Neuropsychological Deficits and Sleep in Myotonic Dystrophy

Abstract

Eight patients with myotonic dystrophy underwent comprehensive neuropsychological testing and overnight polysomnography to assess whether the waking cognitive impairment might be attributable to sleep structure abnormalities or to sleep-related respiratory problems. Patients showed substantial neuropsychological deficits, fragmented nocturnal sleep and, in half the patients, sleep apnea and/or hypopnea both mainly of central type. There was no statistically significant correlation between the degree of daytime cognitive deficit and the degree of sleep fragmentation or of respiratory problems at night. It was concluded that the neuropsychological deficit in mytonic dystrophy cannot be attributed to a secondary effect of nocturnal sleep apnea or sleep disruption but probably represents a direct effect of CNS lesions. RESUME: Deficit neuropsychologique et sommeil dans la dystrophic myotonique Huit malades atteints de dystrophic myotonique ont ete etudies au moyen d'une batterie de tests neuropsychologiques et de la polysomnographie nocturne pour determiner si le deficit cognitif qui existait pouvait etre attribue a une deterioration de la structure du sommeil ou a des difficultes respiratoires au cours du sommeil. On a demontre chez les malades des problemes neuropsychologiques significatifs de meme qu'un sommeil nocturne tres fragmente et, dans la moitie des cas, des apnees et/ou des hypopnees du sommeil, surtout de type central. II n'existait aucune relation significative entre le degre du deficit cognitif et le degre de la fragmentation du sommeil ou des difficultes respiratoires nocturnes. Nous concluons que le deficit neuropsychologique dans la dystrophie myotonique n'est pas un effet secondaire de la perturbation du sommeil ou de l'apnee nocturne, mais qu'il est probablement une consequence directe de lesions du systeme nerveux central.

Patterns and predictors of sleep disordered breathing in primary myopathies

“…As expected, SDB occurred predominantly in REM sleep, a period of relative muscle hypotonia or atonia. SDB differed from the central or obstructive sleep apnoea/ hypopnoea syndromes previously reported [20][21][22] and the RDI did not correlate with IVC. Hypopnoeas predominated in early restrictive disease but, as restriction worsened, changed into poorly circumscribed and ever more prolonged hypoventilatory phases that did not enter the hypopnoea score.…”

Cerebral involvement in myotonic dystrophies

“…There are conflicting data as to the occurrence of anxiety in DM1, 10,20,22 although there are suggestions that DSM-IVR Axis I disorders are frequent in DM1 as in the general population. 41 Meola et al 71 demonstrated that anxiety was not a feature of a subset of patients with DM1 subjected to a battery of neuropsychological tests and psychiatric interviews.…”

“…18,19 There is evidence that excessive daytime sleepiness in DM1 is not the result of sleep apnea 124 but may result from direct involvement of bulbar neurons in the reticular formation of the brainstem. 81,82 Broughton et al 10 concluded that cognitive impairment cannot be attributed to a secondary effect of nocturnal sleep apnea or sleep disturbance in patients with DM1, but probably represents a direct effect of CNS lesions. It is interesting to consider that hereditary canine narcolepsy is caused by mutations in the hypocretin receptor 2 (HcrtR2) gene that induces aberrant splicing of the HcrtR2 pre-mRNA, resulting in a truncated receptor.…”

Sleep apnea in adult myotonic dystrophy patients who have no excessive daytime sleepiness

“…It is the most common form of muscular dystrophy in adults. Patients with MD are prone to various patterns of sleep-related breathing disorders (SRBD) including obstructive apneas and hypopneas, central apneas, nocturnal hypoxemia, and nocturnal hypoventilation [1][2][3][4][5][6][7][8][9][10]. All of these disorders may impact unfavorably on survival by causing pulmonary hypertension, cor pulmonale, and respiratory failure [9][10][11][12].…”