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Periodic Limb Movement
Last edited |
02/08/2009
Written by Maurice M. Ohayon, MD, DSc, PhD
This syndrome is characterized by periodic episodes of
repetitive limb movements caused by contractions of the muscles during sleep
Periodic Limb Movement Disorder (PLMD)
was originally called nocturnal myoclonus by Symonds (1953).
People with PLMD usually complain of difficulty falling asleep, staying asleep
or excessive daytime sleepiness.
They
may also feel their sleep is not refreshing, have hot or cold feet, or hair
wearing off their legs.
The
bed partners often report being kicked, fighting for bed covers, or being
awakened by the movements.
PLMD
should not be confounded with PLMS.
PLMS
is:
- a
polygraphic measure obtained with anterior tibialis EMG monitoring;
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characterized by repetitive muscle contraction lasting usually between 0.5 and 5
seconds separated by an interval of 20 to 40 seconds.
The
number of contractions per hour of sleep is called the PLMS index.
It
is considered to be abnormal when the PLMS index is greater than 5 movements per
hour of sleep.
PLMD
is a sleep disorder diagnosis that is given when no cause other than PLMS can be
identified for insomnia or hypersomnia.
However, the diagnosis of PLMD remains highly controversial.
Several clinical studies failed to report significant differences on PLMS index
between insomniacs, hypersomniacs and normal subjects. For example:
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Youngstedt
et al (1998) studied 22 elderly subjects with complaints of poor sleep or
depression. They found a high level of PLMS (median 25.8 events per hour;
86% of subjects > 5) but there was no association with sleep disturbance
measures.
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Similarly, Montplaisir et al. (2000), comparing 20 insomniacs, 20
hypersomniacs and 20 normal controls did not find significant differences
between these three groups on the PLMS index.
Finally, prior to
our
study, the prevalence for PLMD was unknown in the general population.
Research
Cross-sectional studies were performed in
the United Kingdom, Germany,
Italy, Portugal and Spain.
Overall, 18,980 subjects aged 15 to 100 years old representative of the general population of these five European
Countries
underwent telephone interviews with the Sleep-EVAL system.
A section of the
questionnaire assessed leg symptoms during sleep.
The diagnosis of PLMD
was based on the minimal criteria provided by the International Classification
of Sleep Disorders.
Results
The prevalence of PLMD is 3.9%.
PLMD was
higher in women than in men.
In multivariate models,
were significantly associated:
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being a woman,
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the presence of musculo-skeletal
disease,
-
heart disease,
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obstructive sleep apnea syndrome,
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cataplexy,
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doing
physical activities close to bedtime and the presence of a mental disorder.
PLMD is prevalent in the general population.
This condition is associated with several physical and mental disorders and may
negatively impact sleep.
Greater recognition of these sleep disorders is needed.
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Sleep-EVAL
Research
