Guyon's canal syndrome
The Loge de Guyon 's syndrome is an injury to the ulnar nerve at the little finger side ( ulnar side ) of the wrist. It is accompanied by disturbances of sensation and paralysis of the hand and finger muscles.
The Guyon's canal is a physiological bottleneck at the wrist between the pisiform ( pisiform ) and the hook extension of the leg hook ( hook of the hamate ), through which pass the branches of the ulnar nerve and the ulnar artery. Here, the ulnar nerve splits in the box at a superficial branch ( ramus superficialis ) and a deep branch ( ramus profundus ), which pulls in the depth under an often relatively tight muscle arcade.
Was named the bottleneck site after the Parisian surgeons and urologists Jean Casimir Félix Guyon.
The most common cause is a ganglion in the area of Guyon's canal, followed by occupational or sports-related prolonged or repeated compressions, such as after a long cycling or repeated hammering with the little finger ( hypothenar ). Rare may also be the cause breakage of the hook extension or other adjacent bone, next to, there are other extremely rare causes such as arterial aneurysms, thrombosis, tumors, anatomical variants and Others
Clinic
Typically, it takes longer by external pressure, for example by crutches ( crutch palsy ) or the handlebar grips on day-long cycling or biking tours (bicycle paralysis) in damage to the Endastes of the ulnar nerve. By fixing in Guyon's canal can not escape the oppression of these. Initial symptoms of a lesion are tingling paresthesia ( paraesthesia) of the little finger and the ring finger (only the ulnar { to the little finger facing } flexor surface of the hand). To full-blown clinical picture also boasts a very muscular weakness ( paresis ) for the fingers spread and for merging of fingers ( interossei ).
Depending on the level of nerve compression in the Guyon's canal three types are defined according to Gross and Gelbermann:
- Type I with damage to the sensitive and motor units and associated damage in the proximal area of the lodge before separation of the nerve into its two branches.
- Type II with pure motor deficits of the hand intrinsic muscles and corresponding damage to the deep branch ( ramus profundus ) distal to the Nervenaufzweigung.
- Type III with sensory disturbances and paralysis of the palmaris brevis by damage to the superficial branch ( ramus superficialis ).
Diagnosis
For the detection of a Loge de Guyon 's syndrome has the isolated injury to the Endastes of the ulnar nerve ( deep branch nervi ulnaris ), which is curved in the palmar direction of the thumb, can be detected. Proof is electrophysiologically. For this, the conduction time between a stimulus point of the ulnar nerve by means of motor- evoked potentials just above the wrist and electrically measured muscle contraction in a furnished from the superficial branch of the muscle ( little finger ball Muscle = abductor digiti minimi ) compared to a supplied by the ramus profundus muscle (first interosseous muscle = musculus interosseus dorsalis primus ) measured. If the latter time is absolute and / or extended, side comparison, the damage is covered.
Differential Diagnosis
- Carpal Tunnel Syndrome
- Ulnarisrinnensyndrom
Therapy
If the cause in a pressure load from the outside, as with cyclists, it is usually sufficient to eliminate the injurious stimulus. The nerve recovers then usually spontaneously (which may take several weeks ) because its continuity is not broken ( ie it is a neurapraxia or at most a axonotmesis ago). A surgical decompression is rarely at an external cause necessary, but almost always necessary if the compression is caused by a ganglion or a different anatomical narrowing ( internal cause ).
Prevention
Choosing a road bike handlebar, which allows the grasping hand into different positions, and the use of padded gloves reduce the mechanical pressure effect. In general, these measures for the prevention is sufficient.