A positron emission tomography study of frontal lobe function (verbal fluency) in amyotrophic lateral sclerosis.

Positron emission tomography (PET) was used to investigate the location of cerebral cortical and subcortical abnormalities in non-demented patients with amyotrophic lateral sclerosis (ALS). Involvement of the frontal lobes was investigated with a task of executive frontal lobe function (verbal fluency/word generation), using a PET activation paradigm. Two groups of ALS patients defined by the presence or absence of cognitive impairment were tested. ALS patients who had cognitive impairments showed a region of cortical and subcortical dysfunction which extended across a wide area of the frontal lobes, and included the insular cortex and thalamic nuclear complex. These findings support the notion that extra-motor involvement is relatively common in ALS and broadens concepts of selective vulnerability in ALS.