GABAergic but not anti-cholinergic agents re-induce clinical deficits after stroke.

Our goal was to determine whether the excitatory (i.e., GABA) neurotransmitter system was important in human stroke recovery. We hypothesized that giving midazolam, a GABA(A) agonist, to patients would re-induce clinical deficits to a greater extent than the anti-cholinergic scopolamine. Twelve patients (7 M) who had recovered from hemiparesis and/or aphasia after first-time stroke and 10 age-matched, healthy controls underwent double-blinded drug challenge with midazolam and 90 days later with scopolamine, or vice versa. Language was scored for comprehension, naming and repetition, and motor function was tested with the 9-Hole Peg Test (9HPT) in each hand. The drugs were administered intravenously in small aliquots until mild awake sedation was achieved. The primary outcome was the change scores from baseline to the two drug conditions, with higher scores denoting greater loss of function. Ten of the 12 patients had recovered from hemiparesis and 7 from aphasia. The median time from stroke to participation was 9.3 months (range=0.3-77.9 months). For motor function, analysis of variance showed that change scores on the 9HPT were significantly greater in patients using the previously paretic hand during the drug state with midazolam (p=0.001). Similarly, language change scores were significantly greater among recovered aphasics during the midazolam challenge (p=0.01). In our study, patients demonstrated transient re-emergence of former stroke deficits during midazolam but not scopolamine. These data provide beginning clinical evidence for the specificity of GABA-sensitive pathways for stroke recovery.

Multitasking disorder from right temporoparietal stroke.

Acute behavioral syndromes after right hemisphere stroke (eg, hemi-inattention) resolve in most patients by 6 months. Less is known about the nature of chronic disorders after these lesions when the initial deficits are no longer apparent. We report the case of a woman who suffered a cerebral infarct in the right temporoparietal region and who, after the resolution of neglect, demonstrated a significant disorder of multitasking in her everyday life. Neuropsychologic tests failed to reveal the extent of disruption in her daily functioning. A journal of daily activities elucidates the nature of her deficits and demonstrates, from the patient's perspective, the impact of the lesion on her ability to multitask. Our findings are consistent with the concept of a right frontoparietal attentional axis that governs the ability to hold several tasks in working memory at the same time. We conclude that right hemisphere lesions can disrupt the cognitive system of multitasking through disruption of the attentional matrix.