Bedside sonographic optic nerve sheath diameter measurement in severely pre-eclamptic parturients: A prospective, observational study

Introduction: A simple bedside sonographic measurement of optic nerve sheath diameter (ONSD) has been shown to correlate with raised intracranial pressure (ICP). This study aims to detect serial ONSD changes in severely pre- eclamptic parturients admitted for labour and delivery. Methods: After ethical approval and written, informed consent 30 pre-eclamptic parturients with severe features were subjected to serial bedside ONSD measurements by an experienced anesthesiologist at admission (baseline), 4 & 12 hours following prophylactic IV MgSO4 therapy and at 24 hours postpartum. An average ONSD value of >5.0 mm was taken as corresponding to an ICP of ≥ 20 mm Hg. Hemodynamic profile, serum Mg levels, neurological signs and symptoms and mode of delivery were also recorded. Results: A total of n = 27/30 (90%) parturients showed baseline ONSD >5.0 mm. Neurological symptoms were reported in 74% (n = 20/27) of patients (mean ONSD 6.3 mm). Following MgSO4 therapy, neurological symptoms declined (n = 16/20) but mean ONSD remained >5.89 mm. 18 patients underwent cesarean delivery under spinal anesthesia. None of the patients progressed to eclampsia. Conclusion: Sonographic ONSD measurement is a simple bedside tool to observe intracranial pressure in severely pre-eclamptic parturients with or without neurological symptoms. It may be a useful aid to the attending anaesthesiologist to guide peripartum management of these patients.