Low bispectral index values in hydranencephaly.

Editor, We read with great interest the article by Prabhakar et al. [1] regarding the use of bispectral index (BIS) monitoring for an elective frontal craniotomy and fenestration in a 2-year-old boy with bilateral frontal lobe porencephalic cysts. During the procedure, the patient presented low preanaesthetic BIS values (39) that showed no significant change (between 30 and 40), despite a reduction in the inspired concentration of sevoflurane from 1 to 0.2%. No burst suppression pattern was observed, and BIS values remained low after anaesthetic recovery. In the discussion, the authors suggest that intracranial pressure increments could be responsible for the low BIS values.