Objective: This study aimed to investigate the association between the clinical profiles and the side of tremor onset of patient with Parkinson’s Disease.

Background: Tremor is one of the cardinal symptoms of Parkinson’s disease (PD). Its onset differs in each patient. Whilst studies have shown some association between PD tremor onset laterality, and clinical profiles in some countries, it still remains unclear whether this association exist in patients from Tanzania.

Method: We conducted a cross-sectional study of 136 patients with PD, with presence of tremor at disease onset, from Hai Kilimanjaro and Dar es salaam regions. Clinical profile data included, sex, handedness, MDS-UPDRS III, and Hoehn & Yahr (H&Y) stage. Proportion, frequency and percentage were also sought.

Patients were stratified as left vs right sided tremor onset. Association between side of tremor onset and clinical characteristics were analyzed using chi-square test for categorical variables.

Results: Majority of patients had tremor onset on the right side (60.2%) vs left side (39.7%), were right-handed (83.1%), left-handed (9.6%) and ambidextrous (7.4%), with males constituting the largest majority (61.9%). The MDS-UPDRS III score showed tremor side having significant association with motor severity (p=0.002). With left-sided tremor having more severe motor impairment (55.6%) compared with right-sided tremor (46.3%). Moderate severity was more common in right-sided tremor (50.0%) vs left-sided tremor (25.9%). The association remained significant among males (p=0.007), where severe scores were more frequent in left-sided tremor (59.4%) than right-sided tremor (44.2%), with no difference in females (50%).

Using the (H&Y) stage, no difference in severity was observed between left and right-sided tremor (p=0.894) or after stratification by sex (female p=0.917; male p=0.959).

Furthermore, handedness was not associated with disease severity using H&Y stage (p = 0.285) and MDS-UPDRS III scale (p = 0.487).

Conclusion: The present study highlights the association between the side of tremor onset with sex, handedness and disease severity, in patients with Parkinson’s disease. These findings can pave the way for more individualized patient management and prognostic stratification. However, larger studies are needed to confirm this association.

Handedness and side of tremor onset

Side of tremor onset, sex and MDS UPDRS III SCORE

Side of tremor onset, sex, Hoehn and Yahr Stage

Handedness Hoehn & Yahr Stage and UPDRS Part III

References: 1.Roohani M, Shahidi G, Miri S. Demographic study of Parkinson’s disease in Iran: Data on 1656 cases. Iran J Neurol. 2011;10(1-2):19–21
2. Onder H, Teksut T et al. Symptom onset lateralization and bilaterality in Parkinson’s disease: Clinical implications of motor and non-motor profiles. Parkinsonism Relat D. 2025 Nov:140: 108056.doi: 10.1016/j.parkreldis.2025.108056
3. Baumann C, Held U et al. Body side and predominant motor features at the onset of Parkinson’s disease are linked to motor and nonmotor progression. Mov Disord2014 Feb;29(2): 207-13.doi: 10.1002/mds.25650
4. Solla P, Cannas A et al. Gender differences in motor and non-motor symptoms among Sardinian patients with Parkinson’s disease. J Neurol Sci. 2012 Dec 15;323(1-2): 33-9.doi: 10.1016

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MDS Abstracts - https://www.mdsabstracts.org/abstract/association-between-the-side-of-tremor-onset-and-clinical-profiles-of-patients-with-parkinsons-disease-in-rural-and-urban-tanzania/