Progressive non‐fluent aphasia is associated with hypometabolism centred on the left anterior insula

• Published in: Brain (London, England : 1878) England : 1878), 2003-11, Vol.126 (11), p.2406-2418
• Main Authors: Nestor, Peter J., Graham, Naida L., Fryer, Tim D., Williams, Guy B., Patterson, Karalyn, Hodges, John R.
• Format: Article
• Language: English
• Subjects: Aged; Alzheimer Disease - metabolism; Alzheimer Disease - psychology; Aphasia, Broca - metabolism; Aphasia, Broca - psychology; Aphasia, Primary Progressive - diagnostic imaging; Aphasia, Primary Progressive - metabolism; Aphasia, Primary Progressive - psychology; BA = Brodmann area; Biological and medical sciences; Cerebral Cortex - diagnostic imaging; Cerebral Cortex - metabolism; CMRglc = cerebral metabolic rate for glucose; Disease Progression; Disorders of higher nervous function. Focal brain diseases. Central vestibular syndrome and deafness. Brain stem syndromes; FDG = [18F]fluorodeoxyglucose; Female; Follow-Up Studies; FTD = frontotemporal dementia; FWHM = full width at half‐maximum; Glucose - metabolism; Humans; insula; Magnetic Resonance Imaging; Male; Medical sciences; Middle Aged; MMSE = Mini‐Mental State Examination; MND = motor neuron disease; MNI: Montreal Neurological Institute; Nervous system (semeiology, syndromes); Neurology; Neuropsychological Tests; PET; PNFA = progressive non‐fluent aphasia; progressive non‐fluent aphasia; RCPM = Raven’s coloured progressive matrices; SPECT = single photon emission computerized tomography; SPM = statistical parametric mapping; Tomography, Emission-Computed; TROG = Test for the Reception of Grammar; VBM = voxel‐based morphometry; VOSP = Visual Object and Space Perception Battery; voxel‐based morphometry; WCST = Wisconsin card sorting test
• ISSN: 0006-8950; 1460-2156; 1460-2156
• DOI: 10.1093/brain/awg240

Progressive non‐fluent aphasia (PNFA) is a syndrome in which patients lose the ability to communicate fluently in the context of relative preservation of single word comprehension and non‐linguistic cognitive abilities. Neuroimaging in case studies with PNFA has failed to identify a consistent neural substrate for the language disorder. In this study of a group of patients (n = 10) whose presenting complaint was progressive dysfluency, resting cerebral metabolism was measured using [18F]fluorodeoxyglucose‐PET and analysed with the technique of statistical parametric mapping (SPM). Regional atrophy was assessed with voxel‐based morphometry (VBM). Seven patients had a ‘pure’ PNFA syndrome, while the remaining three had additional features of a more pervasive dementia. Compared with controls, the patients showed hypometabolism in several regions that, most notably, included the left anterior insula/frontal opercular region. The VBM analysis revealed only one small area of atrophy in the left peri‐Sylvian region. Analysis of the pure PNFA cases (n = 7) relative to controls yielded qualitatively similar results to those of the whole group, suggesting that these cases were also at risk of a more generalized dementia, a finding borne out in subsequent follow‐up of two cases to date. The PNFA group was then compared with a group with Alzheimer’s disease (n = 10) whose clinical profile did not include non‐fluent aphasic features. In this analysis, the only persisting hypometabolic region was that centred over the left anterior insula. VBM did not identify any regional differences in atrophy between PNFA and Alzheimer’s disease. In the light of current theories of fluent language production, the findings offer anatomical evidence that the breakdown in fluency is due to a motor articulatory planning deficit (speech apraxia) combined with a variable degree of agrammatism.