Progressive supranuclear palsy. Clinical and pharmacologic update.

A distinct clinicopathologic entity, PSP is differentiated from Parkinson's disease by the presence of supranuclear ophthalmoparesis. Downward gaze palsy that can be overcome by oculocephalic maneuver is the most characteristic clinical finding. The other distinguishing clinical features of PSP include axial distribution of rigidity and broad-based gait with early postural instability. Furthermore, pseudobulbar palsy is an early feature, while profound dementia usually occurs late in the course of the disease. Because of the variable clinical presentation and occasional lag in the onset of ophthalmoparesis and other distinguishing signs, the diagnosis of PSP is often delayed for many years. However, the constellation of axial rigidity, pseudobulbar signs, and parkinsonism without tremor when combined with ophthalmoparesis should suggest the correct diagnosis. Pathologic examination of the PSP brain reveals neuronal cell loss, gliosis, granuolvacuolar degeneration, and unique neurofibrillary tangles in the pontomesencephalic tegmentum, tectum, basal ganglia, vestibular nuclei, periaqueductal gray matter, and dentate nuclei. The etiology of this neurodegenerative disorder is unknown and the neurodiagnostic studies usually are not helpful in proving the diagnosis. The treatment of PSP is unsatisfactory, but the anti-parkinson drugs, particularly dopamine agonists, may be useful in the early stages of the disease.