Abstracts

Rationale: The association between hemimegalencephaly (HME) and tuberous sclerosis complex (TSC), an autosomal dominant genetic disorder, is uncommon. There exists conflicting challenges in the management of the newborn with intractable epilepsy related to HME, and even more so with TSC. Early hemispherectomy to stop seizures and prevent detrimental consequences to future neurocognitive development is weighed against the safety concerns of a major surgery. As an alternative, ‘endovascular hemispherectomy’ was attempted in a neonate in whom surgical hemispherectomy was not a viable option at the time.


Methods: We present a clinical case of a neonate with presumed TSC and HME managed using a strategy of serial transarterial embolizations of the cerebral blood supply to the involved hemisphere for life-threatening seizures.

Results: Term baby with hypotonia, presenting with clusters of focal seizures and desaturation at 1 hr of life. Findings on brain MRI consistent with left HME in addition to multiple cortical and subcortical tubers in the same hemisphere. Other systemic findings included 2 rhabdomyomas, and hypopigmented macules with germline TSC1/TSC2 genetic testing showing a paternally inherited heterozygous c.733C >T (p.Arg245Cys) VUS in TSC2.

Seizures remained refractory to ASM infusions and the ketogenic diet. At 5 weeks, baby developed infantile spasms which responded to Vigabatrin, but focal seizures persisted. At 8 weeks, she presented in status epilepticus with focal and secondary GTCs with significant respiratory compromise >10-20 seizures/hr on 6 ASMs plus additional benzodiazepines every 6-8hrs. Immediate intervention was necessary but at 3.8kg, she was not deemed safe to proceed with conventional hemispherectomy. As such, staged serial endovascular embolizations (described by Pearl et al, J Neurointerv Surg 2023 Dec) with conventional angiogram were performed every 1-2 weeks to infarct the entire left hemispherectomy. A combination of nBCA, microsphere particles, and coils was used to achieve complete devascularization. This case was particularly challenging given the presence of a hypoplastic left A1 and A2 segments supplied by the contralateral ACA. Seizure semiology changed after each procedure with EEG correlation. After the 4^th procedure, EEG background quiescence and clinical seizures abated allowing to wean off 3 ASMs and discharged home after 9 weeks in hospital. Occasional subclinical seizures persist from a small residual region which is planned for a focal resection at a later optimal age. There were no complications of hydrocephalus, vasospasm, hemorrhage or mass effect noted throughout the course. At 4 month follow up, she can now hold her head, fixate visually, socially smile and babble.


Conclusions: Conventional hemispherectomy is often difficult in young neonates due to technical and anaesthetic challenges of this major surgery. This less invasive approach with staged endovascular hemispherectomy can be considered a feasible early alternative to surgical hemispherectomy that is safe and potentially definitive in select patients with HME.

Funding: none