The spectrum of aphasia subtypes and etiology in subacute stroke

Aphasia is one of the most common stroke syndrome presentations, yet little is known about the spectrum of different subtypes or their stroke mechanisms. Yet, subtypes and etiology are known to influence the prognosis and recovery.

Our aim is to analyze aphasia subtypes and etiology in a large subacute stroke population.

Consecutive patients from a dedicated cognitive stroke registry were accrued. A validated cognitive screening examination was administered during the first month of stroke presentation, which enabled a diagnosis of 14 different aphasic subtypes. The evolution from one subtype to another in the acute and subacute period, at times, resulted in more than 1 subtype being diagnosed. Etiology of stroke was determined by the modified Trial of Org 10172 in Acute Stroke Treatment criteria that included intracerebral hemorrhage. Exclusions included dementia, chronic medical illness, substance abuse, and severe depression.

Of 2389 stroke patients, after exclusions (n=593), aphasias numbered 625 (625 of 1796; 34.8%), and the subtype frequencies included Broca aphasia (n=170; 27.2%), anomic aphasia (n=165; 26.4%), global aphasia (n=119; 19.04%), and subcortical aphasia (n=57; 9.12%). Less frequent subtypes (total n=40; 6.7%) included transcortical aphasia (n=11), Wernicke aphasia (n=10), conduction aphasia (n=7), aphemia (n=3), semantic aphasia (n=3), crossed aphasia (n=3), pure word deafness (n=2), and foreign accent syndrome (n=1). Aphasia subtypes and etiologies had some significant associations (chi-square: 855.8, P value<.0001). Bonferroni-adjusted P values revealed that anomic aphasia had a significant association with small-vessel disease (SVD) (odds ratio [OR]=2.0254, 95% confidence interval [CI]: 1.3820-2.9681), and global aphasia patients mostly had cardioembolic (CE) causes (OR=2.3589, 95% CI: 1.5506-3.5885) and less likely SVD (OR=.2583, 95% CI: .1444-.4654). Other notable inferences were included. Wernicke aphasia was caused by either CE (6 of 12; 50%) or hemorrhage (4 of 12; 33.3%) in a combined 83% of cases. Subcortical aphasia was because of SVD in 36% (31 of 85) or because of hemorrhage in 32% (27 of 85) yielding a combined 68% of cases. Sixty percent of transcortical aphasias as a group were because of either large-vessel disease (7 of 20; 35%) or hemorrhage (5 of 20; 25%). Alternatively, a diagnosis of Broca aphasia could be because of any of the etiological categories.

(1) Aphasias are a heterogeneous entity in subtype and etiology; (2) Broca, global, anomic, and subcortical aphasias accounted for the vast majority of aphasia subtypes; (3) SVD, cardioembolism, and hemorrhage are significantly associated with certain signature aphasic syndromes; and (4) determination of aphasia subtype can assist with etiology, prognosis, influence aphasia therapy, and provide the basis for future randomized controlled trials with pharmacological therapy or behavioral therapy.