Objective-To analyse the natural history ofprogressive supranuclear palsy (PSP or Steele-Richardson-Olszewski syndrome) and clinical predictors of survival in 24 patients with PSP confirmed by necropsy, who fulfilled the NINDS criteria for a neuropathological diagnosis of typical PSP. Methods-Patients were selected from the research and clinical files of seven medical centres involving tertiary centres of Austria, England, France, and the United States. Clinical features were analysed in detail. The patients' mean age at onset of PSP was 63 (range 45-73) years. Results-The most frequent clinical features (occurring in at least 75% of the patients) were early postural instability and falls, vertical supranuclear palsy, akinetic-rigid predominant parkinsonian disorder characterised by symmetric bradykinesia and axial rigidity unrelieved by levodopa, pseudobulbar palsy, and frontal release signs. Occasionally, segmental dystonia or myoclonus were described, but neither aphasia nor alien limb syndrome was reported. Fractures occurred in 25% of the patients but were unrelated to the severity of the gait or to the presence of falls. Median survival time was 5*6 (range 2-16-6) years. Onset of falls during the first year, early dysphagia, and incontinence predicted a shorter survival time. Age at onset, sex, early onset of dementia, vertical supranuclear palsy, or axial rigidity had no effect on prognosis of survival. Pneumonia was the most common immediate cause of death. PSP was most often clinically misdiagnosed as Parkinson's disease. Errors in diagnosis suggest that PSP is underdiagnosed.Conclusion-Progressive onset of early postural instability with falls or supranuclear vertical palsy in the fifth decade, should suggest the diagnosis of PSP. Onset of falls during the first year are emphasised, as they could lead to an early diagnosis and influence the prognosis of patients with PSP. Whether appropriate treatment of the dysphagia could prolong the survival of PSP patients needs to be explored.(7 Neurol Neurosurg Psychiatry 1996;61:615-620)

Objective-To analyse the natural history and survival of corticobasal degeneration by investigating the clinical features of 14 cases confirmed by postmortem examination. Methods-Patients with definite corticobasal degeneration were selected from the research and clinical files of seven tertiary medical centres in Austria, the United Kingdom, and the United States. Clinical features were analysed in detail. Results-The sample consisted of eight female and six male patients; mean age at symptom onset was 63 (SD 7.7) years, and mean disease duration was 7.9 (SD 2.6) years. The most commonly reported symptom at onset included asymmetric limb clumsiness with or without rigidity (50%) or tremor (21%). At the first neurological visit, on average 3.0 (SD 1.9) years after symptom onset, the most often encountered extrapyramidal features included unilateral limb rigidity (79%) or bradykinesia (71%), postural imbalance (45%), and unilateral limb dystonia (43%). Ideomotor apraxia (64%), and to a lesser extent cortical dementia (36%), were the most common cortical signs present at the first visit. During the course of the disease, virtually all patients developed asymmetric or unilateral akinetic rigid parkinsonism and a gait disorder. No patient had a dramatic response to levodopa therapy. Median survival time after onset of symptoms was 7.9 (SD 0.7) (range, 2.5-12.5) years, and, after the first clinic visit, 4.9 (SD 0.7) (range, 0.8-10) years. Early bilateral bradykinesia, frontal syndrome, or two out of tremor, rigidity, and bradykinesia, predicted a shorter survival. Conclusion-The results confirm that unilateral parkinsonism unresponsive to levodopa and limb ideomotor apraxia are the clinical hallmarks of corticobasal degeneration, and only a minority of patients with corticobasal degeneration present with dementia. The study also suggests that a focal cognitive and extrapyramidal motor syndrome is indicative of corticobasal degeneration. Survival in corticobasal degeneration was shortened by the early presence of (more) widespread parkinsonian features or frontal lobe syndrome.