[Pneumocephalus as a cause of a decrease in the bispectral index]

Area of Science:

• Neurosurgery
• Anesthesiology
• Neurology

Background:

• Cerebellopontine angle tumors often require complex surgical removal.
• General anesthesia necessitates continuous patient monitoring, including brain activity.
• Retrosigmoid access is a common surgical approach for these tumors.

Observation:

• A significant decrease in bispectral index (BIS) values was noted post-operatively.
• An increase in the brain's suppression rate correlated with the BIS decrease.
• The patient exhibited no overt neurological deficits despite the electrophysiological changes.

Findings:

• The observed electrophysiological changes were attributed to frontal pneumocephalus, a complication of air entering the cranial cavity.
• The bispectral index (BIS) values normalized, and the patient was successfully extubated.
• Conservative management, focusing on air reabsorption, was chosen by the neurosurgical team.

Implications:

• This case highlights the importance of monitoring brain activity during neurosurgery, even in the absence of clinical signs.
• Pneumocephalus can manifest with significant electrophysiological changes without immediate neurological impairment.
• Conservative management can be effective for managing post-operative pneumocephalus in select neurosurgical cases.