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What Is the Best Way to Assess and Classify Spinal Cord—Injured Patients?

Daniel K. Resnick and Nelson M. Oyesiku

This type of question does not lend itself to the standard class I, II, or III method of reviewing the literature. Although such methodology is appropriate for evaluating many kinds of studies, investigations of grading schemes do not readily lend themselves to that type of analysis. For the sake of consistency, the studies discussed in this chapter can be considered to report class III data, but the limitations of using such a classification scheme for this topic should be remembered.

BRIEF ANSWER

Background

SCI affects 12,000 to 14,000 people in the United States each year. Treatment of SCI currently consists of decompression of the spinal cord, stabilization of the spine, and administration of methylprednisolone. Despite these interventions, the functional consequences of a SCI remain severe, and new therapies are required for the treatment of SCI. Evaluation of these therapies requires the use of accurate and reliable functional outcome measures. Furthermore, the ability to provide accurate prognostic information in the early postinjury period is valuable for patient and family counseling. Finally, consistent and reproducible assessment scales are necessary to facilitate communication about patient status to other caregivers. This chapter describes the best clinical assessment tools available to the clinician responsible for the care of patients with SCIs.

Literature Review

A computerized search of the database of the National Library of Medicine from 1966 to December 2000 was performed. The search was limited to human studies in the English language. Searching the key words “spinal cord injuries” yielded 12,072 references. Limiting the search to papers dealing with “classification” yielded 152 references. The titles and abstracts of these 152 references were reviewed. Papers dealing with the assessment of both the acutely and the chronically injured patient were selected. The reference lists of these papers were also reviewed, and the additional references were included as needed. This resulted in the selection of the 32 references that form the basis of this review.

Numerous assessment scales have been used to describe patients with SCI. Scales may be divided into two general types. The first type is disability-specific and focuses on the neurologic deficits suffered as a result of SCI. These scales use the motor and sensory examination, as well as information regarding bowel and bladder function and reflex changes, to assign a numerical value or letter grade. The second type of scale focuses on overall functional outcome, such as the patient’s ability to transfer, ambulate, or participate in personal hygiene. In general, the first type of scale is used for the acute assessment of patients with SCI, whereas both types are important for assessment and description of the chronically injured patient. The most widely used scales incorporate both disability-specific and functional outcome scores in their overall assessment.

Disability-specific scales for the assessment (both acute and long-term) of patients with SCI have existed for decades. Cheshire, Frankel, and Michaelis were early contributors to this effort,1–3 and the Frankel scale (modified thereafter by several authors) was widely adopted for use in the 1970s. This scale consisted of a reported level and a rough assessment of the severity of injury based on motor and sensory function.² However, the Frankel grading system has been largely abandoned as an assessment tool or outcome measure because of its lack of sensitivity. For example, many authors felt that significant improvement in patient function could occur without the patient advancing a Frankel grade.⁴ Modifications of the Frankel scale were made over time in an attempt to solve this shortcoming. A sensitive and specific instrument was required that could be reliably applied by investigators with a variety of backgrounds. Institutions and individuals proposed a variety of new assessment tools.^1,4–8 Additionally, a numerical scoring system that described the patient’s neurologic examination was necessary to permit valid statistical analysis.

In the late 1970s, Lucas and Ducker⁷ developed a scoring system based on motor function at and below the level of injury and used this to characterize over 800 patients seen at the Maryland Institute for Emergency Medical Services. Using a relatively complex mathematical analysis, these authors were able to predict a motor outcome score based on the initial motor examination and an empirically derived understanding of the recovery rate of individual injury subtypes. The scoring system is limited in that many patients are excluded from the analysis (only 436 of over 800 patients were able to be analyzed), the standard deviation of the predicted recovery score is often large, and the calculations are cumbersome.⁷ Bracken and others contemporaneously developed a scoring system that combined motor and sensory function and assigned specific values to the presence or absence of function in certain muscle groups and dermatomes.⁹ This scale still suffered from the lumping of all patients into one of five possible motor scores and one of seven possible sensory scores.⁹ In 1982 Tator et al⁸ proposed a 10-point numerical scale for grading SCI function. This scale, commonly referred to as the Sunnybrook Cord Injury Scale, was essentially a Frankel scale with finer subdivisions.

Chehrazi et al⁶ published what is now referred to as the Yale Scale in 1981. This is a comprehensive spinal cord function scale. This scale employs the British Medical Research Council’s gradation of muscle strength (i.e., the widely used 0–5 scale) in a systematic fashion, using 10 selected muscle groups from each side of the body. Sensory function is also scored on a 0 to 58 point scale, but bowel and bladder function are not scored.⁶ In 1992, Botsford and Esses⁴ published a scale in which 15 muscle groups on each side of the body are examined and given a score of 0 to 5. The scores are divided by 2 to give a maximum possible motor score of 75. Sensory function is graded on a 0 to 10 scale, as is rectal tone. Normal bladder function is scored as 5 points. Thus, the maximum possible total score is 100. Botsford and Esses then applied this scale to a group of patients who had initially been evaluated by the Frankel scale. They found that their new scale was much more sensitive for the detection of improvement in function over time and as a result of intervention, which, in this case, was the surgical treatment of burst fractures.⁴