Effects of intravenous mannitol on EEG recordings in stroke patients.

OBJECTIVES: To evaluate the usefulness of continuous EEG monitoring of stroke patients during and after intravenously infused mannitol.
METHODS: Patients were rapidly administered 50 g of intravenous mannitol solution with continuous EEG monitoring for 3h pre- and post-drug infusion in the neurological intensive care unit. Visual and spectral analyses of EEG recording pre- and post-mannitol infusion were carried out.
RESULTS: The study consisted of 47 patients. Of 38 patients with intracranial hemorrhage, 33 had abnormal EEG findings pre-mannitol administration. After mannitol therapy, visual analysis of the drug-induced EEG changes showed that the EEG findings were unchanged in 13 patients, demonstratively improved in 22 patients, and worse in 3 patients. The spectral analysis demonstrated that mannitol-induced EEG changes increased in alpha power and decreased in delta power in the lesion hemispheres, especially in the central and middle temporal areas. Maximal effects occurred 30 min post-mannitol infusion, and remained significant for 2h post-infusion. Of the 9 patients with cerebral infarction, only one with diffuse background slowing of one-side dominance pre-mannitol improved after the infusion of mannitol.
CONCLUSIONS: The results of our investigation indicated that continuous EEG monitoring of mannitol treatment can reflect the brain edema, raised ICP in stroke patients, and provide assessment the drugs effects of antiedema and intracranial pressure lowering in vivo.