Introduction: Atypical hemolytic uremic syndrome (aHUS) is a rare complement-mediated thrombotic microangiopathy causing renal and systemic injury. We present a unique case complicated by neuroinvasive West Nile virus encephalitis resulting in diagnostic and management challenges. Description: A 74-year-old male with a history of coronary artery disease, chronic kidney disease, hypertension, hypothyroidism, and seizure disorder was transferred from an outside facility for evaluation for possible thrombotic thrombocytopenic purpura (TTP) after presenting with stroke-like symptoms. The patient was febrile and encephalopathic and progressively worsened over several days requiring intensive care unit care. His workup included a negative CT scan of the head and electroencephalography, with labs showing anemia, thrombocytopenia, worsened renal function, elevated lactate dehydrogenase, low haptoglobin, and schistocytes on peripheral blood smear. ADAMTS13 activity was elevated, ruling out TTP. Complement studies showed low C4, and renal biopsy revealed thrombotic microangiopathy. Based on these findings, the patient was diagnosed with atypical hemolytic uremic syndrome (aHUS) and started on eculizumab. His hospital course was complicated by worsening encephalopathy and respiratory failure requiring intubation. Brain MRI was deferred due to metal in his forehead, which required the patient to be awake during imaging. Further infectious workup due to persistent fever and encephalopathy revealed positive cerebrospinal fluid IgM and IgG for West Nile virus, confirming West Nile virus encephalitis. Supportive care continued, but neurologic function did not significantly improve. Eventually, the patient experienced sudden cardiac arrest and despite full resuscitative efforts, he was pronounced deceased. Discussion: The coexistence of aHUS and neuroinvasive West Nile virus encephalitis creates overlapping clinical features that complicate differentiation from conditions like TTP. Treatment with eculizumab, while essential for aHUS, may cause immunosuppression that exacerbates viral infections, underscoring the need for careful diagnostic evaluation and multidisciplinary management.
Odeyemi et al. (Sun,) studied this question.