Frontal type dementia preceding amyotrophic lateral sclerosis: a neuropsychological and SPECT study of five clinical cases

Between 1993 and 1995, we observed five sporadic cases of frontotemporal dementia (FTD) which in all cases preceded the appearance of typical amyotrophic lateral sclerosis (ALS). The FTD rapidly became severe (within 12-18 months) and the delay between the presumed onset of mental change and ALS was short (12-26 months). The frontal dysfunction was characteristic (disinhibited, jocular, impatient, gluttonous, stereotypical gestures). The language impairment (less talkative, persistent errors, fantastic and semantic paraphasia, neologistic errors, echolalia) was constant. Single photon emission computed tomography (SPECT) with 99 Tc-m HMPAO (hexamethyl propylamine oxime) was done at the same time as neuropsychological testing in four cases and showed serious diffuse bifrontal defect, sometimes with less serious internal temporal hypofixation. All patients died with bulbar ALS complications. The total course can last from 14-48 months. Most of the reported cases suggested a relationship between dementia-ALS and frontal dysfunction. The mechanism underlying dementia-ALS remains to be solved. Our five cases resemble those reported by Mitsuyama (1993), who suggested that dementia-ALS has the same clinicopathological entity. Eur J Neurol 6:295-299 (C) 1999 Lippincott Williams & Wilkins.