Progressive frontal gait disturbance with atypical Alzheimer's disease andcorticobasal degeneration

Objectives-The clinical neuropsychological, neuroradiological, and neuropat hological description of two patients presenting with a frontal gait distur bance. Methods-Clinical case note review, neuropsychological assessment, functiona l imaging with O-15(2) and F-18-fluorodopa PET, and neuropathology. Results-Both patients presented with frontal gait impairment and only later developed more widespread cognitive impairment. In both cases O-15(2) PET disclosed focal hypometabolism in the medial frontal lobes and in one patie nt F-18-fluorodopa uptake into the caudate and putamen was normal. The neur opathological examination in one patient showed Alzheimer's histopathology together with large swollen eosinophilic neurons characteristic of corticob asal degeneration, which were particularly prominent in the medial frontal lobes. Conclusion-Focal degeneration of the medial frontal lobes may present as an isolated gait disturbance and should be considered in the differential dia gnosis of patients who present without an obvious structural abnormality on neuroimaging.