Module 1 - NREM Parasomnias Flashcards
What are the three states of human consciousness?
Wake, NREM sleep, and REM sleep.
What is a parasomnia?
A behaviour, emotion, perception, dream, or autonomic nervous system (ANS) activity that occurs at night and may cause injuries, sleep disruption, health issues, or psychosocial effects.
In which sleep stages do parasomnias occur?
NREM and REM sleep.
What are the classical NREM parasomnias?
Sleepwalking, confusional arousals, and sleep terrors.
When do NREM parasomnias typically occur?
During the first third of the night, during slow-wave sleep (SWS).
Are people usually responsive during a parasomnia episode?
No, they typically have inappropriate or absent responsiveness.
What is the prevalence of sleepwalking in children?
17.3% of children aged 3–13 years.
What is the main difference between sleep terrors and confusional arousals?
Sleep terrors involve autonomic activation (e.g., tachycardia, sweating, mydriasis), while confusional arousals do not.
What are some common precipitating factors for NREM parasomnias?
Sleep deprivation, OSA, stress, evening screen time, certain medications, and environmental stimuli (e.g., noise, fever).
What are the three main types of NREM parasomnias?
Confusional arousals (in bed, confused), sleepwalking (leaves bed), and sleep terrors (autonomic activation).
What are the general diagnostic criteria for disorders of arousal (DOA)?
- Recurrent episodes of incomplete awakening from sleep
- Inappropriate or absent responsiveness
- Limited or no associated cognition or dream imagery
- Partial or complete amnesia for the episode
- Not explained by another disorder, medication, or substance use
What is the key pathophysiology of NREM parasomnias?
They occur due to wakefulness intruding into slow-wave sleep (Stage N3), leading to a state where high-level cognitive functions are impaired, but motor and basic behaviours can still occur.
What are the essential features of NREM parasomnias?
- Complex behaviours arising from partial arousals during SWS
- May last from a few minutes up to 30 minutes (especially in children)
- Sleep talking or shouting can accompany episodes
- Open eyes with a glassy stare
- Difficult to awaken, often confused or aggressive when awoken
- High-level cognitive functions (e.g., planning, social awareness) are absent
- Occur during the first third of the night or periods of increased SWS
What are some key demographic trends in NREM parasomnias?
- No significant sex differences
- More common in children but can persist up to age 35
- Confusional arousals and sleepwalking affect ~17.3% of children and 2.9–12% of adults
- Sleep terrors occur in 1–6% of children and ~2% of adults
- Sleepwalking lifetime prevalence: ~18.3% (29% with nocturnal wandering)
What are the genetic influences on NREM parasomnias?
- If one parent has parasomnias: 22% chance in offspring
- If both parents have parasomnias: 60% chance in offspring
- Twin studies suggest genetic factors account for ~65% of cases
How can polysomnography (PSG) assist in diagnosing NREM parasomnias?
- Used for atypical, injurious, or complicated cases
- May reveal high-amplitude hypersynchronous delta waves and frequent SWS arousals
- Spectral analysis shows SWS dysregulation with increased delta power prior to arousals
- Sleep studies are particularly useful in patients with comorbid OSA
What are the key differential diagnoses for NREM parasomnias?
- REM sleep behaviour disorder (RBD): Features counterattacking behaviours, unlike the escape-like reactions in DOA
- Obstructive sleep apnea (OSA): Can exacerbate parasomnias
- Malingering
- Alcohol intoxication
- Sleep-related epilepsy: Stereotyped, purposeless movements with abnormal posturing
What are the forensic implications of sexsomnia?
- Involves sexual behaviours (fondling, intercourse) during sleep
- Often linked to a history of parasomnias and family history
- Can have legal implications (~35% of cases)
- High male predominance (~80%, average age 35)
What are the clinical features of sleep-related eating disorder (SRED)?
- Recurrent episodes of dysfunctional eating after arousal from sleep
- Consumption of unusual or toxic substances
- Potential for injuries while preparing food
- Can lead to obesity, diabetes, or allergies
- Often occurs nightly (>50% frequency)
- Higher prevalence in females (60–83%)
- Mean age of onset: 22–40 years
How can disorders of arousal (DOA) be managed?
- Identify and treat underlying conditions (e.g., OSA, limb movements, narcolepsy)
- Improve sleep hygiene and minimise triggers (stress, alcohol, medications, disrupted sleep environment)
- Ensure a safe sleep setting (bedroom safety measures, inform bed partners)
- Consider anticipatory awakenings for children
- Medications (e.g., clonazepam) can be used but lack strong evidence from RCTs
What are the key takeaway points about NREM parasomnias?
- Occur in NREM sleep, especially SWS, during the first third of the night
- Characterised by incomplete awakenings and impaired awareness
- Include sleepwalking, confusional arousals, sleep terrors, and sleep-related eating disorder
- Common in childhood but can persist into adulthood
- Often linked to genetic predisposition and sleep deprivation
- Treatment focuses on addressing underlying causes and improving sleep environment
How can NREM parasomnias be identified on a sleep study?
They feature frequent awakenings from Stage N3 (slow-wave sleep) without transitioning fully to wakefulness.
What happens to heart rate during sudden arousals from slow-wave sleep (SWS) in NREM parasomnias?
Heart rate increases significantly with the sudden arousal.
Do NREM parasomnias occur in children?
Yes, they are commonly seen in children.
What are the key signs of slow-wave arousal (SWA) disorders on a sleep study?
Sudden abrupt arousals from N3 sleep
Confused behaviour or unexpected movements on video
Increased heart rate
Vocalisation during episodes
Why is video important when diagnosing parasomnias?
It helps capture movements, vocalisations, and behavioural anomalies that cannot be seen on EEG alone.
Are home sleep studies recommended for investigating parasomnias?
No, but they may show indications of NREM parasomnias.
What are the sleep study features of body rocking in NREM parasomnias?
Typically occurs out of N2 sleep
Repetitive movement artefacts on EEG
Movements suddenly stop, and the patient returns to sleep
What sleep stage is associated with Rhythmic Movement Disorder (RMD)?
Stage N2 sleep, with noticeable artefacts on EEG.
What are the scoring criteria for Rhythmic Movement Disorder (RMD) on a sleep study?
Frequency of 0.5–2Hz (0.5–2 seconds per movement)
Minimum of 4 movements
Amplitude at least twice the background activity
Requires video confirmation
What are key takeaways for assessing NREM parasomnias?
Understand normal sleep arousals (PSG & video)
Identify sudden arousals and unusual movement artefacts
Always review video for confirmation
What are parasomnias?
Parasomnias are unwanted physical actions or sensory experiences that occur during sleep onset, during sleep itself, or upon awakening. They can involve abnormal movements, behaviors, perceptions, emotions, or autonomic functions.
What are the three main categories of parasomnias?
NREM Sleep-Related Parasomnias – e.g., sleepwalking, confusional arousals, sleep terrors.
REM Sleep-Related Parasomnias – e.g., REM sleep behavior disorder, nightmare disorder, recurrent isolated sleep paralysis.
Other Parasomnias – e.g., exploding head syndrome, sleep-related hallucinations, sleep enuresis.
What distinguishes sleep-related movement disorders from parasomnias?
Sleep-related movement disorders involve repetitive movements that disrupt sleep (e.g., periodic limb movements), while parasomnias involve unusual behaviors or experiences occurring during sleep.
What is REM sleep behavior disorder (RBD)?
RBD is a condition where muscle atonia (normal REM paralysis) is absent, leading to physically acting out vivid dreams, sometimes violently.
What are common triggers for NREM parasomnias?
Sleep deprivation, stress, fever, alcohol, intense exercise before bed, and arousing stimuli can trigger NREM parasomnias.
What is sleepwalking (somnambulism), and when does it occur?
Sleepwalking involves complex behaviors, from simple gestures to running or driving, typically occurring during deep N3 sleep.
How do confusional arousals differ from sleepwalking?
Confusional arousals involve disoriented, slow-to-respond behavior without purposeful movements like walking.
What are sleep terrors, and how do they present?
Sleep terrors are intense episodes of fear, screaming, and autonomic activation (e.g., rapid heartbeat), typically with no memory of the event.
How can parasomnias be differentiated from nocturnal seizures?
Nocturnal seizures often have stereotyped movements, occur at any time during sleep, and may show epileptiform activity on a polysomnogram.
What are some strategies to manage NREM parasomnias?
Maintain a regular sleep schedule, reduce stress, avoid sleep deprivation, ensure a safe sleep environment, and in some cases, consider medication.
How can a sleep study help differentiate between NREM parasomnias and nocturnal epilepsy?
A sleep study records brain activity, behaviour, and muscle movements during sleep to distinguish between the two conditions based on their different characteristics.
What are the key behavioural differences between nocturnal epilepsy and NREM parasomnias?
Nocturnal Epilepsy: Stereotyped behaviour, distinct start and stop, may interact with the environment, usually recall event.
NREM Parasomnia: Variable behaviour, unclear event ending, may interact with non-existent objects, usually no recall of event.
What are common EEG findings in nocturnal epilepsy vs. NREM parasomnia?
Nocturnal Epilepsy: May show epileptiform activity if not covered by muscle artefact
NREM Parasomnia: Sharp arousals and muscle activity, but no epileptiforms.
At what time of night do nocturnal epilepsy and NREM parasomnia events typically occur?
Nocturnal Epilepsy: Can occur at any time of night, usually in NREM sleep.
NREM Parasomnia: Typically occurs in the first third of the night during slow-wave sleep (SWS).
What tool can be used to diagnose nocturnal epilepsy vs. NREM parasomnia with high accuracy?
The decision tree by Derry et al. (2009) has 94% accuracy in distinguishing between the two conditions.
Why is a full EEG recording necessary for differentiation between nocturnal epilepsy and NREM parasomnia?
It helps identify epileptiform activity, determine where seizures originate, and differentiate from sleep-related movement disorders.
How do different EEG montages assist in detecting epilepsy?
Double banana view and transverse view help pinpoint where the seizure started by tracking the spread of epileptic activity across the brain.
What factors can trigger nocturnal epilepsy?
Sleep deprivation
Disruptions to the sleep/wake cycle
Other sleep disorders like sleep apnea
What percentage of epilepsy patients only have seizures during sleep?
About 10% of epilepsy patients experience seizures exclusively during sleep.
Why might a sleep-deprived EEG be used in epilepsy diagnosis?
Sleep deprivation increases the likelihood of triggering an epileptic event, making it easier to capture during testing.
What additional tests may be needed if nocturnal epilepsy is suspected?
A full sleep study EEG may be performed, especially if sleep apnea is suspected to be triggering epileptic events.
What are some key PSG observations used to differentiate epilepsy from parasomnia?
Behaviour consistency: Epilepsy is stereotyped; parasomnia varies.
Response to interaction: Epilepsy may show appropriate interaction; parasomnia often shows confusion.
Event recall: Epilepsy is usually remembered; parasomnia is not.
What safety measures should be taken during a PSG for epilepsy or parasomnia?
Use bedrails or a low bed for protection.
Ensure high-quality video recording with pan/tilt/zoom cameras.
Monitor sudden arousals and abnormal movements
What test can be done during an episode to assess memory recall and determine if NREM parasomnia or epilepsy?
Give the patient a word (e.g., “pineapple”) and ask them to recall it in the morning—lack of recall suggests NREM parasomnia.
How should an EEG study be scored when investigating epilepsy?
Score normally for sleep staging.
Remove unnecessary channels to focus on abnormalities.
Use additional EEG leads to track where anomalies started.
Present findings in transverse and double banana montages for neurologist review.
Describe the Derry et al., decision tree to differentiate NFLE and NREM parasomnia
Does the patient fully wake up at the end of the episode?
Yes → Check if the episode has a discrete offset (sudden stop vs. gradual waking).
Discrete offset? → Likely NFLE
Gradual waking? → Check movement posture:
Remains lying down (prone/supine)? → NFLE
Sits, stands, or walks? → Parasomnia
No → Check for head turning & dystonic posturing (abnormal muscle stiffening).
Yes? → NFLE
No? → Parasomnia
What was Sleep-Related Hypermotor Epilepsy (SHE) previously known as?
SHE was previously known as nocturnal frontal lobe epilepsy (NFLE), but the name was changed in 2016 to better reflect that seizures occur during sleep, can arise from extra-frontal sites, and are characterized by hypermotor activity.
Why was the term “nocturnal frontal lobe epilepsy” replaced with “Sleep-Related Hypermotor Epilepsy”?
The term was changed because:
Seizures occur during sleep regardless of the time of day.
About 30% of cases originate outside the frontal lobe.
The motor characteristics of seizures are more defining than their location.
What are the key characteristics of SHE seizures?
SHE seizures are:
Brief (<2 minutes) and stereotyped within individuals.
Marked by hypermotor movements, dystonic posturing, and episodic nocturnal wandering.
Predominantly sleep-related but can occur while awake.
What types of movements are common in SHE?
Hypermotor movements include:
Kicking, cycling of limbs, rocking, and vocalizations.
Emotional facial expressions.
Asymmetric tonic/dystonic posturing with or without head/eye deviation.
Episodic nocturnal wandering.
How common is SHE?
SHE is relatively uncommon, with an estimated prevalence of 1.8 per 100,000 people (0.0018%).
How is SHE different from parasomnias?
Unlike parasomnias:
SHE seizures are frequent and often cluster together.
They can occur at any sleep stage, while non-REM parasomnias occur within the first 90 minutes and REM parasomnias later in the night.
They follow a stereotyped pattern and involve hypermotor movements.
What are some common semiological features of SHE?
Features include:
Head turning to the side of seizure activity.
“Fencing posture” (head turns toward an outstretched arm).
Jacksonian march movements.
Dystonic posturing, vocalizations, and episodic wandering.
Why is SHE difficult to diagnose?
SHE can be difficult to diagnose because:
It resembles other nocturnal motor disorders.
EEG may not initially reveal clear seizure activity.
Muscle artifacts often obscure EEG recordings during seizures.
Invasive EEG monitoring may be required in ambiguous cases.
What diagnostic tool is often required for SHE?
Video polysomnography is often needed to differentiate SHE from other nocturnal motor disorders.
How does SHE compare to frontal lobe epilepsy (FLE)?
SHE and FLE overlap, but:
Not all frontal lobe seizures are sleep-related.
Frontal lobe seizures can occur during the day.
SHE seizures are hypermotor and frequently occur during sleep.
What is the prognosis for SHE patients?
The prognosis varies:
A 16-year follow-up study found only 22.3% achieved terminal remission (seizure-free for >5 years).
Some patients experience spontaneous remission without medication.
The presence of underlying brain disorders worsens prognosis.
What are the different seizure manifestations in SHE based on brain region?
Primary motor cortex (posterior frontal lobe): Jacksonian march.
Supplementary motor area (SMA): Fencing posture, dystonic posturing, vocalization, speech arrest.
Orbitofrontal cortex, insula, cingulate gyrus: Staring, non-responsiveness, autonomic signs (e.g., tachycardia, sweating).
How does SHE compare to temporal lobe epilepsy (TLE)?
SHE can resemble TLE, but:
TLE may involve more postictal confusion.
Extra-frontal SHE has shorter EEG latency and longer seizure duration.
TLE often has prominent autonomic signs and staring episodes.
How often do SHE seizures occur?
SHE seizures typically occur almost every night, multiple times per night.
How does EEG help in diagnosing SHE?
About 50% of SHE cases show no abnormalities on scalp EEG during episodes.
Interictal epileptiform activity may also be absent.
Invasive EEG monitoring may be needed for a definitive diagnosis.
What is episodic nocturnal wandering?
It refers to SHE seizures involving complex ambulatory behaviors that resemble sleepwalking.
What are the possible forms of SHE?
SHE can occur in familial, sporadic, symptomatic (associated with structural brain lesions), and idiopathic forms.
What makes diagnosing SHE particularly challenging in young adults?
SHE symptoms can resemble parasomnias, psychogenic non-epileptic seizures (PNES), and other nocturnal movement disorders, requiring extended EEG or video polysomnography for accurate differentiation.
What factors contribute to a poor prognosis in SHE?
The presence of underlying brain disorders is the main factor contributing to poor prognosis.
How is SHE treated?
SHE treatment is challenging due to limited research on medication response. Some patients achieve seizure control with anticonvulsants, while others experience spontaneous remission without medication.
Why do some SHE seizures go unnoticed?
Since SHE seizures occur during sleep and often involve minimal postictal confusion, they may not be recognized as seizures.
What semiological features overlap between frontal and temporal lobe seizures?
Features such as staring, non-responsiveness, automatisms, and autonomic signs (e.g., tachycardia, sweating) can occur in both types, complicating diagnosis.
How does epilepsy impact sleep quality?
Epilepsy can worsen sleep quality, and poor sleep can worsen seizure control. Sleep-wake disorders are 2-3 times more common in adults with epilepsy than in the general population.
What sleep-related complaints do epilepsy patients commonly report?
Daytime sleepiness and insomnia, though research on this is mixed. A large meta-analysis found no increased subjective daytime sleepiness but did find poorer sleep quality.
How do focal and primary generalized seizures affect sleep?
They can lead to sleep fragmentation, increased sleep-stage shifts, and decreased sleep efficiency. Temporal lobe seizures can also reduce REM sleep.
How do antiepileptic drugs (AEDs) affect sleep quality?
While some AEDs negatively impact sleep, overall, seizure control with AEDs improves sleep quality in patients with nocturnal epilepsy.
What are five key behavioral signs favoring parasomnias over NFLE?
Interactive behaviors (talking, responding to surroundings).
Failure to wake up fully after the event.
Waxing and waning intensity.
Event modification by external stimuli (e.g., being calmed).
Coherent speech during events.
What are five key behavioral signs favoring NFLE over parasomnias?
Abrupt onset and offset.
Stereotyped movements (same actions every episode).
Bicycling movements, dystonic posturing, or thrashing.
No interaction with the environment.
Immediate full wakefulness after the event.
How do the time course and progression of parasomnias differ from NFLE seizures?
Parasomnias: Begin gradually with arousal behaviors (eye opening, mumbling), progress into complex movements, and end with either wakefulness or returning to sleep.
NFLE: Start explosively, do not show waxing/waning, and end abruptly with immediate full wakefulness.
From which sleep stages do parasomnias and NFLE seizures typically arise?
Parasomnias: Almost always from deep NREM sleep (Stage 3/4).
NFLE: Typically from light NREM sleep (Stage 1/2).
How useful is EEG in distinguishing parasomnias from NFLE?
EEG is often inconclusive. Parasomnias show non-epileptiform slow activity, while NFLE often has muscle artifacts obscuring EEG changes. However, a robust ictal rhythm is present in 38% of NFLE cases and 0% of parasomnias, making it useful when seen.
What are the three main types of behaviors observed in parasomnias?
Arousal Behaviors (92%) – Eye opening, yawning, mumbling.
Non-Agitated Motor Behaviors (72%) – Sitting up, fumbling with objects, looking around confused.
Distressed Emotional Behaviors (51%) – Screaming, fearful expressions, resisting calming efforts.
Do parasomnias occur in distinct categories (e.g., sleepwalking vs. night terrors), or are they part of a spectrum?
They exist on a continuum rather than as distinct categories.
