Measuring Elevated Intracranial Pressure through Noninvasive Methods

Abstract

Elevated intracranial pressure (ICP) is an important cause of secondary brain injury, and a measurement of ICP is often of crucial value in neurosurgical and neurological patients. The gold standard for ICP monitoring is through an intraventricular catheter, but this invasive technique is associated with certain risks. Intraparenchymal ICP monitoring methods are considered to be a safer alternative but can, in certain conditions, be imprecise due to zero drift and still require an invasive procedure. An accurate noninvasive method to measure elevated ICP would therefore be desirable. This article is a review of the current literature on noninvasive methods for measuring and evaluating elevated ICP. The main focus is on studies that compare noninvasively measured ICP with invasively measured ICP. The aim is to provide an overview of the current state of the most common noninvasive techniques available. Several methods for noninvasive measuring of elevated ICP have been proposed: radiologic methods including computed tomography and magnetic resonance imaging, transcranial Doppler, electroencephalography power spectrum analysis, and the audiological and ophthalmological techniques. The noninvasive methods have many advantages, but remain less accurate compared with the invasive techniques. None of the noninvasive techniques available today are suitable for continuous monitoring, and they cannot be used as a substitute for invasive monitoring. They can, however, provide a reliable measurement of the ICP and be useful as screening methods in select patients, especially when invasive monitoring is contraindicated or unavailable.

Dynamic optic nerve sheath diameter responses to short-term hyperventilation measured with sonography in patients under general anesthesia

“…However, sustained hyperventilation can decrease CBF, resulting in poor prognosis in patients with elevated ICP [19]. Non-invasive monitoring technique such as sonographic ONSD measurement can be promptly applied and performed at bedside to evaluate ICP [9,21] and may help to make optimal strategy in ICP management. Even though patients included in this study did not suffer from intracranial lesion and had normal brain compliance, ONSD showed a significant response in associated CO 2 change.…”

“…Although direct ICP measurement technique such as ventriculostomy is known as a standard, it is invasive and difficult to apply as routine monitoring of all patients likely to experience increased ICP, even in critically ill patients. Sonographic measurement of ONSD is a non-invasive technique and has been reported to provide a good association with ICP [21,28,29]. Thus, ONSD can be a good alternative in predicting ICP increase without risk of infection or bleeding.…”

Recommendations for the use of multimodal monitoring in the neurointensive care unit

“…Nevertheless, the use of an external ventricular drain is the preferred method to monitor ICP, particularly in the setting of hydrocephalus [6]. Noninvasive devices do not reliably quantify ICP [46]. However, they may be used to estimate ICP when invasive monitoring is not feasible, along with information from imaging [47][48][49].…”

Can intracranial pressure be measured non-invasively bedside using a two-depth Doppler-technique?

“…Among them are intraocular pressure assessment [2], tympanic membrane displacement [3], ultrasonography [4,5] and measurement of intracranial blood flow [6][7][8][9]. In the individual, these methods have shown a fairly high correlation between non-invasive and invasive ICP assessments (Table 1).…”