Objective: To correlate subjective and objective symptom fluctuations in patients with a functional (FT) or organic tremor (OT). Furthermore, to study the contribution of factors like mood and stress to both subjective and objective symptom fluctuations.

Background: Functional movement disorders (FMDs) can resemble movement disorders like tremor but do not have a clear underlying neurological cause. Factors like stress or psychiatric disturbances only seem to be present in a subset of FMD patients. In addition, patients with functional tremor (FT) appear to experience a high level of subjective complaints in relation to objectively measured tremor [1].

Methods: Eleven tremor patients, five FT and six organic tremor (OT), completed a web based diary five times a day for 30 days. Patients scored every three hours items on subjective tremor complaints and positive and negative affect on a 1-100 VAS scale (subjective score). Besides, patients wore an accelerometer to record the tremor presence (objective score) during daytime. This accelerometer data was analysed using a previously validated algorithm [2]. Non-parametric tests were used to compare level of subjective or objective symptoms between FT and OT groups. Vector autoregressive modelling was applied to determine whether subjective factors predicted objective symptoms or vice versa.

Results: FT patients had a lower percentage of the time with tremor compared to OT patients (21.5% vs 34.5%, p < 0.001), whilst FT patients reported more subjective complaints (average score 38.0 vs 31.2, p <0.001). In FT, an increase in positive affect preceded an increase in subjective symptoms in one patient and a decrease in a second patient. In OT, an increase in positive affect preceded an increase in subjective symptoms in two patients (Parkinsonian and essential tremor). Positive and negative affect scores were not predictive for fluctuations in objective symptoms in any of the patients.

Conclusions: FT patients have more subjective tremor complaints compared to their objective tremor duration. Fluctuations in mood scores (mainly positive affect) predict subjective symptom fluctuations in a subset of FT and OT patients.

References: [1] Parees et al (2012). Believing is perceiving: mismatch between self-report and actigraphy in psychogenic tremor. Brain: 135; 117–123. [2] Martinez Manzanera et al (2016). “Tremor Detection Using Parametric and Non-Parametric Spectral Estimation Methods: A Comparison with Clinical Assessment”. PLoS One, 11, 6, pe0156822.

« Back to 2018 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/subjective-and-objective-complaints-of-functional-tremor-an-individual-approach/