Periodic paralysis
Periodic paralysis | |
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Other names | Myoplegia paroxysmalis familiaris |
Specialty | Neurology |
Periodic paralysis is a group of rare
The symptoms of periodic paralysis can also be caused by hyperthyroidism, and are then labeled thyrotoxic periodic paralysis; however, if this is the underlying condition there are likely to be other characteristic manifestations, enabling a correct diagnosis.
Types
Periodic paralysis is an
- Hypokalemic periodic paralysis (Online Mendelian Inheritance in Man (OMIM): 170400), where potassium leaks into the muscle cells from the bloodstream.
- Hyperkalemic periodic paralysis (Online Mendelian Inheritance in Man (OMIM): 170500), where potassium leaks out of the cells into the bloodstream.
- Paramyotonia congenita (Online Mendelian Inheritance in Man (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.
- micrognathia) and low-set ears. Patients need to have another form of periodic paralysis to have the Andersen-Tawil. If a patient has hypo or hyper periodic paralysis they have a 50% chance of getting Andersen-Tawil. They just have to have the gene that causes it. This is a rare occurrence of having this. Only around 100 people in the world are recorded to have it.
Cause
One of the most common descriptions of periodic paralysis are episodic attacks of muscle weakness, which are commonly associated with serum potassium levels. Physical activity and diet content (carbohydrates) have been identified as PP triggers. Unlike non-dystrophic myotonias, the periodic paralysis phenotype is triggered after resting following exercise. Voltage-gated sodium channel (Nav1.4) mutations are among the key causes behind periodic paralysis.[3]
Hyper-kalemic PP (hyperPP) is identified with high extracellular potassium levels which are typically greater than 5 mM during attacks; however, HyperPP attacks can also take place without rise in potassium concentrations. HyperPP has a prevalence rate of 1/100,000. Patients become symptomatic around the age of 10. The weakness attacks in hyperPP are relatively short lasting, and range from minutes to hours. The attacks can happen upwards of ten times per month.[citation needed]
Hypo-kalemic PP (hypoPP) is associated with low potassium levels. The onset of hypoPP occurs between the ages of 15 and 35. The prevalence of hypoPP is estimated to 1/100,000. HypoPP can be triggered by many external factors such as stress, high-sugar diet, and rest after exercise. During hypoPP attacks, the serum potassium concentrations can drop to less than 3 mM. Furthermore, hypoPP attacks are considerably longer lasting than hyperPP. As exercise is a trigger for periodic paralysis attacks, recently there is more research going into the physiological changes that accompany exercise including changes in blood pH. [3]
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
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.[citation needed]
Treatment
Treatment of the periodic paralyses may include
Treatment of periodic paralysis in Andersen-Tawil syndrome is similar to that for other types. However,
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.[citation needed]
References
- ^ "Periodic Paralyses: Background, Pathophysiology, Epidemiology". 2017-01-07.
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(help) - ^ "Periodic Paralyses: Background, Pathophysiology, Epidemiology". 2017-01-07.
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(help) - ^ PMID 29674667.
- PMID 19962959.
- PMID 18162704.
- ^ Lee, GM; Kim JB (June 2011). "Hyperkalemic periodic paralysis and paramyotonia congenita caused by a de novo mutation in the SCN4A gene". Neurology Asia. 16 (2): 163–6.
- PMID 19931173.
- Song, YW; Kim, SJ; Heo, TH; Kim, MH; Kim, JB (Dec 2012). "Normokalemic periodic paralysis is not a distinct disease". Muscle & Nerve. 46 (6): 908–913. S2CID 43821573.
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