Intraoperative brain-stem auditory evoked potentials during posterior fossa microvascular decompression.

Area of Science:

• Neurosurgery
• Neurophysiology
• Audiology

Background:

• Intraoperative monitoring is increasingly used in neurosurgery.
• Evoked potential monitoring's role in predicting neurological deficits requires further definition.
• Predictive criteria for neurological deficits during posterior fossa surgery are not well-established.

Purpose of the Study:

• To assess the value of brain-stem auditory evoked potential (BAEP) monitoring in predicting postoperative neurological deficits.
• To evaluate BAEP as a tool during posterior fossa microvascular decompression.

Main Methods:

• BAEP monitoring was performed during 21 posterior fossa microvascular decompression procedures.
• Surgeons were alerted only upon complete disappearance of wave V.
• Latency changes and wave V disappearance were analyzed in relation to surgical events.

Main Results:

• BAEP latencies changed significantly in all patients, indicating high sensitivity.
• Complete disappearance of wave V occurred in four patients during cerebellar retraction.
• No patients experienced postoperative deafness, suggesting potential for "false positive" alerts based on latency alone.

Conclusions:

• BAEP is a sensitive indicator of auditory function during posterior fossa surgery.
• Relying solely on latency changes may lead to frequent "false positive" alerts.
• Complete wave V disappearance may be a more reliable, albeit less frequent, indicator for surgical intervention.