A Rare Case of Shared Paralysis

Abstract

Viral encephalomyelitis is an unusual and the most serious manifestation of infections caused by Flaviviruses, a group of small arboviruses with over 68 species including, West Nile virus, St Louis encephalitis virus, yellow fever virus, dengue virus and zika virus. Case Description: A 77-year-old male with a past history of hypertension and coronary artery disease, presented with high-grade fever, confusion, watery diarrhea and petechial rash on the lower extremities for one week during the month of September. No reported exposure to sick contacts, travel history, known tick or mosquito bites. Hemodynamics were stable but he was febrile (103 F) and lethargic. Neurological examination revealed diminished right corneal reflex, neck stiffness, positive Brudzinski and Kernig signs, quadriparesis (right greater than the left) with increased muscle tone, right leg clonus, bilateral absent lower extremity deep tendon reflexes and positive Babinski sign. Initial labs and imaging studies were unremarkable. Neutrophilic pleocytosis on CSF analysis prompted initiation of antibiotics (vancomycin, ampicillin, cefepime) and acyclovir. His neurological status continued to deteriorate and he developed "locked in syndrome" by the third day of hospitalization. Electromyography and pyridostigmine testing ruled out GBS and myasthenia gravis respectively. Blood and CSF cultures, CSF tick-borne panel, Leptospira, Lymphocytic choriomeningitis virus, Mycoplasma, and HSV were all negative. CSF studies revealed positive West Nile Virus (WNV) IgM and IgG. Later, Arbovirus serology demonstrated high titers of Saint Louis encephalitis (SLE) virus (1:1280). Repeat MRI brain showed abnormal enhancements in the cerebellum and pons. Hence, our patient was diagnosed with neuroinvasive viral encephalomyelitis and treatment with Interferon alpha and IV immunoglobulins was started resulting in substantial improvement within a few weeks. Discussion: Among Flavivirus encephalitids, WNV encephalitis and SLE are the two major public health threats in North America with common mode of transmission through mosquito bites. While encephalitis is not so uncommon, viral encephalomyelitis is an unusual neuroinvasive manifestation of these infections developing in less than 1% of the patients. Asymmetrical flaccid paralysis is the hallmark while other manifestations include meningoencephalitis, ophthalmoplegia, locked in syndrome and diaphragmatic paralysis due to brain stem involvement. Encephalitis is managed conservatively in the majority of the cases with more aggressive treatment in neuroinvasive forms. Treatment modalities for all forms of Flavivirus encephalitis are the same with ongoing research demonstrating some role of ribavirin, interferon alpha and IVIG. Prognosis is usually guarded which emphasizes more on the early recognition and timely initiation of appropriate treatment.