The periodic limb movement is a repetitive jerking or cramping of the legs during the sleep. This is the only movement disorder which is happening only during sleep and this is a reason why in some cases it is called period leg or periodic limb movements during sleep. The term “periodic” means that the movements are repetitive and rhythmic which is happening about every twenty to forty seconds.
The periodic limb movement is also considered as a sleep disorder because the movements disrupt the sleep and this leads to daytime sleepiness. The periodic limb movement may happen with other sleep disorders. Often, it is linked with restless leg syndrome but you should know that these conditions are not the same. The restless leg syndrome is a condition which involves strange sensations in the legs and, in some cases in the arms, while you are awake and you feel an irresistible urge to move the limbs to get a relief from these sensations.
It is noticed that at least 80% of people who have restless leg syndrome have periodic limb movement but the reverse is not true. In the 1950s the periodic limb movement was described for the first time and then it was known as nocturnal myoclonus. The nocturnal mean night. The myoclonus means a rapid and rhythmic contraction of a group of muscles which are similar to those seen in seizures.
You should know that the periodic limb movements are not myoclonus and this is a reason why the original name of this condition is not used today. The periodic limb movement can happen at any age. Like many sleep disorders, the periodic limb movement is more common in middle – aged and older people.
The poor sleep and daytime sleepiness are the most common symptoms which are noticed by people who have this. Many people do not know that they have leg movements until their bed partner tells them. The leg movement involves one or both limbs. The most common symptoms of that are:
There can be irritability, behavior problems and decline in performance at school or work due to lack of quality sleep
Daytime sleepiness and drowsiness
Multiple awakening at night
Restless, un-refreshing sleep
Repetitive leg movement in one or both legs and sometimes in the arms, which may involve flexing of the big toe, upward bending of the knee or ankle, or twitching of the hip
Those people who have periodic limb movement may also have symptoms of restless leg syndrome. This can include tingling or burning sensations in the legs when they lie down. Not every single person who has periodic limb movement ahs restless leg syndrome but there are some studies in which are said that about 80% of people with restless leg syndrome have periodic limb movement. Often, people first become aware that they have it when their partners tell them.
But also they can find their blankets all over the place in the morning which is also a sign of periodic limb movement. The periodic limb movement is diagnosed with polysomnography test which is also called a sleep study. This type of study is done overnight in a laboratory while you sleep.
The exact cause for the periodic limb movement is not known but many people believe that this condition originates in the central nervous system. There are some factors which could lead to it, such as
Metabolic disorders, including diabetes and kidney disease
Iron deficiency anemia
Spinal cord injury
There can be neurodevelopmental disorders, like attention deficit hyperactivity disorder and Williams syndrome
Other sleep disorders, such as narcolepsy or RLS
Certain medications, like antidepressants, anti – nausea drugs, lithium and anticonvulsants
This is more common in older adults. There are some studies in which are said that the periodic limb movement affects only 2% of people that are less than 30 years of age but it can affect up to 40% of people who are 65 or older. It is noticed that it affects men and women equally.