Persistent Cognitive Deficits Associated with Lithium Intoxication: A Neuropsychological Case Description

We present the case of a 51-year-old patient with an acute lithium intoxication associated with several cognitive deficits. During the acute phase of intoxication the patient displayed general psychomotor slowing, dysarthric speech, mood changes, and incoherent discourse. Neuropsychological assessment revealed ideomotor apraxia, profound deficits of visuospatial processing, an impairment of memory and of frontal-executive functions. Other cognitive abilities, such as orientation, spontaneous speech, comprehension, naming, reading, writing, and working memory remained intact. An electroencephalogram revealed diffuse slowing with rhythmic trains, whereas MRI showed no cerebral abnormality. Follow-up examinations at 4 and 14 weeks with lithium levels in the normal range showed substantial recovery of memory abilities and executive functions, whereas praxis and visuoperceptual functions remained impaired, despite the fact that lithium was immediately withdrawn after the intoxication became manifest. We conclude that lithium intoxication may be associated with variable behavioural and cognitive impairments, some of them potentially persistent. Different from other case studies our findings suggest that lithium intoxication may cause a combined, multifocal functional impairment of subcortical and cortical neural mechanisms in both hemispheres.