Esr

Elevated

Low

a-HBD

Normal

Elevated

Chest radiograph

Upper lobe infiltrate

Normal

VQ scan

Normal

Positive

Cultures

Positive blood and sputum or cold

Negative

agglutinins and Mycoplasma titers agglutinins and Mycoplasma titers

4. Hyperhemolytic crisis:

a. Very unusual; may ensue in association with certain drugs or acute infections; G6PD deficiency is a possible contributing cause b. Patient begins to feel weak, looks paler, and shows more scleral icterus; may have abdominal pain c. Hematocrit falls to 15% or less in a few days; reticulocyte count rises; after several days, excessive hemolysis gradually subsides.

Organ dysfunction

Central nervous system

Acute infarction of the brain can result in a stroke, which occurs in approximately 7% of children with SCD. The incidence is 0.7% per year during the first 20 years of life, with the highest rates in children 5-10 years of age. An additional 20% of patients with sickle cell disease have evidence of asymptomatic cerebral infarction on MRI of the brain. These individuals may have significant neuropsychological deficit. The most common underlying lesion is intracranial arterial stenosis or obstruction, usually in the internal carotid, often in the proximal middle cerebral or anterior cerebral arteries. Chronic injury to the endothelium of vessels by sickled red blood cells (SRBCs) results in changes in the intima with proliferation of fibro-blasts and smooth muscle; the lumen is narrowed or completely obliterated, which progresses to moyamoya. Acute sickling may result in acute cerebral infarction, manifesting as:

Motor disabilities (e.g., hemiparesis, gait dysfunction) Focal seizures Speech defects Deficit in IQ

Cortical atrophy and ventricular dilatation on computed tomography (CT).

In untreated patients, the mortality rate is approximately 20%, with about 70% of patients experiencing a recurrence within 3 years.

Patients at high risk for first stroke include those with a high white cell count and those with a low borderline hematocrit. Note that coexistent a-thalassemia may reduce the risk of a stroke.

Figure 7-6 depicts the investigations and treatment of neurologic deficit in sickle cell disease.

Diagnosis

• Head CT scan: May not be positive for infarction within the first 6 hours of the episode.

• Brain MRI: May become abnormal in 2-4 hours in about 90% of patients.

• Magnetic resonance arterial angiography (MRA): Very useful in the early evaluation of the patient with new symptoms.

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