Changes in oro-facial function and hand-grip strength during a 2-year observation period after stroke

Recovery from stroke-related oro-facial impairment has rarely been investigated. In this longitudinal study chewing efficiency, maximum lip and bite force as well as masseter muscle thickness were evaluated and compared with hand-grip force. Thirty-one hospitalized stroke patients and 24 controls were recruited for this cohort study with 2-year follow-up. Chewing efficiency was evaluated with a color mixing ability test, lip forces with a traction dynamometer, bite force with a digital gauge, masseter muscle thickness using ultrasound measurements and grip strength with a hand dynamometer. During the 2-year observation period, patients were evaluated four times. A total of 21 patients dropped out of the study. Stroke patients showed significantly impaired chewing efficiency and lower lip forces than controls with no significant improvement over time. Bite forces were not different between ipsi- and contralesional sides, in contrast to contralesional hand-grip strength which was significantly impaired and did not improve during the observation period. On the first examination with a median of 40 days after stroke, masseter thickness was reduced contralesional, but did not continue to show significant side-differences during follow-up. Stroke affects the upper limb and the masseter muscles differently on a functional and morphological level. Further research is needed to evaluate the predictive value of oro-facial parameters on functional outcome after stroke. Impaired chewing efficiency and reduced lip force are quantifiable symptoms in stroke patients which seem not to improve in absence of oro-facial rehabilitation procedures.