A 35-year-old woman with a history of hypothyroidism and idiopathic small fiber autonomic and sensory neuropathy presented to the emergency department (ED) 48 hours after IV immunoglobulin (IG) infusion with a severe headache, nausea, neck stiffness, photophobia, and episodes of intense positional eye pressure. The patient reported previous episodes of headaches post-IVIG infusion but not nearly as severe. On ED arrival, the patient was afebrile with vital signs within normal limits. Initial laboratory results were notable for levels within reference range parameters: 5.9 × 109/L white blood cell (WBC) count, 13.3 g/dL hemoglobin, 38.7% hematocrit, and 279 × 109/L platelet count; there were no abnormal urinalysis findings, and she was negative for human chorionic gonadotropin.
Due to the patient’s symptoms concerning for an acute intracranial process, a brain computed tomography (CT) without contrast was ordered. The CT demonstrated no intracranial abnormalities, but the patient’s symptoms continued to worsen. The patient was started on IV fluids and 1 g IV acetaminophen and underwent a lumbar puncture (LP). Her opening pressure was elevated at 29 cm H2O (reference range, 6-20 cm), and the fluid was notably clear. During the LP, 25 mL of cerebrospinal fluid (CSF) was collected for laboratory analysis to include a polymerase chain reaction (PCR) panel and cultures, and a closing pressure of 12 cm H2O was recorded at the end of the procedure with the patient reporting some relief of pressure. The patient was admitted to the medicine ward for further workup and observations.The patient’s meningitis/encephalitis PCR panel detected no pathogens in the CSF, but her WBC count was 84 × 109/L (reference range, 4-11) with 30 segmented neutrophils (reference range, 0-6) and red blood cell count of 24 (reference range, 0-1); her normal glucose at 60 mg/dL (reference range, 40-70) and protein of 33 mg/dL (reference range, 15-45) were within normal parameters. Brain magnetic resonance images with and without contrast was inconsistent with any acute intracranial pathology to include subarachnoid hemorrhage or central nervous system neoplasm (Figure 1). Bacterial and fungal cultures were negative.
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Aseptic meningitis presents with a typical clinical picture of meningitis to include headache, stiffened neck, and photophobia. In the event of negative CSF bacterial and fungal cultures and negative viral PCR, a diagnosis of aseptic meningitis is considered.1 Though the differential for aseptic meningitis is broad, in the immunocompetent patient, the most common etiology of aseptic meningitis in the United States is by far viral, and specifically, enterovirus (50.9%). It is less commonly caused by herpes simplex virus (8.3%), varicella zoster virus, and finally, the mosquito-borne St. Louis encephalitis and West Nile viruses typically acquired in the summer or early fall months. Other infectious agents that can present with aseptic meningitis are spirochetes (Lyme disease and syphilis), tuberculous meningitis, fungal infections (cryptococcal meningitis), and other bacterial infections that have a negative culture. Once an infectious cause becomes low on the differential, the remaining 3.5% of cases can be attributed to a noninfectious aseptic etiology.2 This includes neoplasia, autoimmune, auto-inflammatory, iatrogenic, and drug induced (the most common subtype of this category) as possible causes.