Objective: To study dysphagia in pure, unilateral medullary infarction using video fluoroscopic swallowing (VFS) tests and to compare the results between lateral medullary infarction (LMI) and medial medullary infarction (MMI).
Methods: We studied 46 patients with medullary infarction (37 LMI, 9 MMI). Based on the MRI findings, each LMI was classified rostrocaudally as either a rostral or caudal lesion, and horizontally as either a superficial (lateral + dorsal) or nonsuperficial lesion. Each MMI was assigned to either a deep (lesion extending to the dorsal surface) or superficial lesion group. VFS examination was conducted and an 8-point scale was used for assessing the severity of dysphagia. Based on these results, dysphagia was classified as: 1) problems on timing of hyolaryngeal excursion (PT), and 2) problems on range of hyolaryngeal excursion (PR).
Results: Dysphagia was more frequent (p < 0.05) in MMI patients (78%) than in LMI patients (35%). Among the LMI patients, dysphagia was more frequent (p < 0.01) and severe (p < 0.01) in the rostral than in the caudal group and in the nonsuperficial than in the superficial group. In the MMI group, there was no difference in the frequency of dysphagia between the deep and superficial groups. Regarding the characteristics of dysphagia, seven (54%) of the LMI patients had PR, five (38%) had PT, and one (8%) had both. For the MMI patients, PT was frequent (86%) but PR was present in only one patient (14%). Five MMI patients (71%) showed no responses to penetration or aspiration, and silent dysphagia was observed in only four LMI patients (31%).
Conclusions: Dysphagia is as frequent and severe in medial medullary infarction (MMI) as in lateral medullary infarction (LMI) patients. The types and characteristics of dysphagia are different between the LMI and MMI patients, implicating the rationale for a different treatment strategy.