[Circulatory repercussions of arteriovenous fistulae at the carpal tunnel level]

From a series of 84 cases of arterio-venous fistula, created for regular haemodialysis in end-stage chronic renal failure patients, the authors observed only one case of median nerve pathology at the level of the carpal tunnel. They propose three aetiologies: segmental ischaemia of the median nerve from perfusional redistribution, a mononeuritis syndrome aggravated by ischaemia and extrinsic compression of the median nerve by oedema secondary to distal venous reflux following creation of the vascular anastomosis. The authors recommend a termino-lateral anastomosis of a superficial vein (the superficial radial or the cephalic) with the radial artery. Using this approach, they did not observe any distal oedema nor any venous reflux into the hand. When a carpal tunnel syndrome is discovered in a case of arterio-venous fistula, the patient needs to be investigated for venous reflux into the hand and needs fistulography to exclude aspiration of blood from the cubital artery by the palmar arcade.