[Was Emmanuel Kant's dementia symptomatic of a frontal tumor?]

Using a retrospective diagnostic approach based upon an analysis of the clinical data found in biographical documents, the author explores the medical peculiarities apparent in the life of Emmanuel Kant. The clinical history is globally dominated by neurological and ophthalmological symptoms. From a neurological standpoint, the philosopher started to manifest around the age of fifty a subtle deterioration of his mental powers. This disorder gradually impaired his intelligence and judgement, progressing slowly toward dementia. He also manifested signs of raised intracranial pressure, and later, frontal symptoms such as a slackening of social inhibitions, stereotypies and affective disinterest. An anosmia is also reported and several episodes of loss of consciousness are highly reminiscent of late-onset epileptic fits. Ophthalmological findings include transient visual obscurations, a bout of diplopia, and a progressive loss of vision in his left eye. Various diagnostic hypotheses found in the literature are then reviewed. These hypotheses are confronted with the clinical data and the reasons for their inadequacy are assessed. The nature of the clinical features, in conjunction with the similarity underlying the evolution of the neuro-ophthalmological symptoms and the philosopher's psychological profile, leads us to propose a diagnosis of frontal tumor, possibly of meningiomatous origin. This aetiology makes it possible to account for more biographical data than has been the case with other hypotheses presented to date.