Hematologic and Related Diseases
Erythrocyte Disorders
Sickle-Cell Disease
Neurologic disorders with hemoglobin (Hb)-SS, Hb-SC genotypes, or sickle-β-thalassemia syndromes.
Stroke
7% to 15% of homozygous children (250 to 400 times higher risk for stroke than in general population). Cumulative risk
of stroke by age 45 about 24% for SS patients, 10% for SC patients. Transcranial Doppler ultrasonography identifies children at risk for stroke.
of stroke by age 45 about 24% for SS patients, 10% for SC patients. Transcranial Doppler ultrasonography identifies children at risk for stroke.
Approximately 60% ischemic, 40% hemorrhagic. Thrombosis of large and small arteries; less common, dural sinus thrombosis. Often watershed distribution. Subarachnoid hemorrhage more common in children; intraparenchymal in adults.
Risk factors include: prior TIA, low hemoglobin content, frequent acute chest syndrome episodes or one within last two weeks, high systolic blood pressure, family history. Recurrent strokes more frequently in younger patients.
Incidence of stroke recurrence lower if patients given transfusions regularly: 10% vs. 46% to 90% within 3 years of first stroke. Goal of transfusion: Hb-S concentration <30% of total Hb. Repeated thrombosis in ∼65% untreated children.
Cerebrovascular complications less common in sickle Hb-C disease. Risk in sickle cell trait same as in general population.
Other Manifestations
Seizures: 6% to 12% from stroke, meningitis, dehydration, medications (e.g., meperidine).
Headache (28%); myelopathy; acute mononeuropathy; meningitis.
Thalassemia
Transient dizziness, blurred vision (20%); headache (13%); seizures (13%); peripheral neuropathy (mainly motor; 20%); stroke; spinal cord, cauda equina, optic nerve compression (extramedullary hematopoiesis).
Polycythemia
Risk of cerebral infarction increased by hyperviscosity (accelerated atherosclerosis, thrombosis); reduced by aspirin. Peripheral neuropathy (mainly sensory axonal) in 50%.
Headache, dizziness, tinnitus, visual disturbances, cognitive impairment also seen. Improve with lowering red blood cell count by phlebotomy, chemotherapy.
Platelet Disorders
Essential Thrombocytosis (Thrombocythemia)
Headache, paresthesias, TIAs, cerebral infarction, seizures. Bleeding complications seen paradoxically at very high platelet counts (>1,500,000/μL).
Treatment: lower platelet count. (hydroxyurea, platelet pheresis).
Thrombotic Thrombocytopenic Purpura
Neurologic symptoms in 70%: hemiparesis (25%), encephalopathy (50%). Symptoms transient, fluctuating, usually <48 hours. MRI may show reversible posterior leukoencephalopathy.
Treatment: plasma exchange with fresh frozen plasma infusion.
Heparin-Induced Thrombocytopenia (HIT)
Incidence 2.5%. Thrombocytosis associated with 2% of HIT cases; thrombosis may precede thrombocytopenia.
Consider HIT in heparin-treated patients with cerebral ischemia, cerebral venous thrombosis, transient confusion, whether platelet count decreased.
Blood Cell Dyscrasias
Leukemia
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