CLINICAL CORRELATES OF ACOUSTIC NEUROMA MORPHOLOGY

Thirty-eight patients with vestibular schwannomas were reviewed. A cor relation was found between tumour morphology and clinical presentation . Based on our knowledge of the variability in the neurilemmal-neurogl ial junction and therefore the site of origin of these tumours in rela tion to the internal auditory canal, a classification into three diffe rent appearances on magnetic resonance imaging was possible. Dumbbell shaped tumours (21 per cent) represented laterally arising schwannomas , lollipop shaped tumours (18 per cent) were medially arising and cone shaped tumours (61 per cent) were the more common intermediate form. Patients with laterally arising dumb-bell shaped tumours were more lik ely to present early with hearing loss and had smaller tumours than pa tients with medially arising lollipop shaped ones. The relatively well preserved hearing in patients with medially arising tumours made them more likely to present at a later stage with signs of trigeminal comp ression, cerebellar dysfunction and raised intracranial pressure.