Cerebrovascular Accident in Sickle Cell Disease

• Cerebrovascular accidents (CVA) are neurological complications of Sickle Cell Disease (SCD).
• There are two major classifications of CVA:
  • Overt stroke: Focal neurologic deficit lasting for >24 hours and/or abnormal imaging. They are due to large vasculopathy.
  • Silent stroke: No focal neurologic deficit for >24 hours, usually diagnosed using T2-weighted MRI. Typically affects the penetrating arteries.

Pathophysiology of VOC

• Red cell adhesion
• Leucocyte adhesion
• Inflammation
• Endothelial injury
• Activated coagulation pathway
• Obstruction of small vessels by sickle cells

Pathophysiologic Mechanisms in CVA

• Repeated epithelial damage by adherent sickle cells
• Vasoconstriction
• Nitric oxide deficiency

• Prior Transient Ischemic Attack
• Low steady state hemoglobin
• Elevated blood pressure
• Recent history of acute chest syndrome

• Severe headache
• Poor concentration/school performance
• Changes in gait
• Aphasia
• Hemiplegia
• Convulsions
• Loss of consciousness

• History taking
• Physical Examination
• Investigations
• Treatment
• Prevention

Treatment

• It is an emergency
• ABC of resuscitation
• Oxygen to maintain SPO2 >96%
• Simple blood transfusion within 1 hour of presentation to raise Hb to 10g/dl. This increases the oxygen-carrying capacity of the blood. Transfusing beyond 30% PCV may lead to hyperviscosity.
• Prompt exchange blood transfusion with HbAA blood to reduce the sickled cells to an ideal value of <30% or at least 50%
• Supportive care
  • IVF
  • Caloric support
  • Antibiotics/antimalarial if indicated

Investigations

• Specific
  • Brain imaging (Magnetic resonance imaging)
  • Packed cell volume
• Others
  • Full blood count
  • Lumbar puncture for CSF analysis
  • E/U/Cr
  • CT +/- Angiography/venography

Prevention

Transcranial Doppler Ultrasound

• Used as a preventive measure; it measures the velocity of the blood in the terminal portion of the internal carotid and the proximal portion of the middle cerebral artery.
• Measured in Time-Averaged Mean Maximum (TAMM) blood flow velocity.
• Increased risk of CVA if TAMM >200 cm/sec
• Conditional threshold <200 cm/sec but >180 cm/sec
• Normal <180 cm/sec

Prevention of a Repeat Stroke

• Regular blood transfusion may be needed to keep the Hb level around 10 g/dl in children at risk of CVA (TAMM >200 cm/sec)
• Despite regular blood transfusion, 20% will develop a repeat stroke, 30% of which will develop a third stroke
• Hydroxyurea

Rehabilitation

• Physiotherapy
• Nutritional rehabilitation
• Ophthalmic and auditory stimulation
• Use of anticonvulsants