Myoclonus

Willi Gerschlager1, Peter Brown

  • 1Krankenhaus Hietzing mit Neurologischem Zentrum Rosenhügel, Vienna, Austria.

Abstract

Insights

Recent developments in myoclonus research have clarified causes and natural history for conditions like myoclonic dystonia and epilepsy. New insights into primary progressive myoclonus of aging are also emerging.

Area of Science:

  • Neurology
  • Movement Disorders

Background:

  • Myoclonus encompasses a range of involuntary muscle jerks.
  • Understanding the diverse etiologies and clinical presentations is crucial.

Purpose of the Study:

  • To review recent advancements in the field of myoclonus.
  • To synthesize new findings on myoclonic syndromes.

Main Methods:

  • Literature review of recent studies on myoclonus.
  • Analysis of clinical features, pathophysiology, and natural history.

Main Results:

  • Extended clinical features and defined pathophysiology of myoclonic dystonia.
  • Clarified causes of jerky tremor and orthostatic myoclonus, emphasizing drug-induced possibilities.
  • Improved understanding of the natural history of myoclonus with epilepsy, suggesting a potentially more benign course.
  • Identified primary progressive myoclonus of aging as a potential new entity.

Conclusions:

  • Significant progress in characterizing myoclonic syndromes, particularly those associated with dystonia and epilepsy.
  • Therapeutic options for myoclonus remain limited.
  • Functional neurosurgery may offer future therapeutic avenues for severe myoclonic syndromes.

Related Concept Videos

Alterations in Muscle Tone lll01:11

Alterations in Muscle Tone lll

Rigidity and myotonia are distinct abnormalities of muscle tone that affect resistance and relaxation during movement. Although both involve altered muscle contraction, they arise from different neurological and muscular mechanisms.CharacteristicsRigidity is characterized by uniform resistance to passive movement across the entire range, independent of speed, affecting flexors and extensors equally. It may appear as lead-pipe rigidity (smooth, constant resistance) or cogwheel rigidity...
Disorders of the Skeletal Muscle01:28

Disorders of the Skeletal Muscle

The clinical conditions affecting the skeletal muscle tissue are broadly categorized as musculoskeletal and neuromuscular disorders.
Musculoskeletal disorders
Musculoskeletal disorders involve injuries and conditions affecting the skeletal muscles and associated connective tissues. These disorders can arise from acute biomechanical stresses or chronic overuse and can occur across different age groups. Common injuries include sprains, fractures, and muscular strains, often resulting from...
Alterations in Muscle Tone ll01:12

Alterations in Muscle Tone ll

Alterations in muscle tone are common manifestations of neurological disorders and reflect dysfunction within different nervous system regions. Spasticity, paratonia, and dystonia represent distinct forms of hypertonia, each with unique mechanisms, clinical features, and diagnostic importance.CharacteristicsSpasticity happens from upper motor neuron lesions and is characterized by velocity-dependent resistance to passive movement. Clinical features include:Exaggerated deep tendon reflexesClonus...
Motor Unit Stimulation01:20

Motor Unit Stimulation

When the neuron of a motor unit fires an action potential, it triggers a series of events, leading to a twitch contraction in the muscle fibers. The process of excitation-contraction coupling is crucial in relaying the action potential to the muscle fibers.
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
Skeletal Muscle Relaxants: Adverse Effects01:21

Skeletal Muscle Relaxants: Adverse Effects

Skeletal muscle relaxants are widely used for muscle paralysis and relieving pain following any muscle injury or stiffness. However, depending on the drug type, they can have adverse effects that range from mild to severe. Usually, nondepolarizing neuromuscular blockers have minimal side effects. For example, drugs like d-tubocurarine, cisatracurium, and rocuronium cause hypotension, whereas drugs like baclofen, when stopped abruptly, can lead to the recurrence of spastic conditions.
Unlike...
Muscle Stimulation Frequency01:22

Muscle Stimulation Frequency

The contraction strength of muscles is regulated by motor neurons, which modulate the frequency of action potentials dispatched to the motor units based on the body's requirements. This process of varying the muscle stimulation frequency allows muscles to contract with a force that is precisely tailored to the needs of the moment, whether lifting a feather or a heavy box.
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...