To describe the adjunctive use of botulinum toxin for refractory focal motor seizures in a patient with anti-Hu autoimmune encephalitis.

Autoimmune encephalitis associated with anti-Hu antibodies often presents with focal motor seizures that are frequently resistant to conventional antiseizure medications (ASMs) and immunotherapy. Persistent motor seizures can lead to functional impairment, reduced quality of life, and caregiver burden. While botulinum toxin is widely used for spasticity, dystonia, and other movement disorders, its potential role in seizure control is not a common practice.

Our patient is a 56-year-old female with a history of autoimmune encephalitis since age 51 in the setting of small-cell lung cancer, presenting with focal seizures characterized by confusion and facial motor activity. MRI Brain showed bilateral amygdalar hyperintensity, and CSF was positive for anti-Hu antibodies. Despite complete cancer remission, she continued to experience 5–8 daily facial seizures, resulting in tongue injury, denture damage, insomnia, aspiration pneumonia, and pain. Multiple ASMs and immunotherapies, including steroids, plasma exchange, rituximab, and IVIg, were tried, without much improvement. 

 Later trial of botulinum toxin injections targeting facial and jaw muscles resulted in a durable reduction in seizure severity and associated discomfort, with maintenance injections every 12 weeks, besides IVIg every 3-4 weeks. 

This case highlights a potential role of botulinum toxin as adjunctive therapy in refractory focal motor seizures, particularly in autoimmune encephalitis. While not a substitute for disease-modifying therapy, Botox may offer functional benefits, seizure mitigation, and improved patient outcomes when conventional treatments fail. We hypothesize that Botox injection can make the affected muscles weak and help relieve the devastating side effects and damage associated with refractory focal seizures. Further systematic studies are warranted to establish efficacy, optimal dosing, and safety.