[In-depth study of the causes of sudden deafness. Physiopathological mechanisms and their reversal]

This article deals with an investigative work done by the AA. with the aim of determine the final cause of sudden sensorial deafness. Three causes are accepted as source of sudden deafness: viral infections, the tear away of labyrinthine membranes and the vascular theory. An increase in antibody titer suggest a viral origin. The labyrinthine membranes split has been observed at times when performing an exploratory tympanotomy. But circulatory troubles are hardly diagnosed, even with histopathological evidences of vascular upsets in temporal bones belonging to patients who suffered from an auditory stroke, because there are no diagnostic tests for "in vivo" control. Our intend is to investigate on the physiopathology of unforeseen deafness and also try to know the possible mechanisms of reversion of this calamitous pathology. We use, as investigative method of actual vascular changes in sudden deafness, the following; the speed analysis of the blood flow furnished by the A. labyrinthi through echography Doppler color transcranialis and angiography and magnetic resonance (Angio-MR). Both procedures are non invasive and harmless. We comment the findings of 13 patients. And find out, in 4 cases, an important trouble of the arterial vertebrobasilaris flow. The A. labyrinthi, a branch of the A. cerebelli inferior anterior (ACIA) and/or A. basilaris--rarely from the A. cerebelli inferior posterior (ACIP)--showed a heavy hypoplasy of these vessels, stenosis or complete blockage. In 2 of cases, 4 months later, a new exploration of the Doppler flow and angio-MR, was performed, and detected an improvement of the vertebrobasilar flow, in both instances. In those patients with an evident recovery of the hearing, it was attributed to these two compensatory mechanisms: 1) reversal of the flow at the level of cicle of Willis, at the expense of development of A. communicans posterior, and 2) cessation of the vertebral A. spasm and decrease of the vessel's tortuosity so improving the blood flow.