Neurotological Findings in Diphenylhydantoine Intoxication

It is well known that diphenylhydantoine (DPH) can cause such side effects as gingivitis, hypertrichosis, ataxia, nystagmus, diplopia and others. Although there are many reports about DPH intoxication, very few papers mention the neurotological aspects of this condition. Three cases of DPH intoxication which manifested neurotological changes were treated. The common remarkable findings of these cases were equilibrium disturbance, gaze nystagmus and the absence and/or irregularity of optokinetic nystagmus (OKN). As other neurotological findings do not show any peripheral labyrinthine lesion, the equilibrium disturbances noticed in our cases probably did not originate from the labyrinth but from the central nervous system (CNS). The precise origin of gaze nystagmus noted in these cases has not yet been clarified. It seems to be evident, however, that this type of gaze nystagmus is not due to a peripheral labyrinthine lesion. It is well known that the inhibition or the disturbance of OKN may be caused by central lesions, but the origin or localization of the dysfunction in the CNS has not yet been clarified. On the other hand, animal experiments and postmortem examination of patients with DPH intoxication reveal that the main histologic lesions are located in the cerebellum, especially in the Purkinje cells. Although the precise localization of the lesions in our cases is not known the relationship between clinical findings and histological findings of DPH intoxication can be emphasized.