Malignant Ischemic Stroke and Hemicraniectomy



Fig. 8.1
Left-sided malignant middle cerebral artery infarction evolving over 4 days (Images courtesy of Eric Jüttler)



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Fig. 8.2
Computed tomography (left, transversal) and magnetic resonance imaging (right, coronar) after decompressive hemicraniectomy for malignant middle cerebral artery infarction (Images courtesy of Eric Jüttler)




8.3 Initial Evaluation


Patients with severe ischemic stroke may well be managed in the stroke unit at first. The key point is that they must never be without monitoring in the acute phase. If they develop certain features of deterioration, they should be transferred immediately to the NICU (Table 8.1).


Table 8.1
Indications for transfer of acute ischemic stroke patients to the NICU





















Instability during thrombolysis or thrombolysis-related intracerebral hemorrhage

Post-endovascular treatment if this involved intubation and general anesthesia

Progressive decline in level of consciousness

Compromise in airway protective reflexes with risk of aspiration

Respiratory failure and need of invasive ventilation

Substantial hemodynamic instability

Signs of swelling and/or mass effect on cerebral imaging

Need of neurosurgery (e.g., decompression) or invasive interventions


8.3.1 Diagnostic Imaging


Initial imaging should not only help to make the diagnosis of acute ischemic stroke (AIS) but also indicate the potential of an ischemic stroke to grow and swell. Magnetic resonance imaging (MRI) has been proposed for prognostication of severe stroke, including malignant hemispheric stroke. Studies yielded robust results on the predictive potential of certain sizes of the diffusion-weighted (DWI, >145 cm3) and the apparent diffusion coefficient (ADC, <80%, >82 cm3) lesions [5]. However, MRI is not part of the initial stroke work-up at several institutions and has not yet gained widespread acceptance for assessment and prognostication in these patients. This is due to wide availability of computed tomography (CT). Hence, CT is still the most popular imaging modality to judge the course of severe AIS. Horizontal displacement of the pineal gland of >4 mm within 48 h [6], loss of gray and white matter differentiation within the first hours [7], and hypoattenuation in more than 50% of the territory of the middle cerebral artery (MCA) [8] have all been found predictive of an unfavorable clinical course. However, patients show marked interindividual differences in their edema dynamics. Hence, quite often serial CT imaging during the first days post stroke is necessary to assess and anticipate the course of the patients. In large MCA infarction, total or subtotal hypoattenuation of the MCA territory, hypoattenuation in adjacent vessel territories, (partial) involvement of the basal ganglia, and space-occupying effect (e.g. compressed lateral ventricle or midline shift) are radiological criteria to seriously consider decompressive surgery at our institution.


8.4 Management and Interventions


Only a few high-quality studies on general critical care specific for ischemic stroke have been performed. Valuable information is available in guidelines [9] summarized in Table 8.2.


Table 8.2
Medical management of severe ischemic stroke



































Airway and ventilation

Intubation indicated for threatening respiratory failure, decreased level of consciousness with loss of protective reflexes, impaired secretions management with risk of aspiration

Target pCO2 35–45, target pO2 > 60, target SpO2 95–98%

Hemodynamics

Continuous monitoring of EKG and BP

Monitor and treat cardiac arrhythmias

Avoid hypotension, tolerate initial transient hypertension

Bring SBP to <180 mmHg in patients receiving IVT

Utilize isotonic fluid to maintain euvolemia

Glucose

Target glucose 140–180 mg/dL

Avoid hypoglycemia at all times

Temperature

Maintain normothermia

Miscellaneous

Administer subcutaneous low-molecular-weight heparin for DVT prophylaxis or intermittent pneumatic compression

No indication for seizure prophylaxis


8.4.1 Brain Edema and Raised Intracranial Pressure


Extensive AIS leads to the generation of at first cytotoxic and later vasogenic edema, with considerable differences in extent and dynamics between individual patients [10]. On average, clinically relevant edema develops at day 2 or 3 from stroke onset. Basic measures to prevent brain edema comprise restriction of free water, avoidance of hypo-osmolar fluids, avoidance of excess glucose administration, avoidance of hypertension after reperfusion therapies, minimization of hypoxemia and hypercarbia, caution in application of drugs causing cerebral vasodilation, and aggressive treatment of hyperthermia. If clinically relevant edema occurs and is detected by clinical signs (decline in level of consciousness, worsening of neurological deficit, nausea and vomiting, anisocoria), ICP monitoring and cerebral imaging, as well as pharmacological treatment, should be applied. Additionally, patients with severe stroke whose exams are difficult to assess due to sedation should have their ICP measured by parenchymal probe or external ventricular drain (if hydrocephalus is feared or present). The most common potential cause of neurologic worsening in large AIS is edema with mass effect and midline shift. Secondary hemorrhage, seizures, and reduced venous return are additional potential causes. There do not exist specific data on optimal ICP-lowering therapy in severe stroke, so it is recommended to follow a stepwise approach common in other brain injuries (Table 8.3).


Table 8.3
Stepwise approach to lowering ICP in MMI





























Elevate head of bed to about 20°, keep neck straight to support venous return

Start or increase analgesia and sedation

Start mechanical ventilation

Apply hyperventilation, but only short term (!)

Treat seizures, fever, hyperglycemia, respiratory distress, etc. if present

Start osmotherapy

Consider barbiturates

Consider muscle relaxation

Consider surgery

 Decompressive hemicraniectomy for large hemispheric stroke

 External ventricular drain for hydrocephalus

Consider mild to moderate hypothermia

The order of steps may vary individually. Hyperventilation and barbiturate administration can be deleterious and should be only considered cautiously.


8.4.2 Malignant MCA Stroke and Decompressive Craniectomy


Occlusion of the distal ICA or proximal MCA leads to infarction of the total or subtotal MCA territory, possibly combined with infarction of the adjacent anterior cerebral artery (ACA) and/or posterior cerebral artery (PCA) territory. This type of brain infarct is called large hemispheric stroke. As mentioned above, MMI refers to a large hemispheric stroke complicated by significant brain tissue swelling, severe enough to compress critical neural structures.

Patients initially present with a severe hemisyndrome, combined with aphasia or neglect depending on the affected hemisphere, and display quite stereotypical deterioration over the first few days, such as decline in level of consciousness and anisocoria, reflecting swelling of the affected hemisphere. Despite maximal conservative critical care efforts, the mortality of MMI is between 70% and 80% due to massive swelling of the infarcted area leading to horizontal displacement of the brain stem, and intracranial pressure increases within the rigid skull (Fig. 8.1). Medical options to prevent or reduce brain edema have been disappointing so far. Classical osmotherapy is not sufficient to improve clinical outcome in MMI [1, 2, 1317].

The previously bleak perspective of these patients has changed over the last 15 years, since recent evidence has been obtained on the benefits of decompressive craniectomy (DC). This surgical measure, by which a large (>12 cm diameter) bone flap is removed over the affected hemisphere combined with duraplasty, allows for outside swelling of the affected tissue leaving the contralateral unaffected parts of the brain uncompromised (Fig. 8.2). The bone flap is stored frozen or subcutaneously and reinserted after rehabilitation and shrinking of the affected hemisphere, usually between 3 weeks and 3 months from the insult.

After first encouraging results from observational studies [16], the pooled data on 93 patients from 3 European randomized trials showed that DC within 48 h from onset for patients <60 years suffering from MMI reduces mortality by 50%, (number needed to treat (NNT) 2) and severe disability by 40% (NNT 2); on the downside, the number of those surviving with moderate to severe disability increases by 30% [17]. This evidence of survival and outcome benefits from the procedure led to international recognition of DC and to implementation into guidelines for MMI patients under 60 years of age. Recently, the DESTINYII trial on DC for MMI in 112 patients >60 years confirmed the highly significant survival benefit (33% vs. 70%, NNT 4) that was mainly responsible for an “outcome benefit” (mRS 0–4 38% vs. 18%), but showed survival after 6 months with moderate to severe disability (mRS 4) in 32% and with severe disability (mRS 5) in 28% of the surgical patients [18]. These and more randomized trials on DC for MMI have been nicely reviewed by Zha and colleagues [19]. These data provide fairly solid grounds for patient and family counseling on the option of DC, which is a very important element of care in this type of stroke (see below). Surgical treatment of MMI involves optimal and maximal neurocritical care before and after the operation.

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Jan 31, 2018 | Posted by in NEUROSURGERY | Comments Off on Malignant Ischemic Stroke and Hemicraniectomy
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