The authors describe a case where a parkinsonian symptomatology is associated with pneumoencephalographic and RISA-cisternographic findings typical of an occult normal pressure hydrocephalus. They discuss their personal contribution in the light of what has been already reported in the literature on the same subject. They conclude that a CSF dynamics disturbance among the possible physio-pathogenetic mechanisms of an extrapyramidal syndrome in young subjects should be considered. On the other hand, they also emphasize the possibility that the occult normal pressure hydrocephalus may have syndromical expressions which are different from the typical one initially described.