6.4 Endovascular Therapy (EVT) & Post-Acute Care

Endovascular Therapy (EVT) & Post-Acute Care

Endovascular Therapy (Mechanical Thrombectomy)

While intravenous fibrinolytic therapy is a highly effective treatment for dissolving smaller thrombi and restoring cerebral perfusion, it frequently proves inadequate for reopening major cerebral arteries that are blocked by massive, robust clots. For these devastating strokes, Endovascular Therapy (EVT)—specifically mechanical thrombectomy—has revolutionized the landscape of acute neurology. During a mechanical thrombectomy, an experienced neurointerventionalist navigates a highly specialized microcatheter through the arterial system (typically starting at the femoral or radial artery) directly into the affected cerebral vasculature. Once positioned at the site of the blockage, the physician deploys a stent retriever (which physically ensnares the clot) or a large-bore aspiration catheter (which vacuums the clot out) to physically extract the offending thrombus and instantly restore blood flow.

Indications for Mechanical Thrombectomy

Mechanical thrombectomy is not indicated for all strokes. It is primarily indicated for patients suffering from a specific, severe type of stroke known as a Large Vessel Occlusion (LVO) in the anterior circulation. The most common anatomical sites for an anterior LVO are the terminal internal carotid artery (ICA) or the proximal portion (M1 segment) of the middle cerebral artery (MCA). These occlusions cause massive strokes that affect large territories of the brain, leading to profound neurological deficits and historically poor outcomes.

The Expanded 24-Hour Treatment Window

Historically, the time window for attempting mechanical thrombectomy was rigidly restricted to 6 hours from symptom onset. However, the publication of several landmark clinical trials—most notably the DAWN and DEFUSE 3 trials—radically altered the paradigm of stroke care. These studies definitively demonstrated that carefully selected patients can experience massive clinical benefits from EVT up to 24 hours from their Last Known Well time.

Selection for this extended 6 to 24-hour window abandons a strict reliance on the clock in favor of advanced, physiological neuroimaging. Patients must undergo CT Perfusion (CTP) scans or MRI diffusion-perfusion imaging. These modalities are used to visually and quantitatively identify the "mismatch" between the core infarct (tissue that is already irreversibly dead) and the ischemic penumbra (tissue that is severely hypoperfused and malfunctioning, but still viable and salvageable). If the imaging reveals a small core but a large, threatened penumbra, the patient is an excellent candidate for EVT regardless of the elapsed time, up to 24 hours.

The Bridging Approach

It is critically important to understand that eligibility for EVT does not preclude the use of IV fibrinolytics. If an LVO patient presents early and falls within the standard 4.5-hour window for IV fibrinolytics, they should immediately receive the IV "clot-buster." The clinical team must then proceed directly to the neurointerventional suite for mechanical thrombectomy without waiting to see if the IV medication is successful. This strategy, known as the "bridging" approach, ensures the patient receives maximal, rapid medical therapy while the procedural suite is being prepared.

Post-Acute Care in a Specialized Stroke Unit

The acute intervention phase—whether utilizing IV fibrinolytics, mechanical thrombectomy, or both—is only the initial salvo in the continuum of stroke care. Following these interventions, patients must be admitted directly to a dedicated Stroke Unit or a neuro-intensive care unit (ICU). Care in these specialized environments, managed by multidisciplinary teams, is independently associated with decreased mortality and improved long-term functional independence.

Rigorous Neurologic Monitoring

Patients in the immediate post-acute phase require frequent, standardized neurologic assessments, primarily using the NIH Stroke Scale. The primary goal of this intensive monitoring is to detect the earliest clinical signs of severe complications, such as hemorrhagic transformation, malignant cerebral edema (brain swelling that can cause herniation), or recurrent ischemic strokes. Any sudden, unexplained decline in the patient's neurologic status mandates an immediate repeat non-contrast head CT to rule out these devastating complications.

Aspiration Precautions and Dysphagia

Dysphagia, or profound difficulty swallowing, is an extremely common consequence of acute stroke, affecting a significant percentage of patients. It poses a massive risk for aspiration, leading to aspiration pneumonia, which remains a leading cause of morbidity and mortality in stroke survivors. To mitigate this risk, all acute stroke patients must be placed on strict NPO (nothing by mouth) status immediately upon arrival. They must not receive oral medications, food, or even water until they undergo a formalized, evidence-based dysphagia screening, typically administered by a speech-language pathologist or specially trained nurse. If the patient fails the screen, nutrition and medications must be provided via alternative routes, such as a nasogastric feeding tube.

Temperature and Glycemic Control

Maintaining physiological homeostasis is crucial for protecting the vulnerable ischemic penumbra. Both fever and hyperglycemia are highly detrimental to the injured brain, accelerating metabolic demands, increasing oxidative stress, and significantly worsening the expansion of the infarct.

• Hyperthermia Management: Fever in a stroke patient is an emergency. The clinical team must aggressively seek and treat the underlying source of the fever (such as an occult urinary tract infection or early pneumonia). Antipyretic medications (like acetaminophen) should be administered aggressively to maintain strict normothermia.
• Glycemic Control: Blood glucose levels must be meticulously managed. The standard, evidence-based target range for acute stroke patients is 140 to 180 mg/dL. Hypoglycemia (<60 mg/dL) must be strictly and aggressively avoided, as it starves the brain of its primary fuel. Conversely, severe hyperglycemia should be treated using standardized insulin protocols to prevent the exacerbation of cellular cerebral injury.

Early Mobilization and Multidisciplinary Rehabilitation

Once the patient is hemodynamically stable and the hyper-acute risks have subsided, early mobilization out of bed is strongly encouraged to prevent deep vein thrombosis (DVT) and deconditioning. A comprehensive, multidisciplinary approach involving physical therapy, occupational therapy, and speech-language pathology must be initiated as early as safely possible to maximize the patient's long-term functional recovery and reintegration into daily life.