Infantile Hemiconvulsion-Hemiplegia and Epilepsy (IHHE) in a boy with tuberous sclerosis complex

Area of Science:

• Neurology
• Genetics
• Pediatrics

Background:

• Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by TSC1 or TSC2 gene variants.
• TSC involves brain malformations like tubers and abnormal neuronal migration, leading to epilepsy in 80% of patients within the first two years.
• Systemic illness and fever can precipitate seizures, potentially causing status epilepticus in individuals with epilepsy.

Observation:

• Infantile Hemiconvulsion-Hemiplegia and Epilepsy (IHHE), a subset of new-onset refractory status epilepticus (NORSE), is characterized by hemiclonic seizures, fever, unilateral brain abnormalities, and hemiparesis.
• This report details an 18-month-old boy with TSC who experienced IHHE.
• The patient presented with extensive brain malformations and neuronal hyperexcitability in peri-tuberal tissues.

Findings:

• The patient's TSC-related brain malformations and neuronal hyperexcitability likely predisposed him to developing IHHE.
• The occurrence of IHHE in this TSC patient suggests that these neurological factors are critical.
• The study postulates an additional, yet unidentified, genetic predisposition for an exaggerated inflammatory response as a prerequisite for IHHE in TSC.

Implications:

• This case expands the understanding of IHHE presentation within the context of Tuberous Sclerosis Complex.
• It emphasizes the role of underlying brain architecture and neuronal excitability in seizure disorder development.
• Further research into the genetic basis of inflammatory responses in TSC may reveal novel therapeutic targets for preventing or managing severe epilepsy syndromes like IHHE.