Acute hemorrhagic leukoencephalopathy associated with influenza A (H1N1) virus

Acute hemorrhagic leukoencephalopathy (AHLE) is a rare condition associated with H1N1. In this condition the infection triggers an autoimmune response which results in perivascular demyelination and hemorrhage in the brain parenchyma.

We report a case of a patient who developed brain edema and herniation as a result of AHLE.

A 27-year-old presented to a community hospital with fever, dyspnea, and malaise and was found to have H1N1-associated pneumonia. Despite treatment he progressed to acute respiratory distress syndrome and required mechanical ventilation. Due to failure on conventional ventilation, he was transferred to our hospital and was placed on high-frequency oscillatory ventilation. He was showing improvement until day 6 of transfer to our hospital when he was suddenly noted to have a rise in his blood pressure followed by hypotension. The following morning he was noted to have non-reactive pupils and was declared brain dead. Autopsy of the brain was consistent with AHLE.

This case emphasizes the importance of awareness of this disease. The non-specific signs and symptoms, and the use of sedatives, make diagnosis challenging in the early stages of this disease. If suspected early, appropriate imaging can aid in the diagnosis. Treatment with immunosuppressive agents and plasmapheresis may prevent rapid progression and death. This is the first published case of AHLE in association with H1N1 that has been confirmed pathologically.