Persistent global amnesia following right thalamic stroke: an 11-year longitudinal study.

The 11-year longitudinal study of a right-handed male patient, L. C., who suffered from a severe amnesic syndrome following a softening in the right thalamus, is reported. Memory impairment involving retrograde and long-term anterograde memory, both verbal and spatial, persisted without modification. Investigation revealed some residual implicit learning ability. Positron emission tomography studies in the resting state displayed a bilateral hypometabolism of the mesial frontal lobes. Evidence suggests that a lesion confined to the thalamus may not on its own account for severe amnesia; that involvement of other structures is necessary for severe amnesia to appear; and that a functional investigation should always be included in cases of small thalamic lesions before drawing conclusions about the structures responsible for a given deficit.