Clinical characteristics of patients with frontotemporal dementia with and without lobar atrophy on MRI.

INTRODUCTION

The presence of frontal and/or temporal atrophy on neuroimaging has been designated as supportive in the clinical consensus criteria for behavioral variant frontotemporal dementia (bvFTD). As magnetic resonance imaging (MRI) has a relatively low sensitivity for bvFTD, a substantial proportion of patients may present with a normal MRI. Thus, there may be clinical differences between patients with and without lobar abnormalities on MRI. We compared clinical characteristics of bvFTD patients with frontotemporal lobar atrophy on MRI to those lacking the typical pattern at presentation.

METHODS

MRIs of 49 patients from our memory clinic, diagnosed with bvFTD were rated for the presence or absence of frontal and/or temporal atrophy. Demographic, behavioral, and cognitive features were compared between subjects with and without typical bvFTD atrophy pattern.

RESULTS

Twenty-three patients showed lobar atrophy on MRI, whereas 26 patients lacked the characteristic frontotemporal lobar atrophy, including 13 patients with a normal MRI and 13 with other abnormalities. Disinhibition occurred more often in the group with frontal and/or temporal atrophy on MRI compared with the group with other abnormalities, whereas imitation did not occur in patients lacking the typical bvFTD atrophy pattern. No differences were found in neuropsychologic profiles. There was a trend for a lower mean Clinical Dementia Rating and less severe language impairment in patients with a normal MRI compared with the group with frontal and/or temporal atrophy.

CONCLUSIONS

The clinical phenotype of FTD cannot be predicted by the presence or absence of lobar atrophy on MRI, although imitation and disinhibition are more prevalent in bvFTD patients with characteristic MRI abnormalities. Furthermore, patients with a normal MRI seem to be less severely demented in comparison to patients with frontal and/or temporal atrophy.