Morvan syndrome and related disorders associated with CASPR2 antibodies
Jan. 18, 2022
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The author reviews the clinical features of sleep-related eating disorder and highlights the problem of differential diagnosis with nocturnal eating syndrome. Sleep-related eating disorder is now classified within the parasomnias and best conceptualized as a nonrapid eye movement parasomnia, whereas nocturnal eating syndrome has been characterized as a circadian delay of food intake with normal circadian timing of sleep onset. The level of consciousness during episodes of nocturnal eating, impaired in sleep-related eating disorder and spared in night eating syndrome, is considered the main difference between the 2 disorders. Associated with psychotropic medications and with restless legs syndrome, narcolepsy, sleepwalking, or other parasomnias, nocturnal eating disorders may be amenable to treatment with dopaminergic agents, selective serotonin reuptake inhibitors, or topiramate.
• Sleep-related eating disorder is a syndrome of nocturnal sleepwalking associated with compulsive eating behavior, occurring with variable degrees of consciousness impairment.
• Sleep-related eating is compulsive, associated with no feelings of hunger, and with ingestion of often inedible or sloppy food preparations.
• Accidents may occur during sleep-related eating behavior, such as burns, lacerations, or fires, and may adversely impact health (leading to obesity and dental decay).
• Sleep-related eating disorder is often associated with other sleep disorders and parasomnias, such as conventional sleepwalking, sleep apnea, narcolepsy, or restless legs syndrome, and with the use of medications, in particular hypnotic drugs such as zolpidem.
• Nighttime eating also includes nocturnal eating syndrome, which is different than sleep-related eating disorder and is characterized by wakeful eating after the last meal and prior to final awakening.
The first descriptions of sleep-related eating syndrome and nocturnal eating syndrome came from sleep research laboratories and obesity centers, respectively.
A syndrome of morning anorexia (skipping breakfast), hyperphagia in the evening (eating more than half of daily calories after 7 PM), and insomnia (difficulties in falling asleep or maintaining sleep) was first described in 1955 as "night eating syndrome" affecting 20 adults with treatment-resistant obesity (44). In 1999, Birketvedt also added the presence of conscious night eating (eating after an awakening from sleep) as diagnostic criterion.
In 1991, 19 consecutive adult patients who presented to a sleep disorders center with a combination of sleep (mainly somnambulism or periodic limb movements in sleep) and eating disorders were reported by Schenck and colleagues under the term “sleep-related eating disorder” and differentiated from daytime hyperphagia (40). The expanding features of this disorder were then reported in 1993; 38 patients from the same series were reported to have polysomnographic evidence of a disorder of arousal, suggesting that sleep-related eating disorder could be classified as a parasomnia.
However, the precise boundaries between night eating syndrome and sleep-related eating disorders are not clear. Although night eating syndrome is considered a circadian rhythm disorder, Allen suggested that sleep-related eating disorder represents a disorder of arousal within parasomnias, a view currently adopted by the International Classification of Sleep Disorders-III (02).
According to the ICSD-III, the diagnostic criteria for sleep-related eating disorder include the following:
(A) Recurrent episodes of dysfunctional eating that occur after an arousal during the main sleep period.
(B) The presence of at least one of the following in association with the recurrent episodes of involuntary eating:
(1) Consumption of peculiar forms or combinations of food or inedible or toxic substances.
(2) Sleep-related injurious or potentially injurious behaviors performed while in pursuit of food or while cooking food.
(3) Adverse health consequences from recurrent nocturnal eating.
(C) There is partial or complete loss of conscious awareness during the eating episode, with subsequent impaired recall.
(D) The disturbance is not better explained by another sleep disorder, mental disorder, medical disorder, medication, or substance use.
Despite growing research, the diagnostic criteria and clinical relevance of the nocturnal eating disorders remain unclear. Night eating syndrome is currently included in the Diagnostic and Statistical Manual, fifth edition (DSM-V), in the section “Other specified feeding or eating disorders” (03).
Another condition, "nocturnal eating (drinking) syndrome," (NEDS) considered an extrinsic sleep disorder (eg, disorders of sleep originating from outside the body) that primarily affects nursing young children and is generally kept distinct from sleep-related eating disorder, is no longer present in the ICSD-III (02).
The distinction between sleep-related eating disorder and nocturnal eating syndrome is a matter of ongoing debate, and many authors consider both disorders to be at the opposite poles of a continuous clinical spectrum. Vinai and colleagues pointed out how the symptoms and polysomnographic characteristics of sleep-related eating disorder and nocturnal eating syndrome often overlap (48). The authors disclosed that 22 out of 28 patients diagnosed with sleep-related eating disorder by an expert in sleep medicine also received the diagnosis of nocturnal eating syndrome, by an expert in eating disorders. Polysomnogram charts in the same patients failed to aid the differential diagnosis. In addition, video-polysomonographic data from a case series of 20 patients indicate potential different night eating syndrome subtypes regarding eating latency, total episode duration, and sleep latency after eating offset (24). Taken together, these findings stressed the need to redefine the diagnostic criteria for sleep-related eating disorder and nocturnal eating syndrome, outlining the border between them.
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