gms | German Medical Science

Objectives/Interrogation: Nerve palsies after closed fractures of the upper arm and forearm are usually treated by expectation. A broadly recognized exception from this rule is acute carpal tunnel syndrome resulting from distal forearm fractures. In this setting, carpal tunnel syndrome is a special form of compartment syndrome and requires therefore the immediate surgical intervention to restore tissue perfusion, thus preventing muscle contracture and permanent nerve palsy.

Hand surgeons even know the spontaneous acute entrapment of the median nerve without vascular disturbance of the hand. This atraumatic acute carpal tunnel syndrome requires urgent carpal tunnel release to prevent permanent median palsy. An acute compression of the ulnar nerve in Guyon's canal is not an established entity.

But how should you manage a situation when a closed distal forearm fracture is complicated by an acute and complete distal ulnar nerve palsy?

Methods: A 9-year old boy sustained a closed, apex palmar angulated distal forearm fracture, 3 cm proximal the wrist joint. The immediate clinical evaluation registered a classical clawing of the ring and small fingers, a complete sensual loss of the small finger pulp and of the ulnar side of the ring finger pulp, and a partially impaired sensibility of the ulnar-sided dorsum of the hand. After closed reduction and percutaneous pinning of the distal radius and ulna, we revised the ulnar nerve, its dorsal branch, and the ulnar artery in the same operative session. We did not find any signs of injury except a compression mark of the ulnar nerve at the entrance of Guyon's canal. After incising 7 mm of the volar ligament, the entrapment was eliminated, putting aside a formal opening of the whole Loge de Guyon.

Three hours after surgery, the ulnar nerve had completely recovered, the sensibility was completely reestablished, the clawing had gone. The whole case is pre-, intra- and postoperatively documented by photographs and x-ray pictures.

Results and Conclusions: Analogue to acute carpal syndrome, we recommend immediate ulnar nerve revision if a distal forearm fracture is complicated by an acute ulnar nerve entrapment. The entrapment at the entrance of Guyon's canal could otherwise cause a prolonged ulnar palsy. This risk justifies the relatively small operative effort even in the case of closed fracture treatment.