Left hemicranial hypoplasia in 2 patients with primary progressive aphasia.

Background: Primary progressive aphasia (PPA) leads to a gradual and relatively isolated dissolution of language function. The factors that determine the selectivity of the disease process remain unknown. We had speculated that PPA may occasionally arise as a tardive manifestation of genetic or acquired vulnerabilities involving the language network of the brain.

Objective: To explore predisposing factors for PPA.

Results: In 2 patients, PPA developed with a background of mild left hemicranial hypoplasia.

Conclusion: In keeping with other observations of PPA in patients with dyslexia and childhood injury to the left temporal lobe, these 2 patients support the contention that some cases of PPA may arise in settings where the language network has become a locus of least resistance.