Changes in resting motor threshold of the tongue with normal aging and stroke.

AIM OF STUDY:To examine the resting motor threshold of the tongue in healthy adults and stroke survivors. METHODS:Thirty-five healthy adults were classified into three groups: Group 1 (19-38 years; n = 11), Group 2 (50-64 years; n = 12) and Group 3 (66-78 years; n = 12). Six chronic stroke survivors (mean age =59 years, SD = 9.1 years) were recruited (Group 4). The resting motor thresholds (RMTs) of the tongue were measured and compared (i) among the four groups and (ii) between stroke survivors and age-matched healthy adults. RESULTS:Group 3 showed significantly higher RMTs than Group 1 (p = .001) and 2 (p = 0.007). Group 4 showed significantly higher RMTs than Group 1 (p = .003) and 2 (p = .001). The RMTs of Group 3 and 4 were not significantly different (p = .385). The RMT was positively correlated with age (r = 0.534; p = .001). Group 4 showed significantly higher RMTs than the age-matched controls (U = 2.5, p = .009, r = 0.77). CONCLUSIONS:The resting motor threshold of the tongue is significantly increased in adults aged above 65 and in stroke survivors when compared with healthy adults. The findings suggested that the cortical excitability of the tongue deteriorates in the elderly and the stroke population.