[Transient medium- and deep-tone hearing disorders following spinal anesthesia].

In a prospective study, 100 patients who underwent general surgical or urological operations under spinal anesthesia were examined to determine whether there was a relation between the anesthesia and postoperative hearing loss. Audiograms were performed preoperatively and as the 1st, 2nd, 3rd, and 5th postoperative days. It was found that 16 patients had impairment of hearing. The average ages of these patients were similar to those of the total population. The hearing loss was typical: only the frequencies between 125 and 2000 Hz were affected. It began on the 2nd day after spinal anesthesia and disappeared within 3 days without special therapy. The cause of this typical hearing loss after spinal anesthesia is a drop in cerebrospinal fluid pressure transmitted to the perilymph via the cochlear aqueduct. The change in the endoperilymphatic pressure difference results in a change in the oscillation of the basilar membrane. Because 16% of patients may suffer hearing loss after spinal anesthesia, it seems reasonable from a medicolegal point of view to explain the possibility of defective hearing to the patient.