Related Experiment Video
Updated: Jan 13, 2026
07:53
Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation
Published on: September 13, 2015
22.6K
Central and peripheral excitability in restless limbs syndrome
Amedeo De Grado1,2,3,4, Gaia Fanella5,6, James Howells7
1Neurophysiology Unit, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', Milan, Italy.
Brain Communications
|January 12, 2026
Summary
Restless Legs Syndrome (RLS) involves neurological excitability changes, including reduced intracortical inhibition and altered sensorimotor integration, even in unaffected hand areas. Axonal excitability testing suggests hyperpolarization-activated currents may contribute to RLS symptoms.
Area of Science:
- Neuroscience
- Neurology
- Physiology
Background:
- Restless Legs Syndrome (RLS) affects up to 10% of the population, but its underlying mechanisms are poorly understood.
- Neurophysiological excitability testing offers a window into sensorimotor integration, ion channel function, and neural inhibition in RLS.
- Assessing both central nervous system (CNS) and peripheral nervous system (PNS) excitability provides a comprehensive view of neural involvement.
Purpose of the Study:
- To investigate widespread CNS and PNS excitability changes in RLS patients by examining cortical, spinal, and peripheral nerve function.
- To explore potential neural mechanisms, including sensorimotor integration and axonal ion channel dysfunction, in RLS.
- To analyze hand muscle excitability in RLS patients, offering insights beyond the typically affected lower limbs.
Main Methods:
- Threshold-tracking transcranial magnetic stimulation (TMS) assessed cortical excitability (short-interval and long-interval intracortical inhibition).
- Long-latency reflexes (LLRs) measured sensory-motor integration; F-waves, H-reflexes, and RIII-reflexes evaluated spinal cord excitability.
- Extended TRONDNF protocol examined axonal excitability.
Main Results:
- Reduced short-interval intracortical inhibition (SICI) and long-interval intracortical inhibition (LICI) were observed in RLS patients, particularly in the M1 hand area.
- Increased amplitude of the second component of the long-latency reflex (LLR) in the abductor pollicis brevis muscle indicated altered sensorimotor integration.
- Axonal excitability testing showed a graded increase in hyperpolarization-activated currents correlating with RLS symptom severity.
Conclusions:
- Reduced intracortical inhibition in RLS suggests cortical dysfunction, even in clinically unaffected brain regions.
- Altered sensorimotor integration at the cortical level is implicated in RLS pathophysiology.
- Hyperpolarization-activated currents may play a role in RLS symptom development or predisposition.
Related Concept Videos
01:27Restless Leg Syndrome and Night Terrors
473
Restless Leg Syndrome (RLS), also known as Willis-Ekbom disease, is a neurological disorder characterized by an uncontrollable urge to move the legs due to uncomfortable sensations. These sensations typically occur during periods of rest or inactivity, particularly when lying down or sitting, and can severely disrupt sleep.
The exact cause of RLS is not fully understood, but it is believed to involve dopamine, a neurotransmitter that helps regulate muscle movement. Imbalances in dopamine levels...
The exact cause of RLS is not fully understood, but it is believed to involve dopamine, a neurotransmitter that helps regulate muscle movement. Imbalances in dopamine levels...
473
01:09Peripherally and Centrally Acting Muscle Relaxants: A Comparison
4.5K
Skeletal muscle relaxants can target the central nervous system [CNS] to reduce muscle tension or act directly at the neuromuscular junction to induce temporary paralysis. These two classes of muscle relaxants are called centrally acting muscle relaxants and peripherally acting muscle relaxants. They differ in their action, mechanism, administration route, and clinical uses.
Centrally acting muscle relaxants can be further divided into spasmolytic and antispasmodic drugs. Spasmolytic...
Centrally acting muscle relaxants can be further divided into spasmolytic and antispasmodic drugs. Spasmolytic...
4.5K
01:24Local Anesthetics: Differential Sensitivity of Nerve Fibers
1.3K
Local anesthetics (LAs) block the sodium channels of nerve trunks, sensory nerve endings, and neuromuscular junctions. Although LAs can block all kinds of nerves, the sensitivity of nerve fibers differs according to nerve types and structures. LAs are known to block myelinated fibers faster than unmyelinated ones. Also, they block pain or sensory neurons at low concentrations without affecting the motor neurons involved in muscle contractions. This helps relieve labor pain without affecting the...
1.3K
01:15REM Sleep Behavior Disorder
1.3K
REM Sleep Behavior Disorder (RBD) is a sleep disorder characterized by the absence of muscle paralysis that normally occurs during the REM phase of sleep. This absence allows individuals to physically act out their dreams, which are often vivid and disturbing. Common behaviors exhibited during episodes include kicking, punching, and yelling. These actions can be dangerous, potentially leading to injuries for the person with RBD or their bed partner.
RBD is significantly associated with...
RBD is significantly associated with...
1.3K
01:24Centrally Acting Muscle Relaxants: Therapeutic Uses
1.2K
Centrally acting muscle relaxants reduce muscle tone and tension by interfering with the postsynaptic reflexes in the central nervous system.
Centrally acting drugs are classified into spasmolytic and antispasmodic drugs. Spasmolytic drugs such as baclofen, diazepam, and tizanidine inhibit spinal motor neurons and decrease muscle tone. Spasmolytic drugs are administered for severe and chronic spasms due to multiple sclerosis, cerebral palsy, stroke, and spinal cord and muscle injuries. However,...
Centrally acting drugs are classified into spasmolytic and antispasmodic drugs. Spasmolytic drugs such as baclofen, diazepam, and tizanidine inhibit spinal motor neurons and decrease muscle tone. Spasmolytic drugs are administered for severe and chronic spasms due to multiple sclerosis, cerebral palsy, stroke, and spinal cord and muscle injuries. However,...
1.2K
01:23Drugs Acting on Autonomic Ganglia: Stimulants
2.0K
Ganglionic stimulants activate NM nicotinic receptors in autonomic ganglia, falling into two categories: nicotine mimetics [e.g., lobeline, dimethylpiperazine, tetramethylammonium] and muscarinic receptor agonists [e.g., muscarine, methacholine]. The first category's action is rapid and blocked by nicotinic receptor antagonists, while the second category's action is delayed and blocked by atropine-like agents. Nicotine, an alkaloid, affects the heart rate by stimulating...
2.0K