Clinically silent seizures in a neonate with tuberous sclerosis

Electroencephalography in neonatal epilepsies

Neonatal epilepsies - neonatal seizures caused by remote symptomatic etiologies - are infrequent compared with those caused by acute symptomatic etiologies. The etiologies of neonatal epilepsies are classified into structural, genetic, and metabolic. Electroencephalography (EEG) and amplitude-integrated EEG (aEEG) are essential for the diagnosis and monitoring of neonatal epilepsies. Electroencephalography / aEEG findings may differ substantially among infants, even within infants with variants in a single gene. Unusual EEG/aEEG findings, such as downward seizure patterns on aEEG, can be found. Neonatal seizures are exclusively of focal onset. An International League Against Epilepsy task force proposed that the seizure type is typically determined by the predominant clinical feature and is classified into motor or non-motor presentations. Ictal EEG usually demonstrates a sudden, repetitive, evolving, and stereotyped activities with a minimum duration of 10 s. In epileptic spasms and myoclonic seizures, the cut-off point of 10 s cannot be applied. One must always be aware of electro-clinical dissociation in neonates suspected to have seizures. Amplitude-integrated EEG is also useful for the diagnosis and monitoring of neonatal epilepsies but aEEG cannot be recommended as the mainstay because of its relatively low sensitivity and specificity. At present, EEG findings are not pathognomonic, although some characteristic ictal or interictal EEG findings have been reported in several neonatal epilepsies. Deep learning will be expected to be introduced into EEG interpretation in near future. Objective EEG classification derived from deep learning may help to clarify EEG characteristics in some specific cases of neonatal epilepsy.

Electro-clinical and neurodevelopmental outcome in six children with early diagnosis of tuberous sclerosis complex and role of the genetic background

Background

Seizures in individuals affected by tuberous sclerosis complex (TSC) commonly develop in the first year of life, are often preceded by a progressive deterioration of the electroencephalogram (EEG), and likely influence developmental outcome. Although early diagnosis of TSC has offered a tremendous opportunity to monitor affected patients before seizure onset, reports of the neurological manifestations of TSC in infants before seizure onset are still scarce. Here we describe early EEG activity, clinical and genetic data and developmental assessment in a group of TSC infants, with the aim of identifying possible prognostic factors for neurodevelopmental outcome.

Methods

We report on six infants diagnosed with TSC pre- or perinatally, who underwent serial Video-EEG recordings during the first two years of life. EEGs were classified based on distribution and intensity of interictal epileptiform discharges, and Vigabatrin was introduced in case of ictal discharges. Psychomotor development, cognitive functioning and behavioral problems were assessed through standardized scales. Molecular testing included analysis for point mutations and deletions/duplications in TSC1 and TSC2.

Results

EEG abnormalities appeared at a mean age of 4 months. Four of the six patients developed seizures. EEG abnormalities preceded the onset of clinical seizures in all of them. The two individuals with good seizure control showed normal development, while the other two exhibited psychomotor delays. The patients who did not develop seizures had normal development. A pathogenic variant in the TSC2 gene was detected in all patients but one. The one without a mutation identified did not develop seizures and showed normal neurodevelopment. Of note, the two patients presenting with the worst outcome (that is, poor seizure control and intellectual/behavioral disability) both carried pathogenic variants in the GAP domain of TSC2.

Conclusion

Our report supports the importance of EEG monitoring before seizure onset in patients with TSC, and the correlation between prompt seizure control and positive neurodevelopmental outcome, regardless of seizure type. Our results also indicate a possible role of the genetic background in influencing the outcome.

The Utility of Surveillance Electroencephalography to Guide Early Antiepileptic Drug Therapy in Infants With Tuberous Sclerosis Complex

BACKGROUND

Seizures are a common early presentation in infants with tuberous sclerosis complex (TSC) and can be preceded by electrographic changes on electroencephalography (EEG) before clinical seizure onset. A limited number of studies have addressed the initial EEG findings in TSC and the outcome of early treatment with antiepileptic medication prior to clinical seizure onset.

METHODS

We describe two infants with tuberous sclerosis complex whose surveillance EEG showed focal seizures that were not previously recognized by caregivers. We review previously reported patients with TSC with early EEG findings. Our patients were started on vigabatrin after the onset of focal seizures with the aim of preventing seizure recurrence, halting the possible progression to infantile spasms or focal seizures, and preventing neurodevelopmental decline.

RESULTS

Both patients remain seizure free and have reached appropriate developmental milestones.

CONCLUSIONS

We recommend early serial EEG monitoring once a diagnosis of TSC is suspected or confirmed in infants. Additional prospective studies are needed to assess the long-term outcome of early antiepileptic drug initiation as soon as electrographic seizure activity is detected.