DISCUSSION
The elbow is the most common site for ulnar nerve compreesion and the fibro osseous tunnel known as the guyon’s canal remain a rare site of this compresssion (1,2).
Many etiologies have been described in the literature , and have been involved in the ulnar nerve compression in the guyon’s canal.
These conditions can be divided into seven groups (3)
1-tumors such as lipomas , ganglion cysts ..
2-adjacent vascular enlargement ( ulnar artery aneurysm..)
3-repetitive trauma
4-metabolic diseases
5-wrist degeneration
6-variation of the guyon’s canal structure
7-idiopathic conditions
The ganglion cyst remains the most frequent causative agent of the ulnar nerve’s compresison at the guyon’s canal.
Inside This canal the ulnar nerve is a mixed nerve which divides into deep motor branche and a superficial sensory branche. Therefore , based on the affected areas , Mcclain classified ulnar lesions into 3 zones (4):
Zone 1: The proximal part of the ulnar nerve inside the Guyon’s canal: proximal to the motor/sensory bifurcation, causing both motor and sensory symptoms.
Zone 2: it is the most commonly affected region , distal to the bifurcation and affecting only deep motor branches, causing motor deficits and muscle atrophy.
Zone 3: Distal to the bifurcation and affecting the superficial sensory fibers only, causing sensory symptoms.
Treatment’s options of Guyon’ canal syndrome depend on the gravity of the symptoms, duration of the symptoms (acute, sub-acute or chronic), previous treatments given, and underlying etiology.
Non operative treatement is opted for patients with mild or moderate symptoms with a durtion less than three months , also patients should be instructed to avoid activities that apply pressure on the wrist, such as bicycling ot lifting weights , and to limit mechanical overload resulting from repetitive movements or static postures such as prolonged extension of the wrist.
We should highlight that non steroidal anti inflammatory drugs and corticosteroid injections are not beneficial for the treatment of Guyon’s canal syndrome (5,6).
On the other hand , patients with severe symptoms that lasted more than three months may need surgical treatement also mechanical compression of the guyon’s canal is an indication for surgical release (7) which is the case for our patient whose ulnar nerve was pressured by the aneurysm of the ulnar artery causing severe symptoms in a very rare and unusual clincal presentation.
Despite that many surgical approaches are described such as ulnar hypothenar approach, Brunner approach , carpal tunnel incision, and the ulnar hypothenar approach ,There are no consensus on the best surgical approach for the Guyon’s canal release (6).
The crucial aim of any surgical procedure is to to meticulously remove any potentially compressive structure to garantee a succesfull recovery.
Finally ,few reports of guyon’s canal syndrome due to an aneurysm of the ulnar artery have been described, our clinical case highlight the importance of an adequat surgical treatement in order to assure a good and a quick recovery of the hand function.