| Purpose Although lumbar puncture is a simple way to measure the cerebrospinal fluid pressure (CSF-P), it requires invasive procedures. The subarachnoid space around the optic nerve is connected with the whole CSF circulation system and can be visualized using T2-weighted MRI with the fat suppressed sequence. The authors investigated the optic nerve sheath diameter (ONSD), optic nerve diameter (OND), optic nerve subarachnoid space distance (ONSASD) by 3.0-Tesla MRI and CSF-P by lumbar puncture to evaluate the feasibility of optic nerve MRI measure index as a noninvasive monitoring tool of CSF-P.
Methods The design was a prospective observational study. 35 subjects examined in the Neurological Department underwent standardized neurologic and ophthalmologic examinations including MRI of the brain and optic nerve, followed by the lumbar pressure measurement for diagnostic reasons. At least one optic nerve of the subjects was normal. ONSD and OND were determined at 3mm, 9mm, and 15mm behind the eye ball with T2-weighted fast recovery fast spin echo (FRFSE) fat suppressed sequence in 3.0-Tesla MRI providing a spatial resolution of 0.16mm. ONSD minus OND equals ONSASD. Pearson's correlation analysis was used to explore the relationships between ONSD, OND, ONSASD at 3mm, 9mm, 15mm behind the eye ball and CSF-P, whereas Spearman's rho (instead of Pearson's correlation) was utilized in the case of non-parametric variables. We also performed a Stepwise multiple regression analysis between age, mean arterial pressure (MAP), body mass index (BMI) and CSF-P.
Results The mean CSF-P in the subjects was 15.6 ± 6.2 mmHg, ranging from 3.7 to 26.5 mmHg. High positive correlations were found between ONSD, ONSASD at 3mm, 9mm, 15mm behind the eye ball and CSF-P (P<0.001; correlation coefficient>0.620), especially ONSD(P< 0.001;correlation coefficient,0.801) and ONSASD(P< 0.001;correlation coefficient,0.774) at 3mm behind the eye ball. There was a weak and non-significant relationship between OND at 3mm behind the eye ball and CSF-P(P=0.075;correlation coefficient,0.319).Moderate positive correlations were found at 9mm(P< 0.001;correlation coefficient,0.620), and 15mm(P= 0.001;correlation coefficient,0.530). CSF-P was significantly associated with MAP (P < 0.001), BMI (P=0.006) and age (P=0.031).
Conclusions The present results show that ONSD, ONSASD at 3mm behind the eye ball on images obtained using routine sequences, when optic nerve MRI is indicated, can provide a quantitative estimate of CSF-P and may be reliable predictors of CSF-P. CSF-P is significantly associated with MAP, BMI and age. |
