Marking Leg Movements Associated with Arousal in Polysomnography (PSG)
Yes, leg movements associated with arousal should be marked during polysomnography (PSG) as they are essential for accurate diagnosis of Periodic Limb Movement Disorder (PLMD) according to established diagnostic criteria. 1
Diagnostic Criteria and Marking Requirements
According to the American Academy of Sleep Medicine guidelines, the following criteria apply when marking leg movements during PSG:
- Polysomnography must demonstrate repetitive, highly stereotyped limb movements 1
- A PLMS Index exceeding 15 per hour in adults (>5 per hour in children) is required for diagnosis 1
- Clinical sleep disturbance or daytime fatigue must be present 1
- The movements should not be better explained by another sleep disorder, medical condition, medication use, or substance use 1
Technical Aspects of Marking Leg Movements
- Electromyography (EMG) during PSG is the required method for accurate PLM detection 1
- Each movement typically lasts approximately 2-4 seconds with a frequency of about 1 every 20-40 seconds 2
- Movements are characterized by dorsiflexion of the ankle and extension of the big toe, sometimes with flexion of the knee and hip 2, 1
- PLMs typically occur predominantly during the first part of the night 2, 1
Important Considerations When Marking Leg Movements
- PLM should not be counted during REM sleep for the diagnosis of PLMD, as they are primarily assessed during NREM sleep 1
- Leg movements may cause brief awakenings or arousals from sleep, which should be noted in the PSG interpretation 2
- Actigraphy should not be used in place of EMG for the diagnosis of PLMD, as it produces unreliable estimates of periodic limb movements 1
Clinical Significance of Marking Leg Movements with Arousals
- PLMS associated with arousals are linked to disturbed sleep, particularly in older women 2
- The presence of PLMS supports but is not sufficient for the diagnosis of Restless Legs Syndrome (RLS) 2, 1
- PLMS have been implicated as a contributing factor to cardiovascular disease development, with associated elevations in heart rate and blood pressure 1
Common Pitfalls to Avoid
- Failing to distinguish between PLMS and leg movements due to other causes (e.g., respiratory events, position changes)
- Not recognizing that up to 90% of individuals with RLS have PLMS 2
- Overlooking that PLMS are common in patients taking antidepressants 2
- Misdiagnosing PLMD when another sleep disorder is the primary cause of the leg movements 1
- Using default detection parameters in automated systems without customization, which can lead to significant underscoring of PLMW 3
Remember that while the presence of PLMS supports the diagnosis of RLS, limb movements are neither necessary nor sufficient to make the diagnosis of RLS 2. Additionally, polysomnography is indicated when periodic limb movement disorder is suspected as a cause of insomnia 4.