Primary progressive freezing gait: a syndrome with many causes.

Primary progressive freezing gait (PPFG) is characterized by early gait freezing and a stereotyped progression. Of nine patients followed up for 6 to 16 years, two were diagnosed pathologically: pallidonigroluysian degeneration (PNLD) and diffuse Lewy body disease. Four others evolved clinically into progressive supranuclear palsy and corticobasal degeneration. PPFG is not a distinct disorder but a syndrome with diverse causes. Long-term follow-up (> or =10 years) and postmortem are required for accurate diagnosis. PNLD may be the primary form of disease.