What is the diagnosis and treatment for Pediatric Autoimmune Meningioencephalitis (PAME)?

From the Guidelines

Pediatric autoimmune meningoencephalitis should be treated with high-dose intravenous methylprednisolone (20-30 mg/kg/day, maximum 1g daily) for 3-5 days, followed by oral prednisone (1-2 mg/kg/day) with a slow taper over 2-3 months, as recommended by the most recent guidelines 1. The treatment approach should be individualized based on the patient's clinical presentation and response to therapy. For patients who don't respond adequately to first-line treatment, intravenous immunoglobulin (IVIG) at 2 g/kg divided over 2-5 days is recommended 1. In severe or refractory cases, rituximab (375 mg/m² weekly for 4 weeks) or cyclophosphamide may be necessary, with rituximab being the preferred second-line agent in patients with known or highly suspected antibody-mediated autoimmunity 1. Plasma exchange is another option for treatment-resistant cases, particularly in patients with severe hyponatraemia, high thromboembolic risk, or associated brain or spinal demyelination 1. Prompt diagnosis is crucial and typically requires MRI, CSF analysis, and autoantibody testing (including anti-NMDA receptor, anti-MOG, and anti-GFAP antibodies) 1. Early aggressive immunotherapy improves outcomes by limiting neural damage, and supportive care including seizure management, close monitoring for autonomic instability, and rehabilitation services are essential components of treatment 1. Long-term follow-up is necessary as relapses can occur, particularly when immunotherapy is tapered too quickly, and tumour screening should be performed annually for several years, especially if the treatment response is poor or relapses occur 1.

Some key points to consider in the management of pediatric autoimmune meningoencephalitis include:

• The importance of prompt diagnosis and early aggressive immunotherapy to improve outcomes and limit neural damage
• The use of high-dose intravenous methylprednisolone as first-line treatment, followed by oral prednisone with a slow taper
• The role of IVIG and plasma exchange in patients who don't respond to first-line treatment
• The use of rituximab or cyclophosphamide as second-line agents in severe or refractory cases
• The need for long-term follow-up and tumour screening to monitor for relapses and potential underlying malignancies.

From the Research

Pediatric Autoimmune Meningioencephalitis

• Pediatric autoimmune encephalitis is the third most common cause of encephalitis in children, with a diverse clinical presentation and a lack of identifiable autoantibody in some cases 2.
• The most common presenting symptoms include seizures and behavior changes, with more than 90% of patients showing improvement following first-line immunotherapy 2.
• First-line therapies for pediatric autoimmune encephalitis include corticosteroids, intravenous immunoglobulin, and plasma exchange, while second-line therapies include rituximab, cyclophosphamide, and mycophenolate mofetil 3, 4.
• Early treatment initiation and escalation to second-line therapy in patients with refractory disease can improve outcomes, with the potential for full recovery in many patients 3, 5.
• Novel treatments, such as interleukin-6 inhibitors and proteasome inhibitors, have shown promising results in patients with refractory disease 3.
• The importance of autoantibody detection methodology and the possible influence of intrathecal antibody synthesis on the speed of recovery and response to immune therapy are highlighted 6.
• A comprehensive, multidisciplinary approach to the evaluation and management of pediatric autoimmune encephalitis is recommended, with guidelines developed through an iterative process involving pediatric neurologists and rheumatologists 5.
• Immunotherapeutics, including agents and mechanisms, play a crucial role in the treatment of pediatric autoimmune central nervous system disease, with a need for a "risk-versus-benefit" determination to guide therapeutic decision-making 4.