Fahr's disease: a differential diagnosis of frontal lobe syndrome.

Fahr's disease refers to a rare syndrome characterised by symmetrical and bilateral intracranial calcification. The basal ganglia are the most common site of involvement and most cases present with extra-pyramidal symptoms. We describe two men with Fahr's diseases who presented with prominent frontal lobe symptoms. The first man presented with frequent uncontrollable bursts of laughter and crying spells. He later developed mild dysarthric speech and choreoathetoid movement. The second man presented with progressive changes in personality and behaviour. In both cases, there were no parkinsonian features. Computed tomographic scans of both patients demonstrated extensive symmetrical calcification over the basal ganglia and dentate nuclei. A repeated imaging scan in the second patient revealed progressive cerebral atrophy but reduction in the calcification. No underlying cause for the bilateral calcification was found. As frontal lobe symptoms are usually inconspicuous in the early stage, the presence of these symptoms might be overlooked in clinical practice when compared with those suffering from prominent movement disorders.