Diphenylhydantoin (DPH) is known to cause symptoms of intoxication, such as acute cerebellar ataxia, involuntary movements, nystagmus, etc. when given continuously and in excess, although it is also known to be an excellent antiepileptic agent.
We report here a 14-year-old female with DPH intoxication and review the literature on this subject. Neuro-otological examination of this patient revealed reversible functional disturbances in the cerebellum and brain stem, including spontaneous nystagmus, cerebellar ataxia, abnormal findings in the optokinetic pattern test, eye tracking test, etc. These symptoms and test results rapidly improved with reduction of the blood level of DPH.
It is concluded that neuro-otological examination is extremely useful for the diagnosis of and for the evaluation of the therapy of this condition, and should be used in addition to the measurement of blood levels of DPH and/or the follow-up of the clinical symptoms.
