Corticobasal degeneration. A clinical study of 36 cases.

The presenting features and their subsequent evolution in 36 patients with pathologically proven or clinically probable corticobasal degeneration are described. The most common initial complaint was of a unilateral 'clumsy, stiff or jerky arm' (n = 20). Typically the arm was akinetic, rigid and apraxic. In about a third of these the arm was held in a striking and characteristic fixed dystonic posture. Jerking of the arm, due to action and stimulus-sensitive myoclonus accompanied these symptoms in about a third of the cases. The next most common presentation (n = 10) was difficulty walking due to clumsiness and loss of fine motor control of one leg due to apraxia or dysequilibrium, or a combination of both. Sensory symptoms in the affected arm heralded the onset of illness in three and accompanied a motor disturbance in two cases. Presentation with dysarthria or a behavioural syndrome were rare. The symptoms progressed slowly, usually involving first the ipsilateral arm and leg, but gradually spread to affect all four limbs. After a mean follow-up of 5.2 years (range 2-8 years) gait difficulties and a supranuclear ophthalmoplegia had emerged in most patients and dysarthria and pyramidal signs were common. Higher mental function was relatively preserved in most and a cortical sensory loss was evident in a quarter of cases.