Periodic limb movement disorder (or PLMD) is the repetitively and involuntary jerking of the legs while the person sleeps and the symptoms that come as a result of this phenomenon.
Periodic limb movement disorder only happens at night and during sleep, however, this disorder should not be confused with restless leg syndrome (RLS), which is not involuntary.
Periodic limb movement disorder is usually linked with restless leg syndrome symptoms, though they are different. In restless leg syndrome, the symptoms are leg movements while awake, and the person wants to move their legs to relieve the feeling or the sensation they are going through.
It is said that 80% of those people who suffer from restless leg syndrome suffer from Periodic limb movement disorder. However, the opposite is not true, since many people who have PLMD do not have restless leg syndrome.
The causes of PLMD are still unknown, however, many people who have underlying conditions such as Parkinson’s disease or nacrolepsy also suffer from PLMD. Other contributing factors such as snoring, caffeine, stress and benzodiazepine withdrawal, all seem to correlate with PLMD cases.
Causes of PLMD
A lot of evidence points to severe periodic limb movement occurring when the person is under medication such as anti-dopaminergic agents or even 
neuroleptics. It could also be when the person is suffering from withdrawal from barbiturates or benzodiazepines.
This condition is also known to be exacerbated by tricyclic antidepressants, SSRIs, stress and sleep deprivation.
So similar to RLS, it can become a vicious cycle. The less sleep one gets because of this condition, the more the condition gets aggravated and progresses. However, simply taking sleeping pills to go to sleep can often lead to more intense symptoms.
In many cases, Periodic limb movement disorder is unknown by the person, and it is only told to them by their bed partner. Often the knee, ankle, and big toe are all part of the movement.
The limb movements can vary from just slight movements to kicking, and usually last for around 0-5 seconds, occurring at intervals of 5 to 90 seconds.
There is no such periodic limb movement index score, but a diagnostic machine known as a polysomnogram, or PSG is often used to confirm if the person has Periodic limb movement disorder.
Treatments for Periodic Limb Movement Disorder
Conventional treatment for Periodic limb movement disorder involves the use of anti-Parkinson medication or narcotic medications. In fact, the similar kind of treatment is given for those suffering from Periodic limb movement disorder as well as restless leg syndrome. They include Benzodiazepines – which help to suppress the contractions of the muscles and help you to sleep even through the movements.
It also includes dopaminergic agents which increase the levels of dopamine which is used to regulate the muscle movements. The treatment includes anticonvulsant agents to reduce the contractions and GABA to stop some neurotransmitters from being released, so the contractions are relaxed.
Ultimately, even though PLMD and RLS exhibit characteristically different symptoms, the same type of treatment tends to work in many cases. Focusing in on dopamine neurotransmitter functioning is currently where the battle is taking place for both of these conditions.