High resolutional MR images of cochlear nerves and functional PET of temporal lobes in patients with sensory nerve hearing loss.

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The new MR sequence, CISS (constructive interference with steady state), provide high resolutional images which had not been imaged before. Cochlear nerve that is responsible for auditory system can be demonstrated by MR CISS images. We examined the anatomical abnormalities of cochlear nerve in patients with auditory disturbance using MR CISS images. We examined whether there is any differences of cochlear nerve size among various diseases or between before and after treatment. At the same time, brain blood volume was also estimated on positron CT by auditory stimulations before and after treatment and examined the differences of brain blood volume between two patients' groups of improvement and non-respons by treatment.Patients with unilateral sensory neural hearing loss without neoplasms such as acoustic shwanoma were selected. High-resolutional 3D images were scanned with MR CISS sequences (effective slice thickness was 0.7mm), and cranial nerve 7th and 8th were reconstructed vertic … More al to the nerves. The size of cochlear nerve on reconstructed images was compared of right and left. In patients who was infetected by mumpus virus, the size of cochlear nerve at disease side was smaller then the contralateral side. But facial and vestibular nerves were symmetric. On the other hand, in patients with idiopathic hearing loss, which are supposed to be caused by blood flow disturbance, there were no differences of both sides.Pure sound stimulation test was examined in patients with idiopathic auditory disturbance on positron CT. The treatment was steroid and high oxygen therapy. In patients who were improved after treatment, bilateral temporal blood volume were increased compared to that before treatment. There were no blood volume differences between before and after treatment in patients who did not respond by the therapy.It is clinical asset to demonstrate anatomical and functional abnormalities that had not been detected before. We evaluate the morphological change objectively and this method is helpful to precise diagnose in patients with auditory disturbance. Less