Pallidopyramidal disease: A misnomer?
The combination of recessive early-onset parkinsonism and pyramidal tract signs caused by pallidopyramidal degeneration is known as pallidopyramidal disease or syndrome (PPD/S). We investigated whether patients diagnosed as Davison's PPD/S showed any definite proof of pyramidal and pallidal involvement, without findings suggestive of other nosological entities. Since Davison's original description, 15 other PPD/S cases have been reported, yet all lack proof of pyramidal or pallidal degeneration. Because of the doparesponsiveness in all patients subsequent to Davison's report, we argue that these patients probably suffered from early-onset nigral parkinsonism or dopa-responsive dsystonia, rather than pallidal parkinsonism; in such cases, the presumed pyramidal Babinski could be a pseudobabinski ("striatal toe"). Secondary pallidopyramidal syndromes do occur, for example, in multiple system atrophy or Wilson's disease, but in these patients additional findings indicate diseases other than Davison's PPD/S. We conclude that the existence of PPD/S as a distinct clinico-pathological nosological entity, as proposed by Davison, is doubtful. In cases reported as Davison's PPD/S, the description "pallidopyramidal" seems to be a misnomer.