Patients were recruited according to the updated diagnostic criteria of IIH and papilledema was documented in all subjects by an ophthalmological examination including funduscopy. Twenty-five individuals with other neurological disorders served as controls. Sonographic evaluation of the optic nerve was possible in all participants. Compared to controls the ONSD was significantly enlarged among patients with IIH bilaterally [6.4 ± 0.6 mm vs. 5.4 ± 0.5 mm].

After lumbar puncture with a therapeutic removal of 30–50 ml of CSF we observed a significant decrease of the ONSD on both sides (right ONSD 5.8 ± 0.7 mm, left ONSD 5.9 ± 0.7 mm) (Fig. 1). However, in some patients with IIH, the ONSD was not altered or only slightly altered, e.g. a decline of 0.4 mm or more was only documented in five MAPK inhibitor individuals. This may possibly be related to findings of a defective CSF circulation in the optic nerve sheath in this disorder, a state that is referred to as optic nerve compartment syndrome [23]. The ROC curve analysis revealed an optimal

cut-off value for predicting raised ICP of 5.8 mm with a sensitivity of 90% and a specificity of 84%. The mean optic disk elevation in subjects with IIH was 1.2 ± 0.3 mm. Nevertheless, one patient showed no evidence of optic disk elevation in transbulbar sonography but had signs of papilledema in funduscopy. Corresponding to previous studies, we found no decrease of the optic disk elevation after lumbar puncture in the observation period

of 24 h. As a result sonographic ONSD evaluation may be useful in detecting raised ICP in patients find more with presumed IIH. Furthermore, our data suggest a potential usefulness of this technique for monitoring of treatment effects. In addition, ONSD values and optic disk levels were slightly asymmetric, reflecting the complex anatomy of the subarachnoidal space of the optic nerve and its possible influence on the cerebrospinal fluid dynamics. For this reason we recommend that each eye should be evaluated separately and mean ONSD values should be designated for both eyes. Predominantly, the relationship of ONSD alterations and ICP changes was verified in clinical situations with raised ICP. One case series and one prospective study investigated the ONSD in spontaneous intracranial hypotension [24] and [25]. Florfenicol Examining the orbit with T2-weighted MRI techniques, they observed a collapsed optic nerve sheath. Dubost et al. published an ultrasound study on ten patients with postdural puncture headache after lumbar puncture or epidural anesthesia [26]. Consistent with the mentioned MRI-results a small ONSD of 4.8 mm was detected before treatment. After successful therapy with a lumbar epidural blood patch a marked enlargement of the ONSD was found. Accordingly, in one patient in whom the intervention failed to resolve the headache they recorded no ONSD distension.