Effects of stroke-induced damage to swallow-related areas in the brain on swallowing mechanics of elderly patients.

AIM: Our objective was to determine the relationship between defective swallowing mechanics and the location of brain lesions in stroke patients.

METHODS

We evaluated swallowing mechanics in 37 stroke patients and 10 age-matched control subjects by videofluoroscopy. Subjects were asked to swallow 10 successive 1.0-mL and three successive 2.5-mL boluses of barium suspension at intervals of approximately 15-30 s. We measured oral transit time, pharyngeal delay time and pharyngeal transit time.

RESULTS

Patients could be divided into two groups based on the pharyngeal delay time for a 1.0-mL bolus swallow. One group showed little variation during successive swallowing tests, similar to the control group. In the other group pharyngeal delay times varied during successive trials often tending to increase with successive swallows. Magnetic resonance imaging studies of the brain revealed infarcts or hemorrhages in swallow-related areas in the latter group, while in the former group lesions were localized to areas unrelated to swallowing.

CONCLUSION

Damage to swallow-related areas may reduce their sensitivity to incoming signals from the oral cavity thereby impairing preparations to generate motor command signals and compromising their ability to send sufficient voluntary descending command signals to activate the swallowing central pattern generator located in the medulla. This deficiency becomes more evident with successive swallows and manifests as impaired swallowing mechanics.