Rituximab Therapy in the Treatment of Juvenile Myasthenia Gravis: The French Experience.

BACKGROUND AND OBJECTIVES: Corticosteroids are the first-line immunosuppressants in the management of juvenile myasthenia gravis despite their adverse effects. The place of new immunosuppressive therapies is not clearly defined by the last international consensus held in March 2019 due to the lack of clinical trials. The aim of this study is to describe the use of rituximab and its efficacy and safety in 8 main pediatric centers of the French neuromuscular reference network to propose a new place in the therapeutic strategy of juvenile myasthenia gravis. METHODS: We conducted a retrospective multicenter study from January 1, 2009, to April 30, 2020, including a large cohort of children with myasthenia gravis in 8 main French pediatric reference centers of the FILNEMUS network. The type of myasthenia, different lines of immunosuppressive treatment, and clinical course of the patients were collected. To evaluate the efficacy of rituximab, we studied the clinical course of patients on immunosuppressive therapy. Outcome was defined as the clinical and therapeutic status of patients at the last visit: stable without immunosuppressants, stable with immunosuppressants, or unstable. RESULTS: We included 74 patients: 18 children with ocular form and 56 children with generalized form. Of the 37 patients who required immunosuppressive therapy, 27 were treated with rituximab. Patients treated with rituximab had a better outcome than patients treated with conventional immunosuppressants (p = 0.006). The use of rituximab as a first-line immunosuppressant showed a better efficacy with a discontinuation of immunosuppressants in 75% of patients (vs 25%, p = 0.04) and results in cortisone sparing (42% vs 92%, p = 0.03) compared with rituximab treatment as a second- or third-line immunosuppression. Rituximab was well tolerated; no adverse effect was observed. DISCUSSION: The use of rituximab has increased in France over the last 10 years as a first-line immunosuppressant. This study suggests good tolerability and efficacy of rituximab in juvenile myasthenia gravis. Early use appears to improve outcomes and facilitate cortisone sparing in antibody-positive generalized juvenile myasthenia. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that for children with MG, rituximab is effective and well tolerated.

Benign nocturnal alternating hemiplegia of childhood: two cases with positive evolution.

Benign nocturnal alternating hemiplegia (BNAH) of childhood is distinct from the classic form of malignant alternating hemiplegia of childhood [1]. It is characterized by hemiplegic attacks occurring exclusively during sleep [2]. It can be misdiagnosed as migraine, nocturnal frontal lobe epilepsy, benign rolandic epilepsy, Panayiotopoulos syndrome, or sleep-related movement disorder [1-4]. Only nine patients have been described to date, with typically, a normal development [1,5-7]. In order to insist about the benignity of the affection, we report two cases: a new three-year-old boy suffering from BNAH and a patient already published to show positive evolution at fourteen years of age. BNAH is a rare disorder but may be underdiagnosed. Making an early diagnosis can help to describe to the parents the good prognosis without treatment.

Severe neonatal myasthenia due to maternal anti-MuSK antibodies.

Anti-MuSK antibodies have been reported in about 40-50% of patients with seronegative myasthenia gravis. Curiously, this condition has never been reported in association with fetal or transient neonatal myasthenia gravis, despite a known female predominance. We report the case of a 22-year-old woman who developed seronegative, mild steroid-responsive myasthenia gravis. When aged 26, she gave birth to a baby boy with neonatal myasthenia gravis characterized by hypotonia, stridor and sucking difficulties. Intubation was required for a few weeks. Anti-MuSK antibodies were assessed and found positive in both patients. Progressive hydramnios during the last trimester, with a decrease in spontaneous fetal mobility in the last weeks, long-lasting stridor, ptosis and occasional difficulties in swallowing liquids till two years of age, despite anti-MuSK antibodies becoming negative, suggest a fetal onset. The possible pathophysiology of this disorder, based on recent findings on the expression and function of MuSK protein, is reviewed.