The following is a summary of “Progression to corticobasal syndrome: a longitudinal study of patients with nonfluent primary progressive aphasia and primary progressive apraxia of speech,” published in the April 2024 issue of Neurology by Garcia-Guaqueta al.
While nonfluent variant primary progressive aphasia (nfvPPA) and primary progressive apraxia of speech (PPAOS) are known to sometimes progress to corticobasal syndrome (CBS), the specifics of this development are not fully understood.
Researchers conducted a retrospective study to track how nfvPPA and PPAOS develop into CBS, focusing on clinical symptoms and brain imaging changes.
They analyzed 140 patients with nfvPPA or PPAOS, adhering to CBS criteria at each visit, assessing limb rigidity, akinesia, limb dystonia, myoclonus, ideomotor apraxia, alien limb phenomenon, and nonverbal oral apraxia (NVOA). The CBS criteria were adjusted to exclude NVOA due to its link with AOS, and patients were categorized as progressors or non-progressors. The CBS feature frequency was tracked yearly from disease onset, and SPM12 was used to measure gray and white matter volume loss.
The results showed that asymmetric akinesia, NVOA, and limb apraxia were the predominant CBS features observed, with limb dystonia, myoclonus, and alien limb being infrequent. About 82 patients progressed to possible CBS, while only four reached probable CBS. Both nfvPPA and PPAOS had a comparable proportion of progressors, although nfvPPA advanced to CBS sooner (P-value = 0.046), primarily due to the early onset of limb apraxia (P-value = 0.0041). Over time, the premotor/motor cortex’s involvement at baseline expanded into the prefrontal cortex in both non-progressors and progressors.
Investigators concluded that a significant subset of nfvPPA and PPAOS patients progressed to possible CBS, but probable CBS was uncommon even after extended follow-up.
Source: link.springer.com/article/10.1007/s00415-024-12344-x