Subject ReviewMyoclonus
Section snippets
Physiologic Characteristics and Clinical Identification of Myoclonus
Identifying the myoclonic jerk is the initial clinical goal. The appearance of the abnormal movement patterns of myoclonus can be appreciated by examining the electromyographic (EMG) discharge patterns. An EMG burst from the wrist flexor muscle group in a normal subject is shown in Figure I A; EMG was performed as quickly and briefly as possible. An EMG burst from the wrist flexor muscle group during myoclonus of the wrist in a patient is shown in Figure 1 B. This myoclonic burst was brief
Clinical Diagnostic Approach to Myoclonus
The best strategy for using the symptom of myoclonus in the diagnosis of its underlying is to view it within the context of the total clinical picture. Information obtained from the history and physical examination is no more important than the characterization of the associated clinical features. Aspects of the patient's history that aid in the diagnosis include history of drug or toxin exposure, history of seizures, past or current medical problems, and family history. Besides delineating the
Evaluation
Diagnostic testing should be considered an extension of the clinical examination. Such testing is usually necessary unless the diagnosis seems straightforward after elicitation of the history and performance of the physical examination. Basic tests (Table 3) should be done in most patients. If, after such testing, the diagnosis is still unknown, advanced testing (Table 3) should be considered. Expert referral may be useful if such detailed testing is indicated. Other testing may include
Treatment Considerations
Classifying the myoclonus and identifying its underlying disorder are especially critical goals relative to treatment considerations. Some causes of myoclonus are easily reversible, such as an acquired abnormal metabolic state, an excisable lesion, or a side effect of a medication. Physiologic myoclonus needs no management other than reassurance. If the myoclonus arises as part of an epileptic syndrome, standard anticonvulsant therapy is used and often includes valproic acid or clonazepam (or
Conclusion
Myoclonus consists of sudden, brief, shocklike, involuntary movements caused by muscular contractions or inhibitions. The cortex and brain stem are the most common origins. The term “myoclonus,” used by itself, is becoming increasingly nonspecific as the different variants are further defined by clinical, genetic, biochemical, and electrophysiologic means. Thus, the clinician must appreciate the differences among the types of myoclonus. A clinical approach based on the four etiologic
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Cited by (64)
Time-frequency analysis of intracranial EEG in patients with myoclonic seizures
2016, Brain ResearchCitation Excerpt :Despite the subcortical involvement, the cortical discharge precedes and drives the myoclonus event. Therefore, it is considered that myoclonic seizures are generalized without focal onset and are usually accompanied by generalized ictal epileptiform electroencephalogram (EEG) discharges (Caviness, 1996). The primary treatment for myoclonic seizures is antiepileptic drugs, but some seizures remain refractory to medication.
Physical Pain and Emotional Suffering: The Case for Palliative Sedation
2009, Journal of PainCitation Excerpt :This case presents the challenging syndrome of opioid-related myoclonus (ORM). Myoclonus describes involuntary, sudden, shock or jerk-like muscular contractions, usually of the extremities and head.6 Despite this, much of what we know about opioid-related myoclonus is based on anecdote and case reports; there are no widely accepted definitions of or measurement tool for ORM, nor have there been studies performed to specifically investigate its incidence, risk factors, or therapy.20
Familial Benign Neonatal Sleep Myoclonus
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