Familial sinistrality in crossed aphasia: A new case and review of the available literature

From the earliest descriptions onwards, the phenomenon of familial sinistrality (FS) has been strongly implicated in the concept of crossed aphasia in dextrals (CAD). In the early literature on CAD, a positive tract of FS (FS+) was generally regarded as the most important cause of anomalous language lateralisation in dextrals. Although in the more recent literature FS+ is generally regarded a strong exclusion criterion for CAD, in a corpus of 180 published CAD cases we encountered 26 patients with FS+ (14.4%). Critical analysis revealed that only a minority of these cases (5/26; 19%) sufficiently met the adopted criteria for an unambiguous diagnosis of vascular CAD (reliable CAD). One personal observation, reported in this paper, also fulfilled these criteria and is added to this group. To evaluate the presumed impact of FS+ on the anatomoclinical configurations of vascular CAD, all "reliable" CAD cases with FS+ were analysed in a three-epoch time-frame model for aphasia and matched for both aphasia type and lesion-aphasia profile with a representative group of vascular "reliable" CAD cases with negative FS (FS-). Close analysis of the aphasia characteristics revealed that the FS variable did not induce semiological differences between both FS groups. Although the limited study sample does not allow strong conclusions to be drawn, our findings seem to indicate that FS does not act as a strong determinant of lesion- behaviour relationships in CAD.