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Infantile spasms: diagnosis and assessment of treatment response by video-EEG
E Gaily1, E Liukkonen, R Paetau
1Hospital for Children and Adolescents, University of Helsinki, Finland. eija.gaily@hus.fi
Insights
Early diagnosis of infantile spasms using video-electroencephalography (video-EEG) is crucial, especially for infants with symptomatic etiology. Video-EEG reliably assesses treatment response, as spasms and EEG abnormalities change with therapy.
Area of Science:
- Neurology
- Pediatrics
- Clinical Neurophysiology
Background:
- Infantile spasms are a severe epilepsy syndrome in infants.
- Early diagnosis and treatment are critical for optimal outcomes.
- Electroclinical manifestations and treatment responses can be complex and require precise evaluation.
Purpose of the Study:
- To investigate early electroclinical features of infantile spasms.
- To evaluate treatment responses using video-electroencephalography (video-EEG).
- To correlate clinical and EEG findings with etiology and long-term outcomes.
Main Methods:
- Video-EEG recordings were performed in 44 infants with newly diagnosed spasms.
- Infants were assessed before and during treatment, primarily with vigabatrin.
- Follow-up continued until 12 months of age or death, with repeated video-EEG studies for treatment response assessment.
Main Results:
- Typical symmetric spasms were observed in most infants, but subtle or asymmetric spasms were associated with symptomatic etiology and poorer outcomes.
- Interictal EEG showed hypsarrhythmia or multifocal spikes.
- Video-EEG demonstrated treatment effects, including spasm cessation preceding EEG normalization and transitions in EEG patterns during therapy.
Conclusions:
- Video-EEG is essential for the initial diagnosis of infantile spasms, particularly in symptomatic cases where spasms may be subtle.
- Serial video-EEG is the most reliable method for assessing treatment response, as both clinical spasms and EEG abnormalities are modified by therapy.
- Subtle spasms and specific EEG findings correlate with symptomatic etiology and predict a less favorable prognosis.
Abstract:
The purpose of this study was to investigate early electroclinical manifestations and evaluate treatment responses by video-EEG in infants with newly diagnosed spasms. Spasms were recorded in 44 infants (27 males, 17 females) before adequate treatment. Mean ages at onset of spasms and at first video-EEG were 5.3 months (range 0.9 to 9 months) and 5.9 months (range 2.4 to 11.5 months) respectively. Thirteen infants had cryptogenic and 31 had symptomatic aetiology. First treatment was vigabatrin in 36 infants. All infants were followed until 12 months of age or death. Treatment response in the first months of therapy was assessed by repeated video-EEG studies in 23 infants. On the first video-EEG, 34 infants had typical symmetric motor spasms, three infants showed asymmetric or asynchronous behaviour, and seven infants had only subtle spasms. Interictal EEG showed hypsarrhythmia in 27 infants and multifocal spikes with normal or nearly normal background in 17 infants. Subtle spasms, asymmetric or asynchronous spasms, and asymmetric ictal or interictal EEG abnormalities were associated with symptomatic aetiology and poor cognitive and seizure outcome at 12 months. Serial video-EEG recordings showed a transition from motor to subtle spasms during the first 2 weeks of vigabatrin therapy in four infants and only subtle spasms in two therapy-resistant infants at 12 months. Cessation of spasms usually preceded disappearance of hypsarrhythmia or multifocal spikes, but persistence of multifocal spikes over several weeks was always associated with existing spasms. Transition of hypsarrhythmia into multifocal spikes was observed during vigabatrin therapy even in infants with intractable spasms. Initial diagnosis of infantile spasms requires video-EEG studies especially in infants with symptomatic aetiology who may show only subtle spasms. Video-EEG is the only reliable method for assessing treatment response as spasms and interictal EEG abnormalities are modified by treatment and may become subtle.