Non-invasive detection of intracranial pressure related to the optic nerve

Abstract

Intracranial pressure (ICP) is associated with a variety of diseases. Early diagnosis and the timely intervention of elevated ICP are effective means to clinically reduce the morbidity and mortality of some diseases. The detection and judgment of reduced ICP are beneficial to glaucoma doctor and neuro ophthalmologist to diagnose optic nerve disease earlier. It is important to evaluate and monitor ICP clinically. Although invasive ICP detection is the gold standard, it can have complications. Most non-invasive ICP tests are related to the optic nerve and surrounding tissues due to their anatomical characteristics. Ultrasound, magnetic resonance imaging, transcranial Doppler, papilledema on optical coherence tomography, visual evoked potential, ophthalmodynamometry, the assessment of spontaneous retinal venous pulsations, and eye-tracking have potential for application. Although none of these methods can completely replace invasive technology; however, its repeatable, low risk, high accuracy, gradually attracted people's attention. This review summarizes the non-invasive ICP detection methods related to the optic nerve and the role of the diagnosis and prognosis of neurological disorders and glaucoma. We discuss the advantages and challenges and predict possible areas of development in the future.

Keywords: Intracranial pressure (ICP); magnetic resonance imaging (MRI); optic nerve; transcranial Doppler (TCD); ultrasound.

Figure 1

Longitudinal section of a normal human optic nerve. A: dura mater; B: arachnoid mater; C: pia mater; D: central retinal artery and vein; E: subarachnoid space; F: subdural space; G: retina; H: choroid; I: sclera; J: lamina cribrosa.

Figure 2

Ocular ultrasound: 3 views [transverse (top), sagittal (middle), and inferior (bottom)]. Red-optic nerve diameter (internal diameter), yellow-ONSD (external diameter), green-3 mm distance behind globe. Note: photo is of is a research assistant within the research division of the Department of Anesthesiology who gave consent to use pictures of himself for the demonstration of various ultrasound examinations. Reprinted with permission from Raval et al. (31).

Figure 3

Methodology to measure optic nerve sheath diameter (ONSD).

Figure 4

Non-invasive TD-TCD device for absolute ICP measurements. Ultrasound transducer of the Doppler subsystem is surrounded by an externally applied pressure chamber with a controlled external pressure source and measurement. Reprinted with permission from Ragauskas et al. (65). ICP, intracranial pressure. TD-TCD, two-depth transcranial Doppler.