Brain Retraction Monitoring Sensor Study

During neurosurgical operations for aneurysms, tumors, or other lesions located in the skull
base, the surgeon must employ retracting devices in order to displace one or more lobes of
the brain enough to gain adequate surgical exposure. These retractors are adjusted by hand to
optimize exposure. It is often difficult for the surgeon to gauge the amount of pressure
actually applied to the brain during such placement of the retractor. Moreover, it is also
possible to position the blade of the retractor inadvertently such that a focal pressure
point occurs at the tip of the retractor blade against the brain. Thus, injury to the brain
can occur as a result of brain retraction when either the force applied is excessive or when
the pressure is not adequately distributed to a large enough area of brain. This injury is
thought to be the result of ischemia (inadequate blood flow) caused by the retraction, local
trauma, or a combination of both. It has been estimated that this type of brain retraction
injury occurs in approximately 10% of major cranial base tumor procedures or 5% of
intracranial aneurysm surgeries. The specific aim of this research is to identify changes in
electrical activity of brain tissue subjected to necessary retraction during neurosurgical
procedures that may give forewarning of imminent brain retraction injury. It is anticipated
that this information will permit development of guidelines that will enable the neurosurgeon
to take steps to minimize such injury, i.e., by temporarily releasing or otherwise modifying
the brain retraction. Cerebral electrical activity, together with the amount of retraction
pressure being applied, will be recorded directly from the tissue at risk by means of a
silastic electrode grid containing a pressure monitor placed on the surface of the cerebral
cortex underneath the retractor blade.

Inclusion Criteria:

- A patient must be scheduled to undergo skull base surgery requiring significant brain
retraction

- Informed Consent

Exclusion Criteria:

- None, other than patients in whom major surgical complications are encountered that
are unrelated to brain retraction may be excluded from subsequent data analysis