Diagnostic value of neuro-ophthalmological signs in cases of Chiari I malformation.

INTRODUCTION: Our purpose was to evaluate the diagnostic value of measuring diameters of optic nerve sheath (ONSD), presence/absence of papilledema, tortuosity of the optic nerve, flattening of the posterior sclera, and intraocular protrusion of the prelaminar optic nerve for intracranial pressure assessment in cases of Chiari I malformation. METHODS: In a retrospective study, MRI data of 37 consecutive pediatric patients with Chiari malformation and data of 400 patients without intracranial pathology were compared and analyzed. ONSDs were measured at the point where the ophthalmic artery crosses the optic nerve (anatomical landmark). The correlation analysis was performed with clinical findings, gender, age, papilledema, and other neuro-ophthalmological findings. RESULTS: ONSD was enlarged in 38 % of cases of Chiari malformation. The enlargement was bilateral, no correlation with age or gender was found (p = 0.67 and p = 0.76, respectively). The presence of papilledema was detected in 19 % of cases presenting less valuable diagnostic sign if compared with ONSD. The tortuosity of the optic nerve was found in 22 % of cases, but in three patients, it was unilateral. All patients with enlarged ONSD and other neuro-ophthalmological signs present were treated surgically, while most of the patients without these signs (20/23) were treated conservatively. CONCLUSION: In majority of pediatric cases of Chiari malformation, the ONSD is not enlarged and other neuro-ophthalmological signs are not present. Detecting the enlarged ONSD and other neuro-ophthalmological signs in cases of Chiari malformation may indicate the elevated intracranial pressure and necessity for urgent surgical intervention.

Diagnostic value of the optic nerve sheath diameter in pseudotumor cerebri.

If persistent severe headache remains the only complaint of a patient, then the diagnosis of pseudotumor cerebri (PTC) can be delayed because in such cases practitioners are hesitant to immediately apply invasive intracranial pressure (ICP) measurement. Our purpose was to apply the technique of measuring diameters of the optic nerve sheath (ONSD) as a diagnostic tool in cases of PTC. Our aim was to provide practitioners with an additional sign to speed up their decision making about implementation of the lumbar puncture. In a retrospective study, CT scan data of 35 consecutive adult patients with PTC were collected and analyzed. ONSD were measured at the point where the ophthalmic artery crosses the optic nerve (anatomical landmark). The correlation analysis was performed with sex, age, and neuro-ophthalmological findings. We found that the ONSD was enlarged in 94.3% of patients with PTC. The enlarged ONSD were 6.2±1.2mm for the right and 6.3±0.9mm for the left (cut-off value >5.5mm). The enlargement was bilateral, and no correlation with age or sex was found (p=0.67 and p=0.76, respectively). Presence of papilledema was detected in 91.4% of patients (32/35) presenting as a slightly less valuable diagnostic sign compared with ONSD. We conclude that in the majority of cases of PTC the ONSD is significantly enlarged, indicating elevated ICP even if CT scans are negative. Implementing this ONSD method as a diagnostic tool in cases of suspected PTC may help in early accurate diagnosis, avoiding misdiagnosis, and providing appropriate early treatment.