Table 1.

General characteristics of noninvasive ICP monitoring techniques

Method	Population	Continuous	Use	Rank
TCD	Varied	Yes	Estimation	3
TDTD	Varied	No	Estimation	3
Dynamic MRI	Hydrocephalus	No	Classification	2
NIRS	TBI	Yes	Classification	1
TMD	Hydrocephalus/Meniere’s disease	No	Classification	1
OAE	Healthy	Yes	Classification	2
SVP	Unspecified	No	Classification (only)	1
ONSD	Varied	No	Classification	3
Ophthalmoscopy	TBI	No	Classification (only)	1
OCT	N/A	No	N/A	1
VEP	Varied	Possible	Estimation	2
EEG	Varied	Possible	Estimation	1

The Method column refers to the technique name or abbreviation. The Population column refers to the patient population that has been studied using that method. The Continuous column specifies whether the method can be used for continuous monitoring. The Use column refers to whether the method has been primarily indicated for use in estimation of ICP value or classification into ICP labels. Finally, the Rank column offers a subjective ranking of the authors’ assessment of the current state of research regarding the efficacy of the method for monitoring ICP: 1 (inaccurate/not useful/lack of evidence), 2 (potentially useful/needs more research), and 3 (likely useful as a supplement to invasive measurement in some situations). Abbreviations used: TCD (Transcranial Doppler), TDTD (two-depth transorbital doppler), NIRS (near-infrared spectroscopy), TMD (tympanic membrane displacement), OAE (otoacoustic emissions), SVP (spontaneous venous pulsations), ONSD (optic nerve sheath diameter), OCT (optical coherence tomography), VEP (visual evoked potentials), EEG (electroencephalography)