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.