What are the polysomnographic (PSG) findings associated with confusion arousals?

Polysomnographic Findings for Confusional Arousals

Confusional arousals are characterized by specific polysomnographic patterns including abrupt arousals from slow-wave sleep with distinct EEG changes, heart rate acceleration, and associated motor behaviors without preceding EEG abnormalities. 1

Key Polysomnographic Features

EEG Patterns

• Post-arousal EEG during confusional arousals demonstrates three main patterns:
  • Diffuse, rhythmic delta activity with typical frequency of 2.2 Hz, amplitude of 85 μV, and duration of 20 seconds 1
  • Diffuse delta and theta activity intermixed with alpha and beta activity 1
  • Prominent alpha and beta activity following the arousal 1
• Notably, there is an absence of EEG "delta wave buildup" before the arousal events 1

Cardiac Changes

• Heart rate acceleration emerges abruptly with the arousal from slow-wave sleep 1
• Significant changes in mean pre-versus post-arousal heart rate (p<0.001) 1

Sleep Architecture

• Macrostructural sleep parameters ("sleep architecture") typically remain intact despite the presence of confusional arousals 1
• Arousals predominantly occur during slow-wave sleep (stages N3) 1, 2

Motor Activity

• Movements and behaviors are frequently observed during arousals (89.3% during N3 sleep) 3
• Motor activity often involves the head and neck, followed by upper limbs 3
• Movements may include flexing/rotating the neck and trunk, scratching, pulling sheets, and other comfort behaviors 3
• Some movements resemble sleep-associated automatisms (swallowing, chewing) 3

Associated Polysomnographic Findings

Sleep Fragmentation

• Increased CAP (Cyclic Alternating Pattern) rate, particularly subtypes A1 and A2 4
• Higher frequency of EEG arousals compared to normal subjects 4
• Reduced sleep efficiency with increased nocturnal wakefulness and stage 1 sleep 4

Relationship to Other Sleep Disorders

• Confusional arousals may be associated with polysomnographic evidence of obstructive sleep apnea syndrome (OSAS) 5
• May co-occur with hypnagogic or hypnopompic hallucinations 5
• Can be associated with violent or injurious behaviors during sleep 5, 1

Clinical Implications

• Polysomnography is indicated when initial diagnosis is uncertain or when precipitous arousals occur with violent or injurious behavior 2
• The American Academy of Sleep Medicine recommends including arousal-based scoring when evaluating sleep disorders 2, 6
• Arousals, rather than hypoxemia, may better predict daytime symptoms in some sleep disorders 6

Special Considerations

• In REM sleep behavior disorder (RBD), polysomnography demonstrates intermittent loss of REM sleep-associated muscle atonia, with complex motor activity associated with dream mentation 2
• This differs from confusional arousals, which primarily occur during slow-wave sleep 2, 1
• Some confusional arousals may be associated with epileptiform discharges during NREM sleep, suggesting a possible relationship to nocturnal epilepsy in certain cases 7

Diagnostic Pitfalls

• Confusional arousals must be distinguished from other parasomnias and nocturnal seizures 2
• The absence of preceding EEG abnormalities before confusional arousals helps differentiate them from seizure-related events 1
• Multichannel, high-voltage delta activity was observed in less than 2% of all pre-arousal periods, contrary to some previous assumptions 1