Does the right or left hemisphere involvement affect swallowing in patients with hemiplegia?

Background: Stroke is one of the most important causes of swallowing difficulty. It is seen in one of every two patients with stroke. Although the swallowing function is controlled by both hemispheres, it is unknown which hemisphere is more dominant than another for controlling the swallowing function. However, the aspiration and pharyngeal phase dysfunction can be seen in right hemisphere involvement while oral phase dysfunction can be seen in left hemisphere involvement.

Objective: The aim of this study was to investigate whether water swallowing performance, deep cervical flexor muscle endurance, and maximum phonation time were affected in right handed patients with hemiplegia.

Study Design: The study was designed as a cross-sectional study.

Methods: Patients with unilateral strokes that damaged the right (Group I: n = 37) and left (Group II: n = 20) hemispheres were included. Swallowing difficulties were evaluated with the Turkish version of the Eating Assessment Tool. The water swallowing performance was measured with the 100 ml water swallow test. The muscle endurance (ME) of deep neck flexors was measured in the chin-tuck position. The laryngeal function was measured indirectly with maximum phonation time (MPT).

Results: The mean age of patients was 73.54±7.28 years in Group I and the mean age of patients was 73.15±6.94 years in Group II. There were no differences in maximum phonation time, water swallowing performance (swallow volume, capacity, and speed), and swallowing difficulty (p > 0.05). The neck flexor muscular endurance of patients with unilateral strokes that damaged the left hemisphere was better than the patients with unilateral strokes that damaged the right hemisphere (p < 0.05). There was a relationship between MPT and ME, MPT and swallowing difficulty, ME and swallowing difficulty (r:0.637, p:0.000; r:-0.465, p:0.004; r:-0.473, p:0.003 respectively) in the right hemisphere involvement patients. There was a relationship between swallowing difficulty to swallowing volume and swallowing capacity (respectively, r:-0.402 and p:0.014; r:-0.473 and p:0.003) in the patients with unilateral strokes that damaged the right hemisphere. There was no relationship between other parameters in Group I (p > 0.05). There was no relationship between all parameters in Group II (p > 0.05).

Conclusions: This study is the first study to investigate whether water swallowing performance, deep cervical flexor muscle endurance, and maximum phonation time were affected in right handed patients with unilateral strokes that damaged the right or left hemispheres. In light of the findings of the study, it was thought that swallowing should be evaluated in detail especially in hemiplegic patients with right hemisphere involvement. There is a need for studies examining the results of swallowing rehabilitation on right or left hemisphere in hemiplegic individuals.