal is formed by the Volar carpal ligament), it is through this tunnel that the ulnar nerve and artery pass within a neurovascular bundle. The canal is one of the principal sites of ulnar nerve compression.
Guyon's Canal Syndrome is numbness and tingling in the ring and little fingers caused by irritation of the ulnar nerve as it passes through Guyon's Canal.
Causes
Guyon's Canal Syndrome arises when there is pressure on the ulnar nerve within the canal.
This pressure can be caused by:
A cyst within the canal.
Clotting of the ulnar artery.
Fracture of the hamate bone.
Arthritis of the wrist bones.
Symptoms
No matter what the cause of compression of the ulnar nerve, the symptoms are the usually the same.
They include:
Pins and needles in the ring and little fingers.
A burning pain of the wrist and hand.
Decreased sensation and clumsiness in the hand.
In extreme cases, compression of the ulnar nerve at Guyon's Canal can result in a phenomenon known as Claw Hand.
In all cases of compression of the ulnar nerve at Guyon's Canal, sensory supply to the skin of the back of the hand is spared.
This is because the branch of the nerve that supplies this area (the dorsal cutaneous nerve) leaves the main trunk of the ulnar nerve in the arm before it reaches Guyon's Canal.