The level of observed physical movement accompanying periodic limb movements measured in a clinical sleep population

Figures & data

Table 1 Techniques for scoring visual movement

Scoring visual movements
• Movements were viewed on video recordings of polysomnograms.
• No special instructions were given to technicians or patients regarding sheets, covers or bedclothes.
• The reviewing physician chose selected segments of PLMs to review.
• Duration of review was determined by number of PLMs recorded.
• Video viewing was primarily carried out at a speed of eight times normal with additional review at lower speeds performed as needed for questions about movements.
• Movement classification level was chosen based on predominate movements seen.

Abbreviation: PLMs, periodic limb movements.

Table 2 Definitions of level of visual movement observed with measured periodic limb movements

Definition of Movement Levels
Level 0	–	No movements observed
Level I	–	Movement limited to one extremity
		Foot or hand
		Lower extremity
		Leg—Knee and below
		Upper extremity
		Arm—Forearm and hand
		Neck or head
Level II	–	Movement limited to any combination of two extremities
		Feet and hands—any two extremities
		Lower extremity
		Knee and below—two legs or one leg and one arm
		Hip with upper and lower leg—unilateral
		Upper extremity
		Forearm and hand—two arms or one arm and one lower leg
		Arm including movement at shoulder—unilateral
		Neck or head and one extremity
Level III	–	Movement limited to any combination of three extremities
		Feet or hands—any three extremities
		Upper and lower extremities
		Knee and below with forearm and hand—any three
		Upper and lower leg—bilateral
		Neck or head and two extremities
Level IV	–	Movement in excess of above

Table 3 The age distribution of the 460 patients and the frequency of the identified PLMs

PLMs identified	Age
	<30	30–49	50–69	>69
No PLMs	24	71	98	30
PLMI >1	11	70	99	57
Total reviewed	35	141	197	87
No movement, %	68.6	50.4	49.7	34.5
Movement observed, %	31.4	49.6	50.3	65.5

Abbreviations: PLMIs, periodic limb movements events per hour of sleep; PLMs, periodic limb movements.

Table 4 Sex distribution of patients with PLMIs as percent of each index level

PLMIs	Sex of patients with PLMs
	Group	Male	Male %	Female	Female %
PLMI 1–4.9	92	47	32.9	45	47.9
PLMI 5–14.9	58	40	28.0	18	19.2
PLMI 15–29.9	41	24	16.7	17	18.0
PLMI ≥30	46	32	22.4	14	14.9
Total	237	143	100.0	94	100.0

Abbreviations: PLMIs, periodic limb movements events per hour of sleep; PLMs, periodic limb movements.

Figure 1 The observed level of movement in the entire group of patients with periodic limb movements.

Note: The bars represent the percentage of the entire group at each level of observed movements.

Table 5 The PLMI measured and the observed movements for the entire population

Measured PLMIs	Group	None	Level of movements observed
			Level I	Level II	Level III	Level IV
PLMIs <14.9
PLMs <4.9	92	51	18	12	8	3
PLMs 4.9–14.9	58	22	19	11	5	1
Subtotal	150	73	37	23	13	4
PLMIs >15
PLMs 14.9–29.9	41	9	20	5	5	2
PLMs ≥30	46	8	8	16	7	7
Subtotal	87	17	28	21	12	9
PLMIs >1 Total	237	90	65	44	25	13

Abbreviations: PLMIs, periodic limb movements events per hour of sleep; PLMs, periodic limb movements.

Table 6 Relationship between AHI and PLMI

Apnea	PLM index
	PLMI <5		PLMI 5–14.9		PLMI 15–29.9		PLMI ≥30
	Number	Percent	Number	Percent	Number	Percent	Number	Percent
AHI <5	32	34.8	26	44.8	15	36.6	14	30.4
AHI 5–14.9	26	28.3	17	29.3	14	34.1	18	39.1
AHI 15–29.9	16	17.4	8	13.8	7	17.1	9	19.6
AHI 30–59.9	11	12.0	6	10.3	4	9.8	4	8.7
AHI ≥60	7	7.6	1	1.7	1	2.4	1	2.2
Total	92	100	58	100	41	100	46	100

Abbreviations: AHI, apnea hypopnea index; PLMI, periodic limb movement events per hour of sleep; PLMs, periodic limb movements.

Table 7 The level of observed movements in patients without apnea

Measured PLMIs	Group	None	Level of movements observed
			Level I	Level II	Level III	Level IV
PLMIs <14.9
PLMs <4.9	32	14	6	6	5	1
PLMs 4.9–14.9	24	7	10	5	2	0
Subtotal	56	21	16	11	7	1
PLMIs >15
PLMs 14.9–29.9	15	2	8	2	2	1
PLMs ≥30	14	2	3	5	3	1
Subtotal	29	4	11	7	5	2
PLMIs >1 Total	85	25	27	18	12	3
		29%	32%	21%	14%	4%

Abbreviations: PLMIs, periodic limb movements events per hour of sleep; PLMs, periodic limb movements.

Table 8 The level of observed movements in patients with obstructive sleep apnea

Measured PLMIs	Group	None	Level of movements observed
			Level I	Level II	Level III	Level IV
PLMIs <14.9
PLMs <4.9	60	37	12	6	3	2
PLMs 4.9–14.9	34	15	9	6	3	1
Subtotal	94	52	21	12	6	3
PLMIs >15
PLMs 14.9–29.9	26	7	12	3	3	1
PLMs ≥30	32	6	5	11	4	6
Subtotal	58	13	17	14	7	7
PLMIs > 1 Totals	152	65	38	26	13	10
		43%	25%	17%	9%	7%

Abbreviations: PLMIs, periodic limb movements events per hour of sleep; PLMs, periodic limb movements.

Figure 2 This is an example of the variations in the observed level of identified in some individuals.

Notes: It is from a 5-minute segment of a polysomnogram electroencephalogram leads (F3-M2) and (C3-M2), electromyogram leads on left leg(leg1-leg2) and right leg (leg3-leg4), and electrocardiogram (EKG1-EKG2).