Clinical utilisation of the Infant Monitor of vocal Production (IMP) for early identification of communication impairment in young infants at-risk of cerebral palsy: a prospective cohort study

Figures & data

Table 1. Participant Characteristics

Participant Characteristics	At-risk/with CP	18 (%)	TD 18 (%)
Gender	M	9 (50)	13 (72)
	F	9 (50)	5 (28)
Gestational Age	< 28 weeks	3 (17)	-
	28 – < 32 weeks	2 (11)	-
	32 – < 37 weeks	4 (22)	2 (11)
	38–40 weeks	9 (50)	16 (89)
CP motor type	Dyskinetic	9 (50)	-
	Spastic	6 (33)	-
	n/a	3 (17)	-
Distribution	Unilateral	1(6)	-
	Bilateral	14(78)	-
	n/a	3(17)	-
MRI	Timing of Insult
	Anti	3 (17)	-
	Post	1 (5)	-
	Peri	14 (78)	-
	Description
	Grey	11 (61)	-
	White	6 (33)	-
	Maldevelopment	1 (6)
GMFCS (as at 2 years)	GMFCS 1	3 (17)	-
	GMFCS 2	0 (0)	-
	GMFCS 3	2 (11)	-
	GMFCS 4	2 (11)	-
	GMFCS 5	6 (33)	-
	n/a	3 (17)	-
	missing	2 (11)	-
Hearing Impairment	*WNL	15 (83)	15 (83)
	Aided (sensorineural loss)	2 (11)	-
	Episodes of Otitis Media	1 (6)	3 (17)
Oropharyngeal Dysphagia		10 (55)	-
	Feeding Method		-
	Oral	12 (67)	18(100)
	PEG	6 (33)	-

Note: * based on parent report, with one awaiting outcome of hearing assessment. PEG = percutaneous endoscopic gastrostomy tube

Table 2. IMP question ceiling item at <6, 9 and 12 months of age

	At-risk/CP (months)				TD (months)
ID	Diagnosis	< 6	9	12	ID	< 6	9	12
CP1	Spastic	8	10	10	TD001	8	13	16
CP2	Spastic	11	13	16	TD002	8	13	16
CP3	Dyskinetic	7	7	9	TD003	11	13	15
CP4	Dyskinetic	8	8	8	TD004	10	10	14
CP5	Dyskinetic	8	8	10	TD005	8	14	16
CP6	Dyskinetic	10	10	10	TD006	8	15	16
CP7	Dyskinetic	7	10	10	TD007	11	13	16
CP010	Dyskinetic	7	9	11	TD008	9	13	14
CP011	Dyskinetic	8	7	8	TD009	9	13	16
CP012	Spastic	7	7	7	TD010	9	13	14
CP013	Dyskinetic	7	7	10	TD011	10	10	14
CP014	Spastic	8	9	12	TD012	9	16	16
CP0015	DD	10	11	13	TD013	9	14	16
CP0016	Spastic	13	15	16	TD014	9	13	16
CP0017	Dyskinetic	10	10	10	TD015	9	13	16
CP0018	DD	8	13	13	TD016	7	13	15
CP0019	DD	11	13	13	TD017	11	11	16
CP0020	Spastic	11	13	16	TD018	11	11	16

Figure 1. Mean question ceiling score from the Infant Monitor of vocal Production at 6, 9 and 12 months of age for infants at risk of cerebral palsy (CP) and typically developing (TD) infants (with 95% CI).

Figure 2. Mean percentage rank score from the Infant Monitor of vocal Production at 6, 9 and 12 months of age for infants at risk of cerebral palsy (CP) and typically developing (TD) infants (with 95% CI).

Table 3. Factor Loadings for Extracted Dimensions from the Principle Components Analysis of IMP Item Scores at 9 Months of Age (N = 36)

Item	Description	Factor 1	Factor 2
		Speech Motor	Social Receptive
1	A pleasing voice	.639	.322
2	Looks intently at the speaker’s face	.544	.429
3	Makes expressive sounds other than crying	.616	.463
4	Uses voice to respond to an unseen speaker	.084	.813
5	Changes of volume of voice (soft-loud)	−.120	.867
8	Makes closed-mouth “raspberry”-like sounds	.862	−.061
9	Uses voice while mouthing objects	.881	−.139
10	Uses different sounds together	.847	−.083
13	Babbles fluently and rhythmically	.800	.020

Note. Factor 1 explained 55.1%, and Factor 2 14.5%, of total variance among item scores. Loadings in bold are greater than .80 and are taken as significant for dimension interpretation.

Table 4. Factor Loadings for Extracted Dimensions from the Principle Components Analysis of IMP Item Scores at 12 Months of Age (N = 36)

Item	Description	Factor 1	Factor 2
		Speech Motor	Social Receptive
1	A pleasing voice	.527	.521
2	Looks intently at the speaker’s face	.367	.628
3	Makes expressive sounds other than crying	.464	.626
4	Uses voice to respond to an unseen speaker	.032	.830
5	Changes of volume of voice (soft-loud)	−.230	.857
8	Makes closed-mouth “raspberry”-like sounds	.827	.075
9	Uses voice while mouthing objects	.730	.153
10	Uses different sounds together	.758	−.032
12	Copies a familiar sound or word (i.e., moo)	.828	−.161
13	Babbles fluently and rhythmically	.868	−.024

Note. Factor 1 explained 52.9%, and Factor 2 15.9%, of total variance among included item scores. Loadings in bold are greater than .80 and are taken as significant for dimension interpretation.

Table 5. Receptive-Expressive Emergent Language Test Score (REEL-3) for all Participants Across Three Testing Occasions

	6 months				9 months				12 months
ID	EAS	RAS	LAS		EAS	RAS	LAS		EAS	RAS	LAS
At-risk of cerebral palsy
CP0001	97	93	94		88	90	87		79	91	82
CP0002	95	76	83		93	86	87		80	85	79
CP0003	76	75	71		64	60	54		70	68	63
CP0004	70	61	59		65	<55	52		<55	<55	<46
CP0005	65	82	68		60	67	56		<55	<55	<46
CP0006	85	85	82		69	70	63		60	58	51
CP0007	93	90	90		78	85	78		-	-	-
CP0010	98	90	93		83	83	80		62	63	55
CP0011	70	88	75		75	86	77		65	68	60
CP0012	75	90	79		65	60	55		<55	<55	<46
CP0013	85	88	84		64	75	63		63	63	56
CP0014	93	90	90		73	72	67		68	98	80
CP0015	103	105	108		85	102	92		70	92	77
CP0016	105	93	99		103	90	96		99	91	94
CP0017	85	97	89		69	80	69		55	77	59
CP0018	95	93	93		85	90	85		78	75	72
CP0019	103	93	98		90	95	91		81	77	75
CP0020	105	93	99		83	95	87		95	100	97
Typically Developing
TD001	92	90	89		105	105	106		95	98	96
TD002	80	90	88		89	82	83		90	92	89
TD003	93	82	85		89	95	90		81	92	84
TD004	85	87	83		88	75	78		84	85	81
TD005	93	85	87		83	83	80		99	102	101
TD006	103	98	101		104	105	105		110	106	110
TD007	92	83	85		97	95	95		103	95	99
TD008	95	90	91		85	82	80		84	95	87
TD009	98	97	97		110	97	106		115	102	110
TD010	95	87	89		88	95	90		105	92	98
TD011	92	92	89		90	93	90		81	85	80
TD012	95	92	92		95	97	95		100	92	95
TD013	85	88	84		99	100	99		88	91	87
TD014	98	98	98		94	90	90		92	110	101
TD015	98	97	99		88	113	101		98	102	100
TD016	85	85	82		98	92	94		90	75	79
TD017	95	90	91		90	103	96		89	98	92
TD018	98	90	93		93	105	99		89	98	92

Note: EAS = expressive language ability score, RAS = receptive language ability score, LAS = language ability score.

Figure 3. Mean language ability score from the REEL-3 at 6, 9 and 12 months of age for infants at risk of cerebral palsy (CP) and typically developing (TD) infants (with 95% CI).

Figure 4. Mean REEL-3 expressive and receptive raw scores at each time point for infants diagnosed at 24 months with spastic (n = 6) and dyskinetic (n = 9) cerebral palsy (error bars are ± 1 SD).

Table 6. Cross Tabulation Showing the Number of Children At-risk of Cerebral Palsy Below and Within Normal Limits on the REEL-3 Language Ability Standard Score and IMP Total Ceiling Score at 9 and 12 Months of Age

REEL-3 Language Ability Classification
	9 Months		12 Months
IMP Classification	BNL	WNL	BNL	WNL
BNL (p < .05)	11	1	13	1
WNL (p > .05)	0	6	1	2

Note. One at-risk infant was not assessed on the REEL-3 at 12 months of age and was therefore excluded from analysis for that time point. BNL = below normal limits. WNL = within normal limits. REEL-3 is the Receptive-Expressive Emergent Language Test 3rd edition. IMP is the Infant Monitor of vocal Production .