Longitudinally extensive myelitis: a rare parainfectious neurological complication of dengue.

Dengue fever, transmitted by Aedes aegypti, can cause neurological complications in up to 5 % of cases. Longitudinally extensive myelitis is a rare complication that affects three or more spinal segments and may occur in para-infectious or post-infectious phases through direct viral invasion or immune-mediated mechanisms. We report a 34-year-old man with dengue who, on the fifth day of illness, developed paraparesis with urinary and fecal retention. Magnetic resonance imaging showed lesions from T2 to T12, and cerebrospinal fluid analysis revealed lymphocytic pleocytosis with no other infectious or autoimmune causes identified, confirming para-infectious longitudinally extensive myelitis. The patient received high-dose intravenous methylprednisolone and achieved complete recovery without relapses after eighteen months of follow-up. Diagnosis requires clinical correlation, magnetic resonance imaging, and cerebrospinal fluid analysis, since polymerase chain reaction is useful during the viremic phase. Treatment is based on early corticosteroids, reserving immunoglobulin or plasma exchange for refractory cases. This entity should be considered in endemic areas.