11. NEUROLOGIC CONCERNS
STROKE AND TIA
*The risk of perioperative stroke in patients with prior history of stroke
or TIA is likely to be increased, although clinical data has not confirmed this
consistently. Patients with recent
TIA’s, however, clearly represent the group at the highest risk of
perioperative stroke and mortality. Furthermore,
as a group, patients with known cerebrovascular disease are at increased cardiac
risk for surgery due to coexisting coronary artery disease.
(The reciprocal is true as well: patients with known CAD are more likely
to have coexisting cerebrovascular disease.)
the cause of a prior stroke helps in determining the subsequent risk of
recurrence and the modalities for prevention, if any.
Thrombotic strokes are most commonly due to atherosclerosis and
hypertension. Embolic strokes may be
due to atrial fibrillation, cardiac valvular disease,
of surgery following a completed stroke is not clearly defined.
The best data available (carotid endarterectomy procedures following
acute stroke) shows the highest mortality among patients who had surgery within
24 hours following a stroke (44%). Between
1 day and 2 weeks the mortality was 14%, and after 2 weeks the mortality was 6%.
The decision to perform surgery after an acute stroke clearly depends on
the urgency of the procedure itself. If
at all possible, urgent procedures should be delayed at least one or two days
after an acute stroke; non-urgent procedures should be delayed 2 weeks or more.
Elective surgery should wait 6 weeks.
regarding the timing of surgery in patients with TIA’s is even less clearly
defined. The presence of TIA’s,
however, does represent a more unstable pattern of symptomatic cerebrovascular
disease. Perioperative stroke risk
is certainly higher in patients with recent TIA’s than in those with a history
of completed stroke. Perioperative
management of these patients to prevent stroke should be aggressive.
ASYMPTOMATIC CAROTID STENOSIS AND CAROTID BRUIT:
with asymptomatic carotid bruits are NOT at any increased risk of perioperative stroke.
Preoperative carotid doppler studies are certainly not warranted for
these inpatients. (Statistically,
the presence of a carotid bruit is actually a better predictor of perioperative
cardiac mortality than of stroke.)
The data for
carotid stenosis is similar, although there have been contrasting studies.
In general, the likelihood of perioperative stroke is low in patients
with asymptomatic, greater-than-50%
stenosis. Non-elective surgery
should not be delayed simply because of a known asymptomatic carotid stenosis.
(Elective surgery is more controversial in this regard, since the
intervention for asymptomatic high-grade stenosis is itself an elective surgical
therapy—aspirin, plavix, persantine, and ticlid are usually held before
surgery to minimize bleeding risk; however, in patients with a history of
TIA’s or multiple strokes, the benefit of continuing the antiplatelet therapy
up until the time of surgery may outweigh the risk of increased surgical
bleeding. *Always inform the surgeon if you are continuing the
antiplatelet therapy up until surgery. Postoperatively
these medications can safely be resumed if surgical hemostasis is satisfactory
and there is no evidence of bleeding. (For
NPO patients, aspirin can be given rectally at the same dose.)
therapy—patients who are chronically anticoagulated on coumadin for stroke
or TIA should have their anticoagulation reversed by the time of surgery.
The need to place these patients on heparin drip or therapeutic-dose
enoxaparin postop depends on the perceived risk of perioperative stroke.
If low, then simply resume coumadin alone when patient can take pills
postop. If moderate to high, then I
would recommend interim anticoagulation with heparin drip or enoxaparin once
surgical bleeding risk has subsided and continue until the protime is
therapeutic on coumadin.
patient with a history of non-hemorrhagic stroke should be at least considered
for prophylactic beta-blocker therapy, given the very high incidence of
coexisting coronary artery disease and the proven increased perioperative
cardiac risk among patients with prior stroke.
The most important factor in assessing risk for
postoperative seizure in a patient with a chronic seizure disorder is the
patient’s preoperative control. Patients
with good control of seizures by history do not need to have any medication
adjustments performed, even if the anticonvulsant drug level is subtherapeutic.
Patients who do not have good control of seizures should have their
anticonvulsant drug level brought into the therapeutic range preoperatively; an
additional anticonvulsant drug should be considered if a patient does not have
good control of seizures despite a therapeutic drug level already.
Anticonvulsant medications should be continued
perioperatively. Phenobarbital, Dilantin, and
Valproic Acid can be given IV if the patient is NPO, usually at the
equivalent dose of the
Knowing the type of seizure disorder is also important.
In general, simple partial (focal) seizures and absence seizures do not
pose a serious problem perioperatively even if they are recurrent.
Alcohol-related seizures do not require chronic anticonvulsant medication
and typically do not respond well anyway. Management
is acute therapy for alcohol withdrawal (benzodiazepines, beta-blockers, IVF).
Postoperative seizure in a patient with previously
controlled seizure disorder or without a prior history of seizures should prompt
a diagnostic workup to rule out an underlying etiology (infection, electrolyte
abnormality, hypoxia, hypoglycemia, etc.). Postop
seizures are generally NOT due to anesthesia effects.