From primary progressive aphasia to corticobasal syndrome: two clinical and rCBF functional reports

Language in corticobasal syndrome: a systematic review

Language is commonly impacted in corticobasal syndrome (CBS). However, the profile and type of language assessment in CBS are poorly studied.

Brain Perfusion in Corticobasal Syndrome with Progressive Aphasia

Background

Brain perfusion may differ between patients with corticobasal syndrome (CBS) with and without aphasia.

Methods

Twenty-six (9 males and 17 females; mean age 76 ± 5.3 years) patients with CBS were enrolled in the study. Brain MRI and single-photon emission computed tomography were performed in all subjects. Language was evaluated using the Standard Language Test of Aphasia. The patients were divided into two subgroups according to the presence or absence of progressive aphasia. Differences in the regional cerebral blood flow (rCBF) between the two groups were detected based on voxel-by-voxel group analysis using Statistical Parametric Mapping 8.

Results

All patients exhibited asymmetric motor symptoms and signs, including limb apraxia, bradykinesia, and akinetic rigidity. Of 26 patients, 9 had a clinically obvious language disturbance, characterized as nonfluent aphasia. Almost all CBS patients with aphasia exhibited cortical atrophy predominantly in the left frontal and temporal lobes with widening of the Sylvian fissure on MRI. The rCBF in the left middle frontal gyrus differed significantly between CBS patients with and without aphasia.

Conclusion

CBS patients with aphasia exhibit motor symptoms predominantly on the right side and cortical atrophy mainly in the left perisylvian cortices. In particular, left frontal dysfunction might be related to nonfluent aphasia in CBS.

Variability in blood oxygen level dependent (BOLD) signal in patients with stroke-induced and primary progressive aphasia

Although fMRI is increasingly used to assess language-related brain activation in patients with aphasia, few studies have examined the hemodynamic response function (HRF) in perilesional, and contralesional areas of the brain. In addition, the relationship between HRF abnormalities and other variables such as lesion size and severity of aphasia has not been explored. The objective of this study was to investigate changes in HRF signal during language-related neural activation in patients with stroke-induced aphasia (SA). We also examined the status of the HRF in patients with aphasia due to nonvascular etiology, namely, primary progressive aphasia (PPA). Five right handed SA patients, three PPA patients, and five healthy individuals participated in the study. Structural damage was quantified with T1-weighted MR images. Functional MR imaging was performed with long trial event-related design and an overt naming task to measure BOLD signal time to peak (TTP) and percent signal change (ΔS). In SA patients, the average HRF TTP was significantly delayed in the left hemisphere regions involved in naming compared to healthy participants and PPA patients. However, ΔS was not different in SA patients compared to the other two groups. Delay in HRF TTP in the left hemisphere naming network of SA patients was correlated with lesion size and showed a negative correlation with global language function. There were no significant differences in the HRF TTP and ΔS in the right hemisphere homologues of the naming network or in the left and the right occipital control regions across the three groups. In PPA patients, HRF had a normal pattern. Our results indicate that abnormal task-related HRF is primarily found in the left hemisphere language network of SA patients and raise the possibility that abnormal physiology superimposed on structural damage may contribute to the clinical deficit. Follow-up investigations in a larger sample of age-matched healthy individuals, SA, and PPA patients will be needed to further confirm and extend our findings.

Measuring disease progression in corticobasal syndrome

Corticobasal syndrome (CBS) is a complex neurodegenerative disorder with marked clinical, neuropsychological, and pathological heterogeneity. Measurement of disease progression in CBS is complex and little understood. This study aimed to establish clinical and neuropsychological indicators of prognosis in CBS. Patients with CBS were retrospectively recruited from a frontotemporal dementia specific research clinic. All patients underwent detailed clinical and neuropsychological testing including the frontotemporal dementia rating scale (FRS). Using the differences in FRS logit scores over a period of 12 months, CBS patients were divided into rapid and slow progressor groups. Demographic, clinical and neuropsychological features were compared between the two groups. Sixteen participants who met defined criteria were included (9 males, 7 females; mean age 65.8 ± 22 years; median symptom duration 51.8 ± 22 years; mean duration of follow-up 11.4 ± 2.8 months). There were no significant differences between the rapid and slow progressors in age, gender, symptom duration, motor/cognitive presentation, and ACE-R scores at baseline. Clinically, slow progressors were significantly more likely to have a motor speech disorder, with a trend for more frequent dysgraphia, whereas rapid progressors were more likely to exhibit surface dyslexia. Rapid and slow progressor groups did not differ on neuropsychological performance. The presence of motor speech disorder, dysgraphia, and surface dyslexia may be useful in differentiating patients with rapid progression of CBS from those with a more indolent disease course.

Logopenic syndrome in posterior cortical atrophy

Few language disorders have been reported in posterior cortical atrophy (PCA). Furthermore, no study has focused on screening for them and described these language deficits. The goal of this work was to describe linguistic examination of PCA patients and the impact of language disorders on neuropsychological performances compared to patients with other neurodegenerative syndromes and control groups. Linguistic examination of 9 PCA patients was carried out. The neuropsychological performance of the PCA group (16 patients) in the RAPID battery tests was compared with performances of patients with a logopenic variant of primary progressive aphasia (LPPA), patients with Alzheimer's disease and patients with amnestic mild cognitive impairment, as well as the control group. A "logopenic syndrome" with anomia, fluency impairment, and length-dependent deficit was found in 8/9 PCA patients. A comparison with other neurodegenerative syndromes showed that not only visual disorders but also language and verbal short-term memory disorders, such as those found in LPPA, can explain neuropsychological performances. A "logopenic syndrome" is frequently found in PCA and may be associated with poor performance on other verbally mediated neuropsychological tasks (e.g., verbal memory). Specific logopedic rehabilitation should be offered to these patients.