Principles of Neurocritical Care

This chapter includes an accompanying lecture presentation that has been prepared by the authors: .

Key Concepts

Management of blood pressure in the acute phase following stroke is important to maintain tissue perfusion and protect against neurological deterioration.
For ischemic stroke, if tissue plasminogen activator (tPA) has been administered, the blood pressure should kept below 180/105 mm Hg for the first 24 hours. If tPA has not been administered and the blood pressure exceeds 220/120 mm Hg, the goal should be a 15% reduction over 24 hours. If mechanical thrombectomy for large-vessel occlusion has been performed, the blood pressure should be kept below 160/90 mm Hg.
For intracerebral hemorrhage, the goal should be a systolic blood pressure below 140 mm Hg.
For subarachnoid hemorrhage, until the aneurysm is secured, the systolic blood pressure should be kept below 160 mm Hg.
Temperature elevation increases cerebral metabolic rate and can lead to poorer neurological outcomes.
In the setting of acute stroke or subarachnoid hemorrhage, the source of fever should be sought and the temperature controlled.
The leading cause of morbidity and mortality following aneurysmal subarachnoid hemorrhage is vasospasm, which usually occurs between days 3 and 14 following hemorrhage.
All patients with subarachnoid hemorrhage should be administered nimodipine on admission, which has been shown to improve clinical outcome in the presence of vasospasm.
If vasospasm leads to delayed ischemic neurological deficit (DIND), the treatment is hyperdynamic therapy, which consists of intravascular volume expansion, blood pressure augmentation, and lowering of blood viscosity.
Acute hyponatremia can worsen cerebral edema.
It is important to distinguish between the syndrome of inappropriate antidiuretic hormone (SIADH), which occurs in the setting of hypervolemia and normovolemia, and cerebral salt wasting (CSW), which occurs in the setting of hypovolemia.

Critical care management is an integral component of neurosurgical practice. This chapter is a review of the principles of neurocritical care in the management of patients with ischemic stroke, hemorrhagic stroke, subarachnoid hemorrhage (SAH), and spinal cord injury (SCI). Additionally, we summarize some of the most commonly performed bedside procedures in the neurointensive care unit.

Neurocritical Considerations in Ischemic Stroke

Acute ischemic stroke leads to neuronal cell death in a matter of minutes. Therefore therapeutic measures must commence swiftly and are best achieved at centers with expertise in the management of acute ischemic stroke and its associated complications. ^,

Blood Pressure

Hypertension after acute ischemic stroke is common at presentation, especially in patients with a history of hypertension. Studies have shown that the initial increase in blood pressure is temporary, and the pressure starts to decrease spontaneously 90 minutes after the onset of symptoms. ^, Extreme hypertension is deleterious because it may lead to encephalopathy, cardiac complications, and renal insufficiency. Accordingly, elevated blood pressure during hospitalization is linearly associated with poorer neurological outcomes. ^, Despite this, a moderate amount of hypertension may be beneficial in that it increases cerebral perfusion. Blood pressure management in acute stroke is thus a balance of these distinct principles, and both neurological and hemodynamic status must be monitored closely in the acute setting.

Numerous researchers have studied the effect of lowering blood pressure in the acute period after ischemic stroke, with equivocal results. Steep reduction of blood pressure is associated with poorer outcome and increased mortality rate. It is recommended that blood pressure in severely hypertensive patients (systolic blood pressure [SBP] >220 mm Hg or diastolic blood pressure >120 mm Hg) be decreased by about 15% over a period of 24 hours.

For patients not treated with tissue plasminogen activator (tPA), there are no clear guidelines about blood pressure control. There are specific recommendations regarding blood pressure management if intravenous fibrinolytic therapy is considered: in cases of severe hypertension, blood pressure should be gently decreased to below 180/110. After administration of intravenous tPA, blood pressure must be kept below 180/105 for at least 24 hours to decrease the risk for intracerebral hemorrhage (ICH). There are no clear guidelines regarding blood pressure management after mechanical thrombectomy (MT) for patients with large-vessel occlusion (LVO). Higher blood pressures in the acute period after MT have been associated with poorer outcomes. ^, The general consensus is for blood pressures below at least 160/90.

Glucose Control

Hyperglycemia is present in more than 40% of patients with ischemic stroke and is more common in those with a history of diabetes. ^, Multiple studies have shown that higher blood glucose levels, either at admission or during inpatient stay, are associated with an inferior clinical outcome in comparison with normal glucose levels. However, the Glucose Insulin in Stroke Trial–UK (GIST-UK), a study of the efficacy of controlling hyperglycemia after acute ischemic stroke, failed to show any clinical benefit. There is no clinical evidence that targeting the blood glucose to a particular level will improve outcome; however, it is reasonable to follow the current American Diabetes Association recommendation to maintain blood glucose levels between 140 and 180 mg/dL in all hospitalized patients.

Temperature

One-third of all patients admitted with acute stroke are hyperthermic (temperature, >37.6°C) within the first few hours of stroke onset. Hyperthermia in the setting of stroke may be linked to increased metabolic demands, increased amounts of free radicals, or enhanced release of neurotransmitters. As poststroke hyperthermia is associated with a poorer outcome, its source should be investigated. In some instances, the cause of the stroke may be the cause of the hyperthermia (i.e., infective endocarditis), or it may be a complication secondary to the cerebral infarction (i.e., sepsis or pneumonia).

In the Paracetamol (Acetaminophen) in Stroke (PAIS) trial, a large, randomized, placebo-controlled study, investigators evaluated whether early treatment with acetaminophen improved functional outcome and found no statistical difference between the groups. This led to the PAIS 2 trial, which aimed to assess the effect of high-dose acetaminophen on functional outcome in patients with acute stroke and a body temperature of 36.5°C or above. The results showed that acetaminophen did not have any effect on functional outcome; however, this study is limited by its small sample size.

Induced hypothermia has shown promise as a neuroprotective therapy, although it may be associated with significant side effects that include hypotension, cardiac arrhythmias, and pneumonia. A systematic review in 2009 revealed no indication of clinical benefit or harm from the use of hypothermia in the management of stroke.

Nutrition and Hydration

Dehydration after ischemic stroke is common and may predispose to poorer cerebral perfusion, renal impairment, and increased likelihood of developing thrombosis. Hypervolemia, on the other hand, can also be detrimental by exacerbating cerebral edema and increasing myocardial stress. Euvolemia is therefore most desirable overall.

Intravenous fluid maintenance should be initiated for patients presenting in a euvolemic state. For dehydrated patients, rapid replacement of depleted intravascular volume followed by fluid maintenance is a reasonable course of action. Isotonic solutions (i.e., 0.9% saline) are more suitable for this patient population than are hypotonic solutions, which may exacerbate cerebral edema. Patients with certain conditions, such as syndrome of inappropriate antidiuretic hormone (SIADH) or fever, require modifications to the standard hydration protocol.

Before oral administration of fluids or food is instituted, swallowing function must be assessed to prevent aspiration pneumonia. Physicians also must be cautious when replacing fluids in patients who are vulnerable to fluid overload, particularly in patients with impaired renal clearance or heart failure. In some cases, a nasogastric tube (NGT) or nasoduodenal tube (NDT) may be inserted to provide feedings and to facilitate administration of medications. For patients who may require prolonged tube feedings, placement of a percutaneous endoscopic gastrostomy (PEG) may be necessary. Compared with NGT feeding, PEG has shown reduced treatment failure, reduced gastrointestinal bleeding, and a higher feed delivery and albumin concentration.

Cardiac Monitoring

Cardiac monitoring, which typically begins in the prehospital setting, must continue throughout the initial management period for at least the initial 24 hours after the patient’s presentation. The patient should be monitored for cardiac ischemia or changes on electrocardiogram (ECG), especially in cases of right middle cerebral artery (MCA) strokes affecting the insular cortex. Holter monitoring may be more effective in identifying atrial fibrillation or other serious arrhythmias. Echocardiography is indicated in patients with suspected cardioembolic stroke. The efficacy of prophylactic administration of medications to prevent cardiac arrhythmias is unknown.

Antiplatelet Therapy

Administration of aspirin within 48 hours after stroke appears to significantly decrease the rate of mortality and other unfavorable outcomes. ^, This conclusion is based primarily on the findings that aspirin reduced the incidence of early recurrent stroke. Therefore oral aspirin should be administered within 24 to 48 hours after the onset of symptoms. The CHANCE (Clopidogrel in High-Risk Patients with Acute Nondisabling Cerebrovascular Events) trial studied the efficacy of short-term dual antiplatelet therapy (aspirin and clopidogrel) in patients with minor stroke and reported a decreased incidence of recurrent stroke in the first 90 days after symptom onset. Based on these results, the 2018 American Heart Association/American Stroke Association (AHA/ASA) guidelines recommend administration of aspirin and clopidogrel for the first 21 days after a minor ischemic stroke.

Anticoagulants

Anticoagulation with intravenous heparin is a common practice after ischemic stroke, but no studies have shown any clinical benefit. In current guidelines, the AHA/ASA does not recommend the use of heparin within the first 24 hours, especially in cases of moderate to severe stroke because of the risk for hemorrhagic conversion ( eTable 35.1 ). The usefulness of direct thrombin inhibitors (such as argatroban and dabigratan) or factor Xa inhibitors are also not well established. In patients who receive tPA, heparin administration is contraindicated for the first 24 hours after tPA treatment.

Infection

Infection is a common complication in the acute period following ischemic stroke and affects approximately 30% of all patients. Urinary tract infection and pneumonia are two of the most common infections in this population. The influence of infection on outcomes in patients with stroke is debated, with some studies showing infections associated with poor functional outcome and mortality and other studies showing no effect. Prophylactic antibiotics for patients with stroke have not shown any benefit and are not recommended. Additionally, AHA/ASA guidelines recommend against routine placement of indwelling bladder catheters because of the associated risk for catheter-associated urinary tract infections.

Treatment of Acute Neurological Complications

Deterioration after initial stroke assessment occurs in up to 25% of patients. Cerebral edema, hemorrhagic transformation (HT), and recurrent ischemia are among the possible causes. The risk for sudden deterioration underscores the importance of close monitoring in a dedicated stroke center. ^,

Cerebral Edema

The manifestation of cerebral edema following acute stroke is variable. Many affected patients remain clinically stable, whereas others have precipitous neurological deterioration. Cytotoxic edema typically appears 3 to 4 days after stroke onset, but early reperfusion of a large infarct may lead to severe edema within the first 24 hours. Medical management to minimize the development of edema includes restriction of free water, avoidance of excess glucose administration, and minimizing hypoxemia or hypercarbia. Severe cerebral edema increases the risk for elevated intracranial pressure (ICP; eTable 35.2 ). If this occurs, standard

eTABLE 35.1

American Heart Association/American Stroke Association Class I Recommendation for the Management of Acute Ischemic Stroke

Data from Baird TA, Parsons MW, Phan T, et al. Persistent poststroke hyperglycemia is independently associated with infarct expansion and worse clinical outcome. Stroke. 2003;34(9):2208–2214.

Category	Recommendations	Class/Level of Evidence
Blood pressure	In patients who have elevated blood pressure and are otherwise eligible for treatment with intravenous rtPA, systolic blood pressure should be carefully lowered to <185 mm Hg, and diastolic blood pressure to <110 mm Hg before fibrinolytic therapy is initiated.	Class I, Level B
Blood pressure	In patients with markedly elevated blood pressure who do not receive fibrinolysis, a reasonable goal is to lower blood pressure by 15% during the first 24 hours after onset of stroke.	Class I, Level C
Temperature control	Sources of hyperthermia (temperature >38°C) should be identified and treated, and antipyretic medications should be administered to lower temperature in hyperthermic patients.	Class I, Level C
Nutrition and hydration	Hypovolemia should be corrected with intravenous normal saline, and cardiac arrhythmias that may be reducing cardiac output should be corrected.	Class I, Level C
	Swallowing function should be assessed before the patient begins eating, drinking, or receiving oral medications.	Class I, Level B
	Patients who cannot take solid food and liquids orally should receive NG, ND, or PEG tube feedings to maintain hydration and nutrition while undergoing efforts to restore swallowing function.	Class I, Level B
Cardiac monitoring	Cardiac monitoring should be performed for at least the first 24 hours out to screen for atrial fibrillation and other potentially serious cardiac arrhythmias.	Class I, Level B
Antiplatelet therapy	For the treatment of most patients, aspirin should be administered orally (initial dose, 325 mg) within 24 to 48 hours after stroke onset.	Class I, Level A

ND, Nasoduodenal; NG, nasogastric; PEG, percutaneous endoscopic gastrostomy; rtPA, recombinant tissue plasminogen activator.

eTABLE 35.2

American Heart Association/American Stroke Association Class I Recommendations for the Management of Complications Arising from Acute Ischemic Stroke

Data from Baird TA, Parsons MW, Phan T, et al. Persistent poststroke hyperglycemia is independently associated with infarct expansion and worse clinical outcome. Stroke. 2003;34(9):2208-2214.

Category	Recommendations	Class/Level of Evidence
Surgical decompression	Decompressive surgical evacuation of a space-occupying cerebellar infarct is effective in preventing and treating herniation and brainstem compression.	Class I, Level C
Surgical decompression	Decompressive surgery for malignant edema of the cerebral hemisphere is effective and potentially lifesaving.	Class I, Level B
Ventricular drain	Placement of a ventricular drain is useful in patients with acute hydrocephalus secondary to ischemic stroke.	Class I, Level C
Seizures	Recurrent seizures after stroke should be treated in a manner similar to that of other acute neurological conditions, and antiepileptic agents should be selected according to specific patient characteristics.	Class I, Level B

techniques used to manage elevated ICP, including osmotic diuresis, ventriculostomy, and hyperventilation, are recommended.

Neurosurgical decompression for some patients with supratentorial infarcts should be considered. A pooled analysis of the results of three trials of the efficacy of early decompression in malignant MCA stroke (undertaken within 48 hours after presentation) showed a reduction in mortality rate from 78% to 29% and significantly increased favorable outcomes for patients who underwent surgery. A more recent meta-analysis included seven trials of decompressive hemicraniectomy in patients with large MCA stroke (surgery within 96 hours of symptom onset) and similarly showed a large reduction in mortality; however most patients who otherwise would have died are left with significant disability. In one of the largest trials (DEcompressive Surgery for the Treatment of malignant INfarction of the middle cerebral arterY [DESTINY] II), 112 patients 61 years of age or older with malignant MCA infarction were randomly assigned to undergo either conservative treatment or hemicraniectomy within the first 48 hours after the onset of symptoms. The results indicated significantly increased survival rates without severe disability among patients who underwent surgical decompression. Emergency decompression may be advised for patients with severe supratenorial stroke and acutely worsening edema, but the likelihood of survival with severe disability must be discussed with the patient’s family beforehand.

In cases of large cerebellar infarction, edema can cause brainstem compression or hydrocephalus. Emergency posterior fossa decompression with partial removal of the infarcted tissue is often lifesaving, and the clinical outcome is a reasonable quality of life. ^,

Hemorrhagic Transformation

HT occurs in approximately 5% to 6% of patients after the use of intravenous recombinant tPA. Hemorrhage caused by tPA usually occurs in the first 24 hours, and fatal hemorrhage most often occurs in the first 12 hours. If a patient shows signs of ICH, any tPA remaining in the prescription should be withheld. An emergency CT scan without contrast material should be performed, as should a type and screen. A complete blood cell count, coagulation parameters (prothrombin time, partial thromboplastin time, international normalized ratio [INR]), and fibrinogen levels should be measured. Although there are no standardized recommendations for the management of fibrinolytic-associated hemorrhage, most protocols recommend the use of cryoprecipitate to restore the depleted fibrinogen levels. Surgical evacuation may be considered, depending on the site and size of the hematoma and the patient’s overall condition. Evacuation of a large hemorrhage may be lifesaving in some instances. The rate of HT after endovascular thrombectomy has been noted to be much higher (29% to 32.3%). ^, Some of the predictors for an increased risk for HT after thrombectomy include the presence of diabetes mellitus, atrial fibrillation, pre-procedure intravenous tPA, longer time to puncture, and larger stroke volumes on presentation (i.e., higher National Institutes of Health Stroke Scale [NIHSS] score on admission). ^,

Seizures

Seizures occur in approximately 10% of patients with ischemic stroke. ^, The incidence of seizures is higher among older adult patients, patients with preexisting dementia, and patients with HT. The reported rates for delayed or recurrent seizures vary greatly. ^, Data on the efficacy of anticonvulsants in the treatment of seizures in stroke patients are scarce, and current recommendations are based on the established management guidelines for seizures that may complicate any neurological illness. No studies to date have shown benefit of prophylactic anticonvulsant use after stroke.

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