Since the initial study of cases reported between 2009 and 2015, adalimumab has become in France the immunomodulatory reference treatment used after failure of corticosteroids and immunoglobulins before a possible recourse to the hemispherotomy. This observational study is intended to document the long-term efficacy and safety of Adalimumab therapy in patients with Rasmussen encephalitis.

Rasmussen Encephalitis (ER) is a particularly severe chronic inflammatory brain disorder resulting in the progressive destruction of a hemisphere. It is a rare disease although at present no precise prevalence is available. It begins preferentially in children.

This inflammatory process is accompanied by a progressive loss of function of the affected hemisphere, associated with a pharmaco-resistant partial epilepsy. The diagnosis is based on a bundle of clinical, radiological and electroencephalographic arguments. CSF analysis directs diagnosis in 50% of cases.

No anti-epileptic treatment can stop seizures. Only hemispherotomy (surgical disconnection of a cerebral hemisphere) allows it but it is associated with definitive motor and cognitive deficits.

Over the last 20 years, new therapeutic trials have focused on immuno-modulatory treatments targeted at the T-lymphocyte pathway, including tacrolimus. Although they seem to be more effective than immunoglobulins or corticosteroids, it remains transient. In addition, the number of published cases is low. In this context, starting in 2009, it has been proposed to use adalimumab (Ab anti TNF) based on:

• 1 / study of a case index
• 2 / knowledge of the pathophysiology of Rasmussen Encephalitis. To date, very few data provide precise information on the efficacy or tolerance of the use of this product in the longer term. This information is essential to confirm the place of adalimumab in the therapeutic arsenal against Rasmussen encephalitis.

Thus, in the continuation of the work carried out previously (French study on the cases between 2009 and 2015), the aim of this research projet is to complete the follow-up of the patients who previously took part in in the first study and to establish the follow-up of the patients treated by adalimumab since then.

Inclusion Criteria:

• Confirmed diagnosis of Rasmussen Encephalitis
• Patient aged more than 2 years
• Compliant treatment with adalimumab

Exclusion Criteria:

• Patient with a differential diagnosis
• Patient suffering from Rassmussen Encephalitis but not treated with adalimumab
• Patient who has not signed the informed consent

The implementation of a treatment with adalimumab in a patient with an ER requires the performance of a CPR within a reference center Epilepsies Rares if one complies with the rules of good clinical practice. Thus, all ER patients treated with adalimumab are referenced in a referral center. There are 7 reference centers in France, they are all partners of the study.