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Original Article

Modification of Nurick scale and Japanese Orthopedic Association score for Indian population with cervical spondylotic myelopathy Kartik Kumbhar Revanappa, Ranjith K. Moorthy, Visalakshi Jeyaseelan1, Vedantam Rajshekhar Departments of Neurological Sciences, and 1Biostatistics, Christian Medical College, Vellore, Tamil Nadu, India

ABSTRACT Aims: Existing scales for functional grading of patients with cervical spondylotic myelopathy (CSM), such as the Nurick scale and modified Japanese Orthopedic Association (mJOA) scale, do not address certain culture-specific activities of the Indian population while grading patients with CSM. Materials and Methods: We modified the Nurick scale and mJOA scale to develop the Indian modifications of Nurick (imNurick) and mJOA scales (imJOA and imJOA scales), respectively, and then evaluated these modified scales in 93 patients with CSM to determine whether these modifications had a meaningful impact on the functional scores of these patients. Results: There was good interobserver agreement in the assessments documented in all the four scales (Nurick grade, imNurick grade, mJOA scale, and imJOA scale) (kappa = 1). Both Nurick grading (z = 4.4, P = 0.00) and imNurick grading (z = 5.5, P = 0.00) had a valid construct when tested against lower limb mJOA (llmJOA) score. The Indian modified upper limb JOA (imulmJOA) score too had a good construct with modified upper limb JOA (ulmJOA) score (z = 2.5, P = 0.01). There was substantial agreement between Nurick grade and imNurick grade (weighted kappa of 0.75) when taken as a whole group and between ulmJOA score and imulmJOA scores (weighted kappa of 0.75). However, there was significant disagreement between the Nurick grade and imNurick grade scales in patients who were Nurick grade 2 and 3 (kappa = 0.07). Conclusions: The proposed Indian modifications of Nurick grade and mJOA scale that incorporate the ethnic practices of the Indian population and some Asian population are better discriminators of different levels of functional ability among patients with CSM in this population, as compared to the existing Nurick grading and mJOA scale. Key words: Cervical spondylotic myelopathy; functional grading; Nurick grade; modified Japanese Orthopedic Association scale

Introduction Nurick grading[1] [Table 1], Japanese Orthopedic Association (JOA) score and its modified version (mJOA)[2] [Table 2] are the most widely used disease-specific severity scales for grading the degree of functional impairment in cervical Access this article online Website: www.neurologyindia.com DOI: 10.4103/0028-3886.152627 PMID: xxxxx

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spondylotic myelopathy (CSM). Nurick grading, being simpler to administer, is more popular. Nurick grading assesses the employability of the person; and in that sense, is not strictly speaking, disease specific. It has been observed that there is discordance between improvement in lower limb function and regaining employment.[3] The functional disability arising out of myelopathy not only affects the employability of the patient but also affects a host of his/her daily activities. These daily activities are so culture‑dependent that it is almost impossible to devise a generic trans‑cultural grading scale that can be applied across all cultures. We modified the Nurick grade and mJOA scale by incorporating activities that are pertinent to our population, termed as the Indian modification of Nurick grade (imNurick grade) and

Address for correspondence: Dr. Vedantam Rajshekhar, Department of Neurological Sciences, Christian Medical College, Vellore - 632 004, Tamil Nadu, India. E‑mail: [email protected]

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the Indian modification of JOA scale (imJOA scale). We then evaluated these modified scales in Indian patients with CSM to determine whether these modifications had a meaningful impact on the functional scores of these patients. These modifications might also be relevant to the cultural practices Table 1: Nurick grading for cervical myelopathy[1] 0 1 2 3

4 5

Signs or symptoms of root involvement, but without evidence of spinal cord disease Signs of spinal cord disease, but no difficulty in walking Slight difficulty in walking which did not prevent full‑time employment Difficulty in walking which prevented full‑time employment or the ability to do all housework, but which was not so severe as to require someone else’s help to walk Able to walk only with someone else’s help or with the aid of a frame Chair-bound or bedridden

Table 2: Benzel’s modification of Japanese Orthopedic Association scoring system (mJOA score)[2] Score Motor dysfunction Upper extremities 0 1 2 3 4 5 Lower extremities 0 1 2 3 4 5 6 7 Sensory dysfunction Upper extremities 0 1 2 3 Sphincter dysfunction 0 1 2 3

Definition

Unable to move hands Unable to eat with a spoon, but able to move hands Unable to button shirt, but able to eat with a spoon Able to button shirt with great difficulty Able to button shirt with slight difficulty No dysfunction Complete loss of motor and sensory function Sensory preservation without ability to move legs Able to move legs, but unable to walk Able to walk on flat floor with a walking aid (cane or crutch) Able to walk upstairs and/or downstairs with the aid of a handrail Moderate‑to‑significant lack of stability, but able to walk up and/or downstairs without handrail Mild lack of stability, but able to walk unaided with smooth reciprocation No dysfunction

of other Asian populations such as those in the South Asian region, Middle East, and South East Asia.

Materials and Methods Modifications of the functional scales We modified the Nurick grading (imNurick grade) [Table 3] and mJOA scale (imJOA scale) [Tables 4 and 5] by incorporating some of the most frequent daily activities of the average Indian which include sitting cross‑legged, squatting, and rising up from squatting position with/without vertical support and eating with the hand rather than with spoons or chopsticks. We excluded employability in our modification of Nurick grading. We modified the upper limb component of JOA scale (imulmJOA) by incorporating the ability to tear chapatti/roti (flat, round Indian bread) with one hand and scoop rice from the plate without letting it slip through the fingers. Patient population We applied the imNurick grade, imulmJOA scale and the original Nurick grade and mJOA scale prospectively to 93 patients with CSM who were managed in our unit between 2010 and 2012. There were two females among the 93 patients. The mean age was 51.3 ± 11.5 years (range 23– 80 years). All the patients were assessed by two independent observers (RKM and KKR) who were blinded from the other’s Table 3: Proposed modified Nurick (imNurick) grading for cervical myelopathy 0 1 2 3 4 5

Signs or symptoms of root involvement, but without evidence of spinal cord disease Signs of spinal cord disease, but no difficulty in walking Slight difficulty in walking but can get up from squatting or sitting on ground without vertical support Difficulty in walking and requires vertical support to get up from squatting or sitting on ground Able to walk only with someone else’s help or with the aid of a frame Chair-bound or bedridden

Table 4: Proposed modification in upper limb component of mJOA score (imulmJOA) Score

Complete loss of hand sensation Severe sensory loss or pain Mild sensory loss No sensory loss Unable to micturate voluntarily Marked difficulty in micturition Mild‑to‑moderate difficulty in micturition Normal micturition

mJOA - Modified Japanese Orthopedic Association

Motor dysfunction Upper extremities 0 1 2 3 4 5 6

Neurology India / January 2015 / Volume 63 / Issue 1

Definition

Unable to move hands Unable to eat with a spoon, but able to move hands Unable to button shirt, but able to eat with a spoon Able to button shirt with great difficulty Able to button shirt with slight difficulty Able to button shirt, but has difficulty in tearing roti/ chapathi and/or scooping rice from the plate No dysfunction

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Table 5: Proposed modification of mJOA score (imJOA score)

findings. One observer had completed training more than 5 years ago, and the other observer was in the latter half of his post‑graduate training.

Score Motor dysfunction Upper extremities 0 1

The Nurick grade, imNurick grade, llmJOA score, ulmJOA score, and imulmJOA score for each patient were noted and tabulated. We excluded patients with joint pain secondary to other causes (such as arthritis of the hip and/or knee joint) limiting the ability to get up from squatting/sitting positions.

2 3 4 5

Statistical analysis After entering the data into an Excel spreadsheet, analysis was done using commercially available software [IBM Statistical Package of Social Sciences (SPSS) Statistics version 19.0, SPSS Inc., Chicago]. Construct validity of the modified scales was assessed using Cuzick nonparametric trend test, Spearman’s rho, and Cronbach’s alpha by comparing it with the components of mJOA score. Agreement between the various scales was determined using the kappa test.[4]

6 Lower extremities 0 1 2 3 4

Results

5

Interobserver agreement There was good agreement between the assessments (Nurick grade, imNurick grade, mJOA scores, and imJOA scores and its subdivisions) among the two observers (kappa = 1).

6 7 Sensory dysfunction Upper extremities 0 1 2 3 Sphincter dysfunction 0 1 2 3

Construct validity of imNurick scale and imulmJOA score The validity of the construct of any new rating scale has to be measured against an existing gold standard. In the absence of a gold standard scale for disease severity in patients with CSM, we used the components of the mJOA score for comparison. Cuzick nonparametric trend test showed that both Nurick scale (z = 4.4, P = 0.00) and imNurick scale (z = 5.5, P = 0.00) have a valid construct when tested against llmJOA score. The imulmJOA score

a

Definition

Unable to move hands Unable to eat with a spoon, but able to move hands Unable to button shirt, but able to eat with a spoon Able to button shirt with great difficulty Able to button shirt with slight difficulty Able to button shirt, but has difficulty in tearing roti/chapaathi and/or scooping rice from the plate No dysfunction Complete loss of motor and sensory function Sensory preservation without ability to move legs Able to move legs, but unable to walk Able to walk on flat floor with a walking aid (cane or crutch) Able to walk unaided, but requires vertical support to get up from squatting or sitting on the ground Able to walk up and/or downstairs with the aid of a handrail Mild difficulty in walking, but not having difficulty as in 4 or 5 above No dysfunction

Complete loss of hand sensation Severe sensory loss or pain Mild sensory loss No sensory loss Unable to micturate voluntarily Marked difficulty in micturition Mild-to-moderate difficulty in micturition Normal micturition

b

Figure 1: Scatter plot showing the linear relationship between a) Nurick grade (Nu) and lower limb component of mJOA score (llmJOA) and b) imNurick grade (imNu) and llmJOA

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too had a good construct with ulmJOA score (z = 2.5, P  = 0.01). As seen in Table 6, Spearman’s rho value confirmed the progressive trends across various scales. Scatter plot of the scores of Nurick and imNurick against llmJOA [Figure 1] and ulmJOA against imulmJOA [Figure 2] further validate the modified scales. Both Nurick and imNurick scales had excellent internal consistency as a construct with llmJOA score (Cronbach’s alpha 0.95 and 0.92, respectively). Similarly, the imulmJOA had excellent internal consistency with ulmJOA (Cronbach’s alpha 0.96) and good internal consistency with llmJOA score (Cronbach’s alpha 0.75). Agreement between Nurick grade and imNurick grade Though there was substantial agreement between Nurick and the modified grade when taken as a whole group (weighted kappa of 0.75), there was significant disagreement between the two scales in patients who were Nurick grade 2 and 3 (kappa = 0.07), suggesting that the modified grade was different in quality compared to the existing grade. Agreement between ulmJOA score and imulmJOA score There was substantial agreement between ulmJOA score and imulmJOA score  (weighted kappa of 0.75) [Figure 2]. Of the 41 patients who did not have any hand dysfunction on the original mJOA score (a score of 5), 38 had no hand dysfunction on imJOA score (a score of 6). Three of them Table 6: Construct validity of different scales Scales compared Nurick imNurick imulmJOA imulmJOA

llmJOA llmJOA ulmJOA llm JOA

Spearman’s rho

P value

0.96 0.90 0.97 0.65

Modification of Nurick scale and Japanese Orthopedic Association score for Indian population with cervical spondylotic myelopathy.

Existing scales for functional grading of patients with cervical spondylotic myelopathy (CSM), such as the Nurick scale and modified Japanese Orthoped...
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