MRI characteristics of brainstem encephalitis in hand-foot-mouth disease induced by enterovirus type 71--will different MRI manifestations be helpful for prognosis?

The MRI characteristics of 21 HFMD patients with brainstem encephalitis resulting from EV71 infection were examined to identify lesion patterns helpful in disease classification and prognosis. The author reviewed the clinical and MRI data of 21 children with brainstem encephalitis infected during the EV71 outbreak in Hainan, China from May 2008 to September 2010. Thirteen cases of brainstem encephalitis were classified as type I based on unilateral or bilateral symmetrical patch-like hyperintense T₁ and T₂ MRI signals restricted to the posterior brainstem. In a significant minority of these cases (6/13), damage to the spinal ventral horn was also found. Among these 13 type I cases, 2 patients died, 7 recovered fully, and 4 suffered from various neurological sequelae. Eight cases were classified with type II brainstem encephalitis based on a vague, speckled hyperintense T₁ and T₂ signal pattern in the posterior brainstem. Six of these patients recovered fully, and 2 cases suffered from mild sequelae. Reexamination by MRI revealed an enduring lesion in only one type II case, restricted to the medulla oblongata. The prognosis of type II cases was better than that of type I cases. The lesion pattern revealed by MRI can distinguish type I from type II brainstem encephalitis due to EV71 infection and may prove valuable for prognosis. While lesions were usually located in the tegmental part of the brainstem in both patient groups, type I cases also demonstrated spinal, thalamic, and cortical lesions.