Lip and Jaw Tremor in Parkinson's Disease

Parkinson's disease (PD) is characterized clinically by the presence of bradykinesia, rigidity, and tremor. Although upper limb rest tremor is the most common form of tremor in PD, lip/jaw tremor is identified in a proportion of these patients.

We aimed to assess the frequency, features, and correlates of lip/jaw tremor in PD.

We studied 229 consecutive patients with PD. There were 39 (17%) patients with lip/jaw tremor, 22 of them (56.4%) were males. Slight lip/jaw tremor was identified in n = 10 (25.6%), mild in n = 15 (38.5%), moderate in n = 13 (33.3%) and severe in n = 1 (2.6%) case. Patients with lip/jaw tremor had a positive association with older age, greater limb rest tremor scores (P = 0.009), and higher total MDS-UPDRS-III scores (P < 0.001) in the multivariate regression analysis. There were 6 patients with isolated lip/jaw tremor (i.e. without limb rest tremor). These patients were all male (P = 0.038), tended to be older (75.7 vs. 67.7 years, P = 0.078) and had greater cognitive impairment (P = 0.034) than the rest of the cohort, but there was no association with other body tremors or total motor score.

Lip/jaw tremor was identified in 17% of cases; it was associated with greater motor severity and limb rest tremor, suggesting shared pathophysiology with limb rest tremor. A subgroup with isolated lip/jaw tremor showed reduced cognitive performance, but no association with other body tremors.