The diagnosis of PLMD requires a visible cause-effect relationship between PLMS and an observed sleep disturbance or daytime impairment (both disturbance and impairment have to be clinically significant).Other relevant causes of Insomnia and Hypersomnia have to be ruled out before diagnosing PLMD (most importantly anxiety, obstructive sleep apnea, and narcolepsy). Furthermore, symptoms can not be better explained by any other conditions.For the differential diagnosis it is important to differentiate PLMD from other leg movements during sleep, which are high-frequency:
alternating leg movement activity (ALMA) are very similar events and could be mistaken for PLMS
hypnagogic foot tremor (HFT) events are also very similar to PLMS and could be misdiagnosed
excessive fragmentary myoclonus (EFM) events are shorter than PLMS

Classification
PLMD is classified in the third edition of the International Classification of Sleep Disorders (ICSD-3) which presents current sleep disorders nosology. ICSD-3 is divided in 7 sections and PLMD is classified in the Sleep-Related Movement Disorders section. There are some updates from ICSD-2. The diagnosis is more strict. A simple complaint is no longer enough: a significant clinical impairment is needed. Sleep impairments need to be clearly caused by PLMS and the symptoms also need to be explained solely by the PLMS. Treatment
PLMD can be effectively treated with dopaminergic agents (pramipexole, ropinirole, cabergoline, and rotigotine) and it has been found that patients with a low ferritin level respond well to oral iron supplements.
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.