Periodic paralysis is a rare group of genetic diseases that lead to weakness or paralysis (rarely death) from common triggers such as cold, heat, high carbohydrate meals, not eating, stress or excitement and physical activity of any kind. The underlying mechanism of these diseases are malfunctions in the ion channels in skeletal muscle cell membranes that allow electrically charged ions to leak in or out of the muscle cell, causing the cell to depolarize and become unable to move (a channelopathy). The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... // G00-G99 - Diseases of the nervous system (G00-G09) Inflammatory diseases of the central nervous system (G00) Bacterial meningitis, not elsewhere classified (G01) Meningitis in bacterial diseases classified elsewhere (G02) Meningitis in other infectious and parasitic diseases classified elsewhere (G03) Meningitis due to other and unspecified causes (G04) Encephalitis, myelitis... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... Carbohydrates are chemical compounds that contain oxygen, hydrogen, and carbon atoms. ... Another, unrelated ion channeling process is part of ion implantation. ... A top-down view of skeletal muscle Skeletal muscle is a type of striated muscle, attached to the skeleton. ... Drawing of a cell membrane A component of every biological cell, the selectively permeable cell membrane (or plasma membrane or plasmalemma) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ... The chanellopathies are human diseases linked to mutations in genes coding for ion channel subunits or proteins that regulate them. ...

Types

Periodic paralysis is an autosomal dominant disorder with considerable variation in penetrance, leading to a spectrum of familial phenotypes (only one parent need carry the gene mutation to affect the children, but not all family members who share the gene are affected to the same degree). Specific diseases include: An autosomal dominant gene is an abnormal gene on one of the autosomal (non-sex determining) chromosomes. ... Penetrance is a term used in genetics that describes the extent to which the properties controlled by a gene, its phenotype, will be expressed. ... The phenotype of an individual organism is either its total physical appearance and constitution, or a specific manifestation of a trait, such as size or eye color, that varies between individuals. ...

• Hypokalemic periodic paralysis (OMIM 170400), where potassium leaks into the muscle cells from the bloodstream.

• Hyperkalemic periodic paralysis (OMIM 170500), where potassium leaks out of the cells into the bloodstream.

• Paramyotonia congenita (OMIM 168300), a form which often accompanies hyperkalemic periodic paralysis, but may present alone. The primary symptom of paramyotonia congenita is muscle contracture which develops during exercise or activity. Paramyotonia congenita attacks may also be triggered by a low level of potassium in the bloodstream. This means people with both hyperkalemic periodic paralysis and paramyotonia congenita can have attacks with fluctuations of potassium up or down.

• Andersen-Tawil syndrome (OMIM 170390), a form of periodic paralysis that includes significant heart rhythm problems, fainting and risk of sudden death. Potassium levels may be low, high, or normal during attacks of ATS. Patients with ATS may also have skeletal abnormalities like scoliosis (curvature of the spine), webbing between the second and third toes or fingers, crooked fingers, a small jaw and low-set ears.

Hypokalemic periodic paralysis is characterized by a fall in potassium levels in the blood. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... Hyperkalemic periodic paralysis (HYPP), also known as Impressive Syndrome, is an inherited autosomal dominant disorder which affects sodium channels in muscle cells and the ability to regulate potassium levels in the blood of horses. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... Paramyotonia congenita is a rare congenital neuromuscular disorder which is characterized by a condition in which the muscles do not relax after contracting (myotonia). ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... Andersen-Tawil syndrome, also called Andersen syndrome and Long QT syndrome 7 is a form of long QT syndrome. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ...

Diagnosis

This disease is unusually difficult to diagnose. Patients often report years of wrong diagnosis and treatments that made them worse instead of better. Part of this may be that migraines are present in up to 50% of patients and can cause a confusing array of symptoms including headaches, speech difficulties and visual, auditory or sensory auras. DNA testing is available for only a half dozen common gene mutations, while dozens of known mutations are possible but are not routinely tested. EMG results will be normal except during attacks. A properly performed Exercise EMG (Compound Muscle Amplitude Potential Test) can provide an accurate diagnosis in better than 80% of cases. The old glucose/insulin provocative testing can cause life-threatening symptoms and should not be used. Genetic fingerprinting or DNA testing is a technique to distinguish between individuals of the same species using only samples of their DNA. Its invention by Sir Alec Jeffreys at the University of Leicester was announced in 1985. ...

Also of note is that potassium levels do not have to range outside of normal limits to cause serious, even life-threatening paralysis. These diseases are not the same as having a very low level of potassium (hypokalemia) or high potassium (hyperkalemia) and must not be treated as such. The total body store of potassium is usually normal; it is just in the wrong place. Hypokalemia is a potentially fatal condition in which the body fails to retain sufficient potassium to maintain health. ... Hyperkalemia (hyper is high, kalium is the Latin name for potassium) is an elevated blood level (above 5. ...

Treatment

Treatment of the periodic paralyses usually includes carbonic anhydrase inhibitors (such as acetazolamide or dichlorphenamide), taking supplemental oral potassium chloride (for hypos) or avoiding potassium (for hypers), thiazide diuretics to manipulate the amount of potassium retained by the kidneys, and significant lifestlye changes including tightly controlled levels of exercise or activity. However, the exact gene mutation, the ion channel affected, and the amount of genetic change or expression can have significant impact on disability and treatment. Carbonic anhydrase (carbonate dehydratase) is a family of zinc-containing enzymes that catalyze the rapid interconversion of carbon dioxide and water into carbonic acid, protons, and bicarbonate ions. ... Acetazolamide, sold under the trade name Diamox®, is a carbonic anhydrase inhibitor that is used to treat glaucoma, epileptic seizures, benign intracranial hypertension and altitude sickness. ... The chemical compound potassium chloride (KCl) is a metal halide composed of potassium and chlorine. ... Thiazides are a class of drug that promote water loss from the body ((diuretics)). They inhibit Na+/Cl- reabsorption from the distal convoluted tubules in the kidneys. ... A diuretic is any drug that tends to increase the flow of urine from the body (diuresis). ...

Treatment of ATS is similar to that for periodic paralysis, with dichlorphenamide the drug of first choice. Pacemaker insertion or an implantable cardioverter-defibrillator may be required to control cardiac symptoms. This article is about a medical device which electrically stimulates the heart. ... An implantable cardioverter-defibrillator (ICD) is a device that is implanted under the skin of patients that are at risk of sudden death due to ventricular fibrillation. ...

Prognosis

While the disability can range from minor, occasional weakness to permanent muscle damage, inability to hold a normal job and use of a powerchair, most people function fairly well with drugs and lifestyle changes. On a lighter note, people with periodic paralysis are sometimes lovingly called Possums because they play dead when startled or stressed.

External links

• Periodic Paralysis Association
• Periodic Paralysis News Desk
• Periodic Paralysis Society of Australia
• Cleveland Clinic
• eMedicine