To the Editor.
—The editorial by Koller1 in the November Archives is well taken. One can only regret that space alone limited its length. I would like to add that progressive supranuclear palsy (PSP) (Steele-Richardson-Olszewski syndrome) is at times misdiagnosed as Parkinson's disease. The lesions of PSP are located in the basal ganglia, upper brainstem, and cerebellar nuclei.2 The histologic features resemble postencephalitic parkinsonism with cell loss, gliosis, demyelination, and neurofibrillary tangles. The administration of levodopa has no effect that, in itself, is a clue. In time, PSP also results in a paralysis of downward gaze, retraction of eyelids, exophoria with eye covered, dysarthria, and dementia. The clinician may sometimes wonder how he misdiagnosed Parkinson's disease when this occurs, but the real tribute to neurology is how often the diagnosis is right on the nail's head.