Objective:To explore the magnetic resonance imaging(MRI) characteristics and classification of brainstem encephalitis combined with the enterovirus type 71(EV71) epidemic by analyzing 21 patients

and to identify the prognoses and explore the pathogenesis of brainstem encephalitis.Methods:21 cases of hand-foot-mouth disease(HFMD) with brainstem encephalitis during the recent EV71 outbreaks in Hainan Province

China from May 2008 to September 2010 were described

and literatures were reviewed.The recovery of their impairment was followed up for 3 months to 2 years.Results:According to the MRI features

brainstem encephalitis was classified into 2 types.In brainstem encephalitis Type Ⅰ(13 cases)

all lesions were presented as local

spotty and significantly hyperintense in the brainstem as seen in T2WI and hypointense in T1WI.Of the 13 cases

2 died

7 recovered

and 4 got improved with sequela.Lesions in medulla oblongata and pons were found in 2 cases in follow up.Brainstem encephalitis Type Ⅱ(8 cases) appeared to be blurred and slightly hyperintense in T2WI and hypointense in T1WI in the posterior portions of the brainstem.Of the 8 cases

6 recovered

and 2 got improved with sequela.Patients with brainstem encephalitis Type Ⅰ had a worse prognosis than those with Type Ⅱ.Conclusion:MRI is an effective method to investigate brainstem encephalitis combined with the enterovirus 71 epidemic.Posterior portions of the brainstem involvement are characteristic findings of enteroviral encephalomyelitis.The MRI based classification may be helpful in making a better estimation of prognosis.