Non-invasive estimation of cerebrospinal fluid pressure in idiopathic intracranial hypertension: magnetic resonance imaging analysis of optic nerve and eyeball.

PURPOSE

Invasive methods such as lumbar puncture and intraventricular catheters are commonly used to measure intracranial pressure (ICP). This study aims to develop quantitative and non-invasive techniques to measure ICP in patients with Idiopathic Intracranial Hypertension (IIH) using magnetic resonance imaging (MRI) findings.

METHODS

MRI data obtained from 50 patients with IIH and 30 age- and sex- matched controls were analyzed and optic nerve sheath diameter (ONSD), eyeball transverse diameter (ETD) and optic nerve diameter (OND) were measured. ONSD, ONSD/ETD and OND/ONSD indexes were calculated according to different ONSD measurement distances. Correlations of MRI findings with ICP were calculated. Sensitivity and specificity of all methods were analyzed.

RESULTS

ONSD and ONSD/ETD index at 3 mm and 10 mm behind the eyeball were significantly higher (p < 0.001) and OND/ONSD index at 3 mm behind the eyeball was significantly lower (p < 0.001) in the IIH group. The ONSD/ETD index at 3 mm had the highest area under the curve (AUC) value (0.898) with a cut-off of 0.27 mm (82% sensitivity and 91.67% specificity) for predicting high cerebrospinal fluid (CSF) pressure, followed by ONSD measurements at 3 mm (AUC = 0.886) with a cut-off of 6.17 mm (83% sensitivity and 86.67% specificity). The OND/ONSD index at 3 mm posterior to the eyeball decreased significantly as ICP increased, and the strength of the relationship was moderate (p < 0.001; r = -0.358).

CONCLUSIONS

ONSD and ONSD/ETD index measured on MRI sequences are potentially useful in detecting elevated ICP. The OND/ONSD index correlates with CSF pressure and these techniques may be helpful in diagnosing IIH.