Topographic consideration on the occurrence of ipsilesional facial paresis in lateral medullary infarction.

INTRODUCTION: The purpose of this study was to identify course of corticobulbar tract and factors associated with the occurrence of facial paresis (FP) in lateral medullary infarction (LMI).

METHODS: Patients diagnosed with LMI who were admitted totertiary hospital were retrospectively investigated and divided into two groups based on the presence of FP. FP was defined as grade II or more by the House-Brackmann scale. Differences between the two groups were analyzed with respect to Anatomical location of the lesions, demographic data (age, sex), risk factors (diabetes, hypertension, smoking, prior stroke, atrial fibrillation and other cardiologic factors), large vessel involvement on magnetic resonance angiography, other symptoms and signs (sensory symptom, gait ataxia, limb ataxia, dizziness, Horner syndrome, hoarseness, dysphagia, dysarthria, nystagmus, nausea/vomiting, headache, neck pain, diplopia and hiccup).

RESULTS: Among 44 LMI patients, 15 patients (34%) had FP, and all of them had ipsilesional central type FP. The FP group tended to involve upper (p < 0.0001) and relative ventral (p = 0.019) part of lateral medulla. Horizontally large lesion was also related to the presence of FP (p = 0.044). Dysphagia (p = 0.001), dysarthria (p = 0.003) and hiccup (p = 0.034) were more likely to be accompanied by FP. Otherwise, there were no significant differences.

CONCLUSION: The results of present study indicate that the corticobulbar fibers innervating lower face decussate at the upper level of medulla and ascend through the dorsolateral medulla where the concentration of the fibers is densest near the nucleus ambiguus.