CEREBROVASCULAR STROKES

Cerebrovascular stroke is an important cause of acute neurological injury in children with considerable risk of long-term morbidity and sometimes, mortality. Most of these cases present with acute or sub-acute onset of motor deficit, e.g.

According to the pathogenesis, strokes may be broadly divided into three groups—(a) Arterial ischemic strokes, (b) Cerebral sinovenous Thrombosis, and (c) Hemorrhagic strokes (Table 18.21).

Arterial ischemic strokes (AIS) are caused by thrombo­embolic events involving internal carotid, vertebrobas­ilar or any other major artery forming circle of Willis (Fig. 18.2). Middle cerebral artery is most commonly affected due to being in direct anatomical continuation of internal carotid artery.

Etiologically, Vascular malformations, intracranial infections, severe dehydration and systemic diseases

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Fig. 18.2: Circle of Willis.

predisposing thromboembolic complications are pre­dominantly identified causes of AIS in young children, though ~50% cases are idiopathic in origin (Table 18.21).

Transient, focal and non-progressive childhood pri­mary angiitis of the central nervous system (cPACNS) is an important emerging cause of AIS in healthy school children, discussed later. Diffuse and progressive vasculitis is rare and can represent progressive cPACNS or secondary vasculitis in intracranial infections or collagen disorders.

Cardioembolic stroke account for ~25% of AIS in children, often associated with cyanotic heart diseases, infective endocarditis or invasive cardiac procedures/ surgery.

Moyamoya disease is an idiopathic, chronic cerebro- vasculopathy, characterized by progressive stenosis of the distal internal carotid artery and its main branches along with development of compensatory collateral vessels at the base of the brain giving a puff of smoke appearance on angiography.

Prothrombotic or hypercoagulable states may be inherited, e.g. protein C or S deficiency, factor V leiden thrombo­philia or acquired, e.g. in severe dehydration, nephrotic syndrome or DIC.

Large vessels, e.g. internal carotids or vertebral arteries are usually involved in traumatic or infective lesions of neck, spine and head. Medium-sized vessels are predominantly involved in embolic episodes from extracranial sources, e.g. sickle cell disease, infective endocarditis, etc. Thrombosis of small and distal vessels is usually caused by end-arteritis obliterans in meningitis, sickle cell anemia and collagen disorders.

Clinically, AIS usually present with acute catastrophic onset of motor deficit, specially hemiplegia with or

TABLE 18.21: Causes of cerebrovascular strokes

Arterial Ischemic Strokes (Thrombo-embolic)

• Idiopathic: Childhood primary angiitis of CNS

• AV malformations: Moyamoya disease, Sturge-Weber syndrome

• Infections:

- Intracranial: Meningitis, encephalitis, brain abscess

- Extracranial: Sepsis, head and neck infections

• Hypovolemia: Severe dehydration, diabetic ketoacidosis

• Hematologic: Sickle cell disease, polycythemia, prothrom- botic states

• Cardiac: Cyanotic heart disease, arrhythmia, infective endocarditis

• Vasculitis: Aortoarteritis, collagen disorders

• Metabolic: Homocysteinuria, mitochondrial encephalopathies

• Traumatic: Cerebral arterial dissection, crush injuries (fat embolism)

• Neoplasms: Leukemia, brain tumors

• Others: Migraine, Abromuscular dysplasia

Cerebral Sinovenous Thrombosis

• Hypercoagulable states:

- Inherited: Factor V Leiden, protein C or S deficiency

- Acquired: Dehydration, DIC, nephrotic syndrome

• Infections:

- Intracranial: Meningitis, brain abscess

- Extracranial: Sepsis, sinusitis, mastoiditis

• Traumatic: Head injury, neurosurgery, jugular lines

• Developmental Venous malformations

• Systemic: Leukemia, SLE, homocystinuria

Hemorrhagic States

• Trauma: Head and neck injuries

• AV malformation: Moyamoya disease, aneurysms

• Hemorrhagic disorders: Hemophilia, DIC, anticoagulant therapy

• Others: Hypertension, brain tumors

without sensorium, speech and vision involvement.

Diagnosis: Neuroimaging is an urgency in AIS. While CT scan may demonstrate mature AIS and exclude hemorrhage, MRI is preferable to identify early and small infarcts. MR angiography is required to assess the site and extent of vascular occlusion as well as feasibility for vascular interventions.

All cases also need thorough cardiac, prothrombotic and infection work-up to identify the etiology and risk of recurrence.

Management involves early anti-thrombotic therapy to prevent re-infarction with anticoagulants, e.g. unfractionated or low-molecular weight heparin (SC 0.5-1 mg/kg q12hr to target INR of 2-3) followed by low-dose anti-platelet agents, e.g. aspirin, for 4-6 months. Duration of therapy depends on the risk of recurrence. Emergency thrombolysis with tissue plasminogen activator (tPA), widely used in adults, is generally not recommended for children.

Supportive measures to prevent progressive ischemic brain injury include management of seizures, ventilation and cerebral perfusion along with maintenance of normothermia, normotension, normovolemia, and normoglycemia. Cerebral edema may be life-threatening and need emergency surgical decompression.

Disease-specific treatments include blood transfusion in sickle cell disease, immunosuppression in vasculitis and revascularization surgery in moyamoya disease. Appropriate physiotherapy and occupational therapy is necessary for residual deficits. Secondary prevention may need long-term anti-platelet therapy or anticoagulation, depending on the cause.

Outcome includes risk of immediate mortality in 6-10%, recurrent strokes in 10-50% and neurological sequelae in 60-70%.

Cerebral sinovenous thrombosis (CSVT) is more common in children than in adults. Normal cerebral venous drainage involves superficial (cortical veins, superior sagittal sinus) and deep (internal cerebral veins, straight sinus) systems that converge at the torcula to exit via the paired transverse and sigmoid sinuses and jugular veins.

Etiologically, CSVT is usually caused by severe dehydration, prothrombotic states and infections (Table 18.20). Sagittal sinus thrombosis is usually a complication of bacterial meningitis while Cavernous sinus thrombosis generally follows intracranial extension of paranasal or retroorbital infections. Lateral sinus thrombosis may develop as a complication of mastoiditis.

Clinically, onset of CSVT is relatively more insidious than AIS with raised intracranial pressure as predominant presentation. Most cases present with progressive headache, vomiting, diplopia and papilledema. Seizures and focal neurological deficits are less common. Proptosis is common in cavernous sinus thrombosis.

Diagnosis requires CT or MR venography to demon­strate filling defects in the cerebral venous system, though contrast CT or MRI may be informative.

Management revolves around anticoagulant therapy with unfractionated or low-molecular weight heparin followed by oral anticoagulants, e.g. Warfarin for 3-6 months, till reimaging confirms recanalization. Children with persistent risk factors may require long-term anti­coagulant prophylaxis.

Supportive measures include management of infec­tion, seizures and raised intracranial pressure along with maintenance of normothermia, normotension, normovolemia, and normoglycemia. Appropriate physiotherapy and occupational therapy is necessary for residual deficits. Optic neuropathy secondary to increased intracranial pressure is common and regular fundoscopy is required to detect and prevent visual loss. Hemorrhagic strokes (HS) are relatively uncommon in children than in adults, usually seen in cases with

intracranial arteriovenous malformations, accidental or non-accidental (battered baby) head injuries and bleeding disorders. Bleeding may occur within (intraparenchymal, intraventricular) or outside (subarachnoid, subdural, epidural) the brain.

Clinical presentation varies with size and location of bleeding. Unlike AIS, HS usually evolve slowly with progressive headache, altered sensorium and nuchal rigidity, followed by seizures and focal neurologic deficits. However, some HS can be rapidly fatal. In bleeds due to vascular malformations, pulsatile tinnitus, cranial bruit and high-output heart failure may be present.

Diagnosis rests on neuroimaging. While CT is highly sensitive for acute HS, MRI may be more useful to detect small and chronic bleeds. Conventional or CT/MRI angiography is required to exclude vascular anomalies. Lumbar puncture helps to exclude subarachnoid hemorrhage.

Management involves emergency neurosurgical decom­pression for large or rapidly expanding hematoma along with supportive measures as discussed earlier for ischemic infarcts. Reversal of anticoagulant therapy (e.g. vitamin K, fresh-frozen plasma) may be required. Definitive management of vascular malformation may require surgical or endovascular interventions.

Outcome depends on size, location, and etiology of bleeding. Immediate mortality is higher in HS than in AIS or CSVT. Recurrence risk is high in cases with untreated vascular malformations (Table 18.21).

Childhood Primary Angiitis of Central Nervous Systems (cPACNS)

cPACNS, also termed as Focal cerebral arteriopathy, is an idiopathic cerebrovasculopathy characterized by-(a) newly acquired neurologic deficits and/or psychiatric symptoms, plus (b) angiographic or histologic evidence of vasculitis with luminal stenosis, and (c) in absence of a systemic, identifiable cause.

cPACNS may involve large/medium vessels or small vessels. While large/medium vessel disease may be progressive or non-progressive, small vessel disease is usually progressive and easily missed on angiography. Clinically, most cases present with unexplained AIS or refractory status epilepticus, though presentation is extremely wide. Cognitive dysfunction, behavior changes and loss of social/emotional is common.

Diagnosis is confirmed on neuroimaging, i.e. inflam­matory or ischemic parenchymal lesions on MRI and evidence of vessel stenosis on angiography. Brain biopsy is required only in small vessel disease where angiography may be normal.

Treatment involves antithrombotic therapy with low- molecular-weight heparin or long-term anti-platelet agents, e.g. aspirin for 12 months. Re-imaging is advised after 3 months to monitor progression of disease. However, anti-platelet agent should continue for 18-24 months to prevent recurrent ischemic events. Role of steroids is controversial in non-progressive cases. However, some studies have shown reduced recurrence risk when steroids are used in combination with aspirin.

Long-term steroids or second-line immunosuppressive agents, e.g. cyclophosphamide or mycophenolate may be required in cases of progressive or small/medium vessel cPACNS. Outcome is relatively better in large vessel disease than in those with small vessel disease. Children presenting with status epilepticus and Small vessel disease have the poorest outcome.

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