In the United States, approximately 10,000 individuals sustain a spinal cord injury (SCI) every year. An underestimated 3% to 5% of the injuries occur in persons younger than 15 years and about 20% occur in individuals younger than 20 years.1–6 Although motor vehicle accidents are the most common cause of SCI in children, other leading causes are violence, accidental falls, medical complications, and sports injuries.7,8
In an effort to provide neurological assessment for patients with SCI, the International Standards for Neurological Classification of Spinal Cord Injury (ISCSCI)9,10 were developed in 1982. Although the neurological assessment is only one aspect of the overall assessment of children with SCI, it is a critical one. It is essential in the planning of treatment and in establishing anticipated outcomes of rehabilitation.1,11,12 These standards have been used to define inclusion criteria for entry into clinical trials and have been used to evaluate treatment effectiveness in clinical trials when neurological recovery is a primary endpoint.13–16
During the last decade, revisions have been made to the ISCSCI based on psychometric studies with adults, and efforts are currently underway to develop formal training modules on the examination and classification techniques of the ISCSCI. Although the ISCSCI are used with persons of all ages, only recently there have been reports investigating their utility in pediatrics.17 In a study of 74 children, Mulcahey et al17 found that regardless of whether children had paraplegia or tetraplegia or complete or incomplete injuries, those younger than 4 years were unable to comprehend and follow the standardized test instructions. On the basis of their study sample, Mulcahey et al suggested that 4 years of age may be the lower age limit in which the motor examination generates reliable scores.
The findings of Mulcahey et al about the utility of standard motor function testing is not novel. Other authors have reported that when assessing infants and children up to age 6 years, standardized testing and scoring needs to be modified because children are unable to cooperate with standard testing procedures.18 Children between 2 and 5 years of age can assume and initiate a test position but are unable to understand the concept of exerting force against an examiner's resistance.18,19 McDonald et al20 found that therapists are more confident in manual muscle test results when examining children aged 5 years and older and that consistent results of repeated strength examinations are not achieved until 5 to 6 years of age.
The inability to evaluate motor function in young children has significant clinical implications for some diagnostic groups. For example, the decision to surgically repair the brachial plexus in children with C5–C6 birth brachial plexus palsies is largely dependent upon the motor function of the infant's biceps muscle. Because of the clinical need for a reliable measure of biceps function in young infants, in 1995 Curtis et al21,22 developed the Active Movement Scale (AMS), an observational movement assessment designed to evaluate upper extremity joint action to detect small changes in motor function. This assessment is used commonly to determine treatment in infants with brachial plexus palsy.
The need for a reliable measure of motor function of infants and young children with SCI is becoming increasingly important. With the promise of biological and other novel therapies,23 and in the current environment of body-supported treadmill training and other therapies that are designed to maximize recovery,15,24,25 the ability to evaluate motor function in young children with SCI is paramount. Although it may appear simple, evaluation of voluntary motor function in infants and young children with SCI is difficult and complicated by reflexive movement and spasticity. In addition, if an acute injury is due to some type of trauma, infants and children may present with an unstable spine that requires surgical fixation or the placement of a halo to prevent any movement at the injured vertebral site. Before corrective surgery, spinal movement is restricted resulting in the inability to place the child in positions that facilitate voluntary motion.
The primary purpose of this pilot study is to examine the utility of an observational movement assessment in infants and children with SCI by evaluating interrater agreement of joint actions assessed in the ISCSCI using the AMS testing technique and scoring criteria.
A series of 5 consecutive subjects, ranging in age from 12 months to 4 years, participated in this pilot study designed to evaluate interrater agreement of observational movement using AMS testing technique and scoring.
Convenience sampling was used to identify children aged 4 years and younger with a chronic SCI. At the time of the study, all subjects were being seen for initial or routine follow-up care related to their chronic SCI. Potential subjects were excluded if they had an unstable spine causing restriction in movement or other medical restrictions or conditions that interfered with joint range of motion, had a documented severe brain injury, or if their parents refused to allow the child to participate.
The AMS is an assessment tool designed to measure upper extremity motor function in infants with obstetrical brachial plexus palsy.21,22 While being evaluated, the infant is on a flat firm surface and movement is observed during attempts at rolling, positional changes, and with tactile stimulation. Observational movement scores are assigned to the child's joint actions using an 8-point ordinal scale that ranges from 0 and 7. As described in Table 1, gravity eliminated movements are assessed where “0” is no contraction, “1” is a muscle contraction with no motion, “2” is motion less than or equal to ½ range, “3” is motion greater than ½ the range, “4” is full motion. If a grade of 4 is achieved, the joint action is assessed against gravity where “5” is motion less than or equal to ½ range, “6” is motion greater than ½ range, and “7” is full motion.
Curtis et al22 and Bae et al26 conducted studies to assess intraobserver and interobserver reliability of the AMS in subjects with obstetrical brachial plexus palsy. Using the kappa statistic, Curtis et al determined that there was an excellent agreement (kquad = 0.89 with a 95% confidence interval of 0.87–0.91) when using the scale as a whole and that patient factors such as fatigue, interest, and age accounted for more variability in scores than rater factors (such as experience). Also using the kappa statistic, Bae et al reported “almost perfect agreement” (k = 0.85) for intraobserver reliability of individual AMS movements and what they termed “excellent agreement” (k = 0.66) for interobserver reliability of individual AMS movements.
The ISCSCI neurological examination is made up of 2 components: a motor and a sensory examination.10 As summarized in Table 2, the standardized motor examination involves bilateral manual muscle strength testing of 5 key muscles in the arm and 5 key muscles in the leg. Each joint action is tested in the supine position and its corresponding strength is graded on an ordinal scale where “0” represents no movement, “1” represents trace movement, “2” represents full movement, gravity eliminated, “3” represents full movement against gravity, “4” represents movement against gravity, some resistance and, “5” represents normal strength (Table 1).
Observational Motor Assessment of ISCSCI Key Muscles Using AMS Testing Technique and Scoring.
In this study, the key muscles included in the ISCSCI (Table 2) were evaluated by raters using the AMS testing techniques and scoring system. The T1 joint action was not assessed to exclude the intrinsics of the hand; in this population these muscles are not routinely used due to immature prehension patterns.27 As with standard AMS testing procedures, movement of ISCSCI key muscles were first observed in the gravity eliminated positions followed by observation of movement against gravity. As per the AMS testing technique, movement was observed through facilitation and sensory input and scored according to the AMS 8-point ordinal scale. Facilitation and sensory inputs can include but are not limited to position, the use of toys, and stroking.
Observational movement assessments, including both the upper and lower extremities, were conducted by 3 occupational therapists with extensive experience in using the AMS with children with birth brachial plexus palsy. Each subject underwent 2 separate observational movement assessments by 2 different examiners with each assessment separated by at least 2 hours. Movement was facilitated and observed starting with the C5 spinal segment and moving caudally. Positioning of the subject was limited to the supine, side lying, or sitting positions; movement was observed after the subject was purposefully placed in this position. Observational movement examination scores were documented on separate forms by each rater. All examinations took place in a quiet setting, such as a private treatment room. The sessions were videotaped and viewed at a later date to confirm observations.
For all comparisons without absolute agreement, kappa (k) and weighted kappa (kw) coefficients were calculated to correct for chance agreement. Interpretation for the strength of the agreement for the kappa coefficient was fair for values 0.40 to 0.60, good for values 0.60 to 0.75, and excellent for values greater than 0.75.28
As summarized in Table 3, 5 children with SCI, 12 months to 4 years of age receiving routine care, were enrolled in this pilot study. No subject had any significant joint range of motion limitation that would interfere with data collection.
AMS scores for each spinal segment of each of the 5 subjects are shown in Table 4. Among 90 comparisons (9 spinal cord segments bilaterally for each of 5 subjects), 55.6% of the comparisons had the same examination score; with the exception of 4 comparisons in 3 subjects, all of the agreements were seen in muscles that were scored as “7” (normal) or “0” (paralyzed,absent). Of the 40 upper extremity comparisons (4 spinal cord segments bilaterally for each of 5 subjects), there was 77.5% agreement as compared to 38.0% agreement in the 50 lower extremity comparisons (5 spinal cord segments bilaterally for each of 5 subjects). There was lower agreement in upper and lower extremity scores of subjects with tetraplegia (subject 1 = 50.0%, subject 3 = 33.3%, subject 4 = 50.0%) as compared to subjects with paraplegia (subject 2 = 83.3%, subject 5 = 61.1%).
Table 5 summarizes the kappa and weighted kappa values for each comparison. As shown in Table 5, all upper extremity comparisons had fair to excellent agreement with the exception of C6 which showed poor agreement (right C6, k = 0.333; left C6, k = 0.333).
In contrast, a majority of the lower extremity comparisons had poor to fair agreement.
In this pilot study, we applied the observational movement testing method and scoring system of the AMS, an established observational infant movement assessment, to children with SCI in an effort to explore the utility of observation as a means to evaluate movement. Agreement for observational movement activity was high for muscles that were either completely normal (score of 7) or completely paralyzed (score of 0). These findings are consistent with the findings of others who have noted strongest agreement in examination scores when testing “normal” or completely paralyzed muscles and more variation in scores of muscles that are partially intact in individuals with SCI.29 In this study, for muscles with partial motor preservation (scores between 1 and 6), there was never agreement in examination scores. This finding was somewhat surprising based on the psychometric studies of the AMS that describe a tool that yields reliable data when used with infants and children with brachial plexus palsy. The difference between our pilot data and previous reliability studies on the AMS may be explained by the differences between the 2 populations. Brachial plexus injuries cause lower motor neuron damage and, as a result the muscles are flaccid. In contrast, SCI results in a mixed lesion where there is typically lower motor neuron involvement at and immediately surrounding the neurological level and upper motor neuron injury below the neurological level.30
Because of the upper motor neuron lesion, muscles distal to the injury, including those with partial volitional movement, demonstrate reflexive activity and tone. In practice, manual muscle testing of spastic muscles involves positioning the limb to minimize the influence of tone. Also, patients with SCI are asked to move and stop the muscle activity on command to distinguish between isolated voluntary movement and reflexive muscle activity. In this study, observation of movement in the absence of these common techniques provided an inadequate method to determine isolated and voluntary movement activity as evidenced by the disagreement of scores in every muscle distal to the neurological level. In an effort to improve reliability of observational movement assessment, future work in children with SCI may need to include a means to distinguish between isolated voluntary movement versus reflexive movement. Although not used with infants or toddlers, in many motion analysis laboratories, Muscle Selectivity Grading Scales are used in conjunction standardized strength assessments (Tucker C; personal communication, February 21, 2008). Until a standardized observational measure for infants and toddlers with SCI is established, therapists should continue to use observational movement skills in multiple assessment sessions with these patients. However, it is critical to not mistake spastic movement for volitional movement.
The typical administration of the AMS encourages positional changes to facilitate upper extremity movement; movement is observed as the infant or child moves through various positions as well as movement within a position. The ISCSCI examination assesses motor function in the supine position so that an examination may be completed at all stages of care, including the acute stage, where instability of the spine may preclude movement. In this pilot study, we tested the children in the supine, side lying, and sitting positions only after they were purposefully placed in this position. Observed movement during positional change was not used as a means to score movement. The decision to standardize the testing positions as much as possible, but still be able to observe movement given the age of the subjects, was based on our goal to establish a common method to evaluate motor function in children with SCI while mirroring the ISCSCI motor examination. Standardized test positioning (supine) imposes limitations to observing movement patterns in infants and young children but is often the position of the child through the subacute hospitalization where the neurological evaluation may be most important to guide early treatment decisions.
A reliable assessment of motor function for infants and toddlers with SCI is needed for clinical monitoring and for outcomes research. Clinicians assessing infants and toddlers with SCI require a means to examine motor function without using standardized instructions which are unable to be followed by this age group. In addition, it may be difficult to realize the motor function available when only one position is maintained throughout an examination. The observational movement assessment method used with this small sample demonstrated high agreement in examination scores of muscles that were unimpaired and in those that were completely paralyzed. The frequency of disagreement in examination scores of partially intact muscles was unacceptably high and likely a result of the inability to distinguish between voluntary motor control and reflex activity using observation. More work is needed with a larger sample size toward this effort and must address the ability to distinguish voluntary motor function from reflexive movement; as this is a constant challenged faced by clinicians working with the SCI population.
The authors thank the following people for their help in developing and carrying out this pilot study: Diane Barus, OTR/L, CHT, Sarah D'Emilio, ORT/L, Cheryl Lutz, OTR/L, Danielle Wilson-Dunn, OTR/L, Jennifer Schottler, PT, Susan Duff, PT, OTR/L, CHT, Megan Schaeffer, DPT, PCS and Brenda McCann, DPT.
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Keywords:© 2009 Lippincott Williams & Wilkins, Inc.
child; infant; human movement system; muscle strength; neurologic examination; physical therapy/methods; spinal cord injury; reliability