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Neurophysiology of spasms
F Vigevano1, L Fusco, C Pachatz
1Division of Neurology, Bambino Gesù Children Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy. vigevano@opbg.net
Insights
Infantile spasms, characteristic of West syndrome (WS), present unique clinical and EEG features. These seizures may not fit traditional partial or generalized classifications, suggesting a distinct subcortical origin with cortical involvement.
Area of Science:
- Neurology
- Pediatric Neurology
- Epileptology
Background:
- Infantile spasms are a hallmark of West syndrome (WS), presenting with characteristic flexor-extensor movements.
- The electroencephalography (EEG) patterns associated with spasms, typically diffuse triphasic waves, are debated regarding their origin.
- Current classifications of partial vs. generalized seizures may not adequately describe infantile spasms in WS.
Purpose of the Study:
- To investigate the origin and classification of infantile spasms in West syndrome.
- To analyze the clinical and electrophysiological characteristics of spasms in WS.
- To determine if spasms in WS can be accurately categorized as partial or generalized seizures.
Main Methods:
- Review of clinical presentations of infantile spasms.
- Analysis of ictal and interictal electroencephalography (EEG) findings in West syndrome.
- Consideration of polygraphic recordings to assess muscular contraction patterns during spasms.
- Evaluation of factors supporting partial and generalized seizure origins.
Main Results:
- Infantile spasms in WS exhibit variable muscular contraction sequences, even when clinically similar.
- Evidence exists for both focal cortical lesions and generalized EEG patterns in WS patients.
- Spasms in WS may occur alongside other seizure types, complicating classification.
- The study suggests that traditional partial and generalized seizure categories are not applicable to spasms in WS.
Conclusions:
- Spasms in West syndrome possess a peculiar nature that challenges conventional seizure classification.
- The findings support the hypothesis that infantile spasms in WS may originate from subcortical structures, requiring cortical activation.
- Further research is needed to fully elucidate the neurophysiological underpinnings of these seizures.
Abstract:
Spasms are a form of epileptic seizure typical of infancy. From a clinical point of view, the child presents a flexor-extensor movement involving the trunk and limbs and lasting about 1s. Although asymmetry can be present, the seizure involves both sides of the body. The ictal discharge most frequently associated with spasms in West syndrome (WS) is a diffuse triphasic slow high-amplitude wave and less frequently a low-amplitude brief rapid rhythm. The origin of the spasm in WS and classification as either partial or generalized seizure are the subject of much discussion. Factors supporting partial origin include: interictal electroencephalography (EEG) characterized by multifocal anomalies; high incidence of focal cortical lesions and remission of spasms following surgical removal of focal lesions. Factors supporting generalized origin are: clinical involvement of the entire body; mostly generalized ictal EEG pattern; existence of idiopathic cases and possibility of spasms immediately following a partial seizure like a particular form of secondary generalization. In our opinion, the categories of 'partial' and 'generalized' seizures are not applicable to spasms in WS. Sometimes the spasms in WS can be observed together with other types of partial or generalized seizures. Polygraphic recordings have demonstrated that despite being clinically similar, each spasm is different from the other because of a variable sequence in muscular contraction. These data support the peculiar nature of the spasm in WS that could be a subcortical phenomenon that requires a cortical trigger.