Brain SPECT imaging in transcortical aphasias: the functional status of the left perisylvian language cortex*

Abstract

Single photon emission computerized tomography (SPECT) with 99mTc-HMPAO was used to examine the functional status of the left perisylvian language cortex (PLC) in eight patients with transcortical aphasias (TAs) due to cerebrovascular accidents. According to the lesion location within the left hemisphere, the aphasic patients were divided into two groups: (a) patients with corticosubcortical lesions involving portions or the whole PLC (perisylvian group, n = 4); (b) patients with corticosubcortical lesions sparing the PLC (extraperisylvian group, n = 4). Results showed that, as expected, the perisylvian group had significant decrements in regional cerebral blood flow (rCBF) in structurally damaged regions of the left PLC, although some morphologically spared regions of the left PLC (Wernicke's area) also had perfusion defects in one patient. Among the extraperisylvian group, there was structural and functional damage to the posterior association areas, but two patients additionally had significant decrements of rCBF in morphologically spared regions of the PLC (Wernicke's area, sensorimotor cortex, Broca's area). These findings demonstrate not only that the left PLC may be structurally and functionally damaged among patients with TAs, but additionally suggest a major contribution of the right hemisphere in the mediation of residual language repetition.

Unexpected brain-language relationships in aphasia: Evidence from transcortical sensory aphasia associated with frontal lobe lesions

“…A brain SPECT showed that all these regions had significant decrements in perfusion rates. Hypoperfusion, though less dramatic, was also observed in morphologically spared parietal and temporal-occipital cortices and subcortical structures (basal ganglia, thalamus, and anterior periventricular white matter) (see further neuroimaging findings of this case and of the two following cases in Berthier et al, 1997).…”

“…Some of them have also been described in a number of other papers (Berthier, 1995;Berthier et al, 1991Berthier et al, , 1997. Patients were selected if they met the taxonomic criteria of the Western Aphasia Battery (Kertesz, 1982) for TCSA which is based on a fluency score of ¶ 5; a comprehension score of µ 7; and a repetition score of ¶ 8.…”

“…Relevant demographic data (age, sex, handedness, years of education, and time since stroke onset) and language profiles were obtained for every patient. All patients underwent high-resolution computerised tomography (CT) or magnetic resonance imaging (MRI) scans and three patients were additionally examined with single photon emission computerised tomography (SPECT) and [ 99m Tc]-HMPAO (see further details in Berthier et al, 1997). Lesion location on CT/MRI scans was mapped on axial and saggital templates in specific brain regions with the aid of an atlas (Matsui & Hirano, 1978) using Brodmann's areas (BA) methodology (Damasio, 1998).…”

“…And as a result of this influential methodology it has long been recognised that there is an anterior-posterior dichotomy in language deficits after lesions of the left hemisphere, with anterior (frontal) damage causing nonfluent spontaneous speech with relative sparing of auditory comprehension and fluent yet paraphasic speech with impaired auditory comprehension accompanying posterior (temporal-parietal) damage (Benson, 1993). Nevertheless, this brain-language relationship is not a straightforward one and exceptions to this traditional account have been described for ''classical'' aphasic syndromes (Broca's, conduction, and Wernicke's) (Alexander, Naeser, & Palumbo, 1990;Daffner et al, 1991;Deleval et al, 1989;Lhermitte et al, 1973;Mendez & Benson, 1985;Mohr, 1976;Raymer, Maher, & Pellegrino, 1999) and also for transcortical aphasic syndromes (Basso et al, 1985;Berthier et al, 1991Berthier et al, , 1997.…”

“…The most common topographical distribution of lesions was found involving the anterior perisylvian language zone of the left hemisphere compromising the Broca's area, frontal operculum, anterior insula, external part of the putamen, and subcortical white matter (Basso et al, 1985;Berthier et al, 1991Berthier et al, , 1997Hadano et al, 1992;Papagno & Basso, 1996;Sartori et al, 1987). Other cases of TCSA were described even after extensive lesions that involved large portions of both the anterior and posterior perisylvian cortex (Berndt, Basili, & Caramazza, 1987;Berthier et al, 1991;Lesser, 1989;Martin & Saffran, 1990).…”