Autoimmune encephalitis: Case

Summary and immediate impression

This 13-year-old girl presents a textbook case of anti-NMDA receptor encephalitis. The tempo is subacute over days. The psychiatric phase of agitation, insomnia, and auditory hallucinations preceded the neurological phase of seizures, orofacial dyskinesia, and hypoventilation. The CSF is inflammatory with lymphocytic pleocytosis and oligoclonal bands, and the MRI is normal, which is fully compatible with the diagnosis. The antibody result is pending and must not delay treatment. [1]

The first 24 hours — resuscitation and workup

The priority is to protect the airway and breathing because hypoventilation is a defining and life-threatening feature. I would secure the airway, monitor oxygen saturation and respiratory rate, and prepare for ventilatory support, and place her on cardiac and haemodynamic monitoring for autonomic instability. Seizures are treated with a benzodiazepine ladder and continuous EEG is set up because non-convulsive status is common and easy to miss behind an obtunded patient. [5]

The workup runs in parallel. I send viral PCR including herpes simplex virus on the CSF, a paired CSF and serum neural antibody panel with CSF as the more sensitive sample for NMDAR, and an EEG to look for the extreme delta brush pattern. I start empirical intravenous aciclovir and antibiotics until infection is excluded. I arrange a pelvic ultrasound then pelvic MRI to search for an ovarian teratoma in this post-pubertal girl, and I involve paediatric neurology and intensive care and plan retrieval to a tertiary centre. [5]

I start first-line immunotherapy as soon as infection is reasonably excluded, without waiting for the antibody result, because early treatment is the strongest predictor of good outcome. I give intravenous methylprednisolone 20 to 30 mg per kg per day, maximum 1 g, for three to five days, combined with intravenous immunoglobulin 2 g per kg over two to five days. [7]

Day 12 — the escalation decision

On day 12 she remains agitated, has ongoing seizures despite antiseizure medication, and has not returned to baseline. Her pelvic MRI confirms a left ovarian teratoma. A poor response at 10 to 14 days is the trigger to start second-line immunotherapy, because Titulaer showed that early second-line therapy within the first four weeks is an independent predictor of good outcome. I start rituximab 375 mg per m2 weekly for four weeks and arrange urgent gynaecological removal of the teratoma, because tumour removal is the single most effective intervention in paraneoplastic anti-NMDAR disease. [2][7]

Intensive care and the prolonged recovery

The intensive care course is dominated by the management of dysautonomia and hypoventilation, which can require weeks of mechanical ventilation. Cardiac instability is treated with haemodynamic support and arrhythmia management, and movement disorder and severe agitation are managed with careful sedation, avoiding dopamine-blocking antipsychotics where possible because of the risk of worsening movement disorder. Multidisciplinary neurorehabilitation, with physiotherapy, occupational therapy, speech and language therapy, and neuropsychology, runs throughout the admission because the cognitive and functional burden outlasts the acute illness. [5]

Prognosis, counselling, and follow-up

I would tell the family that most children recover well, with good outcome in around seventy-five percent within the first twenty-four months, and that relapse occurs in around twelve to fifteen percent, so surveillance continues after discharge. I would be honest that recovery is long, that cognitive, psychiatric, seizure, and movement disorder sequelae can persist for months, and that formal neuropsychological assessment and a structured school reintegration plan are part of treatment. I would give the family a relapse safety-net and arrange paediatric neurology follow-up with cognitive and psychiatric assessment. [2]

I would also note that around twenty percent of children who recover from herpes simplex encephalitis develop a secondary autoimmune encephalitis, so any new neurological relapse in a child with prior HSE is treated as possible post-HSE autoimmune disease until proven otherwise. [11]

Marking domains

• Diagnosis and reasoning: applies the Graus criteria, recognises the multidomain presentation, and does not delay treatment for the antibody result. [1]
• Management — acute: protects the airway and breathing, treats seizures, sends the workup, and starts first-line immunotherapy on suspicion. [5]
• Management — definitive: times second-line therapy at 10 to 14 days and arranges urgent teratoma removal. [2][7]
• Communication: counsels the family honestly on the prolonged recovery, the relapse risk, and the cognitive and school reintegration plan. [2]