Deficit of episodic memory: anatomy and related patterns in stroke patients

Despite numerous studies performed in selected populations, major uncertainties regarding the anatomy and patterns of episodic memory deficit still persist. Such objectives require the analysis of consecutive unselected patients with well-delimitated lesions and the use of specific methodology.

Nonaphasic stroke patients (n = 73) referred for cognitive complaints or deficits were examined using a standardized neuropsychological battery. Verbal episodic memory was assessed by the Grober and Buschke test.

Episodic memory deficit was related to lesions of medial temporal, thalamic, frontal, lenticular, and centrum semiovale regions, with a left hemisphere predominance. Although not specific, an immediate recall deficit was frequently observed in thalamic lesions (OR: 5.2, 95% CI: 1.09-24.9). False recognitions (OR: 25.7, 95% CI: 2.7-249) and efficiency of cued recall (OR: 8.6, 95% CI: 1.3-57) were highly specific of frontal damage. When combined with the usual 'frontal lobe' tests, this pattern of memory disorder was an independent predictor (OR: 36, 95% CI: 4.3-302) and increased the sensitivity of diagnosis of frontal damage (sensitivity: 0.92, specificity: 0.89).

This study extends the classical anatomy of episodic verbal memory. In addition, the 'frontal memory pattern' was found to be relatively specific and to be an independent predictor of frontal damage.