Postinfectious encephalomyelitis: Etiologic and diagnostic trends

Fifty cases of postinfectious encephalomyelitis admitted to our Pediatric Department during the period 1980 to 1997 were consecutively collected and reviewed. There were 28 males and 22 females. The age of onset ranged from 9 months to 14 years. The antecedent infections included measles (6 cases), rubella (5 cases), mumps (4 cases), chicken pox (4 cases), Epstein-Barr virus infection (11 cases), mycoplasma infection (6 cases), and unknown etiology (14 cases). The cessation of measles, rubella, and mumps as causes for encephalomyelitis in our patients corresponds with the introduction of a measles-mumps-rubella nationwide vaccination program in Taiwan commencing in 1992. The main clinical symptoms were fever, headache, and/or vomiting, seizure, and motor weakness. The presenting signs included altered consciousness, meningeal signs, cranial nerve palsy, brainstem signs, involuntary movement, and cerebellar signs. Computed tomography scans were abnormal for 14 (56%) of 25 patients studied, whereas magnetic resonance imaging (MRI) disclosed lesions in 14 (82%) of 17 patients, with abnormal signals in various parts of the cerebral hemisphere, as well as in the basal ganglion, diencephalon, midbrain, brain stem, and cerebellum. Of the three patients with negative MRI findings, an abnormal finding on somatosensory evoked potential was noted for one patient, and a focal decrease in tracer uptake on single photon emission computed tomography (SPECT) was found for the other two patients. This study demonstrates that the causative agents of postinfectious encephalomyelitis in Taiwan have changed from those of traditional exanthematous diseases to nonspecific respiratory infections and suggests that this may also be the case in other parts of the world. MRI remains the imaging method of choice, whereas other neurofunctional studies such as evoked potentials and SPECT are complementary for the diagnosis.