Sleep - Periodic Limb Movements

Periodic Limb Movements in Sleep (PLMS) is a symptom that is commonly associated with another type of sleep disorder known as Restless Leg Syndrome (RLS). However, PLMS is a separate condition and RLS need not be present.

Although the problem itself does not seem to cause or aggravate any other medical conditions, the frequent limb movements can cause a disruption in a person's sleep. In fact, it can lead to significant insomnia, which can have adverse affects. It is for this reason that PLMS is considered a sleep disorder.

Symptoms are few but they are obvious. As the name, periodic limb movements, implies, the lower limbs of individuals with this disorder move, often repetitively, for varying periods of time. These movements, which are characterized as either sudden jerks, or twitches, or a flexing of the foot upwards, occur while the affected individual is asleep. These types of limb movements occur in episodes that can last just a minute or they can last for many hours. Once an episode stops, however, it typically takes less than a minute for the episode to repeat.  

An individual may also have symptoms of Restless Leg Syndrome (RLS) which also consists of awkward feelings in the limbs. Those with RLS describe these feelings as a crawling, or prickly, or tingling sensation in the upper and lower legs and the arms. Absent RLS, there generally aren't any other symptoms. And since the leg movements happen during sleep, an individual may not even be aware of this condition. Interestingly, it is more often the bed partner who first becomes aware of the condition because he or she will notice the annoying movement of the bed.

To date, no one has been able to identify the primary cause of PLMS. Many do believe that the movements have something to do with the way the individual's central nervous system functions. It can be secondary meaning that it is caused by some other condition such as diabetes, sleep apnea, narcolepsy and anemia.

If a person experiences these types of movements during sleep, and if the person also has symptoms of Restless Leg Syndrome, a diagnosis of PLMS is generally suspected. If an individual is complaining of constant fatigue for which no other cause has been identified, a doctor might suspect PLMS. To confirm a diagnosis, a doctor will prescribe spending a night in a sleep center so that the patient's sleeping patterns can be closely monitored.

It is difficult to prescribe a treatment for PLMS because its cause is not known. For some patients, treatment consists of medications such as Benzodiazepines that can help them get a better night's sleep. There are also medications that can be taken to help control the movements including anticonvulsive agents, dopaminergic and GABA agonists.