Bispectral Index Changes during Acute Brainstem TIA/Ischemia

Area of Science:

• Anesthesiology
• Neurology
• Neurophysiology

Background:

• Intraoperative monitoring is crucial for patient safety during cardiac surgery.
• The Bispectral Index (BIS) is commonly used to assess depth of anesthesia.
• Brainstem function is vital for maintaining consciousness and cortical activity.

Observation:

• A 76-year-old patient experienced a brainstem transient ischemic attack (TIA) immediately prior to anesthesia induction for cardiac surgery.
• The TIA event was captured by BIS monitoring, showing a notable decrease from baseline to a value of 60.
• Following the event, as spontaneous consciousness returned, the BIS value increased to 85.

Findings:

• The brainstem TIA correlated with a significant reduction in cortical electrical activity, as indicated by the BIS.
• The observed drop in BIS suggests a disruption in brainstem input to the frontal cortex.
• This case demonstrates the potential of BIS to reflect neurological changes beyond anesthetic depth.

Implications:

• BIS monitoring may serve as an early warning system for intraoperative neurological events, including TIAs.
• Understanding the relationship between brainstem function and BIS readings can enhance intraoperative neuroprotection strategies.
• Further research is warranted to explore the utility of BIS in detecting and managing perioperative neurological complications.