Bilateral pedunculopontine nuclei strokes presenting as freezing of gait

The penduculopontine nucleus (PPN) has been suggested to play an important role in locomotion, based on animal studies, but its function in humans has not been well defined. Autopsy studies have suggested that PPN pathology correlates with gait dysfunction in Parkinson's disease and in progressive supranuclear palsy but direct clinical evidence is lacking. We report a patient with bilateral PPN infarcts whose dominant clinical feature was freezing of gait, thus providing evidence that PPN is involved in human locomotion and that damage to the PPN may lead to abnormal gait.