Moreover, diagnosis of PLMD cannot be used when narcolepsy, restless legs syndrome (RLS), REM sleep behaviour disorder (RBD) or untreated obstructive sleep apnea (OSA) is already diagnosed, since abnormal movements during sleep are frequent in these disorders. Signs and symptoms
People with PLMD often have excessive daytime sleepiness (EDS), falling asleep during the day, trouble falling asleep at night, and difficulty staying asleep throughout the night. Patients also display involuntary limb movements that occur at periodic intervals anywhere from 20 to 40 seconds apart. They often only last the first half of the night during non-REM sleep stages. Movements do not occur during REM because of muscle atonia. PLMS can be unilateral or bilateral and not really symmetrical or simultaneous. PLMS is often a symptom of RLS but evidence for differences between those two sleep disorders was found in literature. Sleep structure differed, when RLS patients had significantly more REM sleep and less stage 1 sleep compared to PLMD patients. Besides, PLMI was significantly higher in patients with PLMD. Causes
It is mostly unknown what causes PLMD, but in many cases the patient also has other medical problems such as Parkinsons disease or narcolepsy. Medical agents must be taken into consideration: several psychopharmacological drugs (serotonergic and tricyclic antidepressants, venlafaxine and mirtazapine) heighten the risk of PLMD.
For women, the presence of musculoskeletal disease, heart disease, obstructive sleep apnea, cataplexy, doing physical activities close to bedtime and the presence of a mental disorder were significantly associated with having a higher risk of both PLMD and restless legs syndrome.PLMS seems to have an origin in the spinal cord. In fact, PLMS was suggested to be associated with increased spinal reflexes. Manifestations of PLMS seem to occur mostly in disorders associated with dopaminergic dysfunctions.Hypothesis of low ferritin levels in adult population was raised to explain PLMD where increased RLS severity and increased PLMS were significantly correlated with low ferritin levels. Research evidence suggested iron is possibly contributing to PLMD. Thus, lack of iron may induce inhibition of dopamine formation which might underlie PLMS. Diagnosis
People with PLMD often do not know the cause of their excessive daytime sleepiness and their limb movements are reported by a spouse or sleep partner. PLMD cannot be diagnosed by polysomnogram (PSG) alone, it is necessary to obtain a full medical history and taking into account all available information.Polysomnography is recognized as the assessment method which brings most precise information on sleep quality, sleep structure and physiological parameters during sleep (respiration, heart rate, movements). Therefore, diagnostic of PLMD can usually be established only in laboratory settings.