THE ANESTHETIC MANAGEMENT OF INTRACRANIAL ANEURYSMS USING HYPOTHERMIA AND CIRCULATORY ARREST.
Steven Robicsek, M.D., Ph.D. and Michael Mahla, M.D.
Dept of Anesthesiology, University of Florida
Case: A sixty year-old female experienced a severe headache one
week prior to admission. Her arteriogram revealed a 3 cm basilar
tip apex aneurysm with a Fischer grade 4 subarachnoid
hemorrhage. Clinically she was a Hunt-Hess grade I and was
otherwise healthy except for hypertension. The patient was
induced uneventfully. In addition to standard monitors an
arterial line, pulmonary artery catheter and transesophageal
echo were placed. A lumbar spinal drain was placed by the
surgical team. Electroencephalogram and somatosensory evoked
potentials were monitored. Two units of whole blood were
withdrawn for infusion following bypass, and barbiturate
infusion to 90% burst suppression were initiated prior to the
institution extracorporeal circulation for deep hypothermia
(14oC). A very low flow state (0.3 L/min) was used for 36
minutes. During this time, two Yasergil clips were placed across
the aneurysm. On rewarming it became apparent from the evoked
potentials that somesthetic information was not getting through
to the right hemisphere unless significant hypertension was
induced to a mean arterial blood pressure of 120mm Hg.
Reinspection of clip placement demonstrated that the tip of one
of the clips was partially obstructing the outflow to the right
posterior cerebral artery. The clip was moved with immediate
return of the evoked potential. Hypertension was also no longer
necessary to preserve the evoked potential. Upon awakening the
patient exhibited minor weakness on the left. Several days
postoperatively she became she became hemiparetic on the right.
One month after surgery she was discharged following simple
commands on the right and complex on the left. Verbal output
increased throughout hospitalization. Continued neurological
recovery is expected.
Surgery for giant complex intracranial vascular lesions is
technically challenging with high operative morbidity exceeding
fifty percent with standard surgical techniques . Basilar artery
aneurysms are of special concern because of an inability to
adequately visualize the vascular anatomy, especially the
smaller thalamoperforating arteries. Deep hypothermia,
circulatory arrest and barbiturate cerebral protection can
provide useful adjuncts in the operative management , , . This
technique affords a bloodless surgical field, reduction of
aneurysm size thereby facilitating exposure of the vascular
anatomy, and elimination of the risk of aneurysm rupture. The
anesthetic technique, using closed-thorax extracorporeal
circulation, will be described and rational for its use
reviewed.
