INTRODUCTION: Legionnaire's disease is a pneumonia syndrome that can have a variety of extrapulmonary manifestations. We describe a case of Legionnaire's that was associated with interval development of diffuse cerebral edema that subsequently resolved spontaneously.
CASE PRESENTATION: A 59 year-old female with a history of bipolar disorder and resident of a group home initially presented with a six day history of fatigue and myalgias, associated with a mildly productive cough, shortness of breath, pleuritic chest pain and diarrhea. Three days prior to admission she developed fevers and chills. In the ED the patient was normotensive, tachycardic and in moderate respiratory distress with an oxygen saturation of 92 percent on 2–4 liters of oxygen. Her lung exam was notable for bilateral crackles in the lower lung fields. Cardiac exam was significant for tachycardia. Abdominal, extremity/skin, and neurological exam were unremarkable. Relevant laboratory data included a BUN and creatinine of 83 mg/dL and 6.1 mg/dL, a sodium of 128 mmol/L, bicarbonate of 13 mmol/L, WBC count of 15.7 αL, and a CK of 16,810 U/L. A chest x-ray revealed bilateral lower lobe alveolar infiltrates. The patient was admitted to the ICU and was treated with ceftriaxone and azithromycin for community-acquired pneumonia. Intubation and mechanical ventilation were required for worsening hypercapnic respiratory failure. On hospital day 5, she suddenly became unresponsive and was noted to have unequal pupils; her left pupil measuring 4–5mm and the right pupil measuring 1–2 mm. Brain CT showed poor distinction of gray versus white matter, consistent with diffuse cerebral edema. On hospital day 6, the anisocoria resolved, her mental status began to improve, and a repeat brain CT done at that time showed interval resolution of the cerebral edema. The patient's mental status continued to improve and she was extubated on hospital day 8. Multiple respiratory cultures were negative, however, a urine legionella antigen sent at the time of admission returned positive. The patient was continued on a full course of azithromycin and was discharged on hospital day 11. At follow-up, she was found to have normal renal function, an almost completely normalized chest radiograph and normal mental status.
DISCUSSIONS: Legionnaire's disease, the pneumonia syndrome caused by bacteria of the genus Legionella is not an unusual cause of community acquired pneumonia; it's incidence varying between 2–15% of all cases that require hospitalization. It is an important cause to recognize as cases can be severe, with legionella ranking second to pneumococcal pneumonia in terms of ICU admissions and mortality. Often times, respiratory symptoms may not be prominent. Gastrointestinal symptoms such as diarrhea and abdominal pain are commonly associated with Legionnaire's. Other manifestations can include rashes, relative bradycardia and neuropathies. Laboratory findings can be varied as well, including a higher incidence of hyponatremia compared to other causes of pneumonia, as well as rhabdomyolysis In addition, the presence of neurologic signs, in particular confusion, can be seen in Legionnaire's disease. The incidence of neurologic signs in Legionnaire's is not well studied and can be present in 4–53% of cases. However the type of neurologic signs present are not well defined in the literature. It is plausible that the confusion seen in some hospitalized patients with Legionella pneumonia could be due to transient changes in intracerebral edema however this needs to be studied further.
CONCLUSION: Legionnaire's disease can be a cause of severe pneumonia, and some of its extrapulmonary manifestations, including neurologic abnormalities should be recognized as part of it's disease spectrum.
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