The Link Between Lateral Trunk Flexion In Parkinson’s Disease And Vestibular Dysfunction:a Clinical Study

Objective:Lateral trunk flexion(LTF)is a common postural deformity in Parkinson’s disease(PD);PD patients with LTF are more likely to have balance problems which are assumed as a result of the vestibular dysfunction.Therefore,the study was planned to investigate the link between LTF and vestibular function,in order to explain the reason of imbalance.Methods:We enrolled a total of 19 PD patients with LTF(LTF+)and 19 age-and sex-matched PD patients without LTF(LTF-).All patients completed vestibular tests,including spontaneous nystagmus,gaze-evoked nystagmus,ocular movements,optokinetic eye test,fast positioning maneuvers,and the bithermal caloric test.We also measured vestibular-evoked myogenic potential(VEMP),which included ocular VEMP(oVEMP)and cervical VEMP(cVEMP).Results:Most of the LTF+had abnormal vestibular function(11/19,57.9%),while there were fewer vestibular injuries in the control group(3/19,15.8%).The Fisher’s exact test showed that vestibular dysfunction was more obviously in LTF+group(p=0.017),and the difference in bithermal caloric test between the two groups was the greatest(p=0.038).According to stratified analysis by disease duration,LTF+had more vestibular function injuries than controls when their disease duration was less than 5 years with Fisher’s exact tests(p=0.015).In LTF+group,there were 5 patients of peripheral vestibular dysfunction,2 patients of central vestibular damage,and 4 patients of mixed injuries.The vestibular deficiencies could be either bilateral(7/11)or unilateral(4/11).The VEMP revealed absence of oVEMP responses in LTF+group was 18/18 cases(except for one case of incomplete examination),but only 11/18 cases in the control group were abnormal.The Fisher’s exact test showed that oVEMP was significantly absent in LTF+group(p=0.008).Conclusion:Vestibular dysfunction may be a risk factor for LTF in PD,when the disease duration is less than 5 years.Abnormalities of the vestibular tests combined with VEMP could be considered as a biomarker for the development of LTF in PD.