Modified Ashworth Scale and Spasm Frequency Score in Spinal Cord Injury
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Spinal Cord (2016) 54, 702–708 & 2016 International Spinal Cord Society All rights reserved 1362-4393/16 www.nature.com/sc ORIGINAL ARTICLE Modified Ashworth scale and spasm frequency score in spinal cord injury: reliability and correlation CB Baunsgaard1,3, UV Nissen1,3, KB Christensen2 and F Biering-Sørensen1 Study design: Intra- and inter-rater reliability study. Objectives: To assess intra- and inter-rater reliability of the Modified Ashworth Scale (MAS) and Spasm Frequency Score (SFS) in lower extremities in a population of spinal cord-injured persons, as well as correlations between the two scales. Setting: Clinic for Spinal Cord Injuries, Rigshospitalet, Hornbaek, Denmark. Methods: Thirty-one persons participated in the study and were tested four times in total with MAS and SFS by three experienced raters. Cohen’s kappa (κ), simple and quadratic weighted (nominal and ordinal scale level of measurement), was used as a measure of reliability and Spearman’s rank correlation coefficient for correlation between MAS and SFS. Results: Neurological level ranged from C2 to L2 and American Spinal Injury Association impairment scale A to D. Time since injury was (mean ± s.d.) 3.4 ± 6.5 years. Age was 48.3 ± 20.2 years. Cause of injury was traumatic in 55% and non-traumatic for 45% of the participants. Antispastic medication was used by 61%. MAS showed intra-rater κsimple = − 0.11 to 0.46 and κweighted = − 0.11 to 0.83. Inter-rater κsimple = − 0.06 to 0.32 and κweighted = 0.08 to 0.74. SFS showed intra-rater κweighted = 0.94 and inter-rater κweighted = 0.93. Correlation between MAS and SFS showed non-significant correlation coefficients from − 0.11 to 0.90. Conclusion: Reliability of MAS is highly affected by the weighting scheme. With a weighted-κ it was overall reliable and simple-κ overall unreliability. Repeated tests should always be performed by the same rater and in a very standardized manner. SFS was found reliable. MAS and SFS are poorly correlated, and ratings were inversely distributed and suggest that it assesses different aspects of spasticity. Spinal Cord (2016) 54, 702–708; doi:10.1038/sc.2015.230; published online 9 February 2016 INTRODUCTION the symptoms increased tone, clonus and spasms, and hyperreflexia Spasticity is a symptom of the upper motor-neuron syndrome and can exist independently of each other and do not necessary share the common among people with spinal cord injury (SCI). The prevalence exact same pathophysiology.8 of spasticity among people with SCI varies in different studies from 65 A number of ways to measure spasticity exist: scales for manually to 78% depending on the definition of spasticity, level and severity of testing, biomechanical and electrophysiological methods,7 as well as the SCI, method of measurement and possibly the time post injury.1–3 self-rating scales. About half of these use antispastic medication.2 In one study, roughly A measurement of spasticity that is simple and easy to administer is 40% reported the spasticity as problematic.3 important both in daily clinical practice, for monitoring fluctuations An often used definition of spasticity is the one by Lance:4 ‘amotor and changes over time, to measure the effect of antispastic medication, disorder characterized by a velocity-dependent increase in the tonic as well as for research purposes. stretch reflex with exaggerated tendon jerks, resulting from hyper Two of such clinical measures of spasticity are The Modified excitability of the stretch reflex, as one component of the upper Ashworth Scale (MAS) and the self-reported Spasm Frequency Score motor-neuron syndrome’.Thisdefinition has the benefitofbeing (SFS). Each of the two scales could be viewed as indirect measures of precise but has been challenged5 and does not reflect the two single constructs of spasticity. The MAS is a scale of perceived multidimensional nature of spasticity. For the purpose of this study, resistance (tone) against passive movement of the limb and is an we used a relatively broader definition developed by the SPASM adjustment of the original Ashworth Scale where the category 1+ has consortium:6 ‘Disordered sensory–motor control resulting from an been added. The SFS is a scale from 1 to 4 on the number of upper motor-neuron lesion presenting intermittent or sustained self-reported spasms per day.9 The SFS is an adaption of Penn SFS involuntary activity of muscles’.Thedefinition distinguishes spasticity (PSFS) where self-reported number of spasms the last hour is rated.10 from the passive viscoelastic changes of muscle properties such as Definitions are shown in Table 111 and Table 2.9 contractures, which are also associated with SCI.3 These changes in Correlation between the MAS, other clinical measures, as well as soft tissues and joints can be very difficult to distinguish clinically from biomechanical measures of spasticity has generally been low, and the the active part of spasticity.7 It is also important to keep in mind that validity of the MAS has been questioned.12 Despite the limitations of 1Clinic for Spinal Cord Injuries, Rigshospitalet, University of Copenhagen, Hornbaek, Denmark and 2Department of Public Health, Section of Biostatistics, University of Copenhagen, Hornbaek, Denmark 3These authors contributed equally to this work. Correspondence: Dr CB Baunsgaard, Clinic for Spinal Cord Injuries, Rigshospitalet, University of Copenhagen, Havnevej 25, Hornbaek 3100, Capital Region, Denmark. E-mail: [email protected] or [email protected] Received 30 March 2015; revised 23 October 2015; accepted 30 October 2015; published online 9 February 2016 Reliability and correlation of MAS and SFS CB Baunsgaard et al 703 Table 1 The Modified Ashworth Scale (MAS)11 Score Modified Ashworth Scale 0 No increase in muscle tone. 1 Slight increase in muscle tone, manifested by a catch and release or by minimal resistance at the end ROM when the affected part(s) is moved in flexion or extension. 1+ [2] Slight increase in muscle tone, manifested by a catch, followed by minimal resistance throughout the remainder (less than half) of the ROM. 2 [3] More marked increase in muscle tone through most of the ROM, but the affected part(s) is easily moved. 3 [4] Considerable increase in muscle tone, passive movement is difficult. 4 [5] Affected part(s) rigid in flexion or extension. Abbreviation: ROM, range of motion. In square brackets, transcription sometimes used for the Modified Ashworth Scale. Table 2 Spasm Frequency Score9 range of motion (ROM) with a limited ROM of knee and hip together of 430°, same criteria as previously used by Craven and Moris 2010.20 Score Spasm Frequency Score Raters and procedure 0 No spasms All assessments were carried out by three physiotherapists experienced in 1 One or a few spasms per day treating people with SCI and used MAS in their daily practice. To ensure MAS 2 Between 1 and 5 spasms per day assessment was performed in a standardized and an uniform manner,3 the 35oro10 spasms per day three raters practiced the MAS assessment and interpretation prior to the study. 4 Ten or more spasms per day or continues contraction During the data collection, the raters did not discuss the testing procedures, outcomes or other study-related issues. the MAS, it is still the most widely used scale in the clinical setting,3 To keep testing conditions as constant as possible, all assessments were and its use is recommended by the National Institute of Neurological carried out at the same time in the morning, before participants got out of bed, and participants only wore the clothes they had been sleeping in. This was done Disorders and Stroke Common Data Element.13 The MAS has been to keep activity level before testing at an absolute minimum. Participants who tested in populations with spasticity after SCI, stroke, multiple sclerosis, did not have an indwelling catheter went to the bathroom before testing. traumatic brain injury, as well as cerebral palsy, showing varying results The participants were moved directly from bed to bench in supine position of the reliability; in general, the reliability was unsatisfactory.7,14,15 The to avoid any unnecessary activity. Testing was always performed for the right mechanism of spasticity between SCI and other upper motor-neuron side first in the order of hip flexors, hip extensors, knee flexors, knee extensors, lesions may have a different etiology.16 A literature search found four ankle plantar flexors and ankle dorsi flexors. Then, the rater moved around the studies17–20 that assessed the reliability of the MAS of lower extremities bench and performed the same procedure for the left side. among people with SCI. The choice of statistical method differed; some On the day of MAS assessment, participants were screened for symptoms of urinary tract infection24 and asked whether they felt ok, and pain was used simple (unweighted) kappa other used weighted kappa, while documented if present. According to the protocol, the rater was instructed to fi 7 others used correlation coef cients. There were also differences in test postpone testing to another day if the participant did not feel ok. This was not protocols and differences in how confounders were controlled. This necessary for any of the tests however. Room temperature was measured, and makes studies difficult to compare, and in light of this we find that the participant was asked to rate the number of spasms the day before there still is a need to reassess the MAS for lower extremity after SCI. according to the SFS. The need to reassess MAS and self-reported spasticity scales are also During each movement raters counted ‘one second’ to move the joint as supported by the review from Hsieh et al.14 smooth and constant as possible, to imitate the way MAS was performed in the 11 Self-rating scales are a way of clinically assessing another construct original Bohannon study.