The study, “Perampanel attenuates myoclonus in a patient with neuronal ceroid lipofuscinoses type 2 disease,” was published in Brain & Development.
Late infantile Batten disease, also known as CLN2 disease, is a rare neurodegenerative disorder caused by genetic mutations in the TPP1 gene, which provides instructions to make an enzyme called tripeptidyl peptidase 1 (TPP1).
As the disease progresses, myoclonic seizures (seizures in which a muscle or group of muscles contract and relax, causing rapid twitching and/or jerking) become increasingly frequent, posing a significant burden to patients and their caregivers. These seizures are usually refractory, meaning that they normally fail to respond to treatment with antiepileptic drugs.
In this study, a group of Chinese researchers described the clinical case of a girl with CLN2 disease who experienced almost continuous myoclonic seizures that were reduced after she started treatment with Fycompa, a new antiepileptic medication.
The girl (born to parents who were unrelated to each other) showed the first signs of the disorder when she was 3 and started experiencing language delays. By that time she also experienced her first generalized tonic-clonic seizure and underwent neurological examination.
The exam revealed that she had mild brain atrophy (shrinkage), accompanied by ataxia (loss of movement control) and cognitive decline. In the meantime, she developed other types of seizures, including autonomic — those accompanied by abdominal discomfort or nausea — and myoclonic seizures.
She was diagnosed with CLN2 disease after a genetic screening revealed that she had a mutation and a partial deletion in the sequence of the TPP1 gene.
Her health rapidly deteriorated from that point on. By the time she was 5, the girl had lost her vision and was unable to communicate. She gradually lost control of her body movements, and by age 6, she was bed-ridden and had to be fed by a nasogastric feeding tube.
Despite multiple attempts with different antiepileptic medicines (valproate, levetiracetam, topiramate, clobazam, piracetam, and phenobarbital) and a ketogenic diet — a low-carbohydrate, high-fat diet — her seizures failed to respond to treatment.
By the time she was 8, her myoclonus (muscle twitching/jerking that may or may not be associated with epileptic brain activity) had become almost continuous.
The girl was eventually treated with Fycompa at a starting dose of 1 mg/day, which slowly increased to 6 mg/day over the course of a month. Treatment with Fycompa reduced the frequency of daily myoclonous episodes she was experiencing by more than 50% during a follow-up period of six months, with no evidence of side effects.
She now remains in a stable state, and her sleep and quality of life have improved substantially.
“In conclusion, perampanel adjuvant therapy may be considered in treating myoclonus of CLN2 like other patients with PME [progressive myoclonus epilepsy]. Although present case showed significant improvement in myoclonus control, further clinical or animal studies are warranted as this is only based on a single clinical case observation,” the scientists concluded.