A 74 year old woman was referred to the neurological department for evaluation of progressive gait disturbance. On admission she complained of alienation and loss of control of her left arm for six months. There were no spontaneous movements without the patient's intention, but she had always to rely on visual cues. For example, when she was cooking, eating, or doing exercises with her home trainer she had to watch her left arm to be sure of its movement. On examination she was alert, fully oriented, and cooperative. Snout and palmomental reflexes were positive. There was no visual, somatosensory, or auditory extinction. Motor examination revealed a mild left sided facial droop and a left sided pronator drift but strength was full and symmetric and there was no lack of spontaneous movement in the left upper limb. The plantar response was extensor on the left. Gait was slow, unsteady, and wide based. The steps were short with reduced step height. Neuropsychological assessment showed fluent speech without dysarthria. Comprehension and reading were intact. Performance in verbal and non-verbal fluency tasks was diminished, and colour-word interference was slightly increased. Long term memory was slightly deficient for verbal and non-verbal material. Visuo-constructive abilities were normal and there was no …