OCT allows noninvasive assessment of pulsatile intracranial pressure

Optical coherence tomography (OCT) can be used for the noninvasive measurement of pulsatile intracranial pressure (ICP), especially when using the OCT parameters peripapillary Bruch’s membrane angle (pBA) and optic nerve head height (ONHH), according to a recent study.

“Moreover, the pBA and ONHH significantly predicted the mean ICP wave amplitude (MWA) scores,” the researchers said. “Accordingly, the present method shows promise as a noninvasive way of detecting abnormal pulsatile ICP.”

Twenty patients with idiopathic intracranial hypertension (IIH) participated in the present study and underwent continuous overnight diagnostic monitoring of both pulsatile and static ICP using a parenchymal sensor. Spectral-domain OCT was also performed. A parallel group of 12 patients with no verified cerebrospinal fluid disturbances was included for reference.

Compared with controls, IIH patients had significantly higher pulsatile ICP, as expressed by MWA (mean, 6.7 vs 3.5 mm Hg; p<0.001) and static ICP, as expressed by mean ICP (13.4 vs 6.8 mm Hg; p=0.003). No such difference was reported for intraocular pressure. [Transl Vis Sci Technol 2022;11:31]

In terms of OCT parameters, pBA was significantly smaller in IIH patients (–0.24 vs –3.03 degrees; p=0.038), suggesting that the Bruch’s membrane had a more anterior deflection in this group. On the other hand, ONHH was significantly greater in the IIH group (520.0 vs 385.2 µm; p=0.013). No other OCT parameters differed between groups.

Pearson’s correlation analysis found that pBA and ONHH were significantly and positively correlated with ICP scores. Specifically, pBA was increasingly smaller, indicating more anterior deflection, with higher overnight average MWA, as a measure of pulsatile ICP (R, 0.49; p=0.008). A similar interaction was reported for the overnight percentage of MWA ≥5 mm Hg (R, 0.59; p=0.002).

Moreover, ONHH was also significantly correlated with overnight average MWA (R, 0.73; p<0.001), the proportion of MWA ≥5 mm Hg (R, 0.69, p<0.001), and overnight mean ICP (R, 0.53; p=0.005).

Logistic regression and receiver operating characteristic curve analyses were performed to assess the ability of OCT parameters to predict ICP abnormalities.

Unadjusted ONHH was significantly associated with elevated mean ICP at an optimal cut-off point of 517 µm, though such an interaction was attenuated after adjusting for age and body mass index (BMI).

However, the predictive ability of pBA (odds ratio [OR], 1.98, 95 percent confidence interval [CI], 1.17–3.36; p=0.011; area under the curve [AUC], 0.85) and ONHH (OR, 1.01, 95 percent CI, 1.00–1.02; p=0.01; AUC, 0.86) for elevated MWA remained significant even after adjusting for age and BMI.

“This study provides evidence that OCT may be used to noninvasively estimate the pulsatile ICP. The OCT parameters pBA and ONHH correlated with the overnight pulsatile ICP,” the researchers said, pointing out that at the optimal cutoff values, pBA achieved a sensitivity of 75 percent and specificity of 92 percent for predicting MWA elevation. Corresponding values for ONHH were 88 percent and 69 percent.

Important limitations included the potential of examiner dependence in pBA and ONHH determination and the inability to perform ICP and OCT measurements simultaneously, often with delays of weeks or months between examinations.