Indications for Carotid Surgery or Vertebral Artery Surgery
Carotid Endarterectomy
Vascular surgeons have been convinced for many years of the value
of carotid endarterectomy in the prevention of stroke. Many
physicians have disagreed, pointing to the incidence of stroke
associated with the operation itself. Major published controlled
series of the past few years have not only clarified the issues
pertaining to carotid surgery but have been generally accepted by
the medical community. These studies form the basis for the modern
management of cerebrovascular disease, and I would like to review
them briefly.
The North American Symptomatic Carotid Endarterectomy Trial (NASCET)
reported in 1991 studied 669 symptomatic patients with a carotid
stenosis of 70% or greater. The patients were randomized into
medical or surgical groups. Medically treated patients were treated
using the regimen often attributed to "contemplative physicians."
26% had strokes within 2 years. Of the surgically treated group 9%
had strokes. Risk reduction of ipsilateral stroke due to surgery was
17% +/-3.5 p<.0001. Risk reduction of fatal stroke was 10.6% +/- 2.6
p<.001.1
The European Carotid Surgery Trial (ECST) also published in 1991
studied 879 patients collected over 10 years with 70% or greater
stenosis randomized into medical or surgical therapy. The 3 year
stroke rate among medical patients was 21.9% and among surgical
patients was 12.3%, even though the 30 day stroke and death rate was
high by current American standards. They concluded that successful
carotid surgery produced a 6 fold reduction in strokes (p<.0001).2
The Veterans Administration (VA) Carotid Endarterectomy Trial for
Symptomatic Stenosis studied 190 symptomatic patients with carotid
stenosis 50% or greater randomized into medical or surgical therapy.
At a mean follow-up of 11.9 months there was a significant reduction
in stroke or crescendo transient ischemic attacks (TIA) in patients
who underwent carotid endarterectomy (7.7% vs 19.4%). The relative
risk reduction was 60% (p=.011).3
The VA Carotid Endarterectomy Trial for Asymptomatic Carotid
Stenosis was reported in 1993. In that study 444 asymptomatic
patients with carotid stenosis of 50% or greater were randomized
into medical or surgical therapy. Again surgical patients did much
better than medial patients. Of the surgical patients the incidence
of stroke at 4 years was 4.7% with 8.0% having other neurological
events. Medical patients had a 9.4% incidence of strokes and a 20.6%
incidence of other neurological events. This study included a high
risk and aged group of patients who had a stroke and death rate at 4
years of over 40% .4 Surgical patients lived out their lives
without the morbidity of neurological events and that is the usual
patient's goal.
Finally, the Asymptomatic Carotid Artery Stenosis study (ACAS),
published in 1995 randomized 1662 patients with stenosis of 60% or
greater into best medical therapy or best medical therapy plus
surgery. The 5 year stroke rate for surgical patients was 5.1% and
for medical patients 11%. These favorable statistics were achieved
even though of the 17 strokes in the surgical group 2 occurred after
randomization but before surgery and 5 were from the arteriogram.
The beneficial effect of carotid endarterectomy in these
asymptomatic patients was realized in only 10 months.5 This study
was terminated early because of these findings and the physicians
participating in the study were notified and advised to reevaluate
unoperated patients. In an unusual move, the National Institutes of
Health sent a Clinical Advisory to every physician in the country on
28 September 1994. This advisory preceded formal publication and was
sent so that the findings could be acted upon by practicing
physicians immediately. You and the members of the panel undoubtedly
received a copy of this advisory.6 The importance of carotid
surgery for asymptomatic patients with 60% stenosis was then front
page news throughout the United States.7
Last year the Department of Surgery, the Cardiovascular Surgery
Section and the Quality Management Department of Presbyterian St.
Lukes Medical Center, Denver, Colorado, decided to adopt the
criteria of the ACAS study as the screening criteria for
appropriateness of carotid surgery and the results reported in that
study as the results our surgeons were expected to achieve. Review
of two years of data found the Department in compliance both with
indications and results.
Vertebral Artery Reconstruction
Vertebral artery surgery is much less common than carotid
surgery, and is usually the province of the Certified Vascular
Surgeons. Vertebral territory symptoms are quite nonspecific and may
even alternate from side to side with different attacks.
Vertebrobasilar symptoms are usually a manifestation of global brain
ischemia, as a complex collection of lesions in the extracranial
cerebral circulation and the Circle of Willis are found. Clouding of
consciousness, confusion, unconsciousness and drop attacks are
characteristic of this condition and have been recognized since the
first description of the syndrome in 1955.8 Virtually every
textbook written since which mentions vertebral basilar
insufficiency or global cerebral ischemia describes this.9 Note that
a proximal vertebral reconstruction is carried out thru the same
incision as a carotid endarterectomy, and repairing both lesions at
the same time makes logistical sense. The indications for this
surgery are discussed in most of the vascular surgical texts. There
are three accepted indications for repair, a symptomatic lesion,
global ischemia of the brain, or an asymptomatic lesion of a single
dominant vertebral repaired in conjunction with a planned carotid
reconstruction.10 Workup of the lesion involves ruling out other
causes of the nonspecific symptoms, and may include cardiology
consultation, neurology consultation, Holter monitoring, EEG, CT or
MR scan of the brain or cerebral angiography. Addition of a proximal
vertebral reconstruction adds little mortality and morbidity to a
well-performed carotid endarterectomy.
Dr Brantigan wrote this article in 1997
1 North American Symptomatic Carotid Endarterectomy
Trial Collaborators, Beneficial effect of carotid endarterectomy in
symptomatic patients with high-grade carotid stenosis, N Engl J Med
325:445-53 (1991)
2 European Carotid Surgery Trialists' Collaborative
Group, MRC European carotid surgery trial: interim results for
symptomatic patients with severe (70-99%0 or with mild (0-29%)
carotid stenosis, Lancet 337:1235-43 (1991)
3 Mayberg, MR. et al, Veterans affairs cooperative
studies program trial for carotid endarterectomy in patients with
symptomatic carotid stenosis, in Moore, WS, Surgery for
Cerebrovascular Disease, WB Saunders.
4 Hobson, RW et al, Efficacy of carotid
endarterectomy for asymptomatic carotid stenosis, N Engl J Med
328:221-7 (1993)
5 Executive Committee for the Asymptomatic Carotid
Atherosclerosis Study, Endarterectomy for asymptomatic stenosis,
JAMA 273:1421-8 (1995)
6 National Institute of Neurological Disorders and
Stroke, Asymptomatic Carotid Atherosclerosis Study (ACAS) Clinical
Advisory 28 September 1994.
7 New York Times, 1 October 1994 p1.
8 Millikan, CH et al, Studies in cerebrovascular
disease. I The syndrome of intermittent insufficiency of the basilar
arterial system, Proc Staff Meetings Mayo Clinic, 30:61-68 (1955)
9 Gelabert HA and Moore WS, Carotid endarterectomy:
Current Status, Current Problems in Surgery 28:183-262 (1991).
"Global events are manifested by vertigo, dizziness, ataxia, or
syncope. These symptoms are associated with brain stem or posterior
circulatory dysfunction. Unlike the carotid embolic events, these
symptoms are often associated with diminished flow.
Encyclopedia Britannica CD Version 2.0. "..brief
reduction in consciousness, vertigo, slurred speech, impaired vision
in both eyes or imbalance point to ischemia in the vertebrobasilar
circulation."
Berkow, R, ed, Merck Manual 1992, "..confusion,
vertigo, weakness, drop attacks, slurred speech......."
Horn, GV, Cerebrovascular Disease, Disease a Month
June 1973, "Vertebrobasilar insufficiency may be manifested by
vertigo, ataxia, hemianopia, nausea, drop attacks, perioral
numbness, facial weakness, or a variety of sensory deficits.."
Scientific American Medicine, "...attacks of
vertigo, unsteadiness, drop attacks, memory loss, confusion,
retrograde amnesia..."
10 Berguer, R, Vertebrobasilar ischemia:
Indications, techniques and results of surgical repair, in
Rutherford, RB, Vascular Surgery p1392ff, 1989 |
