Abstract

ABSTRACT:
BACKGROUND:
In cases of Pseudotumor Cerebri Syndrome, increased intracranial pressure is transmitted to the subarachnoid space surrounding the optic nerve, causing increase in the optic nerve sheath diameter and Optic nerve sheath to optic nerve diameter ratio. Magnetic Resonance Imaging is the image of choice in Pseudotumor Cerebri Syndrome and it can be used to measure precisely the diameter of optic nerve and its surrounding sheath.
OBJECTIVE:
To evaluate the diagnostic value of optic nerve sheath diameter, Optic nerve sheath to optic nerve diameter ratio, and their correlation with lumbar puncture opening pressure in Pseudotumor Cerebri Syndrome
PATIENTS AND METHODS:
In a prospective blinded correlational diagnostic yield study, a 3 tesla Magnetic Resonance Imaging data of 34 patients with Pseudotumor Cerebri Syndrome, and 34 normal control were collected and analyzed, optic nerve sheath diameter and optic nerve diameter were measured in an axis perpendicular to the optic nerve, 3 mm behind the globe.
RESULTS:
Both optic nerve sheath diameter and Optic nerve sheath to optic nerve diameter ratio were found to be significantly larger in patient's group compared to control. Lumbar puncture opening pressure in patient was measured and found to be correlated significantly with both optic nerve sheath diameter and optic nerve sheath to optic nerve diameter (r 0.79-p 0.000, r 0.45-p 0.007 respectively). The optic nerve sheath diameter in patients were 5.75 ±0.6 mm, cut-off value for diagnoses of Pseudotumor Cerebri Syndrome was 4.9 mm with a sensitivity of 91% and specificity of 88%. The cut-off value of optic nerve sheath to optic nerve diameter ratio was 2.39 with a sensitivity of 100% and specificity of 97%.
CONCLUSION:
Magnetic Resonance Imaging -determined (optic nerve sheath diameter & optic nerve sheath to optic nerve diameter ratio) have excellent diagnostic value in Pseudotumor Cerebri Syndrome, and they were correlated significantly with LP opening pressure.
KEYWORDS: MRI, Optic nerve, Pseudotumor Cerebri Syndrome