Recommended Citation
Banh C, Awad P, Matics TJ, Appalaneni U, McKenzie S. When Lightning Strikes Twice - A Rare Case of Siblings with Autoimmune Encephalitis. Presented at Scientific Day; May 20, 2026; Milwaukee, WI.
Abstract
Introduction/Background:
Pediatric autoimmune encephalitis is a rare condition with high morbidity. Diagnosis requires a high index of suspicion. Earlier initiation of treatment, particularly in refractory cases, improves long-term outcomes. We describe a case of anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis in a child whose diagnosis and treatment were hastened due to a history of the same in her sibling, a previously described but rare occurrence.
Description:
A 4-year-old female presented with acute onset of fever, truncal ataxia, and altered speech. Her parents noted that their older daughter had similar symptoms two years ago and was diagnosed with autoimmune encephalitis. In our patient, head CT and MRI brain/spine with and without contrast were normal. Her nasal swab was positive for rhino/enterovirus, suggesting viral/postviral encephalitis, though cerebrospinal fluid (CSF) rapid meningitis viral panel was negative. On hospital day (HD) 4, she developed episodes of agitation and unresponsiveness which prompted repeat neuroimaging (normal), lumbar puncture (second negative CSF rapid meningitis viral panel), and sedation. EEG showed encephalopathy without seizures. Her serum NMDAR titer was negative but due to a high clinical suspicion, first-line treatment of anti-NMDAR encephalitis – intravenous immunoglobulin and steroids – was started on HD6. On HD8, it was confirmed with a neurologist in Missouri that her sister had anti-NMDAR encephalitis treated with rituximab. On HD10, her CSF NMDAR IgG returned positive with a titer of 1:320. After confirming the absence of latent infections, rituximab was started on HD12. Over the next 4 weeks, her symptoms improved, allowing sedation medications to be titrated off. She was initially fed by nasogastric tube, then gastrostomy tube due to involuntary oral movements and poor secretion management. Because she remained far from baseline in terms of speech, motor, and feeding capabilities, she was transferred to a long-term rehabilitation center for intensive multimodal rehabilitation.
Discussion:
This case highlights the importance of family history when diagnosing rare conditions. We were able to quickly initiate both first line and second-line treatments for our patient due to cross-hospital collaboration. Three months after discharge, she remains admitted at the long-term rehabilitation center with little cognitive recovery, but it is known that outcomes continue to improve up to 18 months after presentation.
Presentation Notes
Presented at Scientific Day; May 20, 2026; Milwaukee, WI.
Full Text of Presentation
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Document Type
Poster
Open Access
Available to all.
When Lightning Strikes Twice - A Rare Case of Siblings with Autoimmune Encephalitis
Introduction/Background:
Pediatric autoimmune encephalitis is a rare condition with high morbidity. Diagnosis requires a high index of suspicion. Earlier initiation of treatment, particularly in refractory cases, improves long-term outcomes. We describe a case of anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis in a child whose diagnosis and treatment were hastened due to a history of the same in her sibling, a previously described but rare occurrence.
Description:
A 4-year-old female presented with acute onset of fever, truncal ataxia, and altered speech. Her parents noted that their older daughter had similar symptoms two years ago and was diagnosed with autoimmune encephalitis. In our patient, head CT and MRI brain/spine with and without contrast were normal. Her nasal swab was positive for rhino/enterovirus, suggesting viral/postviral encephalitis, though cerebrospinal fluid (CSF) rapid meningitis viral panel was negative. On hospital day (HD) 4, she developed episodes of agitation and unresponsiveness which prompted repeat neuroimaging (normal), lumbar puncture (second negative CSF rapid meningitis viral panel), and sedation. EEG showed encephalopathy without seizures. Her serum NMDAR titer was negative but due to a high clinical suspicion, first-line treatment of anti-NMDAR encephalitis – intravenous immunoglobulin and steroids – was started on HD6. On HD8, it was confirmed with a neurologist in Missouri that her sister had anti-NMDAR encephalitis treated with rituximab. On HD10, her CSF NMDAR IgG returned positive with a titer of 1:320. After confirming the absence of latent infections, rituximab was started on HD12. Over the next 4 weeks, her symptoms improved, allowing sedation medications to be titrated off. She was initially fed by nasogastric tube, then gastrostomy tube due to involuntary oral movements and poor secretion management. Because she remained far from baseline in terms of speech, motor, and feeding capabilities, she was transferred to a long-term rehabilitation center for intensive multimodal rehabilitation.
Discussion:
This case highlights the importance of family history when diagnosing rare conditions. We were able to quickly initiate both first line and second-line treatments for our patient due to cross-hospital collaboration. Three months after discharge, she remains admitted at the long-term rehabilitation center with little cognitive recovery, but it is known that outcomes continue to improve up to 18 months after presentation.
Affiliations
Advocate Children's Hospital