The differential diagnosis of normal pressure hydrocephalus

Hakim and colleagues, in their paper describing the syndrome of normal pressure hydrocephalus (NPH) in three patients, recapitulated the clinical presentation as follows: “a mild impairment of memory, slowness and paucity of thought and action, unsteadiness of gait and unwitting urination” (Hakim’s triad) [1]. They also highlighted two important features of the syndrome: “The symptomatology was unobtrusive, having no assignable date of onset, and evolved over a period of weeks and few months … The most striking feature of the condition was the rapid restitution of the patient’s health as the result of lowering of the cerebrospinal-fluid pressure through surgical shunting.” They further stressed that because “the clinical picture corresponds essentially to that of a mild form of dementia,” it was obligatory for the treating physician to distinguish such a mild dementia “occurring without obvious cause in a middle-aged person … from the large number of dementing illnesses of the presenium and the senium.” Interestingly, pneumo-encephalography demonstrated, in all three cases described in the original paper by Hakim, an obstruction to the CSF, due to a blockage of the subarachnoid space (SAS) at the cervical-medullary junction in the first two cases and to a colloid cyst in the third [1].