[Neurological evaluation of the leper king Baldwin IV of Jerusalem].

INTRODUCTION: In the medieval period, physicians became more aware of leprosy symptoms and differentiated it from other similar diseases. Baldwin, the leper king of Jerusalem (1161-1185), probably contributed to an increasing interest and tolerance to this disease in medieval Christian states. We review historical descriptions of the neurological manifestations he developed.

DEVELOPMENT: William of Tyre gives us a description of first symptoms experienced by the prince when aged nine. He notices that half of his right arm and hand were partially numb. No skin or nervous lesions are described. By his early twenties, muscle weakness makes him unable to walk. He gets blinded, probably due to keratopathy related to facial nerves involvement. Repeated attacks of fever lead to progressive worsening of his disease. He finally dies in Jerusalem, aged twenty-five, probably due to a septicaemia from infected sores. The earliest sign of Baldwin's disease is anaesthesia. Though skin lesions are not described, it is likely that at this point he had a tuberculoid form of leprosy. As his disease finally takes a lepromatous form, we suspect that it began as a borderline, immunologically unstable form.

CONCLUSION: Leper king Baldwin biography gives us interesting descriptions of neurological clinical features of leprosy. Besides, it helps us to discover twelfth century medicine knowledge about this disease.