How to Do an Electrophysiological Study of Myoclonus

Abstract

Summary:Diagnosing and characterizing myoclonus can be challenging. Many authors agree on the need to complement the clinical findings with an electrophysiological study to characterize the movements. Besides helping to rule out other movements that may look like myoclonus, electrophysiology can help localize the source of the movement. This article aims to serve as a practical manual on how to do a myoclonus study. For this purpose, the authors combine their experience with available evidence. The authors provide detailed descriptions of recording poly-electromyography, combining electroencephalography and electromyography, Bereitschaftspotentials, somatosensory evoked potentials, and startle techniques. The authors discuss analysis considerations for these data and provide a simplified algorithm for their interpretation. Finally, the authors discuss some factors that they believe have hindered the broader use of these useful techniques.

Clinical Utility of Neurophysiologic Classification (and Declassification) of Myoclonus

“…In conclusion, this study provides extensive real-world evidence that MNS can effectively clarify movement classification and physiologic subtype in cases of possible myoclonus, and MNS findings are associated with clinically useful and impactful changes in diagnostic reasoning and patient treatment. Greater adoption and clinical use of these studies in movement specialty centers may be clinically beneficial for patient care: interested clinicians are referred to Supplement 1, recent practical reviews of myoclonus movement studies, 11,19 the new freely accessible Handbook of Clinical Neurophysiology: Movement Disorders series, 1,20 and the Movement Disorder Society (MDS) Clinical Neurophysiology Study Group (https://www.movementdisorders.org/MDS/About/Committees--Other-Groups/Study-Groups/Clinical-Neurophysiology.htm). Moreover, referral of cases of myoclonus and possible myoclonus to centers that perform MNS should be encouraged.…”

“…Reasons include lack of specialized training and equipment required to perform and interpret these studies, as well as lack of reimbursement schemes. 11,12 A majority of movement specialists perceive movement neurophysiology as clinically valuable and cost-beneficial, 12 and prior research has confirmed that MNS frequently result in changes in hyperkinetic movement classification, [13][14][15] but there has been limited demonstration of how this impacts real-world clinical management, particularly for myoclonus physiologic subtyping. MNS have been available at the Mayo Clinic in Arizona for clinical evaluation of patients with suspected myoclonus and other abnormal movements in the outpatient and inpatient settings since 1992.…”