Has anyone ever reported seizures in a fetus?

Yes. Although rare, fetal seizures have been repeatedly documented in the medical literature. Fetal seizure activity is typically identified by stereotyped, repetitive, rhythmic movements of the fetal trunk or extremities on real-time ultrasound that cannot be voluntarily suppressed by fetal behavioral state.

What do fetal seizures look like on ultrasound?

Reported cases describe:

• Repetitive, rapid limb or truncal movements
• Tonic–clonic–like patterns lasting 30–60 seconds
• Movements occurring in clusters and recurring
• Movements distinct from hiccups, breathing motions, or startle reflex

In one case, a mother at 28 weeks noted rapid repetitive fetal movements; ultrasound at 30 weeks showed tonic–clonic movements of the trunk and extremities [1]. Similarly, Abrams et al. reported repeated clusters of rapid limb movements lasting 30–60 seconds in a 32-week fetus [2].

What causes fetal seizures?

The largest review (Patane & Ghidini) reported that the majority of fetal seizures were associated with:

• Congenital anomalies (7 of 13 cases)
• Primarily central nervous system anomalies (6 of 7)
• Metabolic disorders (rare)
• Infections
• Ischemia or hypoxic injury

When to suspect a fetal seizure

• Episodes of rhythmic, repetitive movements lasting >20–30 seconds
• Movements that recur despite fetal rest periods
• Patterns that are stereotyped and reproducible
• Associated CNS anomalies or polyhydramnios

Differential diagnosis

• Fetal hiccups (regular, non-clonic)
• Breathing movements
• Startle reflex
• Normal limb jerks
• Myoclonic fetal activity

Prognosis

Reported outcomes vary widely. Many fetuses with seizures have underlying structural or metabolic conditions that may worsen prognosis. Others may have isolated events with more favorable outcomes. In all cases, fetal seizures warrant detailed neurosonography, MRI, and neonatal neurology involvement.

See Also

UOG videoclip: Fetal seizures observed on ultrasound can guide diagnosis and treatment of neonatal epileptic encephalopathy
Ultrasound in Obstetrics & Gynecology