Review
Sleep and neuromuscular disorders
Hrayr Attarian
Washington University School of Medicine, Box 8111, 660 S Euclid Ave, St. Louis, MO 63110, USA
Received 5 October 1999; received in revised form 6 December 1999; accepted 6 December 1999
1. Introduction and overview
Sleep disordered breathing (SDB) is very common
in the setting of neuromuscular disorders. About 42%
of patients with neuromuscular disorders have signif-
icant and symptomatic SDB (respiratory disturbance
index or RDI of more than 15/h) [1] vs. 4% of men
and 2% of women without any neuromuscular disor-
ders [2]. Despite the high incidence of SDB in this
population group only about 5% of patients with
symptomatic SDB and neuromuscular disease are
recognized and treated for respiratory problems and
only 1.7% with speci®c recognition of SDB [1].
Respiratory dysfunction, due to neuromuscular
disease, may become apparent or aggravated in the
setting of the unique physiologic conditions that
occur during sleep. Physiologic reduction of muscle
tone in non-rapid eye movement (NREM) sleep, and
frank loss of muscle tone in rapid eye movement
(REM) sleep [3] in addition to increased upper airway
resistance in REM [4], with enhancement of the
diaphragmatic drive and loss of activity in the inter-
costal muscles bring forth a unique series of circum-
stances in patients with neuromuscular illness. Sleep-
related physiological changes interact with a compro-
mised neuromuscular system to create conditions that
result in different form of sleep-related hypoxemia
and sleep fragmentation [3].
Diaphragmatic weakness is the major determinant
of the pattern of ventilatory compromise in neuromus-
cular diseases. Other determinants include: chest wall
muscle weakness leading to restrictive lung disease;
weakness of pharyngeal muscles leading to collapse
of pharyngeal wall and secondary increased upper
airway resistance and obstructive sleep apnea; scolio-
sis, common among patients suffering from neuro-
muscular illness, compromises diaphragmatic and
intercostal muscle activity, mechanically and a seden-
tary life style of neuromuscular patients promotes
obesity that further reduces ventilatory function
during sleep [3].
Sleep-related ventilatory de®cit in patients with
neuromuscular disorders causes different degrees of
sleep-related hypoxemia and multiple episodes of
oxyhemoglobin desaturation leading to sleep frag-
mentation and daytime somnolence [3]. Severe
oxyhemoglobin desaturation associated with REM
sleep-related respiratory insuf®ciency may even
present as nocturnal seizures [5].
Severe sleep-related oxyhemoglobin desaturation,
in the setting of SDB, can lead to peripheral nerve
dysfunction whose severity is partly due to the level
of sleep-related hypoxemia [6]. This may potentially
complicate matters in the setting of a pre-existing
neuromuscular disorder. In more severe cases patients
may also have alveolar hypoventilation while awake,
which becomes complicated with hypercapnia [3].
These problems are correctable and their treatment
with relatively simple and non-invasive means, lead-
ing to improved quality of life, hence it is important
that they be recognized and treated [7].
Sleep Medicine 1 (2000) 3±9
1389-9457/00/$ - see front matter q 2000 Elsevier Science B.V. All rights reserved.
PII: S1389-9457(99)00003-9
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E-mail address: attar1@pol.net (H. Attarian)