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decompression148,152 or a lumboperitoneal shunt is required.150
stenosis
 Non-inherited  Pseudotumor cerebri
Effect of pregnancy and obstetric management  Dandy-Walker anomaly  Arnold-Chiari malformations
Some authors suggest that symptoms worsen during preg-
 Acquired, secondary to:  Brain tumor or other mass
nancy,149 suggesting a hormonal etiology, but Digre and col-  subarachnoid lesion
leagues153 found that visual loss occurred with the same
 Hydrocephalus
hemorrhage
frequency in pregnant and nonpregnant patients. Obstetric com-  infection  Lyme disease
plications occurred more frequently in the controls, so obstetric  tumor  Severe hypertension
management should not be significantly altered by this disor-
 Inherited neural tube defect
der.153 Treatment of pseudotumor cerebri during pregnancy is
 Arnold-Chiari malformation
the same as for nonpregnant patients, except that calorie restric-
tion and diuretic use (acetazolamide) are contraindicated. The
can exclude other processes, such as benign intracranial
condition usually resolves postpartum.
hypertension.

Anesthetic management
Neurosurgical management
General anesthesia may be required for placement of a lumboper-
Shunts are placed or replaced when the patient develops signs of
itoneal shunt or replacement of a blocked shunt. The usual precau-
raised ICP. Ventriculoperitoneal shunts are the most resistant to
tions for nonobstetric surgery during pregnancy apply.154 Regional
infection, and are used commonly. Prophylactic antibiotics are
analgesia for labor and delivery has been described and deemed to
recommended to prevent infection of the shunt during revision.
be safe,148,155 but caution is warranted as cerebellar tonsillar her-
niation has been described after diagnostic lumbar puncture in two
Effect of pregnancy and obstetrical management
nonpregnant patients (see earlier).151 If a lumboperitoneal shunt is
Pregnancy may precipitate symptoms of hydrocephalus in a
in place, GA may be preferable for C/S as the impact of the shunt on
patient with a previously well-functioning shunt or in a woman
extension of spinal anesthesia is unknown. With an unknown CSF
without a preexisting shunt,157 but these are unlikely to increase
volume or pressure it might be difficult to adjust the dose of local
obstetric complications.160 In 59% of pregnant patients with a
anesthetic. However, spinal anesthesia has been successfully used
preexisting shunt pregnancy increased ICP resulting in symp-
in a patient who likely had low CSF volume and pressure from a
toms of severe headache.157 If ICP is normal there are no specific
continuous CSF leak at the base of the skull.156 As parturients with
obstetric considerations. However, prophylactic antibiotics will
benign intracranial hypertension often undergo a diagnostic spinal
reduce the risk of shunt infection, especially if the peritoneum is
tap they have the potential to develop a postdural puncture head-
entered during C/S or tubal ligation.
ache and an epidural blood patch may be considered. Blood placed
in the epidural space may increase ICP through compression of the
Anesthetic management
dura mater, so slow injection may be warranted.
General anesthesia is used for shunt placement, with emphasis
on controlling ICP (see Table 9.11), BP, and maintaining adequate
anesthetic depth. Regional anesthesia has been used for vaginal
Hydrocephalus with shunt
birth as well as C/S in these patients,158,161,162 although there is
Hydrocephalus is an abnormal accumulation of CSF in the brain. concern about the dose required and potential spillage of the
The CSF is often under increased pressure, which can compress and local anesthetic into the peritoneal cavity. Kaul et al. reported
damage the brain. Hydrocephalus can be due to many causes (see that the duration of local anesthetic inadvertently injected into
Table 9.10) and may require ventriculoperitoneal or ventriculoatrial the subarachnoid space in a parturient with a lumboperitoneal
shunts to relieve raised ICP. The incidence of pregnant patients with shunt was shorter than normal. They postulated that this might
CSF shunts is unknown, but successful treatment of congenital have been caused by washout of the anesthetic into the peritoneal
hydrocephalus in childhood has translated into more women with cavity and felt that spinal anesthesia may not be practical in
ventricular shunts reaching childbearing age.157,158,159 parturients with lumboperitoneal shunts.163

Clinical presentation and diagnosis
Increased intracranial pressure
In patients with shunts, hydrocephalus may recur due to shunt
malfunction, commonly due to infection or mechanical damage. One of the most damaging aspects of brain trauma and various
A physical examination and a CT/MRI scan should be performed other conditions is elevated ICP that can cause a reduction in
to rule out other causes. If the scan is normal, a lumbar puncture cerebral perfusion. An elevated ICP correlates directly with poor



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Table 9.11 Methods of reducing intracranial pressure

Method Effect Caution

Diuretics
Mannitol (0.25“1.0 g/kg) Hyperosmolar diuresis Acts only if BBB intact
# brain water, volume of brain, and ICP Can increase ICP, if BBB not intact
Transient vasodilation, hence increases ICP
May precipitate pulmonary edema
Can cause fetal dehydration, and fetal brain shift and
hemorrhage
Furosemide (1 mg/kg) Systemic diuresis Fetal dehydration
# CSF production Moderate doses usually safe
# ICP
Short term: minimal effects on the fetus94
# elevated ICP by restoring integrity of the
Corticosteroids
*

dexamethasone BBB, allowing diuretics to work more Long-term therapy may cause hyperglycemia, gastrointestinal
effectively bleeding, electrolyte disturbances, infection, and fetal
adrenal suppression24
May take hours to days to have that effect
# fetal perfusion secondary to uterine vasoconstriction
Acute hyperventilation Cerebral vasoconstriction
*

# CBF
(normal pCO2 is 32“34 mmHg
# ICP by 4%/1 mmHg reduction in pCO2
in term parturient) Shifts O2 dissociation curve to left, reducing fetal O2 delivery
Moderate ventilation to PaCO2 of 25“30 Effect limited by renal compensation over prolonged
not harmful to fetus hyperventilation
CSF drainage
*

Ventriculostomy Can monitor ICP Additional risk of infection requires antibiotic cover
Lumbar spinal catheter Control ICP precisely
Posture Increases the probability of pulmonary air emboli
*

Head up Improves venous drainage Use precordial Doppler
Neutral, if possible Reduces ICP Neck rotation may decrease venous return thereby
increasing ICP

BBB ¼ Blood Brain Barrier; ICP ¼ intracranial pressure; CSF ¼ cerebrospinal fluid; CBF ¼ cerebral blood flow
Arterial pressure and ICP should be measured at brain level.



neurological outcome. The symptoms of raised ICP are headache, and diagnostic CT or MRI scan a secondary issue. Immediate
nausea and vomiting, ataxia, papilledema, visual disturbances, and treatment may involve cardiopulmonary resuscitation, tracheal
decreasing levels of consciousness. An acute increase in ICP due to intubation, and hyperventilation. If the ICP exceeds 25 mmHg, it
an expanding intracranial lesion, can lead to brain-stem hernia- must be reduced to maintain cerebral perfusion. Periods of risk
tion, but loss of consciousness may occur before signs of hernia- for increased ICP during pregnancy include: laryngoscopy and
tion are seen. Signs and symptoms of brain-stem herniation intubation, extubation, straining during labor and delivery, and
include: decreasing level of consciousness, lateralizing neurologic postpartum when the uterine autotransfusion leads to an acute
signs (˜˜unilateral blown pupil™™, abducens nerve palsy), sudden increase in blood volume. A number of methods may be used to
changes in BP and pulse (Cushing triad), vomiting, irregular control ICP during the perioperative period (see Table 9.11).
respiration, respiratory collapse (Cheyne-Stokes respiration),
Anesthesia for delivery in a parturient with raised ICP
and seizures. The differential diagnosis includes acute obstetric
disasters, such as amniotic fluid embolism. In the parturient, To prevent increases in ICP, labor should be as pain free as
increased ICP can occur secondary to uterine contractions (result- possible and the second stage should be shortened by using
ing in a 200“300 ml autotransfusion) and increases in arterial and oxytocin, and instrumental delivery. Monitor BP, oxygen satura-
venous pressure from pain and the Valsalva maneuver. tion, and ICP (if indicated) throughout labor and in the immedi-
ate postpartum period when the cardiovascular changes are
Monitoring and control of intracranial pressure maximal.
The normal ICP is <15 mmHg.164 An ICP that remains between The decision concerning pain relief must be individualized.
30“35 mmHg for prolonged periods may prove fatal. Intracranial Systemic analgesics may depress respiration and increase ICP.
pressure should not be allowed to go above 40 mmHg for even A paracervical block provides adequate anesthesia during the first
brief periods. The rapid progression of this life-threatening emer- stage, but can compromise the fetus. Pudendal block with local
gency makes immediate surgical intervention the first priority infiltration may be used for the second stage and assisted delivery.



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3 Nervous system disorders


Segmental lumbar epidural anesthesia reduces the pain of clinical evidence suggests that phenylephrine, which increases
afterload, is safe for the fetus.22,168,169 However, in large doses,
labor, limits straining, and helps with pain-free assisted vaginal
delivery. In the parturient with increased ICP there is the risk of a phenylephrine has the potential to reduce uteroplacental perfu-
˜˜wet-tap™™ during epidural placement that could cause a sudden sion secondary to its alpha-adrenergic effect on uterine vascula-
leakage of CSF and theoretically lead to brain-stem herniation. ture. Antihypertensive agents such as labetalol, hydralazine,
Therefore, the anesthetic technique should be selected with these nifedipine, nitroglycerin, and brief infusions of nitroprusside are
safe for the fetus in normal doses.22,170,171 The lack of placental
complications in mind. If there is concern about increased ICP, a
ventriculostomy can be used to measure ICP and withdraw CSF, if autoregulation means that placental perfusion is directly related
needed. The ability to withdraw CSF should be checked prior to to maternal mean blood pressure. The effect of volume expan-
attempting the epidural. An epidural bolt measures ICP, but ders, diuretics, vasopressors, or vasodilators must be considered
cannot be used to withdraw CSF. Placement of a lumbar epidural in terms of their impact on cerebral perfusion, maternal end-
catheter by the most experienced person available reduces the organ perfusion, and placental perfusion. Clearly, in some situa-
chance of a dural puncture. A caudal approach may reduce, but tions what is best for maternal homeostasis may be detrimental to
not eliminate, the possibility of dural puncture, but it is rarely the fetus.
used. Spinal anesthesia should not be used if the ICP is elevated.
Brain protection
Cesarean delivery may be required for obstetric indications.
General anesthesia allows a simultaneous neurosurgical proce- Various methods may be used to minimize further neurological
dure.106,107 For the patient with a possibly difficult airway, the damage in the perioperative period by reducing continuing
effects of respiratory obstruction and straining on BP and ICP damage to surrounding tissues. Many of these methods are
during a fiberoptic intubation must be considered.165,166 If lum- experimental and the effects on the fetus are unknown.
bar epidural anesthesia is selected, the same considerations apply
as for vaginal delivery. Some authors have used epidural115 and Anesthetic management for neurosurgery during
spinal167 anesthesia for C/S in patients with intracranial lesions. It pregnancy
can be argued that spinal anesthesia with a small, pencil-point Emphasis is placed on selection of surgical procedures with the
spinal needle is unlikely to cause a significant CSF leak in patients welfare of the parturient in mind, since the well-being of the
with raised ICP167 but this remains controversial. If labor occurs mother determines fetal outcome. Method of delivery is often
when neurosurgery is planned, an emergency C/S followed selected based on obstetric considerations. The impact of pre-
immediately by an intracranial procedure may be performed operative therapy and anesthetic intervention on the mother and
under GA. fetus should be considered when formulating an anesthetic plan.
Urgent surgical intervention is required only in the most severe
cases (massive trauma, epidural hematoma, brain-stem hernia-
Considerations for neurosurgery during pregnancy
tion). Major considerations include the neurological status
Monitoring (including level of consciousness, ICP), diagnosis, cardiorespira-
It is important to monitor oxygen saturation, EKG, end-tidal CO2, tory compromise, and status of the fetus. Maternal condition
FHR, direct arterial and central venous pressures, ICP, and, occa- should be as stable as possible before proceeding to surgery and
sionally, electroencephalogram (EEG) and sensory-evoked appropriate monitors should be in place.
potentials. Preanesthetic and anesthetic goals include control of BP, cere-
bral blood flow, and ICP, prevention of aspiration, and main-
Intravenous fluid management and blood pressure control tenance of fetal perfusion. Anesthetic management for a
In unconscious patients and those with intracranial lesions, fluid neurosurgical procedure during pregnancy is similar to that for
and electrolyte balance can be problematic as a result of a nonpregnant patient with the following exceptions: surgery is
decreased fluid intake, vomiting, and the use of hyperosmolar best deferred until the second trimester, the well-being of the
dyes for angiography. Severe fluid restriction produces minimal fetus is assessed throughout surgery by monitoring FHR, and
reduction in ICP because fluid loss is isotonic, but it can cause a left uterine displacement is ensured to avoid aortocaval compres-
reduction in uteroplacental perfusion. Intravenous fluid loading sion especially during late third trimester. After preoxygenation
is sometimes used to maintain BP, cerebral perfusion, and fetal and induction, cricoid pressure is applied until the endotracheal
perfusion. Hypotension and hypovolemia can exacerbate intra- tube is secured. These precautions also apply when intubating
cranial vasospasm112,113 so judicious hypervolemia, while meas- the trachea of a comatose, unstable patient, remote from sur-
gery.4 Succinylcholine (100“120 mg) remains the most reliable
uring ICP and FHR, is appropriate. Control of BP throughout the
perioperative period is important for maintaining ICP, cerebral neuromuscular blocker for intubation. The resulting fascicula-
perfusion, and fetal perfusion. tions may temporarily increase ICP and BP, but this is of little
Vasopressors and antihypertensives should be selected with clinical consequence. If succinylcholine is contraindicated and
the fetus in mind. Although ephedrine benefits fetal perfusion the woman has an adequate airway, rocuronium may be given in
by constricting capacitance and resistance vessels, and increasing a dose 0.6“1.0 mg/kg.
Most anesthetic drugs are safe for the fetus,172 but second tri-
myocardial contractility, it may increase shear stress on sensitive
intracranial vessels and so must be used cautiously. Most recent mester surgery negates concerns about teratogenesis. Premature



180
Chapter 9


labor can occur following any nonobstetric surgery. The risk is History, physical examination, laboratory tests (including co-
much greater following abdominal or pelvic than neurosurgery. agulation studies, blood gases), and other imaging studies are
Early detection with continuous monitoring for uterine contrac- useful to establish the extent of injury to the brain and other
tions and treatment is important. systems. If neuroradiologic examination is needed, it should be
Induced hypotension is used occasionally to control bleeding performed promptly. The fetus can usually be shielded, and
during clipping of intracerebral aneurysms,110,111,173 but it may radiation of the fetus should be considered a minor risk in life-
have adverse effects on the fetus.10 If induced hypotension is saving situations.
used, it should be limited in depth and duration, adjusting the
mean BP upwards if the FHR pattern becomes unfavorable (e.g.
Neurosurgical management
sudden fetal tachycardia or decelerations). Improvements in FHR
pattern have been described after correcting hypoxemia,174 or by Management includes control of BP, ICP, ventilation, maternal
increasing flow during cardiopulmonary bypass.175 cerebral perfusion, and fetal perfusion. Surgical intervention is
indicated for subdural and epidural hematomas, for intracerebral
hematomas associated with a mass effect and/or neurological
Cerebral trauma
deterioration, for symptomatic ICP greater than 25 mmHg that
A variety of traumatic head injuries have been reported in the is not responding to treatment, depressed skull fractures, hydro-
parturient,6,172 and the incidence of traumatic brain injury in the cephalus, and to place ICP monitors.
USA is in the range of 152“430 per 100 000/year. The mortality
rate is 30 per 100 000/year with a large number suffering perma-
Effect of pregnancy and obstetric management
nent disabilities. Approximately 7% of pregnant women will suf-
fer a bodily injury, with motor vehicle accidents and alcohol The incidence and morbidity of cerebral trauma in pregnant
women are similar to a matched nonpregnant population.6 In
ingestion as major contributory factors. Prompt diagnosis and
management can be life saving. the presence of severe head trauma, injuries to other organ sys-
Head injury may be classified as closed or open (penetrating). tems must be ruled out, especially the vulnerable gravid uterus,
Closed injuries may be diffuse or focal. Diffuse injury, often with the potential for uterine rupture, placental separation, and
caused by acceleration“deceleration, ranges from simple concus- fetal trauma. A discussion of fetal injury is beyond the scope of
sion (transient loss of consciousness) to severe axonal disruption. this chapter. Injury may precipitate premature labor, and since
Focal injuries include subdural hematoma, epidural hematoma, the obtunded patient cannot indicate that she is in labor, fetal
and cerebral contusion. A subdural hematoma occurs when the monitoring should be initiated and early delivery anticipated.
bridging veins between the brain and the dural venous sinuses are Method of delivery is based on obstetric considerations.
disrupted as a result of an acceleration injury. Epidural hemato-
mas are caused by direct skull trauma leading to rupture of the
Anesthetic management
meningeal arteries, which are embedded in the grooves of the
skull. Cerebral contusions are heterogeneous areas of necrosis, Anesthetic management for neurosurgery is similar to that in the
infarction, hemorrhage, or edema. Coup contusions result from nonpregnant patient, bearing in mind those factors important in
dealing with nonobstetric surgery during pregnancy.154 Exposure
deformation of the skull at the point of impact, and contracoup
contusions result from deceleration of the brain against the skull. to teratogens is of concern, but judicious use of commonly used
Intracerebral hematomas result from depressed skull fractures, agents is safe in the absence of hypoxemia, acidemia, and hyper-
penetrating wounds, or acceleration“deceleration injuries. carbia. Anesthetic management for delivery is similar to that in
Missiles produce a variety of injuries. In addition to neurologic pregnant patients suffering from intracranial hemorrhage (see
damage, major long-term complications of cerebral trauma earlier).
include epilepsy and hydrocephalus.

The comatose parturient
Clinical presentation and diagnosis
Coma is the term used to describe unconsciousness from which a
Concussion injury ranges from temporary unconsciousness, dis- person cannot be aroused. A multitude of etiologies exist, all of
orientation, amnesia, dizziness, and disequilibrium to coma and which may complicate pregnancy and pose great threat to the
death. Acute subdural hematomas present as rapidly expanding mother and her fetus (see Table 9.12). Further along the con-
mass lesions, with hemiparesis, pupillary abnormalities, or both. tinuum of CNS deficits are the entities of chronic vegetative state
Cerebral epidural hematomas can present with immediate loss of and brain death, which pose medical, ethical, and legal dilemmas,
consciousness, followed by a lucid interval, later followed by especially when considered in the context of a viable pregnancy.
neurologic symptoms such as headache and increased lethargy. The immediate treatment goals are prevention of further ner-
Some may not experience unconsciousness until some time after vous system damage, rapid correction of hypotension, hypogly-
the injury. Symptoms of subarachnoid hemorrhage can also cemia, hypoxia, hypercapnia and hyperthermia, and control of
occur. Contusions, hematomas, and missile injuries produce a seizures. The unconscious parturient may require endotracheal
variety of localized and diffuse signs and symptoms. intubation and ventilation to protect the airway from aspiration



181
3 Nervous system disorders


term maternal hypoglycemia the FHR pattern changes, and fol-
Table 9.12 Differential diagnosis of coma lowing treatment it returns to a fully-reactive trace and normal
baseline.179 Another rare cause of hypoglycemia in pregnancy is
Intracranial Extracranial
lymphocytic hypophysitis, which causes anterior pituitary defi-
1. Vascular 1. Hypotension
ciency in the absence of a radiographically identifiable pituitary
Hemorrhage (subarachnoid) Hemorrhage
tumor or neurofibroma. In one report, treatment consisted of an
Cerebral infarction (embolus, thrombus, Myocardial infarc-
initial 50% glucose infusion with good response, followed by
or vasculitis) tion
thyroxine and cortisol replacement once the diagnosis of panhy-
2. Tumor Septic shock
popituitarism was established.180
Hemorrhage 2. Hypertension
Edema Encephalopathy:
Management of maternal vegetative state
3. Abscess eclampsia
and brain death
Hemorrhage 3. Metabolic
Edema Endocrine
A chronic vegetative state is defined as a subacute or chronic
4. Infection Hepatic
condition that sometimes occurs after brain injury and consists
Meningitis Renal
of a return of wakefulness accompanied by an apparent total lack
Encephalitis Hypoxia
of cognitive function. The vital functions of respiration, blood
5. Trauma Hypercarbia
pressure, and thermal regulation are retained and may be subject
Edema 4. Drugs/toxins
to periods of overactivity.
Hemorrhage (subdural, extradural, or 5. Physical
Brain death results from total cessation of cerebral blood flow
intracerebral) Hypothermia
at a time when cardiorespiratory function is preserved by artificial
6. Epilepsy Electrocution
life support. It is a diagnosis made according to strict criteria.
Postictal
Brain stem and hypothalamic centers do not function, resulting
Status epilepticus
in a lack of spontaneous respiration, hypotension, hypothermia,
and panhypopituitarism, including diabetes insipidus with con-
comitant treatment problems.
pneumonitis and to correct hypoventilation. Fetal viability Advances in intensive care, life-support systems, and neonatol-
should be assessed after maternal stabilization. ogy make possible the continuation of pregnancy in the vegeta-
History and a thorough clinical examination with neurological tive or brain-dead parturient. Moral and ethical problems abound
and laboratory evaluation will indicate the need for neuroimaging regarding withdrawal of support from the vegetative mother post-
techniques such as CT scanning, MRI, MR angiography, and partum. No rules can be laid down as each case must be assessed
conventional angiography. An accurate diagnosis allows for individually with liaison among family members, legal advisors,
development of an individualized management plan, utilizing a ethicists, and the multidisciplinary care team. Beware of medico-
multidisciplinary approach. Specific treatment is directed legal implications of issues regarding consent and cessation of
towards pathology leading to coma. Long-term management treatment, planned C/S, and perimortem C/S.
goals are adequate nutrition and avoiding complications like The management of a pregnant patient with irreversible anoxic
infections, bed sores, and contractures. brain damage and in a persistent vegetative state from 14 weeks™
In general, neurosurgical considerations dictate management gestation until delivery at 34 weeks™ by C/S is described by Hill
et al.181 Management issues in this case included: seizure control,
in the case of life-threatening intracranial hemorrhage, while
obstetric decisions are based on fetal viability. In mothers with respiratory support ranging from tracheobronchial toilet to
Hunt and Hess Grades IV and V postsubarachnoid hemorrhage, mechanical ventilation, hemodynamic monitoring and cardiovas-
supportive intensive care is preferred to early repair.176 Brain cular support, nutritional support, maintenance of normothermia,
tumors, especially meningiomas, may increase in size during treatment of infection, physiotherapy, thromboembolism prophy-
pregnancy leading to possible coma. The outcome for the fetus laxis, and fetal monitoring with serial ultrasound examinations,
is determined by the individual circumstances. If the fetus is biophysical profile scoring, and lung-maturity assessment. The
viable and neurosurgical intervention mandatory, C/S before authors stressed a team approach to decision-making with each
craniotomy may be indicated.177 Steroids may be administered case assessed individually with regard to the likelihood of maternal
survival and fetal prognosis with continued life support.181
to enhance fetal lung maturity.
Hypoglycemic coma, not associated with insulin therapy, is Betamethasone may be administered to stimulate fetal lung
rare in pregnancy, chiefly because pregnancy confers insulin maturation, if indicated. The timing of delivery, often by classical
resistance. Insulinoma may be diagnosed with simultaneous C/S, is determined by maternal condition and fetal maturity.
determination of plasma glucose, insulin, and C-peptide levels Case reports in the literature outline scenarios and manage-
in the fasting state. In one case report, treatment consisted of a ment issues. Fulminant subacute sclerosing panencephalitis is a
50% glucose infusion and supportive care until the pancreatic rare cause of rapid neurological deterioration culminating in a
tumor was excised postpartum.178 Prolonged maternal hypogly- vegetative state. Pregnancy as a state of natural immunosuppres-
cemia may cause precipitous fetal compromise. During short- sion was suggested as the trigger for the delayed onset and



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Chapter 9


fulminant course of this measles virus-associated, progressive,
Table 9.13 Clinical manifestations and anesthetic concerns in
fatal disease in two pregnant women. One mother developed
a parturient with Sturge-Weber syndrome
the disease postpartum while the other became ill at week 14
and stuporous two weeks later. Supportive and intensive obstetric Clinical manifestations Anesthetic concerns
care was provided and C/S was performed after the onset of
 Seizures  Control of seizures
spontaneous labor at 33 weeks™ gestation.182
 Contralateral  " ICP
 " IOP
hemiparesis

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