![]() The tremor occurred only in the resting jaw position, with 10 episodes per day on an average, and lasted from 10 minutes to hours. A 40-year-old man presented with history of paroxysmal jaw tremor for 3 years with no other neurological symptoms, psychiatric conditions, or a family history of neurological disorders. Jaw tremor is usually associated with tremor or other abnormal involuntary movements affecting additional body parts, but isolated jaw tremor is a rare clinical presentation. However, limitations of the tests should be recognized, and the results should be interpreted together with clinical observations. Several reflex circuits, such as the long latency reflex, blink reflex and startle reflex, can be elicited with different types of external stimuli and are useful in the assessment of myoclonus, excessive startle and stiff person syndrome. ![]() Organic and functional cervical dystonia can potentially be distinguished by EMG power spectral analysis. EMG burst durations, distributions and muscle recruitment orders may identify and classify myoclonus to cortical, subcortical or spinal origins and help in the diagnosis of functional myoclonus. The presence of Bereitschafts-potentials and beta-band desynchronization recorded by EEG before movement onset provide strong evidence for functional movement disorders. The effects of voluntary tapping, ballistic movements and weighting of the limbs can help to distinguish between organic and functional tremors. Frequency and coherence analyses of sEMG signals may reveal the nature of tremors and the source of the tremors. The most commonly used measures are surface electromyography (sEMG), electroencephalography (EEG) and accelerometry. They are useful in the diagnosis of hyperkinetic movement disorders, particularly tremors and myoclonus. Application in a larger cohort, incorporation in a test battery, and validation studies, including quantitativeĮvaluation of suggestibility, are required to assess the reliability and the added value of this test.Įlectrophysiological studies can provide objective and quantifiable assessments of movement disorders. Suggestibility as an electrophysiologic criterion to aid in the diagnosis of FMD. Significance: This case series is an essential first step in evaluating the applicability of Results: We present three cases with equivocal clinical features, but with findings onĮlectrophysiologic studies that were consistent with “laboratory-supported definite” FMD.Ĭonclusion: When combined with other tests, demonstration of suggestibility inĮlectrophysiologic studies may increase the accuracy in differentiating functional from organic movement disorders. Recordings where suggestibility was included in the test battery were then selected. Methods: We retrospectively reviewed the electrophysiological studies performed in our center on patients with FMD. Future research on the neurochemical and anatomical characteristics of tremulous jaw movements could yield important insights into the brain mechanisms that generate tremulous movements.Objective: To evaluate the application of suggestibility in electrophysiological studies as a tool to increase the diagnostic certainty of “laboratory-supported definite” FMD. Striatal cholinergic and dopaminergic mechanisms are involved in the generation of tremulous jaw movements, and substantia nigra pars reticulata appears to be a major basal ganglia output region through which the jaw movements are regulated. Tremulous jaw movements are induced by many of the conditions that are associated with parkinsonism, and suppressed by several different antiparkinsonian drugs, including scopolamine, benztropine, l-DOPA, apomorphine, bromocriptine, amantadine and clozapine. These movements occur within the 3–7 Hz peak frequency range that is characteristic of parkinsonian tremor. Although the clinical significance of these movements has been a subject of some debate, considerable evidence indicates that the non-directed, chewing-like movements induced by cholinomimetics, dopamine antagonists and dopamine depletions have many of the characteristics of parkinsonian tremor. Several pharmacological and neurochemical conditions in rats induce `vacuous' or `tremulous' jaw movements.
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