Magnetoencephalography as a Novel Tool for Prenatal Diagnosis of Fetal Seizures.

Fetal seizures represent one of the rarest phenomena in prenatal medicine, with fewer than 50 documented cases. Diagnosis has traditionally relied on maternal reports and ultrasound visualization of abnormal movements, lacking the neurophysiologic confirmation available in neonatal care. This case report presents the first neurophysiologic assessment of fetal seizures using fetal magnetoencephalography (fMEG), demonstrating a novel diagnostic approach for prenatal neurologic evaluation. A 22-year-old primigravida with controlled epilepsy presented with a fetus showing severe growth restriction and multiple anomalies at 23 weeks gestation. At 32 weeks, repetitive rhythmic jerking movements suggested in utero seizures and were confirmed with real-time ultrasound. fMEG was performed using the SQUID Array for Reproductive Assessment (SARA) system, revealing immature patterns indicative of encephalopathy with alternating periods of severe bilateral suppression and low-amplitude activity. Bursts lasting up to 6 seconds coincided with erratic body movements confirmed by actogram. The infant was delivered at 37 weeks weighing 1,200 g and continued to exhibit myoclonic and clonic seizures postnatally. Postmortem whole exome sequencing identified biallelic pathogenic variants in PSAT1 , confirming Neu-Laxova syndrome. The infant died on the fifth day of life after transition to comfort care. This case demonstrates the feasibility of direct neurophysiologic assessment of fetal brain activity using fMEG, providing objective confirmation of fetal seizures for the first time. The technology offers potential for distinguishing true fetal seizures from other conditions that mimic seizure-like movements, enabling more accurate prenatal counseling and informed decision making. This represents a significant advancement in prenatal neurologic assessment, with implications for early diagnosis and targeted interventions.