Diagnosis of Periodic Limb Movement Disorder
The diagnosis of Periodic Limb Movement Disorder begins with an accurate history given by the bed partner, which is then confirmed by polysomnography.
True PLMD- is characterized by periodic limb movements during sleep, which is not caused by another primary sleep disorder.
The diagnosis of the typical PLMD starts with the exclusion of other sleep disorders.
To establish the diagnosis of PLMD an accurate history that describes the patient’s sleeping patterns along with his past and present medical history is essential. A bed partner may be able to describe these movements better.
Maintaining a sleep diary gives clearer picture of a person’s sleeping patterns. A sleep diary is maintained for two weeks and a record is made of a person’s sleeping habits, which includes the time of going to sleep, the time of awakening and the time in between when he is awake.
Epworth sleepiness scale is a self-assessment tool, in which a questionnaire is filled out by the patient, evaluating the likelihood of falling asleep in various situations. This permits a standardized subjective assessment of daytime sleepiness and how it affects daily life.
The Polysomnography (PSG) is an overnight test that is done in a laboratory that takes continuous multiple measurements, while a patient is asleep, to document abnormalities in the sleep cycle.
Diagnosis of Periodic Limb Movement Disorder
Polysomnography is the ultimate test for PLMD. The study is undertaken in a laboratory where the patient’s leg movements are documented. The criteria to score leg movements in a sleep study are:
- A minimum of four movements should occur in succession
- Each movement should last for 0.5sec-5secs
- The interval between the leg movements should range from 5secs-90secs
- The number of times the patient awakes during the leg movements are scored, which indicates the severity of the movements and how they affect sleep.
Blood tests can be done to look for underlying conditions that can cause PLMD. These tests are carried out to identify:
- Low iron stores or iron deficiency
- Diabetes
- Kidney disease
- Vitamin and mineral deficiencies
