Cranial Doppler

Abstract

The bedside use of ultrasound for both neuromonitoring, and as an aid to diagnosis on the intensive care has not had the same surge in popularity as other modes of ultrasound. Reasons for this include an absence of familiarity, lack of equipment or a perception of difficulty in comparison to more standard measures of intracranial pressure (ICP) and pathology. However, neuro-ultrasound is much less invasive than standard ICP monitors, cost-effective and portable. The assessment of optic nerve sheath diameter with ultrasound compares favourably with other modes of ICP measurement. Ultrasonic assessment of pupillary reflexes provides a valuable alternative to direct clinical examination. Transcranial Doppler has many potential applications on the intensive care unit—as an assessment of intracranial pressure, of vasospasm post subarachnoid haemorrhage or as an ancillary test in diagnosing cerebral circulatory death or brainstem death. Supporting evidence and the basic techniques in practical ultrasound of the optic nerve, pupil and transcranial Doppler are described.