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2015-05-04 01:17 毕业

Anesthetic Management for Surgical Treatment of Cerebral Aneurysm
Updates in USA
Hamilton Shay M.D.
Dept. of Anesthesiology, Montefiore Medical Center, Bronx, NY, USA
What research is being done on cerebral aneurysm in United States
The National Institute of Neurological Disorders and Stroke (NINDS) recently
sponsored the International Study of Unruptured Intracranial Aneurysms, which included
more than 4,000 patients at 61 sites in the United States, Canada, and Europe. The
findings suggest that the risk of rupture for most very small aneurysms (less than 7
millimeters in size) is low.
NINDS scientists are studying the effects of an experimental drug in treating
vasospasm that occurs following rupture of a cerebral aneurysm. The drug, developed at
NIH, delivers nitric oxide to the arteries and has been shown to reverse and prevent brain
artery spasm in animals.
Other scientists hope to improve diagnosis and prediction of cerebral vasospasm
by developing antibodies to molecules known to cause vasospasm. These molecules can
be detected in the cerebrospinal fluid of subarachnoid hemorrhage patients. An
additional study will compare standard treatment for subarachnoid hemorrhage to
standard treatment plus transluminal balloon angioplasty immediately after severe
bleeding. Transluminal balloon angioplasty involves the insertion, via catheter, of a
deflated balloon through the affected artery and into the clot. The balloon is inflated to
widen the artery and restore blood flow (the deflated balloon and catheter are then
withdrawn).
Researchers are building a new, noninvasive, high-resolution x-ray detector
system that can be used to guide the placement of stents (small tube-like devices that
keep blood vessels open) used to modify blood flow during treatment for brain
aneurysms.
Scientists are investigating the use of intraoperative hypothermia during microclip
surgery as a means to improve the rate of recovery of cognitive functions and to reduce

early and postoperative complications and neurological damage. Other studies are
investigating ways to improve or replace the coils used in endovascular embolization.
Cerebral Aneurysm statistics in United States
The true incidence of intracranial aneurysms is unknown but is estimated at 1-6%
of the population (Wiebers, 2003). Published data vary according to the definition of
what constitutes an aneurysm and whether the series is based on autopsy data or
angiographic studies. In one series of patients undergoing coronary angiography,
incidental intracranial aneurysms were found in 5.6% of cases, and another series found
aneurysms in 1% of patients undergoing 4-vessel cerebral angiography for indications
other than subarachnoid hemorrhage (SAH). Familial intracranial aneurysms have been
reported (Schievink, 1997). Whether this represents a true increased incidence is unclear.
Aneurysms typically become symptomatic in people aged 40-60 years, with the
peak incidence of SAH occurring in people aged 55-60 years (Greenberg, 2001).
Intracranial aneurysms are uncommon in children and account for less than 2% of all
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cases. Aneurysms in the pediatric age group are often more posttraumatic or mycotic than
degenerative and have a slight male predilection. Aneurysms found in children are also
larger than those found in adults, averaging 17 mm in diameter. Aneurysms have shown a
slightly more frequent in women than man.
Current diagnostic Tests for Intracranial Aneurysms
Patients with ruptured aneurysms producing SAH are usually diagnosed by CT
scan. However, no test is 100 percent sensitive, and CT scans may not always detect SAH,
particularly when it is mild, or if it occurred more than 24 hours before the scan.
Therefore, whenever a diagnosis of SAH is being entertained, if the CT scan is negative,
a lumbar puncture (spinal tap) must be performed for analyzing the spinal fluid for blood 您可以访问中国科教评价网（www.NsEac.com）查看更多相关的文章。
or its byproducts ("xanthochromia").
All patients with a diagnosis of SAH, or in whom an aneurysm is suspected
require 4-vessel cerebral angiography. Cerebral angiography is currently the only test
sensitive enough to definitively confirm the presence of an aneurysm, and also provides
critical information regarding the size, shape, and location of the aneurysm, as well as the
presence of vasospasm.
For the patients without recent SAH, the initial diagnostic test is usually a
Magnetic Resonance Image (MRI), a Magnetic Resonance Angiogram (MRA), or a
Computed Tomographic Angiogram (CTA). These noninvasive tests have become
increasingly sensitive in detecting intracranial aneurysms and the findings are generally
sufficient for deciding whether the four vessel angiography is warranted. In certain
situation noninvasive imaging can be used to make treatment decisions.
Current treatment Options for Intracranial Aneurysms
Aneurysms that have ruptured require treatment to prevent another rupture
(rebleeding). Following the initial rupture of an aneurysm, rebleeding is very common
(especially within the first two weeks after rupture), and is usually more severe than the
initial rupture. Therefore, ruptured aneurysms need to be treated immediately to prevent
the risk of rebleeding.
The two primary treatment methods are surgical clipping and endovascular
coiling. The optimal treatment choice depends upon the patient's history, physical
examination, age, risk factors, and the anatomical characteristics of the aneurysm. It is
estimated that 60-65% cerebral aneurysm patients in the United States have received
surgical clipping, while approximately the other 30-35% of the patents have received
endovascular coiling.
Optimal treatment of patients with intracranial aneurysm requires a highly
experienced center that is capable of both coiling and clipping.
Anesthesia for cerebral aneurysm coiling
An interventional neuroradiologist does the aneurysm coiling in radiology suite.
The procedure involves placement of small plastic tube (micro-catheter), which is
threaded from the groin to the aneurysm in the brain. Then fine platinum threads (coils)
are inserted into the aneurysm to fill it up from the inside, much like filling a pothole.
The catheter is then removed and the small groin incision covered with a Band-Aid. For
an unruptured aneurysm, the patient is discharged home within 24 to 48 hours. During the
coiling, general anesthesia is required at most of time. Neither SSEP nor MEP monitoring
is often necessary. However, arterial BP monitoring is needed in most of the cases. There
is no limitation for administering inhalation agents if patient is not on evoked potential
(EP) study.
Anesthesia for cerebral aneurysm clipping
Since advanced radiological diagnostic tests have been applied to the patients,
neurosurgeons are able to more precisely identify and localize cerebral aneurysm.
Microscopic clipping and EP and electroencephalography (EEG) monitoring become
very popular intraoperatively, which results in total intravenous anesthesia (TIVA) being
required more often than before. As a trend, intentional hypotension technique and
central lines are less needed since excessive introperative blood loss become less frequent.
However, invasive BP mentoring still remains as pertinent requirement for the procedure.
Newly designed arterial transducer (Edward-Swan) is able to calculated cardiac output.
Popofol and Ramifentanyl continue infusion has provided patient with good anesthesia
and analgesia with reduced time for emergence. The concept of tight control of blood
glucose level is also applied, which directly affect postoperat

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