Periodic Limb Movement Disorder
The periodic limb movement disorder (PLMD) is a disease in which next periodic limb movements simultaneously in sleep (PLMS) sleep disorders exist. It is described in the International Classification of Sleep Disorders (ICSD-2, 2005) as an independent syndrome and is one of the sleep-related movement disorders . According to ICD-10, it is one of the other extrapyramidal diseases and movement disorders (G25.8).
Periodic movements of the extremities during sleep (PLMS) or while awake (PLMW) also occur in healthy people, especially in the elderly, and alone have no disease value.
In contrast to the more common restless legs syndrome , the symptoms lack the typical urge to move while awake.
Polysomnography , which is carried out in a sleep laboratory , shows periodic movements of the extremities, preferably of the legs and, more rarely, of the arms , with a frequency of more than 5 / h in children and more than 15 / h in adults during sleep. These periodic movements are usually bilateral, but not necessarily at the same time.
In addition, the patients complain of sleep disorders or daytime sleepiness .
Before diagnosing PLMD, it must be checked whether the periodic movements can be better explained by other means. Sleep- related illnesses such as restless legs syndrome and REM sleep behavior disorder , PLMS at the end of apnea phases or neurological or internal illness, drug use or substance abuse must be considered.
There are no standard values for PLMS in the various age groups. PLMS occurs in 30% of people over 50 years of age, but mostly without consequences such as sleep disorders or increased fatigue.
Usually, sleep disturbances or daytime sleepiness are the reason patients sought help. The clinical complaints are in the foreground when it comes to the need for therapy.
Epidemiology, risk factors
The poorly precise definition of PLMD in the past led to a false equation of the polysomnographic findings of periodic extremity movements during sleep (PLMS) with the clinical picture of PLMD. Epidemiological studies on the prevalence of PLMD in accordance with the nosological criteria as clearly described in ICSD-2 from 2005 are not available to date. Methodologically well-founded studies with a sufficient number of cases on the prevalence of periodic extremity movements during sleep in the normal population, especially in different age groups, also do not exist. Previous studies show that periodic extremity movements already occur in childhood and, at over 50%, are a very common phenomenon in older people. Based on the results of a telephone survey (Sleep-EVAL) of 18,980 adults, an estimate of the prevalence of PLMD in the total population of 3.9% was obtained. The informative value of existing studies is mostly limited by the fact that in many studies insufficiently sensitive monitoring techniques were not used to exclude leg movements in the differential diagnosis, as they often occur at the end of pathological respiratory events. Another disturbance that has hardly been taken into account is the sometimes considerable night-to-night variability of the periodic extremity movements. Most of the studies also did not record centrally effective drugs and substances that can induce, increase or suppress periodic extremity movements. These include: selective serotonin reuptake inhibitors, tricyclic antidepressants, mirtazapine, lithium, classic and atypical neuroleptics and alcohol.
The pathophysiology of PLMD is unknown. A dysfunction in the dopaminergic system is assumed to be the common cause of various diseases associated with periodic extremity movements. This is especially true for diseases in which the pathophysiological importance of dopaminergic mechanisms has been shown, such as
- Restless Legs Syndrome (RLS)
- REM sleep behavior disorder
- Post Traumatic Stress Disorder (PTSD)
The high prevalence of periodic extremity movements in older people could be explained by the loss of dopamine in old age or by the physiological decrease in dopamine receptors. The fact that periodic extremity movements are not particularly frequent in patients with Parkinson's disease suggests that it is less the nigrostriatal than other dopaminergic systems such as the dopaminergic diencephalospinal pathways that play a pathophysiological role. The similarity of the periodic extremity movements with the spinally generated flexor reflex in the form of the flight reflex to painful stimuli on the sole of the foot and the fact that periodic extremity movements usually occur in complete spinal cross-sectional syndromes as an expression of a disinhibition phenomenon speak for the development of periodic extremity movements at the spinal cord level. A dopaminergic control of the flexor reflex is also known. The fact that central nervous activations in the form of arousals often precede periodic extremity movements also suggest that central nervous mechanisms are not only responsible for motor but also for autonomic activations such as heart rate increases and are not directly triggered by periodic extremity movements. In summary, a pathophysiologically significant imbalance between spinal over-excitability and disinhibition of supraspinal descending dopaminergic pathways can be assumed.
- R. Natarajan: Review of periodic limb movement and restless leg syndrome. In: Journal of postgraduate medicine. Volume 56, Number 2, 2010 Apr-Jun, pp. 157-162, doi : 10.4103 / 0022-3859.65284 . PMID 20622400 . (Review). .
- JS Durmer, GH Quraishi: Restless legs syndrome, periodic leg movements, and periodic limb movement disorder in children. In: Pediatric Clinics of North America . Volume 58, Number 3, June 2011, pp. 591-620, . doi : 10.1016 / j.pcl.2011.03.005 . PMID 21600344 . (Review).
- YA Lee, P. Huynh, JO Neher, S. Safranek: Clinical Inquiry. What drugs are effective for periodic limb movement disorder? In: The Journal of family practice. Volume 61, Number 5, May 2012, pp. 296-298, PMID 22577635 . (Review). .
- S1 guideline Restless Legs Syndrome (RLS) and Periodic Limb Movement Disorder (PLMD) of the German Society for Neurology (DGN). In: AWMF online (as of 2012)