Optic nerve sheath diameter: present and future perspectives for neurologists and critical care physicians

Abstract

Background: Estimation of intracranial pressure (ICP) may be helpful in the management of neurological critically ill patients. It has been shown that ultrasonography of the optic nerve sheath diameter (ONSD) is a reliable tool for non-invasive estimation of increased intracranial pressure (ICP) at hospital admission or in intensive care. Less is known about the estimation of increased ICP and usefulness of ONSD in the prehospital setting. The aim of this review was to elucidate both prevailing and novel applications of ONSD for neurologists and critical care physicians.

Methods: In this review, we discuss the technique and the novel approach of ONSD measurement, the clinical applications of ONSD in neurology and critical care patients.

Results: ONSD measurement is simple, easy to learn, and has diverse applications. ONSD has utility for ICP measurement in intracranial hemorrhage and ischemic stroke, meningitis and encephalitis, and idiopathic intracranial hypertension (IIH). It is also valuable for lesser known syndromes, where an increase of ICP is postulated, such as acute mountain sickness and posterior reversible encephalopathy syndrome. ONSD changes develop in inflammatory or ischemic optic neuropathies. Some papers demonstrate the usefulness of ONSD studies in symptomatic intracranial hypotension.

Conclusions: ONSD is a safe and low-cost bedside tool with the potential of screening patients who need other neuroimaging and those who may need an invasive measurement of ICP.

Keywords: Acute mountain sickness (AMS); Intracranial pressure (ICP); Optic nerve; Optic nerve sheath diameter (ONSD); Symptomatic intracranial hypotension (SIH); Transorbital ultrasonography (TSO).