Rare DDX3X Gene Mutation in a Male Newborn With Super-refractory Status Epilepticus Responding to Lacosamide Drug Therapy

Super-refractory status epilepticus (SRSE) is defined as status epilepticus that persists or recurs after treatment with anesthetic agents for more than 24 hours, including cases with recurrent seizures on reduction or withdrawal of anesthetic drugs. Super-refractory status epilepticus presents a significant challenge for neurologists, particularly when standard treatments fail to achieve seizure control. Lacosamide, which has a unique mechanism involving modulating voltage-gated sodium channels by enhancing their slow inactivation, has emerged as a potential option for managing SRSE. We report a case of a male neonate with SRSE who failed to respond to first-line and second-line antiepileptic drugs (AEDs), including benzodiazepines, phenobarbital, levetiracetam, and midazolam infusion. Following an extensive review of the available treatment options, lacosamide was introduced as a third-line agent. When lacosamide was introduced to the treatment regimen, it led to a significant reduction in seizure frequency and ultimately achieved seizure control. Lacosamide was well tolerated by the patient with no significant side effects. Upon further assessment of the patient using whole exome sequencing (WES), it was elucidated that he is a carrier of the DDX3X gene mutation, which is known as syndromic X-linked intellectual developmental disorder of the Snijders Blok type (MRXSSB). This syndrome is characterized by global developmental delay, intellectual disability, behavioral disorders, and seizures. However, the neonate described in our case report presents in an atypical manner in comparison to those with a DDX3X gene mutation. This case highlights lacosamide's potential role in the management protocol of SRSE, particularly in neonatal patients with MRXSBB who are unresponsive to standard therapies. It is important to shed light on the possibility of using lacosamide in SRSE in neonates. However, further studies are needed to establish lacosamide's efficacy and safety profile more comprehensively. This case contributes to the growing body of evidence supporting lacosamide's use in difficult-to-treat seizure disorders.