A Case of Vaccine‐associated Paralytic Poliomyelitis

25 September 2000 Dear Editor A CASE OF VACCINE-ASSOCIATED PARALYTIC POLIOMYELITIS In a recent issue of the Journal of Paediatrics and Child Health, Edwards et al.1 described live poliovirus vaccine- associated acute flaccid paralysis (AFP) in a 4-month-old infant, 2 weeks after the second dose of the vaccine. The paralysis in the left leg led to 2 cm shortening of the leg, muscular wastage and flexion and/or extension of hip and ankle joints. A magnetic resonance imaging (MRI) scan of the spinal cord on admission was negative for any space occupying lesions. There was no information about a sagittal-spin proton-density weighted and T2 imaging of the anterior horn cells in the spinal cord. During an MRI of a 7-month-old boy who developed AFP of the left upper limb after an asthmatic attack, high-intensity areas were observed in the left anterior horns at the cervical 4–6 levels.2 At the Rhode Island Hospital, an MRI of the cervical spine of a 27-year-old man who developed AFP, 3 weeks after his 2-month-old infant was immunized with trivalent live poliovirus vaccine, revealed smooth hyperintense bands. Sagittal, spin-proton density-weighted and T2-weighted images showed involvement of areas corresponding to the anatomic locations of the ventral horn.3 In all probability, a T2-weighted imaging of the 4-month infant1 would have revealed spinal cord involvement during hospitalization. The clinical course of illness in the infant described by Edwards et al.1 might have been modified by an antiviral therapy. Interferon-α therapy within 24 h of admission halted disease progression in two patients: a 16-month-old infant and a 34-year-old man with AFP due to type-1 wild poliovirus and type-2 vaccine virus, were administered 1 and 3 million units, of interferon-α intramuscularly, respectively, for 16 days.4 Clinical improvement was evident within 24 h or so. Antiviral therapy with interferon-α or pleconaril after an indication of anterior horn cell involvement on MRI could be expected to ensure a prompt recovery with no residual damage. A recent World Health Organization report stated that 125 countries were free from poliomyelitis at the end of 1999. However, episodes of AFP attributable to non-polioviruses would continue in polio-free countries.5 MRI of a 4-year-old boy afflicted by Coxsackie type A10 on the second day of hospitalization revealed anterior horn cell involvement at T4–T10 levels.6 Surely, an earlier MRI indication regarding affliction of target neurons in the brain and spinal cord by neurotropic viruses, if followed by an antiviral therapy, should eliminate residual disability associated with episodes of AFP.1