Noninvasive Estimation of Pulsatile and Static Intracranial Pressure by Optical Coherence Tomography

Abstract

Purpose: To explore the ability of optical coherence tomography (OCT) to noninvasively estimate pulsatile and static intracranial pressure (ICP).

Methods: An OCT examination was performed in patients who underwent continuous overnight monitoring of the pulsatile and static ICP for diagnostic purpose. We included two patient groups, patients with idiopathic intracranial hypertension (IIH; n = 20) and patients with no verified cerebrospinal fluid disturbances (reference; n = 12). Several OCT parameters were acquired using spectral-domain OCT (RS-3000 Advance; NIDEK, Singapore). The ICP measurements were obtained using a parenchymal sensor (Codman ICP MicroSensor; Johnson & Johnson, Raynham, MA, USA). The pulsatile ICP was determined as the mean ICP wave amplitude (MWA), and the static ICP was determined as the mean ICP.

Results: The peripapillary Bruch's membrane angle (pBA) and the optic nerve head height (ONHH) differed between the IIH and reference groups and correlated with both MWA and mean ICP. Both OCT parameters predicted elevated MWA. Area under the curve and cutoffs were 0.82 (95% confidence interval [CI], 0.66-0.98) and -0.65° (sensitivity/specificity; 0.75/0.92) for pBA and 0.84 (95% CI, 0.70-0.99) and 405 µm (0.88/0.67) for ONHH. Adjusting for age and body mass index resulted in nonsignificant predictive values for mean ICP, whereas the predictive value for MWA remained significant.

Conclusions: This study provides evidence that the OCT parameters pBA and ONHH noninvasively can predict elevated pulsatile ICP, represented by the MWA.

Translational relevance: OCT shows promise as a method for noninvasive estimation of ICP.

Figure 1.

The pBA. The Bruch's membrane/retinal pigment epithelium is marked by a red line. The pBA (yellow) is the angle that is formed between the deviated peripapillary Bruch's membrane (red line) and the unaltered part (blue line). A mean of nasal and temporal angles was calculated.

Figure 2.

The ONHH. A line connecting both sides (nasal-temporal) of the scleral canal opening (red line) was used as a reference line. The height was measured from the highest point of the optic nerve head to the reference line (yellow line).

Figure 3.

Association between the pBA and pulsatile and static ICP scores. There was a significant positive correlation between (a) the pBA and the average overnight MWA and (b) between the pBA and the overnight percentage of MWA ≥5 mm Hg. No significant correlation was found between pBA and (c) average of overnight mean ICP or (d) overnight percentage mean ICP ≥15 mm Hg. Each plot shows the fit line and Pearson correlation coefficient with significance levels. ns, nonsignificant.

Figure 4.

Association between the ONHH and pulsatile and static ICP scores. There was a significant positive correlation between (a) the ONHH and the average overnight MWA and (b) between the ONHH and the overnight percentage of MWA ≥5 mmHg. There also was significant positive correlation between (c) ONHH and average of overnight mean ICP but no correlation between (d) ONHH and overnight percentage mean ICP ≥15 mm Hg. Each plot shows the fit line and Pearson correlation coefficient with significance levels. ns, nonsignificant.

Figure 5.

Receiver operating curves for ability of OCT parameters to predict ICP scores. The pBA showed better ability to predict (a) the overnight MWA than (b) the overnight mean ICP. Likewise, the ONHH showed better ability to predict (c) the overnight MWA than (d) the overnight mean ICP. For details about ROC results, see Tables 2 and 3.