Diagnosis and therapy of functional tremor a systematic review illustrated by a case report

Abstract

Background Diagnosis of functional movement disorders and specifically functional tremor (FT) (representing 50% of them) remains demanding. Additionally, due to heterogeneity of the disorders, structured concepts and guidelines for diagnosis and therapy are difficult to establish. Ascertaining the state of knowledge to derive instructions for operating procedures is the aim of this review. Main text Based on a standardized systematic literature research using the term “psychogenic tremor” in the MEDLINE database dating back ten years, 76 studies were evaluated. Conventional features of FT are variability of frequency and amplitude. Further, response to distraction by motor and cognitive tasks is a key diagnostic feature in differentiation between organic and functional origin. A variety of electrophysiological tests have been evaluated including surface electromyography and accelerometry to establish laboratory-supported criteria for diagnosing tremor. Also, finger tapping tests have been used to identify FT, showing positive potential as supplementary evidence. Imaging studies in general are mostly underpowered and imaging cannot be used on an individual basis. Therapeutic studies in FT often have a diagnostic component. Cognitive behavioral therapy should be the preferred psychological treatment independent of additional psychiatric symptoms. Other psychotherapeutic methods show lack of evidence concerning FT. Relaxation techniques and physiotherapy are an important additional feature, especially in children and adolescents. In regard to drug therapy, randomized and blinded trials are not available. A significant decrease in rating scales could be detected after active, not sham repetitive transcranial magnetic stimulation with a long-lasting effect. Also root magnetic stimulation seems to be effective. The clinical feature of tremor entrainment in FT can be used in combination with biofeedback as so-called tremor retrainment, using self-modulation of frequency and severity, to bring the movements under volitional control. Conclusion Diagnosis and treatment of FT is challenging and should include a combination of intensive clinical examination and targeted addition of standardized testing, especially electrophysiological methods. Often therapeutic effects have a diagnostic component. A multimodal strategy, considering psychological factors as a potential origin as well as maintaining effects seems to be most effective.

Terapia Cognitivo‐Comportamental no Tratamento dos Sintomas Neurológicos Funcionais/Dissociativos: Estado da Arte

“…A revisão sistemática de Bartl et al (2020) 19 focada no tratamento de tremor funcional, descreve que, apesar de os estudos existentes serem ainda de pequena escala, estudos cegos têm apontado que a TCC deve ser o tratamento psicológico preferencial; outros métodos psicoterapêuticos não demonstraram o mesmo nível de evidência. Referem um ensaio controlado aleatorizado (ECA) de Espay et al (2019) 20…”

“…Os estudos apresentam alguma evidência sobre a eficácia da TCC no tratamento de diferentes subtipos de SNF/D. No estudo de Bartl et al (2020) 19 sobre tratamento do tremor funcional, a TCC foi descrita como o tratamento psicológico preferencial, demonstrando redução significativa na severidade do tremor num ECA (Espay et al (2019)). 20 Para a tontura postural -perceptiva persistente, uma revisão sistemática (Trinidade et al (2018)) 21 sugeriu que a TCC, juntamente com outras abordagens multidisciplinares, como a reabilitação vestibular e inibidores da recaptação da serotonina e serotonina/noradrenalina, desempenha um papel importante no manejo desses casos.…”

Electrophysiology in Functional Movement Disorders: An Update

“…The EEG preceding the movement artifact is averaged over multiple trials of self-initiated movements and BP is identified as a slow rise in the EEG that is seen prior to the movement onset. BP recorded before the EMG activity in patients with functional myoclonus is similar in appearance to that of normal voluntary movements [9]. It was Kornhuber and Deecke who described BP for the first time in 1964.…”

“…Functional tremor (FT) is the most common form and represents about 50% of all FMDs [9]. FMDs are a great concern to the patient as it reduces the quality of life.…”

Investigation of Phase Shifts Using AUC Diagrams: Application to Differential Diagnosis of Parkinson’s Disease and Essential Tremor

“…Researchers have expressed different and sometimes directly opposite opinions on this issue. In particular, several publications indicate the possibility of the differential diagnosis of PD and ET by analyzing the phase difference in antagonist muscle EMG signals with high accuracy [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. However, other authors have discussed about the inapplicability of this approach to the differential diagnosis of PD and ET because it cannot provide acceptable accuracy [ 13 , 14 , 15 , 16 , 17 , 18 ].…”