Abstract SNACC-39

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Neuronal Protection and Intraoperative Stability in Patients with Moyamoya Disease

Patel V, Aryan E, Zelman V
University of Southern California, Los Angeles, CA, USA

Background:
Moyamoya is a progressive cerebral vasculopathy characterized by stenosis or occlusion of the circle of Willis and associated vasculature. Clinical manifestations are varied and include symptoms of focal cerebral ischemia along the Cerebrovascular Accident spectrum (CVA). Patients may manifest with symptoms of transient ischemic attack (TIA), ischemic or hemorrhagic stroke, or epilepsy. Progressive neurologic deficit or debilitating acute cerebrovascular events may warrant prompt surgical revascularization. We present five such case reports and our anesthetic technique designed to optimize neuroprotection during general anesthesia in the Moyamoya patient.

Methods/Results:
We selected five surgical patients in order of presentation to our institution. All had previous history of varied CVA symptoms ranging from TIA to rapidly debilitating stroke. After confirmation with Neuroradiology, each individual was definitively diagnosed with Moyamoya disease on either MRA or CT Angiography. In addition, given each individual’s history of recurrent symptoms or significant gravity of an acute cerebrovascular event, neurosurgical intervention was warranted. Each individual was treated with a Superficial Temporal Artery to Middle Cerebral Artery (STA-MCA) bypass while applying the principles of our specified anesthetic protocol.

Our methods applied neuroprotection in the form of mild hypothermia (35°C to 36°C); mild hemodilution (Hematocrit of 30% to 42%); normo- to mild hypercapnia (PaCO2 38 mmHg to 45mmHg); and limited diuresis. In addition, hemodynamic stability was established with strict maintenance of Mean Arterial Pressures (MAP) to within +/- 10mmHg throughout the intraoperative period.

Each individual’s intraoperative events were unremarkable. In addition, postoperative follow-up did not demonstrate significant complication until stable discharge. Three of the five patients who are followed on an outpatient basis do not demonstrate further worsening of gross neurologic deficits.

Discussion:
Abnormal cerebral autoregulation, as often seen in ischemic brain matter, requires a delicate anesthetic choice to allow optimal preservation of compromised tissue. Cerebral Perfusion Pressure (CPP) should be maintained above baseline as autoregulation becomes pressure dependent. We therefore contend that MAPs should be maintained in the normal-to-high range. In addition, normo- and mild hypercapnia should be maintained to restrict cerebral vasoconstriction. A hematocrit of 30% to 42% will also promote adequate oxygen delivery while limiting viscosity through occluded vasculature. Furthermore neuroprotective measures such as burst suppression and mild hypothermia should be implemented during bypass. Finally, N2O, inhalational agents, and cerebral vasodilators should be avoided to prevent intracerebral steal phenomenon.

We present our anesthetic protocol designed to optimize outcomes during surgical revascularization of the Moyamoya patient. All patients tolerated their interventions and had favorable outcomes.

References:

i Parray et all: Moyamoya Disease: A Review of the Disease and Anesthetic Management, JNA, V 23, #2, April 2011


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