Investigators at Department of Pediatrics, Neurology Division, Adana Medical Research Center; and Division of Child Neurology, Ankara, Turkey, retrospectively evaluated 15 children with acute disseminated encephalomyelitis (ADEM) in children from the center in Adana. ADEM was seasonal, 73.3% cases presenting in winter or spring. The majority (13/15, 86.7%) had an acute febrile upper respiratory illness 2 to 40 days before presentation. Five children had serological evidence of specific triggers: mycoplasma (2), influenza-A (H1N1) (1 child), and Epstein-Barr virus (2 children). One patient had received a combined vaccine (DTPP-Haemophilus influenzae B) 6 weeks before onset. Gait disturbance (12/15, 80%) was the most common presenting symptom, followed by altered consciousness (10/15, 66.7%), fever (7/15, 46.7%), headache (4/15, 26.7%), seizures (4/15, 26.7%), meningismus (4/15, 26.7%), and vomiting (3/15, 20%). EEG recorded in 8 patients showed generalized slowing in 3 patients and focal epileptiform discharges in 1. CT scan obtained in 14 patients showed lesions in only 3 cases, whereas MRI revealed cerebral lesions in all 15 patients (with complete resolution following treatment in 12, partial in 2). Treatment in all cases was a standard protocol of 3 to 5 days of IV methylprednisolone and IV immunoglobulin for patients with persistent deterioration. Oseltamivir and clarithromycin were administered in patients with influenza-A and mycoplasma. Follow-up evaluation ranged from 0.6 to 4 years (median 1.8 years). Neurologic symptoms and signs resolved in 13 patients; one patient had severe neurologic sequelae, and one had recurrent attacks and a final diagnosis of MS. [1]

COMMENT. ADEM is an inflammatory demyelinating disease of the CNS that follows an infection or vaccination in three-quarters of the cases.

Post-vaccination ADEM. Several vaccines have been implicated including rabies, DTP, smallpox, measles, mumps, rubella, pertussis, and influenza [2]. A patient presenting with bilateral optic neuropathies within 3 weeks of “inactivated” influenza vaccination had a delayed onset of ADEM 3 months post-vaccination.

A case of ADEM is reported in a 34-month-old boy who presented with a seizure and left-sided weakness 5 days after vaccination against novel influenza A (H1N1). Following IV corticosteroids, symptoms improved and he recovered without neurologic sequelae [3]. A PubMed search found 5 reports of ADEM following 2009 H1N1 vaccination, one occurring simultaneously with Guillain-Barre disease [4]. With increased demand for mandatory vaccination for health-care workers, recognition of the occasional association of ADEM with influenza vaccine should prompt early diagnosis and steroid therapy.