Transcranial Doppler Using Standard Duplex Equipment in Children

Abstract

Transfontanelle duplex Doppler ultrasound is widely used in the neonatal period to evaluate abnormalities of cerebral flow in infants with asphyxia, cerebral edema, patent ductus arteriosus, hydrocephalus, and arteriovenous malformations. Three other portals for evaluation of cerebral flow in older children after the fontanelle has closed are also available: (a) transophthalmic imaging of the ophthalmic artery and internal carotid; (b) transtemporal imaging of the anterior, middle, posterior, and basilar circulation; and (c) use of the foramen magnum as a window to view the posterior, basilar, and vertebral circulation. The technique, safety, efficacy, and equipment available for both the transfontanelle and the transcranial approaches are discussed. Transcranial Doppler in three specific groups of children is proving useful: (a) measuring the resistive index in patients with shunts and following the patient for possible shunt malfunction by detecting a decrease in the diastolic flow and an increase in the resistive index as intracranial pressure increases; (b) evaluating abnormal flow in patients with cerebral vascular disease in sickle cell anemia; and (c) determinating cerebral edema and brain death in patients post-trauma or significant cerebral insult by detecting a reversal of diastolic flow.