Detection of increased intracranial pressure by ultrasound

Increases in intracranial pressure (ICP) may damage the brain by compression of its structures or restriction of its blood flow, and medical providers my encounter elevated ICP in conventional and non-conventional medical settings. Early identification of elevated ICP is critical to ensuring timely and appropriate management. However, few diagnostic methods are available for detecting increased ICP in an acutely ill patient, which can be performed quickly and noninvasively at the bedside. The optic nerve sheath is a continuation of the dura mater of the central nervous system and can be viewed by ocular ultrasound. Pressure changes within the intracranial cavity affect the diameter of the optic nerve sheath. Data acquired from multiple clinical settings suggest that millimetric increases in the optic nerve sheath diameter detected via ocular ultrasound correlate with increasing levels of ICP. In this review, we discuss the use of ocular ultrasound to evaluate for the presence of elevated ICP via assessment of optic nerve sheath diameter, and describe critical aspects of this valuable diagnostic procedure. Ultrasound is increasingly becoming a medical fixture in the modern battlefield where other diagnostic modalities can be unavailable or impractical to employ. As Special Forces and other austere medical providers become increasingly familiar with ultrasound, ocular ultrasound for the assessment of increased intracranial pressure may help optimize their ability to provide the most effective medical management for their patients.