Central apnea secondary to disseminated histoplasmosis
INTRODUCTION: Occupational exposures can be an important cause of pathology, especially in the respiratory system. Histoplasmosis is an endemic, yet oft-missed multisystem pathogen, which involves the central nervous system in up to 10% of cases (1). CASE PRESENTATION: A previously healthy man was found unresponsive in the driver's seat of his car in the parking lot at work; he did not arouse to narcan and was intubated. A new lung nodule with a "halo sign" prompted fungal work up, positive for urine and serum antigens consistent with disseminated histoplasmosis. Bronchoalveolar lavage and lumbar puncture fungal studies were negative. MRI had right cerebellar lesion and EEG showed left temporal focal delta waves. When ventilated he was well-appearing and followed commands, but failed initial extubation due to apnea and marked acidosis. He was initiated on amphotericin B and re-extubated, transitioned to 1 year azole. Urine drug screen was positive for methadone, a potential confounder, however the lack of response to narcan and his level of alertness while the ventilator was controlling his acid-base status makes opiates less likely. Later he admitted extensive exposure to bird feces over the month prior to admission; his work as a Heating, Ventilation, and Air Conditioning technician inside an old office building in the Midwestern United States involved "cleaning up dead birds." DISCUSSION: Mr. H's case is an atypical presentation in an atypical patient. While he did have a stereotypical lung nodule, his primary problem was neurologic, respiratory drive rather than the lung parenchyma. He was HIV-negative, not immunosuppressed, with excellent functional status. 5-10% of disseminated histoplasmosis will have CNS infection and up to half of those cases occurred in immunocompetent individuals (1). CNS histoplasmosis has varied symptoms; current review of literature does not yield any mentioning central apnea, however, one case series centered on the well-known outbreak in Indianapolis discussed 18 cases with CNS involvement, of which 4 had the presenting symptom of "coma" (1). Review of other cases (compilation of 104 case reports) showed that with CNS involvement of histoplasmosis, "altered level of consciousness" was present in 50% (1). CONCLUSIONS: Histoplasma capsulatum is an endemic mycose which can impact immunocompetent patients and involve the CNS. It is often taught in medical school that "histo hides" because it is notoriously difficult to detect; it is even harder to find if one is not looking for it, so careful review of imaging and thorough occupational history are critical to including fungal pathogens on the differential.
O'Connor D. Central apnea secondary to disseminated histoplasmosis. Chest. 2021 Oct;160(4 Supplement):A325. doi: 10.1016/j.chest.2021.07.328.