Abstract
RATIONALE: Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune encephalitis characterized by diverse neurological and psychiatric symptoms. It predominantly affects young women, particularly those with ovarian teratomas. However, cases without teratomas are also commonly reported, often exhibiting poorer treatment responses and higher relapse rates. Persistent fever and signs of meningitis are rare in such cases. Diagnosis is confirmed through the detection of anti-NMDAR antibodies. PATIENT CONCERNS: A 15-year-old female presented with episodic loss of consciousness, fever, nuchal rigidity, limb convulsions, and psychiatric symptoms following a stressful exam period. Initial symptomatic treatments were ineffective. DIAGNOSIS: The diagnosis of anti-NMDAR encephalitis was confirmed through lumbar puncture, brain imaging, and the detection of anti-NMDAR antibodies in cerebrospinal fluid and serum. INTERVENTIONS: The patient received tailored first-line therapy, including high-dose methylprednisolone and 3 courses of intravenous immunoglobulin (IVIG). OUTCOMES: The patient exhibited significant clinical improvement, with a reduction in seizure frequency and eventual complete seizure control. Body temperature normalized, and follow-up showed progressive recovery in cognitive and motor functions. LESSONS: This case highlights the importance of early diagnosis and individualized treatment in anti-NMDAR encephalitis. Repeated IVIG courses proved effective, underscoring the need for personalized treatment plans in managing this condition. Persistent fever and signs of meningitis were rare and contributed to the diagnostic challenge, highlighting the clinical complexity of this case.