Principles of Electrophysiological Assessments for Movement Disorders

Tremor Syndromes: An Updated Review

“…Careful assessment of these features may help in distinguishing functional tremor from other common diseases presenting with tremor including ET and PD ( 152 ). Electrophysiological assessment, using a scoring system, may provide additional information to support the diagnosis of functional tremor ( 150 , 154 ). However, it needs to be emphasized that the positive signs on the clinical examination mentioned above are the key to the diagnosis of functional tremor.…”

Suggestibility as a valuable criterion for laboratory-supported definite functional movement disorders

“…Physical examination findings include variability in frequency and distribution, distractibility with cognitive and motor tasks, entrainability, and suggestibility ( Hallett, 2016 ). Electrophysiologic studies (ES), including surface electromyography (sEMG) and EEG backaveraging, are occasionally needed to support the diagnosis, especially for functional tremor and myoclonus ( Chen and Chen, 2020 ). Thus, ES has been included in the most recent operational criteria for FMD, wherein cases with evidence from ES supportive of a diagnosis of FMD are considered “laboratory-supported definite” ( Gupta and Lang, 2009 ).…”

“…rectus abdominis muscle) 3. EMG burst duration longer than 1,000 msec 4. less consistent bursts, i.e., variable first muscle where EMG bursts are noted initially 5. presence of facial movements (particularly eye blinks) or vocalization together with the axial jerks 6. rapid conduction velocities (>16 m/sec) 7. presence of Bereitschaftspotential (Bereitschaftspotential has not been documented in organic myoclonus) 8. presence of event-related desynchronization (ERD) of the beta (13–30 Hz) or mu rhythms (8–12 Hz) from the sensorimotor area (C3/C4) Tics or movements resembling tics d 1. inconsistent pattern of muscle activation 2. presence of variability, entrainment and distractibility of the motor bursts 3. presence of late Bereitschaftspotential (although short duration Bereitschaftspotential can be seen in a proportion of patients with organic tics) a Adapted from Schwingenschuh et al, 2011 , Schwingenschuh et al, 2016 ; b Adapted from Brown and Thompson, 2001 , Pal, 2011 , Chen and Chen, 2020 ; c Adapted from Kang and Sohn, 2006 , van der Salm et al, 2010 , van der Salm et al, 2014 , Erro et al, 2013 , Chen and Chen, 2020 ; d Adapted from Vial et al, 2019 . …”

“… a Adapted from Schwingenschuh et al, 2011 , Schwingenschuh et al, 2016 ; b Adapted from Brown and Thompson, 2001 , Pal, 2011 , Chen and Chen, 2020 ; c Adapted from Kang and Sohn, 2006 , van der Salm et al, 2010 , van der Salm et al, 2014 , Erro et al, 2013 , Chen and Chen, 2020 ; d Adapted from Vial et al, 2019 . …”

Minimum Electromyographic Burst Duration in Healthy Controls: Implications for Electrodiagnosis in Movement Disorders

“…Electrophysiological investigations are widely used in the diagnosis of hyperkinetic movement disorders, most notably tremor and myoclonus, 1,2 where they may be helpful in identifying patients with functional hyperkinetic movement disorders. Electromyography, which is a commonly available modality, is perhaps the least challenging of the electrophysiological techniques in terms of data acquisition.…”