Myotonia
Myotonia Congenita
NAV1.4 Voltage-Gated Sodium Channel
Myotonic Disorders
Myotonic Dystrophy
Chloride Channels
Paralyses, Familial Periodic
Mexiletine
Channelopathies
Paralysis, Hyperkalemic Periodic
Voltage-Gated Sodium Channel Blockers
Sodium Channels
Muscle Cramp
Orphenadrine
Muscle, Skeletal
Muscle Weakness
Electromyography
Hypokalemic Periodic Paralysis
The muscle chloride channel ClC-1 has a double-barreled appearance that is differentially affected in dominant and recessive myotonia. (1/89)
Single-channel recordings of the currents mediated by the muscle Cl- channel, ClC-1, expressed in Xenopus oocytes, provide the first direct evidence that this channel has two equidistant open conductance levels like the Torpedo ClC-0 prototype. As for the case of ClC-0, the probabilities and dwell times of the closed and conducting states are consistent with the presence of two independently gated pathways with approximately 1.2 pS conductance enabled in parallel via a common gate. However, the voltage dependence of the common gate is different and the kinetics are much faster than for ClC-0. Estimates of single-channel parameters from the analysis of macroscopic current fluctuations agree with those from single-channel recordings. Fluctuation analysis was used to characterize changes in the apparent double-gate behavior of the ClC-1 mutations I290M and I556N causing, respectively, a dominant and a recessive form of myotonia. We find that both mutations reduce about equally the open probability of single protopores and that mutation I290M yields a stronger reduction of the common gate open probability than mutation I556N. Our results suggest that the mammalian ClC-homologues have the same structure and mechanism proposed for the Torpedo channel ClC-0. Differential effects on the two gates that appear to modulate the activation of ClC-1 channels may be important determinants for the different patterns of inheritance of dominant and recessive ClC-1 mutations. (+info)Cardiac involvement in proximal myotonic myopathy. (2/89)
Proximal myotonic myopathy (PROMM) is a recently described autosomal dominantly inherited disorder resulting in proximal muscles weakness, myotonia, and cataracts. A few patients with cardiac involvement (sinus bradycardia, supraventricular bigeminy, conduction abnormalities) have been reported. The cases of three relatives with PROMM (weakness of neck flexors and proximal extremity muscles, calf hypertrophy, myotonia, cataracts) are reported: a 54 year old man, his 73 year old mother, and 66 year old aunt. All three presented with conduction abnormalities and one had repeated, life threatening, sustained monomorphic ventricular tachycardia. This illustrates that severe cardiac involvement may occur in PROMM. (+info)Potassium current suppression in patients with peripheral nerve hyperexcitability. (3/89)
Acquired neuromyotonia (Isaac's syndrome) is considered to be an autoimmune disease, and the pathomechanism of nerve hyperexcitability in this syndrome is correlated with anti-voltage-gated K(+) channel (VGKC) antibodies. The patch-clamp technique was used to investigate the effects of immunoglobulins from acquired neuromyotonia patients on VGKCs and voltage-gated Na(+) channels in a human neuroblastoma cell line (NB-1). K(+) currents were suppressed in cells that had been co-cultured with acquired neuromyotonia patients' immunoglobulin for 3 days but not for 1 day. The activation and inactivation kinetics of the outward K(+) currents were not altered by these immunoglobulins, nor did the immunoglobulins significantly affect the Na(+) currents. Myokymia or myokymic discharges, with peripheral nerve hyperexcitability, also occur in various neurological disorders such as Guillain-Barre syndrome and idiopathic generalized myokymia without pseudomyotonia. Immuno-globulins from patients with these diseases suppressed K(+) but not Na(+) currents. In addition, in hKv 1.1- and 1.6-transfected CHO (Chinese hamster ovary)-K1 cells, the expressed VGKCs were suppressed by sera from acquired neuromyotonia patients without a change in gating kinetics. Our findings indicate that nerve hyperexcitability is mainly associated with the suppression of voltage-gated K(+) currents with no change in gating kinetics, and that this suppression occurs not only in acquired neuromyotonia but also in Guillain-Barre syndrome and idiopathic generalized myokymia without pseudomyotonia. (+info)Increased hindrance on the chiral carbon atom of mexiletine enhances the block of rat skeletal muscle Na+ channels in a model of myotonia induced by ATX. (4/89)
1 The antiarrhythmic drug mexiletine (Mex) is also used against myotonia. Searching for a more efficient drug, a new compound (Me5) was synthesized substituting the methyl group on the chiral carbon atom of Mex by an isopropyl group. Effects of Me5 on Na+ channels were compared to those of Mex in rat skeletal muscle fibres using the cell-attached patch clamp method. 2 Me5 (10 microM) reduced the maximal sodium current (INa) by 29.7+/-4.4 % (n=6) at a frequency of stimulation of 0.3 Hz and 65.7+/-4.4 % (n=6) at 1 Hz. At same concentration (10 microM), Mex was incapable of producing any effect (n=3). Me5 also shifted the steady-state inactivation curves by -7. 9+/-0.9 mV (n=6) at 0.3 Hz and -12.2+/-1.0 mV (n=6) at 1 Hz. 3 In the presence of sea anemone toxin II (ATX; 5 microM), INa decayed more slowly and no longer to zero, providing a model of sodium channel myotonia. The effects of Me5 on peak INa were similar whatever ATX was present or not. Interestingly, Me5 did not modify the INa decay time constant nor the steady-state INa to peak INa ratio. 4 Analysis of ATX-induced late Na+ channel activity shows that Me5 did not affect mean open times and single-channel conductance, thus excluding open channel block property. 5 These results indicate that increasing hindrance on the chiral atom of Mex increases drug potency on wild-type and ATX-induced noninactivating INa and that Me5 might improve the prophylaxis of myotonia. (+info)Spectrum of sodium channel disturbances in the nondystrophic myotonias and periodic paralyses. (5/89)
Several heritable forms of myotonia and periodic paralysis are caused by missense mutations in the voltage-gated sodium channel of skeletal muscle. Mutations produce gain-of-function defects, either disrupted inactivation or enhanced activation. Both defects result in too much inward Na current which may either initiate pathologic bursts of action potentials (myotonia) or cause flaccid paralysis by depolarizing fibers to a refractory inexcitable state. Myotonic stiffness and periodic paralysis occur as paroxysmal attacks often triggered by environmental factors such as serum K+, cold, or exercise. Many gaps remain in our understanding of the interactions between genetic predisposition and these environmental influences. Targeted gene manipulation in animals may provide the tools to fill in these gaps. (+info)From tonus to tonicity: physiology of CLC chloride channels. (6/89)
Chloride channels are involved in a multitude of physiologic processes ranging from basal cellular functions such as cell volume regulation and acidification of intracellular vesicles to more specialized mechanisms such as vectorial transepithelial transport and regulation of cellular excitability. This plethora of functions is accomplished by numerous functionally highly diverse chloride channels that are only partially identified at the molecular level. The CLC family of chloride channels comprises at present nine members in mammals that differ with respect to biophysical properties, cellular compartmentalization, and tissue distribution. Their common structural features include a predicted topology model with 10 to 12 transmembrane regions together with two C-terminal CBS domains. Loss of function mutations affecting three different members of the CLC channel family lead to three human inherited diseases : myotonia congenita, Dent's disease, and Bartter's syndrome. These diseases, together with the diabetes insipidus symptoms of a knockout mouse model, emphasize the physiologic relevance of this ion channel family. (+info)Respiratory abdominal muscle recruitment and chest wall motion in myotonic muscular dystrophy. (7/89)
Abdominal muscles are selectively active in normal subjects during stress and may increase the potential energy for inspiration by reducing the end-expiratory lung volume (EELV). We hypothesized that a similar process would occur in subjects with myotonic muscular dystrophy (MMD), but would be less effective, because of to their weakness and altered chest wall mechanics. Fine-wire electromyography (EMG) of the transversus abdominis (TA), internal oblique (IO), external oblique, and rectus abdominis was recorded in 10 MMD and 10 control subjects. EMG activity, respiratory inductive plethysmography, and gastric pressure were recorded during static pressure measurement and at increasing levels of inspiratory resistance breathing. EELV was reduced and chest wall motion was synchronous only in controls. Although the TA and IO were selectively recruited in both groups, EMG activity of the MMD group was twice that of controls at the same inspiratory pressure. In MMD subjects with mildly reduced forced vital capacity, significant differences can be seen in abdominal muscle recruitment, wall motion, work of breathing, and ventilatory parameters. (+info)Increased rigidity of the chiral centre of tocainide favours stereoselectivity and use-dependent block of skeletal muscle Na(+) channels enhancing the antimyotonic activity in vivo. (8/89)
1. Searching for the structural requirements improving the potency and the stereoselectivity of Na(+) channel blockers as antimyotonic agents, new derivatives of tocainide, in which the chiral carbon atom is constrained in a rigid alpha-proline or pyrrolo-imidazolic cycle, were synthesized as pure enantiomers. 2. Their ability to block Na(+) currents, elicited from -100 to -20 mV at 0.3 Hz (tonic block) and 2-10 Hz (use-dependent block) frequencies, was investigated in vitro on single fibres of frog semitendinosus muscle using the vaseline-gap voltage-clamp method. 3. The alpha-proline derivative, To5, was 5 and 21 fold more potent than tocainide in producing tonic and 10 Hz-use-dependent block, respectively. Compared to To5, the presence of one methyl group on the aminic (To6) or amidic (To7) nitrogen atom decreased use-dependence by 2- and 6-times, respectively. When methylene moieties were present on both nitrogen atoms (To8), both tonic and use-dependent block were reduced. 4. Contrarily to tocainide, all proline derivatives were stereoselective in relation to an increased rigidity. A further increase in the molecular rigidity as in pyrrolo-imidazolic derivatives markedly decreased the drug potency with respect to tocainide. 5. Antimyotonic activity, evaluated as the shortening of the time of righting reflexes of myotonic adr/adr mice upon acute drug in vivo administration was 3 fold more effective for R-To5 than for R-Tocainide. 6. Thus, constraining the chiral centre of tocainide in alpha-proline cycle leads to more potent and stereoselective use-dependent Na(+) channel blockers with improved therapeutic potential. (+info)Myotonia is a condition characterized by the delayed relaxation of a muscle after voluntary contraction or electrical stimulation, resulting in stiffness or difficulty with relaxing the muscles. It's often associated with certain neuromuscular disorders such as myotonic dystrophy and myotonia congenita. The prolonged muscle contraction can cause stiffness, especially after periods of rest, and may improve with repeated contractions (warm-up phenomenon).
Myotonia Congenita is a genetic muscle disorder characterized by delayed relaxation after voluntary muscle contraction, leading to stiffness or difficulty in relaxing the muscles following use. This muscle stiffness is called myotonia and can be aggravated by voluntary muscle action, such as handgrip or walking, and also occurs after periods of rest.
There are two main forms of Myotonia Congenita: Thomsen's disease (autosomal dominant inheritance) and Becker's disease (autosomal recessive inheritance). The disorder is caused by mutations in the CLCN1 gene, which encodes a chloride channel that helps regulate muscle excitability.
Myotonia Congenita primarily affects skeletal muscles, causing stiffness and cramping, but it does not typically affect muscle strength or size. Symptoms usually begin in childhood and may improve with repeated muscle use (warm-up phenomenon). Treatment options include medication to reduce muscle stiffness and physical therapy to maintain muscle flexibility and strength.
NAV1.4, also known as SCN4A, is a gene that encodes for the α subunit of the voltage-gated sodium channel in humans. This channel, specifically located in the skeletal muscle, is responsible for the rapid influx of sodium ions during the initiation and propagation of action potentials, which are critical for muscle contraction.
The NAV1.4 Voltage-Gated Sodium Channel plays a crucial role in the functioning of skeletal muscles. Mutations in this gene can lead to various neuromuscular disorders such as hyperkalemic periodic paralysis, paramyotonia congenita, and potassium-aggravated myotonia, which are characterized by muscle stiffness, cramps, and episodes of weakness or paralysis.
Myotonic disorders are a group of genetic muscle diseases characterized by the inability to relax muscles (myotonia) after contraction. Myotonia can cause symptoms such as stiffness, muscle spasms, and prolonged muscle contractions or cramps. These disorders may also be associated with other symptoms, including muscle weakness, wasting, and various systemic features.
The most common myotonic disorder is myotonic dystrophy type 1 (DM1), which is caused by a mutation in the DMPK gene. Myotonic dystrophy type 2 (DM2) is another form of myotonic dystrophy, resulting from a mutation in the CNBP gene. These two forms of myotonic dystrophy have distinct genetic causes but share similar clinical features, such as myotonia and muscle weakness.
Other less common myotonic disorders include:
1. Myotonia congenita - A group of inherited conditions characterized by muscle stiffness from birth or early childhood. There are two main types: Thomsen's disease (autosomal dominant) and Becker's disease (autosomal recessive).
2. Paramyotonia congenita - An autosomal dominant disorder characterized by muscle stiffness triggered by cold temperatures or physical exertion.
3. Potassium-aggravated myotonia (PAM) - A rare, autosomal dominant condition with symptoms similar to paramyotonia congenita but without the cold sensitivity.
4. Myotonia fluctuans - A rare, autosomal dominant disorder characterized by fluctuating muscle stiffness and cramps.
5. Acquired myotonia - Rare cases of myotonia caused by factors other than genetic mutations, such as medication side effects or underlying medical conditions.
Myotonic disorders can significantly impact a person's quality of life, making daily activities challenging. Proper diagnosis and management are essential to help alleviate symptoms and improve overall well-being.
Myotonic dystrophy is a genetic disorder characterized by progressive muscle weakness, myotonia (delayed relaxation of muscles after contraction), and other symptoms. It is caused by an expansion of repetitive DNA sequences in the DMPK gene on chromosome 19 (type 1) or the ZNF9 gene on chromosome 3 (type 2). These expansions result in abnormal protein production and accumulation, which disrupt muscle function and can also affect other organs such as the heart, eyes, and endocrine system. Myotonic dystrophy is a progressive disease, meaning that symptoms tend to worsen over time. It is typically divided into two types: myotonic dystrophy type 1 (DM1), which is more common and severe, and myotonic dystrophy type 2 (DM2), which tends to be milder with a later onset of symptoms.
Chloride channels are membrane proteins that form hydrophilic pores or gaps, allowing the selective passage of chloride ions (Cl-) across the lipid bilayer of cell membranes. They play crucial roles in various physiological processes, including regulation of neuronal excitability, maintenance of resting membrane potential, fluid and electrolyte transport, and pH and volume regulation of cells.
Chloride channels can be categorized into several groups based on their structure, function, and mechanism of activation. Some of the major classes include:
1. Voltage-gated chloride channels (ClC): These channels are activated by changes in membrane potential and have a variety of functions, such as regulating neuronal excitability and transepithelial transport.
2. Ligand-gated chloride channels: These channels are activated by the binding of specific ligands or messenger molecules, like GABA (gamma-aminobutyric acid) or glycine, and are involved in neurotransmission and neuromodulation.
3. Cystic fibrosis transmembrane conductance regulator (CFTR): This is a chloride channel primarily located in the apical membrane of epithelial cells, responsible for secreting chloride ions and water to maintain proper hydration and mucociliary clearance in various organs, including the lungs and pancreas.
4. Calcium-activated chloride channels (CaCCs): These channels are activated by increased intracellular calcium concentrations and participate in various physiological processes, such as smooth muscle contraction, neurotransmitter release, and cell volume regulation.
5. Swelling-activated chloride channels (ClSwells): Also known as volume-regulated anion channels (VRACs), these channels are activated by cell swelling or osmotic stress and help regulate cell volume and ionic homeostasis.
Dysfunction of chloride channels has been implicated in various human diseases, such as cystic fibrosis, myotonia congenita, epilepsy, and certain forms of cancer.
Familial periodic paralysis is a group of rare genetic disorders characterized by episodes of muscle weakness or paralysis that recur over time. There are several types of familial periodic paralysis, including hypokalemic periodic paralysis, hyperkalemic periodic paralysis, and normokalemic periodic paralysis, each with its own specific genetic cause and pattern of symptoms.
In general, these disorders are caused by mutations in genes that regulate ion channels in muscle cells, leading to abnormalities in the flow of ions such as potassium in and out of the cells. This can result in changes in muscle excitability and contractility, causing episodes of weakness or paralysis.
The episodes of paralysis in familial periodic paralysis can vary in frequency, duration, and severity. They may be triggered by factors such as rest after exercise, cold or hot temperatures, emotional stress, alcohol consumption, or certain medications. During an episode, the affected muscles may become weak or completely paralyzed, often affecting the limbs but sometimes also involving the muscles of the face, throat, and trunk.
Familial periodic paralysis is typically inherited in an autosomal dominant pattern, meaning that a child has a 50% chance of inheriting the disorder if one parent is affected. However, some cases may arise from new mutations in the affected gene and occur in people with no family history of the disorder.
Treatment for familial periodic paralysis typically involves avoiding triggers and managing symptoms during episodes. In some cases, medications such as potassium-binding agents or diuretics may be used to help prevent or reduce the severity of episodes. Lifestyle modifications, such as a low-carbohydrate or high-sodium diet, may also be recommended in some cases.
Mexiletine is defined as an antiarrhythmic agent, classified as a Class IB medication. It works by blocking sodium channels in the heart, which helps to stabilize cardiac membranes and reduces the rate of firing of cardiac cells. This makes it useful for treating certain types of irregular heart rhythms (ventricular arrhythmias).
Mexiletine is also known to have analgesic properties and is sometimes used off-label for the treatment of neuropathic pain. It is available in oral form, and its use should be under the close supervision of a healthcare provider due to its potential side effects, which can include gastrointestinal symptoms, dizziness, tremors, and cardiac arrhythmias.
Channelopathies are genetic disorders that are caused by mutations in the genes that encode for ion channels. Ion channels are specialized proteins that regulate the flow of ions, such as sodium, potassium, and calcium, across cell membranes. These ion channels play a crucial role in various physiological processes, including the generation and transmission of electrical signals in the body.
Channelopathies can affect various organs and systems in the body, depending on the type of ion channel that is affected. For example, mutations in sodium channel genes can cause neuromuscular disorders such as epilepsy, migraine, and periodic paralysis. Mutations in potassium channel genes can cause cardiac arrhythmias, while mutations in calcium channel genes can cause neurological disorders such as episodic ataxia and hemiplegic migraine.
The symptoms of channelopathies can vary widely depending on the specific disorder and the severity of the mutation. Treatment typically involves managing the symptoms and may include medications, lifestyle modifications, or in some cases, surgery.
Hyperkalemic periodic paralysis (HypPK) is a rare genetic disorder characterized by episodes of muscle weakness or paralysis due to an abnormality in the ion channels that regulate the movement of potassium into and out of muscle fibers. This results in an excessive accumulation of potassium in the blood (hyperkalemia) during attacks, which can interfere with the ability of nerve cells to communicate with muscles and cause temporary muscle weakness or paralysis.
HypPK is caused by mutations in the SCN4A gene, which encodes a sodium channel protein found in skeletal muscle. These genetic changes disrupt the normal functioning of the ion channels, leading to an imbalance in the flow of ions across the muscle cell membrane and affecting muscle excitability.
Episodes of paralysis in HypPK typically begin in childhood or adolescence and can last from several hours to days. Triggers for attacks may include rest following exercise, cold or hot weather, stress, alcohol consumption, infection, or certain medications. Between episodes, individuals with HypPK usually have normal muscle strength and function.
Management of HypPK includes avoiding triggers, maintaining a low-potassium diet, and using medications to prevent or treat attacks. Medications such as thiazide diuretics, acetazolamide, or dichlorphenamide can help lower potassium levels in the blood and reduce the frequency and severity of episodes. In some cases, intravenous glucose and insulin may be used to drive potassium into cells during an attack, thereby reducing its concentration in the blood and alleviating symptoms.
Voltage-gated sodium channel blockers are a class of pharmaceutical drugs or toxins that work by inhibiting the function of voltage-gated sodium channels. These channels are crucial for the initiation and propagation of action potentials in excitable cells, such as neurons and muscle fibers. By blocking these channels, the drug reduces the flow of sodium ions into the cell, which stabilizes the membrane potential and prevents or reduces the generation of action potentials.
This class of drugs is used to treat a variety of medical conditions, including cardiac arrhythmias, neuropathic pain, and epilepsy. Examples of voltage-gated sodium channel blockers include Class I antiarrhythmics such as lidocaine, flecainide, and propafenone, as well as some antiepileptic drugs like carbamazepine and lamotrigine. Some toxins, such as those found in certain types of cone snails and spiders, also act as voltage-gated sodium channel blockers.
Sodium channels are specialized protein structures that are embedded in the membranes of excitable cells, such as nerve and muscle cells. They play a crucial role in the generation and transmission of electrical signals in these cells. Sodium channels are responsible for the rapid influx of sodium ions into the cell during the initial phase of an action potential, which is the electrical signal that travels along the membrane of a neuron or muscle fiber. This sudden influx of sodium ions causes the membrane potential to rapidly reverse, leading to the depolarization of the cell. After the action potential, the sodium channels close and become inactivated, preventing further entry of sodium ions and helping to restore the resting membrane potential.
Sodium channels are composed of a large alpha subunit and one or two smaller beta subunits. The alpha subunit forms the ion-conducting pore, while the beta subunits play a role in modulating the function and stability of the channel. Mutations in sodium channel genes have been associated with various inherited diseases, including certain forms of epilepsy, cardiac arrhythmias, and muscle disorders.
A muscle cramp is an involuntary and forcibly contracted muscle that does not relax. It can involve partial or complete muscle groups, often occurring in the legs and feet (hamstrings, quadriceps, calves, and foot intrinsic muscles) during or after exercise, at night, or while resting. The exact cause of muscle cramps is unclear, but they can be associated with muscle fatigue, heavy exercising, dehydration, electrolyte imbalances, or underlying medical conditions (e.g., nerve compression or disorders, hormonal imbalances). The primary symptom is a sudden, sharp pain in the affected muscle, which may be visibly tightened and hard to touch. Most muscle cramps resolve on their own within a few minutes, but gentle stretching, massage, or applying heat/cold can help alleviate discomfort.
Orphenadrine is an anticholinergic and skeletal muscle relaxant drug. It is primarily used to treat symptoms associated with muscle pain and stiffness, such as those caused by strains, sprains, or other muscle injuries. Orphenadrine works by blocking the action of acetylcholine, a neurotransmitter that plays a role in muscle contraction. This helps to reduce muscle spasms and relieve pain. It is available in immediate-release and extended-release forms, and is often prescribed in combination with other medications, such as aspirin or acetaminophen, to provide additional pain relief.
It's important to note that Orphenadrine can have side effects, including dizziness, dry mouth, blurred vision, and constipation. It should be used under the direction of a healthcare professional, and patients should follow their instructions carefully when taking this medication. Additionally, it may interact with other medications, so it's important to inform your doctor about all the medications you are currently taking before starting on Orphenadrine.
Skeletal muscle, also known as striated or voluntary muscle, is a type of muscle that is attached to bones by tendons or aponeuroses and functions to produce movements and support the posture of the body. It is composed of long, multinucleated fibers that are arranged in parallel bundles and are characterized by alternating light and dark bands, giving them a striped appearance under a microscope. Skeletal muscle is under voluntary control, meaning that it is consciously activated through signals from the nervous system. It is responsible for activities such as walking, running, jumping, and lifting objects.
Muscle weakness is a condition in which muscles cannot develop the expected level of physical force or power. This results in reduced muscle function and can be caused by various factors, including nerve damage, muscle diseases, or hormonal imbalances. Muscle weakness may manifest as difficulty lifting objects, maintaining posture, or performing daily activities. It is essential to consult a healthcare professional for proper diagnosis and treatment of muscle weakness.
Electromyography (EMG) is a medical diagnostic procedure that measures the electrical activity of skeletal muscles during contraction and at rest. It involves inserting a thin needle electrode into the muscle to record the electrical signals generated by the muscle fibers. These signals are then displayed on an oscilloscope and may be heard through a speaker.
EMG can help diagnose various neuromuscular disorders, such as muscle weakness, numbness, or pain, and can distinguish between muscle and nerve disorders. It is often used in conjunction with other diagnostic tests, such as nerve conduction studies, to provide a comprehensive evaluation of the nervous system.
EMG is typically performed by a neurologist or a physiatrist, and the procedure may cause some discomfort or pain, although this is usually minimal. The results of an EMG can help guide treatment decisions and monitor the progression of neuromuscular conditions over time.
Hypokalemic Periodic Paralysis (HPP) is a group of rare inherited disorders characterized by episodes of muscle weakness or paralysis, often associated with low potassium levels in the blood (hypokalemia). During an attack, muscles may become weak or fully paralyzed, typically affecting the legs and arms. The episodes can last from several hours to days. HPP is caused by genetic mutations that affect ion channels in muscle cells, leading to an imbalance of electrolytes and impaired muscle function. There are two main types: primary (or classic) HPP and secondary HPP. Primary HPP is further divided into thyrotoxic HPP and normokalemic HPP. Secondary HPP can be caused by various factors, such as medications or underlying medical conditions that cause hypokalemia.
Electrodiagnosis, also known as electromyography (EMG), is a medical diagnostic procedure that evaluates the health and function of muscles and nerves. It measures the electrical activity of skeletal muscles at rest and during contraction, as well as the conduction of electrical signals along nerves.
The test involves inserting a thin needle electrode into the muscle to record its electrical activity. The physician will ask the patient to contract and relax the muscle while the electrical activity is recorded. The resulting data can help diagnose various neuromuscular disorders, such as nerve damage or muscle diseases, by identifying abnormalities in the electrical signals.
Electrodiagnosis can be used to diagnose conditions such as carpal tunnel syndrome, peripheral neuropathy, muscular dystrophy, and amyotrophic lateral sclerosis (ALS), among others. It is a valuable tool in the diagnosis and management of neuromuscular disorders, helping physicians to develop appropriate treatment plans for their patients.
Myotonia
Myotonia congenita
Potassium-aggravated myotonia
Fainting goat
New Forest pony
Chromosome 7
List of OMIM disorder codes
Muscle contracture
Metabolic myopathy
Pseudoathletic appearance
CLCN1
John David Spillane
Mecasermin rinfabate
Brody myopathy
Channelopathy
Myotonic dystrophy
Paramyotonia congenita
Richard Lindsey Batten
Chloride channel blocker
Nav1.4
Harald Jockusch
Center for Molecular Neurobiology Hamburg
CBS domain
G6PC3
Hoffmann syndrome
Kocher-Debre-Semelaigne syndrome
Ball and chain inactivation
Atrophy
PURA syndrome
Magnesium transporter
Myotonia - Wikipedia
Potassium-aggravated myotonia: MedlinePlus Genetics
MedlinePlus - Search Results for: "Myopathy," granulovacuolar "lobular," with electrical myotonia
Myotonia Congenita
PARAMYOTONIA CONGENITA & SODIUM CHANNEL MYOTONIA: ARE THEY DISTINCT DISEASES? | Journal of Neurology, Neurosurgery & Psychiatry
Clinical Trials : Myotonia Atrophica
What Is Myotonia? - Klarity Health Library
Myotonia Congenita - Pediatrics - MSD Manual Professional Edition
AKUTNĚ.CZ Anaesthesia in myotonia congenita Becker
Myotonia Atrophica - Causes, Symptoms, Treatment - Health | RXharun
Osteochondrodysplasias - Medical Dictionary online-medical-dictionary.org
Nexien BioPharma Advances in Clinical Use of a Cannabinoid-Based Formulation for the Treatment of Myotonic Dystrophies and...
myotonia congenita sound - myotonia congenita pronunciation - how to pronounce myotonia congenita
A case report of recessive myotonia congenita and early onset cognitive impairment
Events - Pharmacology & Physiology - University of Rochester Medical Center
Genetics 101 | PPT
Quest Magazine | Muscular Dystrophy Association
Periodic Paralyses: Background, Pathophysiology, Epidemiology
Periodic Paralyses Follow-up: Prognosis, Patient Education
Focal seizures in a patient with myotonic disorder type 2 co-segregating with a chloride voltage-gated channel 1 gene mutation:...
List of Rare Diseases | A-Z Database | NORD
The non-dystrophic myotonias: Molecular pathogenesis, diagnosis and treatment<...
Potassium Phosphate/Sodium Phosphate: Uses, Side Effects
Automatic Detection of Myotonia using a Sensory Glove with Resistive Flex Sensors and Machine Learning Techniques - synbrAIn -...
Clinical and research tests for C0015644 - Genetic Testing Registry (GTR) - NCBI
Biophysical characterization of M1476I, a sodium channel founder mutation associated with cold-induced myotonia in French...
The Triumph Of Time Over Space with Orges Thu May 27, 2004 - KZSU Music - Zookeeper Online
Myotonic9
- Myotonia is the defining symptom of many channelopathies (diseases of ion channel transport) such as myotonia congenita, paramyotonia congenita and myotonic dystrophy. (wikipedia.org)
- Myotonia Atrophica / Myotonic dystrophy is characterized by progressive multisystem genetic impairment in relaxation of muscles after voluntary contraction due to repetitive depolarization of the muscle membrane disorders muscle wasting and weakness. (rxharun.com)
- Myotonia, due to myotonic dystrophy, improves with repeated exercise and is worsened by exposure to cold. (rxharun.com)
- Mild Myotonic Dystrophy - The mild form of DM1 or the oligosymptomatic form is associated with mild weakness, myotonia, and cataracts that begin between 20 to 70 years (typically after age 40 years). (rxharun.com)
- Denver, Colorado, November 5, 2018 /AxisWire/ Nexien BioPharma Inc. (OTC QB: NXEN) ("Nexien" or the "Company") announced that it was initiating an investigation into the use of cannabinoid-based formulations for the treatment of patients suffering from Myotonic Dystrophy (DM) and Myotonia. (greenmarketreport.com)
- The patient group consists of patients suffering from non-dystrophic myotonia, and both types of myotonic dystrophies. (greenmarketreport.com)
- Earlier this year Nexien filed a utility patent application with the United States Patent and Trademark Office (USPTO) relating to the use of cannabinoids to treat myotonia, myotonic dystrophy, and other related dystrophies. (greenmarketreport.com)
- Alex Wasyl, Chief Executive Officer stated, "There is significant anecdotal evidence reinforced by the patient questionnaire results that the use of cannabinoids provides relief to many myotonia and myotonic dystrophy patients. (greenmarketreport.com)
- Many distinct clinical phenotypes are now recognized and range in severity from severe neonatal myotonia with respiratory compromise through to milder late-onset myotonic muscle stiffness. (elsevierpure.com)
Potassium-aggravat8
- Potassium-aggravated myotonia (PAM) results from in a mututation of the SCN4A gene that causes skeletal muscles to be unable to relax after contracting in bouts, typically following the consumption of potassium rich food. (wikipedia.org)
- It is debated if potassium-aggravated myotonia is a distinct disease from Paramyotonia Congenita, and recent academic papers have classified it both ways. (wikipedia.org)
- Potassium-aggravated myotonia is a disorder that affects muscles used for movement (skeletal muscles). (medlineplus.gov)
- Potassium-aggravated myotonia ranges in severity from mild episodes of muscle stiffness (myotonia fluctuans) to severe, disabling disease with frequent attacks (myotonia permanen). (medlineplus.gov)
- Unlike some other forms of myotonia, potassium-aggravated myotonia is not associated with episodes of muscle weakness. (medlineplus.gov)
- Potassium-aggravated myotonia is caused by variants (also known as mutations) in the SCN4A gene. (medlineplus.gov)
- Potassium-aggravated myotonia is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. (medlineplus.gov)
- M1476I, a French Canadian founder mutation of Na⁺ channel Nav1.4, causes potassium-aggravated myotonia, with cold-induced myotonia as the most distinctive clinical feature. (ulaval.ca)
Thomsen4
- There are two forms of myotonia congenita, Thomsen disease and Becker disease, both of which involve the same gene, CLCN1 . (msdmanuals.com)
- Rationale: Myotonia congenita (MC) is a non-dystrophic myotonia inherited either in dominant (Thomsen) or recessive (Becker) form. (unisa.it)
- On the contrary, it often leads to larger, stronger muscles.There are two types of myotonia congenita: Becker disease and Thomsen disease. (mda.org)
- Thomsen or Becker myotonia? (bvsalud.org)
Congenita is an inherited3
- Myotonia congenita is an inherited neuromuscular disorder characterized by the inability of muscles to quickly relax after a voluntary contraction. (brainfacts.org)
- Myotonia congenita is an inherited disorder causing muscle stiffness and hypertrophy beginning during childhood. (msdmanuals.com)
- Myotonia congenita is an inherited myopathy that prevents affected individuals from relaxing certain muscles after contracting them. (mda.org)
Becker5
- Myotonia congenita Becker is an autosomal recessive disease, non-dystrophic myotonia. (akutne.cz)
- The algorithm is dedicated to a rare neurological disease, congenital recessive form of myotonia congenita Becker. (akutne.cz)
- Anaesthesia recommendations for patients suffering from Recessive myotonia congenita (Becker´s disease) Orphan Anesthesia. (akutne.cz)
- KOSINOVÁ M, ŠTOURAČ P, KŘIKAVA I, HRUBAN L, JANKŮ P, VOHÁŇKA S. Myotonia congenita becker u pacientky podstupující plánovaný císařský řez v celkové anestezii kazuistika. (akutne.cz)
- Muscle strength is normal between attacks but, after a few years, some degree of fixed weakness develops in certain types of PP (especially primary PP). All forms of primary PP (except Becker myotonia congenita [MC]) are either autosomal dominant inherited or sporadic (most likely arising from point mutations). (medscape.com)
Weakness4
- Similar to Paramyotonia Congenita, where potassium exacerbates myotonia in many phenotypes, Hyperkalemic Periodic Paralysis is another disorder of the SCN4A gene where high blood potassium levels result in muscle weakness, muscle paralysis (through weakness or through over excitation preventing movement), and sometimes myotonia. (wikipedia.org)
- Lehmann-Horn F, Orth M, Kuhn M, Jurkat-Rott K. A novel N440K sodium channel mutation causes myotonia with exercise-induced weakness--exclusion of CLCN1 exon deletion/duplication by MLPA. (medlineplus.gov)
- [rx] Some physical examination findings include early-onset cataracts (younger than 50 years), varying grip myotonia, proximal muscle weakness or stiffness, hearing loss, and myofascial pain. (rxharun.com)
- Core clinical features are proximal muscle weakness, pain, myotonia and early-onset cataract. (ru.nl)
Congenital2
- Congenital myotonia) of which two types called Becker's disease and Thomsen's disease exist. (wikipedia.org)
- Hypotonia, rather than myotonia, is a hallmark of congenital DMI since myotonia or electrical myotonia are seldom present in the first year of life. (rxharun.com)
Muscular3
- Dystrophic myotonia includes Muscular Dystrophy or DM, "Dystrophia Myotonica" in Latin. (klarity.health)
- Thomsen's disease is also known as Myotonia Congenita, a muscular disorder with autosomal dominant inheritance. (klarity.health)
- The degree of stiffness varies within the breed, with the more muscular (meatier) animals displaying more myotonia. (tennesseemeatgoats.com)
Individuals with myotonia2
- Most individuals with myotonia congenita lead long, productive lives. (brainfacts.org)
- Because a repeated effort is required to relax the muscle, individuals with myotonia may have significant trouble with normal daily activities, including releasing their grip on objects (i.e. knife, fork and spoon), and having difficulty rising from a seated position, or beginning to walk. (greenmarketreport.com)
Channelopathies3
- Non-dystrophic myotonia is mainly caused by channelopathies (diseases of ion channel transport). (klarity.health)
- Non-dystrophic myotonia is caused by channelopathies resulting from the dysfunction of ion channels in the membranes of all cells and many cellular organelles. (klarity.health)
- The non-dystrophic myotonias are an important group of skeletal muscle channelopathies electrophysiologically characterized by altered membrane excitability. (elsevierpure.com)
Symptoms7
- Brody disease (a disease of ion pump transport) has symptoms similar to myotonia congenita, however, the delayed muscle relaxation is pseudo-myotonia as the EMG is normal. (wikipedia.org)
- citation needed] Symptoms of myotonia (documented in myotonia congenita) are more frequently experienced in women during pregnancy. (wikipedia.org)
- Current research is exploring how, at the molecular level, the defective gene in myotonia congenita causes the specific symptoms of the disorder. (brainfacts.org)
- Myotonia describes symptoms experienced by individuals experiencing impaired muscle relaxation (prolonged contraction). (klarity.health)
- Unlike myotonia, where symptoms of muscle stiffness wear off when the muscle is exercised, paramyotonia congenita is when muscle stiffness is brought on upon exercising - the stiffness worsens as exercising is carried on. (klarity.health)
- Most common clinical presentations of Myotonia present with few prominent symptoms. (klarity.health)
- Membrane-stabilizing drugs may be used to decrease muscle stiffness and other symptoms associated with myotonia. (msdmanuals.com)
Stiffness3
- Myotonia causes muscle stiffness that worsens after exercise. (medlineplus.gov)
- Myotonia refers to delayed relaxation after muscle contraction, which can cause muscle stiffness. (msdmanuals.com)
- In children with myotonia congenita, there is delayed relaxation after muscle contraction, which can cause muscle stiffness. (msdmanuals.com)
Hyperkalemic Periodic1
- Mutations of Na V 1.4 give rise to a heterogeneous group of muscle disorders, with gain-of-function defects causing myotonia or hyperkalemic periodic paralysis. (jci.org)
Autosomal dominant1
- Myotonia is carried on an autosomal dominant gene, which means that it is not carried on the sex gene. (tennesseemeatgoats.com)
Skeletal5
- Myotonia is a symptom of a small handful of certain neuromuscular disorders characterized by delayed relaxation (prolonged contraction) of the skeletal muscles after voluntary contraction or electrical stimulation, and the muscle shows an abnormal EMG. (wikipedia.org)
- Myotonia may present in the following diseases with different causes related to the ion channels in the skeletal muscle fiber membrane (sarcolemma). (wikipedia.org)
- The ClC-1 ion channel is responsible for the major part of chloride conductance in the skeletal muscle cell, and lack of sufficient chloride conductance may result in myotonia, (see myotonia congenita). (wikipedia.org)
- Reduced chloride conductance may result in myotonia, due to accumulation of potassium in the transverse-tubules in skeletal muscle (see myotonia congenita). (wikipedia.org)
- Myotonia could be caused by genetic mutations in the SCN4A gene that encodes the skeletal muscle sodium channel subtype 4 (Nav1.4). (wikipedia.org)
Disorders3
- People with disorders involving myotonia can have life-threatening reactions to certain anaesthetics called anaesthesia-induced rhabdomyolysis. (wikipedia.org)
- The National Institute of Neurological Disorders and Stroke (NINDS) conducts research related to myotonia congenita and also supports additional research through grants to major research institutions across the country. (brainfacts.org)
- Neuromuscular disorders could cause myotonia and are best observed when there is a slowed relaxation or muscle unable to relax following a normal muscle contraction. (klarity.health)
Paramyotonia Congenita1
- Generally, repeated contraction of the muscle can alleviate the myotonia and relax the muscles thus improving the condition, however, this is not the case in paramyotonia congenita. (wikipedia.org)
Muscles4
- This inability of muscles to relax worsening with exercise is often termed "paradoxical myotonia. (wikipedia.org)
- Beginning in childhood or adolescence, people with this condition experience episodes of sustained muscle tensing (myotonia) that prevent muscles from relaxing. (medlineplus.gov)
- When there is dysfunction at the location where nerves and muscles connect, it is called neuromuscular junction dysfunction, which can cause myotonia. (klarity.health)
- People with this disorder often have prolonged muscle contractions (myotonia) and are not able to relax certain muscles after use. (rxharun.com)
Disorder1
- In this disorder, episodes of myotonia may also be triggered (aggravated) by eating foods that are high in the mineral potassium, such as bananas and potatoes. (medlineplus.gov)
Awkward gait1
- Patients suffering from myotonia often walk with a stiff, slow, and awkward gait. (greenmarketreport.com)
Becker's2
- On the other hand, Becker's disease is another type of Myotonia Congenita caused by autosomal recessive inheritance. (klarity.health)
- The reduced chloride conductance of the mutated chloride channels in Becker's myotonia causes hyper-excitability of the muscle fibre membrane leading to bursts of aberrant action potentials. (akutne.cz)
Recessive1
- Diagnosis: Recessive myotonia congenita was diagnosed. (unisa.it)
Nondystrophic1
- Guidelines on clinical presentation and management of nondystrophic myotonias. (medlineplus.gov)
Sodium2
- The influx of extra sodium ions triggers prolonged muscle contractions, which are characteristic of myotonia. (medlineplus.gov)
- Biophysical characterization of M1476I, a sodium channel founder mutation associated with cold-induced myotonia in French Canadians. (ulaval.ca)
Genetic1
- Myotonia was probably originally the result of a genetic mutation during the evolutionary process. (tennesseemeatgoats.com)
Chloride conductance1
- The majority of patients with myotonia have either a primary or secondary loss of membrane chloride conductance predicted to result in reduction of the resting membrane potential. (elsevierpure.com)
Relaxation1
- Myotonia refers to a neuromuscular condition in which the relaxation of a muscle is impaired, and can affect any muscle group of the body. (greenmarketreport.com)
Clinical Trials1
- She has been involved in several clinical trials and was site PI for some of the landmark trials in non-dystrophic myotonia and periodic paralysis. (utsouthwestern.edu)
Neurological1
- Some of her notable publications include the natural history study in non-dystrophic myotonia and the role of denture cream in neurological disease. (utsouthwestern.edu)
Defective1
- and (4) both myotonia and PP result from defective ion channels. (medscape.com)
Symptom1
- Myotonia is the primary initial symptom. (rxharun.com)
Prominent1
- [rx] Dysarthria and hand muscle myotonia may be prominent features and might exacerbate learning difficulties. (rxharun.com)
Treatment2
- Treatment of myotonia congenita is primarily symptomatic and supportive. (msdmanuals.com)
- Myotonia may require treatment. (medscape.com)
Generally1
- Generally, myotonia could affect any muscle group, and organs such as the heart, lungs, digestive tract, brain and eyes could be affected. (klarity.health)
Describes1
- Myotonia congenita is the technical term that describes stiffening. (tennesseemeatgoats.com)
Goats1
- Myotonia has also been observed in utero in goats. (tennesseemeatgoats.com)
Types1
- There are two types of myotonia - dystrophic and non-dystrophic myotonia . (klarity.health)
People1
- Most people with myotonia congenita don't require special treatments. (brainfacts.org)