(753) Central Neurogenic Hyperventilation as the Main Clinical Manifestation of Bacterial Meningitis

Introduction: Acute bacterial meningitis has an onset over 2-3 days. Symptoms/signs include meningism, encephalopathy, fever, seizures, vasculitis, or hydrocephalus. Elderly and immunocompromised patients may have partial or atypical clinical manifestations. This case discusses an elderly patient with severe refractory respiratory alkalosis due to central neurogenic hyperventilation (CNH) as the main presentation of gram positive cocci meningoencephalitis. CNH is not known to be a meningitis complication but has been identified in lymphoma cases. A study of animals with pneumococcal meningitis showed that CSF lactic acid elevation may lead to a centrally driven respiratory alkalosis via medullary chemoreceptors detecting an acidotic environment.

Description: A 62 year-old female with past medical history of end stage renal disease on dialysis, lower extremity calciphylaxis, hypothyroidism, type 2 diabetes, and hypertension who presented with lower extremity wound serosanguinous drainage and hypotension. An extensive infectious work-up was unrevealing and empiric antibiotics were discontinued. Over the next several days, the patient had continued leukocytosis and hypothermia. She then developed acute encephalopathy and progressed to a comatose state, requiring intubation. EEG showed nonclinical seizures arising independently from bilateral posterior regions, which resolved with antiseizure medications. MRI Brain was absent for acute intracranial abnormalities. CSF gram stain revealed gram positive cocci.

The patient had refractory tachypnea for several days during the neurologic work-up that caused a severe primary respiratory alkalosis. A hyperventilation work-up was completed but was unrevealing for an alternative explanation other than CNH. Sedation and a paralytic drip were required to resolve the alkalosis. Hyperventilation remained improved after the paralytic drip was discontinued likely due to sedation being continued until the patient’s family decided to palliatively extubate the patient five days later. Of note, CNS empiric antibiotics were started the same day as sedation.

Discussion: Uncommon bacterial meningitis presentations are important to recognize so as to ensure a potentially fatal infection is treated. This case report aims to identify CNH as a novel meningitis presentation.