Evaluation of optic nerve sheath diameter measurements in postictal pediatric patients.

Introduction: Prolonged seizures cause cytotoxic edema and increase intracranial pressure. Optic nerve sheath diameter (ONSD) and its ratio to eyeball transverse diameter (ONSD/ETD) offer a noninvasive method for monitoring intracranial pressure changes. We calculated the ONSD and ONSD/ETD ratio of postictal children using computed tomography and evaluated the relationship between those values and seizure duration.

Methods: The ONSD and ONSD/ETD ratios were calculated using non-contrast computed head tomography for 88 postictal children with generalized and focal seizures and 109 healthy controls. ONSD was measured as the thickness at 3 mm from the optic disc and the ETD was measured as the widest diameter of the eyeball from retina to retina. The ONSD/ETD ratio was obtained by averaging the left and right ONSD values and dividing that value by the mean of the left and right ETD values.

Results: Fifty-eight (63.6%) of the children had focal seizures, and 64% of the seizures of 59 children (67%) were classified as prolonged seizures. The median ONSD and ONSD/ETD ratio were significantly higher in postictal children compared to healthy controls (p < 0.001 and p < 0.001, respectively). In postictal children presenting with generalized seizures, nonsignificant differences in the median ONSD and ONSD/ETD ratio were observed (p = 0.43 and p < 0.87, respectively). Children with prolonged seizures had significantly different ONSD values (p = 0.015) but the ONSD/ETD ratio did not differ significantly (p = 0.87). The analysis of postictal children indicated a significant correlation between seizure duration and ONSD (r = 0.257, p = 0.016), but not the ONSD/ETD ratio (r = 0.065, p = 0.545). ONSD values of (> 4.84 mm) were most effective in distinguishing patients with prolonged seizures compared to those without, with sensitivity and specificity of 65.6% and 72.5%.

Conclusion: ONSD and ONSD/ETD values are potentially useful in the evaluation of postictal children, but they do not exhibit adequate discriminative accuracy by themselves. The significance of these parameters in observing seizure duration in postictal children may be a critical area of interest for future investigations.