Periodic Leg Movement vs Restless Leg Movement

Periodic Leg Movements in Sleep (PLMS or sleep myoclonus)

PLMS is characterised by involuntary leg movements (rhythmic, synchronised/ non-synchronised) during sleep. These movements are usually seen as flexing of the toes/foot, bending the ankle or knee or twitching of the hip. The movements are more common during non-REM sleep. Some people may experience hundreds of movements during the night, which may wake them, disturb their sleep and wake their bed partners.

PLMS is more common in middle-age, older people than in young adults and children. PLM occurs in approximately 2% of the population aged 30 or less, 5% in those aged 30-50, 25% in those aged 50-60, 44% in individual aged over 60 and in 1-15% of patients with insomnia.

PLM is usually asymptomatic, but can lead to excessive tiredness, daytime somnolence and even insomnia. The cause of PLM is still unknown. PLM can be diagnosed with a sleep study, leads are attached to the legs while the person sleeps and movements are measured.

Treatment

If PLM is severe and it is disrupting sleep, the same drugs that are used to treat RLS are used. Also patients are encouraged to cut back on caffeine and alcohol consumption and smoking.

Restless legs syndrome (RLS)

Is a movement disorder characterised by uncomfortable sensations in the legs and sometimes the arms. Features Individuals usually complaint of unbearable dysaesthesiae [Subjective cutaneous sensations (e.g., cold, warmth, tingling, pressure, etc.) that are experienced spontaneously in the absence of stimulation], sensations of cold, discomfort weakness. This is usually felt in the calves and it is accompanied by the overpowering desire to move the legs and the failure to keep the still. The restlessness is most common in the evening and may persist for many hours, it is frequently severe before sleep onset. To provide some temporary relief some people do rapid exercise, walking, kicking or leg massage.

The severity of restlessness increases with age, sleep deprivation and mental stress. RLS occurs in both sexes. Symptoms can begin at any time but are more common in older people.

Causes

The cause of RLS is unknown, although certain factor may be associated with it:

• If the individual's parents had RLS, there is a 30-50% chance that he/she will suffer from it. The familial RLS is transmitted as an autosomal dominant trait. The age of onset usually varies but it is usually in the second decade of life.
• RLS may arise during pregnancy (particularly in the last trimester), however it disappears after the baby is born •  Low iron and anaemia can contribute to it
• Some chronic diseases may lead to RLS, particularly kidney failure. Other conditions include diabetes, rheumatoid arthritis, parkinson's disease, damage to nerves in the arms and/or legs, motor neuron disease, acute poliomyelitis and drug toxicity.
• High caffeine intake, alcohol, smoking and stress may make RLS worse

Treatment

If RLS is caused by anaemia, treating this will resolve the problem. In mild cases of RLS, activities such as taking a hot bath, massaging the legs or using a hot/cold pack will alleviate the symptoms. In severe cases medications are prescribed to alleviate the symptoms.

The most commonly used medications include benzodiazepines (Valium), dopaminergic drugs and opioids. Benzodiazepines and opioids tend to cause dependency when used over long periods of time; however this is not the case when they are used to treat RLS, since only small doses are used.