Infantile spasms: diagnosis and assessment of treatment response by video‐EEG

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.

The EEG in Selected Generalized Seizures

“…However, as with the asymmetric hypsarrhythmic pattern, an asymmetric ictal EEG pattern does correlate with focal or lateralized structural lesions. Asymmetric spasms frequently occur in association with asymmetric ictal patterns (Donat and Lo, 1994;Gaily et al, 1995Gaily et al, , 2001.…”

Vigabatrin: a comprehensive review of drug properties including clinical updates following recent FDA approval

“…Typical diagnostic criteria for IS include neonatal or infantile myoclonic-type extensions or flexions involving the whole body and characteristically disorganized electroencephalogram (EEG) wave patterns (i.e., hypsarrhythmia) [6]. IS are rare, can be catastrophic in nature, and are associated with a wide variety of neuropathological abnormalities [7].…”

Recent Advances in the Pharmacotherapy of Infantile Spasms

“…It should be noted that vigabatrin treatment may make spasms milder. Serial video EEG recordings have shown that during vigabatrin treatment there has been transition of motor spasms to subtle spasms that may remain unnoticed [26]. In contrast, ACTH was effective in 71/119 (59 %) patients [99] and ACTH or prednisolone in 21/30 (70 %) patients [22], for a total of 92/149 (62 %) patients.…”