16
AASM Membership Sections Newsletter
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Issue #6
American Academy
of Sleep Medicine
features of PLMS occurring alone. The authors suggest leg movements
that are ‘respiratory-related’ should not be considered separately from
PLMS.
RLS is a treatable condition, but at times can be refractory to several
medications. Thus, it is important to have several medication options
that can be tried in cases of decreased medication efficacy. Pregabalin
can now confidently be added to the list of medications that can be
used to treat RLS thanks to a randomized, double blind, placebo
controlled trial published in the New England Journal of Medicine
by Allen et al. in February of 2014. The authors found that Pregabalin
provided significantly improved treatment outcomes as compared
with a placebo, and augmentation rates were significantly lower with
pregabalin than with 0.5 mg of pramipexole. One of the strengths of
the study was that it was conducted over a period of 52 weeks, much
longer that most randomized controlled trials.
Update on SRMD Other Than RLS/PLM
Sleep related movement disorders are characterized by simple,
usually stereotyped movements that disturb sleep or its onset.
Some of them are common in childhood, some of them might be
triggered by medications, but most of them are diagnosed based on
clinical history. This fact may explain the paucity of evidence-based
data regarding most of these disorders, despite their relative high
frequency and impact on sleep. Since sleep medicine practitioners
see only a few of these patients, it is possible that many patients do
not receive correct diagnosis and treatment.
Establishing diagnostic criteria seems to prompt research. The
publication of diagnostic criteria for sleep related bruxism in 2013
(Lobezzo et al 2013) was closely followed by a large epidemiological
study of sleep bruxism during early childhood (Insana et al 2013)
and tens of studies since. We hope that by increasing awareness to
all the sleep related movement disorders, evidence-based data will
follow. A higher than expected prevalence of sleep bruxism was
recently reported in 183 Brazilian dental students (Serra-Negra et
al 2014). Based on self-reported data, sleep bruxism prevalence
was 21.5% and was associated with poor sleep quality and daytime
dysfunction. The authors underlined the importance of addressing
sleep quality in undergraduate students. Frauscher et al (2014)
attempted to quantify the motor phenomena present during sleep
in healthy sleepers. The authors assessed not only LM’s and PLM’s,
but also high frequency limb movements (HFLM), fragmentary
myoclonus, neck myoclonus (NM) and REM related EMG activity.
The results suggested relatively high incidence of movements
during sleep. Specifically, each one of the 100 healthy sleepers had
fragmentary myoclonus and a third of them had HFLM and NM.
The authors concluded that “various motor phenomena are observed
during physiological sleep, albeit of lower frequency than in
pathological sleep” and this may reflect the “highly complex motor
regulation during sleep”. A future discussion on this new motor
entity and on its possible integration among the SRMD in the ICSD
is warranted.
Respiratory Related Leg Movements
Periodic leg movements during sleep (PLMS) are repetitive
contractions of foot and leg muscles which occur during sleep.
PLMS occur in approximately 90% of patients with restless legs
syndrome (RLS) but they are commonly found in other sleep or
neurological disorders and also in normal persons without any sleep
complaints. In 1993 the American Sleep Disorders Association
(ASDA) established the criteria to recognize and quantify PLMS
following Coleman’s proposal. Recently, on the basis of new
computerized scoring and using an analytic approach, the time
structure of PLMS has been redefined. The results of this analysis
prompted a revision of the existing scoring criteria of PLMS to yield
new criteria proposed by a task force from the International RLS
Study Group (IRLSSG), endorsed by the World Association of Sleep
Medicine (WASM) and later revised by the American Academy of
Sleep Medicine (AASM) in 2007 and then again in 2013. Although
currently the scoring rules for PLM are better addressed than in the
past, still sleep experts frequently face some unresolved issues in
their clinical or research practice. Two main issues lie in the few but
significant differences existing between the AASM and the IRLSSG
(WASM) criteria, and by the rules concerning respiratory related
leg movements (RRLM). The latter issue in particular has never
been considered in past revisions, which have addressed PLMS
and not RRLM. PLMS occur frequently (24-48%) in patients with
obstructive sleep apnea (OSAS). Current criteria do not allow for
scoring of PLMS when the movement occurs during a period of 0.5
seconds preceding and 0.5 seconds following an apnea or hypopnea.
The rationale for this exclusion seems to be that RRLM are different
pathophysiologically from “real” PLMS. One of the topics was the
Movement Disorder section proposal to unify and revise the current
scoring criteria for periodic and respiratory-related leg movements.
A discussion is currently open with the aim to explore the
opportunity to challenge the current rules for RRLM with the new
computerized method of analysis. This issue is still under discussion
with the official permanent commission (AASM) dedicated to the
sleep related events scoring rules – we will keep you updated on this.
