15
AASM Membership Sections Newsletter
■
Issue #6
She is the clinical director of
Comprehensive Sleep and Research
Center and of Advanced Sleep
Center and is an assistant professor
at the Tulane University School of
Medicine in New Orleans, where
she initiated the fellowship in sleep
medicine. Her clinical focus is the
diagnosis and treatment of sleep
disorders in adults and children. Her
research interests are the diagnosis
and treatment of RLS, various
treatments for sleep disorders and
treatment compliance.
Brian Koo, MD
Dr. Brian Koo, MD, is an assistant
professor in Neurology at Yale
University School of Medicine. Dr.
Koo’s main research interest lies in
the association among restless legs
syndrome/periodic limb movements
during sleep and cardiovascular
disease, including hypertension and
myocardial infarction.
M. Suzanne Stevens, MD, MS
Dr. Suzanne Stevens, MD, is a
neurologist sleep specialist and is
the director of the Neurology Sleep
Medicine program at the University
of Kansas Medical Center. She is
also associate program director for
the sleep medicine training program.
Her research interests include REM
Behavior Disorder.
Lynn Marie Trotti, MD, MSc
Dr. Lynn Marie Trotti, MD, MSc, is an
Assistant Professor of Neurology at
Emory University School of Medicine
in Atlanta, GA. Her movement
disorders related research interests
include RLS/PLMS and sleep in
patients with Parkinson’s disease. ■
Changes to the International
Classification of Sleep-related
Movement Disorders (SRMDs):
The ICSD-2 listed 8 SRMDs, of which
all 8 remain in the ICSD-3. These include
RLS, PLMD, sleep related leg cramps, sleep
related bruxism, rhythmic movement
disorder and movement disorders related
to drug/substance, medical condition or
unspecified. However, the ICSD-3 also
includes two additional disorders. The
first is benign sleep myoclonus of infancy.
The disorder is characterized by recurrent
myoclonus (of extremities, trunk or whole
body) that is exclusive to sleep and resolves
with arousal, occurring in an infant less than
six months of age. Although the disorder
is thought to be both benign and relatively
rare (incidence of 3.7 per 10,000 live births),
it was included as a disorder because it is an
important differential for neonatal seizures.
The second newly included disorder is
propriospinal myoclonus at sleep onset.
This is characterized by sudden myoclonus
(usually of neck, trunk and abdomen) during
drowsiness/relaxed wakefulness. Either
mental activity or stable sleep will cause the
jerks to abate, but their occurrence during
drowsiness causes difficulty with sleep
onset. The movements spread rostrally and
caudally, following a propriospinal pattern. It
is thought to be rare. Both of these disorders
were previously classified as “isolated
symptoms, apparently normal variants, and
unresolved issues” in the ICSD-2 before
being moved into the category of “disorders”
in the current version. Remaining in the
“Isolated symptoms and normal variants”
category of the ICSD-3 are sleep starts (aka
hypnic jerks), hypnagogic foot tremor and
alternating leg muscle activity during sleep
and excessive fragmentary myoclonus.
Update on Restless Legs Syndrome
and Periodic Limb Movements
Of the sleep related movement disorders,
the restless legs syndrome (RLS) and periodic
limb movement during sleep (PLMS) are the
most often researched. In 2014, there have
been many high quality studies published.
Below are some highlights:
To date, there have been a number of
genome wide association studies for RLS
but not for PLMS, save for the Icelandic
study from Stefansson et al. (2007) which
used a phenotype of RLS plus PLMS.
Moore et al. (2014) in the journal SLEEP
determined that many single nucleotide
polymorphisms that are associated with
RLS are also linked to PLMS. BTBD9
was most associated with PLMS (OR =
1.65, p = 1.5×10-8), but so too were OX3/
BC034767, MEIS1, MAP2K5/SKOR1 and
PTPRD.
Co-varying for RLS symptoms
only modestly reduced the associations.
This study affirms that RLS and PLMS are
phenomena that are related.
Szentkirályi et al.
in Neurology (2014) analyzed data from the
Dortmund Health Study (DHS) and Study
of Health in Pomerania (SHIP) to look at the
association of co-morbidity with incident
RLS. Co-morbidity was considered for the
following conditions: diabetes, hypertension,
myocardial infarction, obesity, stroke, cancer,
renal disease, anemia, depression, thyroid
disease and migraine. An increase in the
number of comorbid conditions at baseline
predicted incident RLS (DHS: OR = 1.32,
95% CI 1.04-1.68; SHIP: OR = 1.59, 95% CI
1.37-1.85). In summary, multi-morbidity
was a strong risk factor for RLS. There is a
complex and poorly understood relationship
between breathing and PLMS. Manconi et al.
(2014) in the journal SLEEP studied patients
with both obstructive sleep apnea and PLMS
and were specifically interested in looking at
leg movements that were related to apneas
and/or hypopneas. They found that the time
structure of leg movements occurring in
conjunction with respiratory events exhibit
