Case Presentation: A 65-year old man with a history of coronary artery disease, heart failure, and Crohn’s disease, who is a resident of northern Wisconsin presented with fevers, headache, and neck stiffness. Due to concern for meningitis, he was started empirically on Ceftriaxone, Vancomycin, Ampicillin, and Acyclovir. One day after initiation of therapy, he developed right lower extremity weakness, which progressed to flaccid paralysis of his right lower extremity over several days.On admission, his temperature was 102.9 °F, his heart rate was 90 bpm, and his blood pressure was 140/50mmHg. His physical exam was notable for normal bulk and tone in his bilateral upper and lower extremities. Strength in his upper extremities was 5/5. In his right lower extremity, right hip flexor, abductor, and adductor strength was 1/5, and knee flexion, knee extension, foot dorsiflexion, and plantar flexion was 0/5. Strength in his left lower extremity was 5/5 throughout. Achilles and patellar reflexes were absent in the right lower extremity but 2+ elsewhere. Sensation was intact to light touch, pinprick, cold, and vibration diffusely. Labs obtained revealed his cerebrospinal fluid (CSF) with 107 nucleated cells, of which 10% were neutrophils, 53% were lymphocytes, and 37% were monocytes. CSF glucose was 49 mg/100mL, and protein was 54mg/100mL. Serum and CSF West Nile Virus (WNV) IgM was positive. MRI lumbar spine with and without contrast showed enhancement of his lumbar and sacral nerve roots consistent with an aseptic meningitis. Once the WNV testing resulted, all anti-infectives were discontinued, and he was treated conservatively. By time of discharge, he had minimal recovery of strength in his right lower extremity. Nine months from his original presentation, he continued to have decreased strength in his right lower extremity with hip flexion strength 1/5, hip adduction strength 2/5, hip abduction 3/5. Right patellar and Achilles reflexes also remained absent.
Discussion: WNV is the most common of the arboviruses in the United States. Its transmission occurs between arthropods such as ticks and mosquitos to vertebrate hosts. While the majority of people infected are asymptomatic, up to 40% can have symptoms including fever, headache, malaise, nausea, vomiting, pharyngitis, maculopapular rash. Rare manifestations include neuro-invasive disease. Deficits are often described as “polio-like,” affecting the ventral horns and roots, in an acute, asymmetric fashion without sensory deficits. CSF studies have elevated protein, moderate pleocytosis, with a lymphocytic predominance, though can have neutrophilic predominance in early infection. Those with paralysis have varying degrees of recovery; one-third recover to baseline, one-third improve to some degree, and one-third do not improve.
Conclusions: This case is an example of a devastating and relatively uncommon presentation of WNV. Given the wide spectrum of disease, diagnosis is often not obvious, but should be considered in patients with an exposure history.