Consistency of AMA Impairment Evaluation : Spine Pt 2

Saturday, December 17, 2005 | 0

The following is part 2 of Consistency of AMA Impairment Evaluation : Spine

By: Luis Perez-Cordero & Craig Andrew Lange

DRE Rating Criteria - Diagnosis Related Estimates

'Injury' is the common denominator in Workers Compensation impairment and the DRE method remains the principal method to evaluate an individual having an injury. "The DRE method is the primary method used to evaluate individuals with an injury." (AMA 5th Ed., 374) Physician identifies findings (ROM, Symptoms, Signs, Appropriate Test Results) supporting the DRE Category.

DRE model relies on the history, physical examination findings (neurological deficits not spinal motion), and the results of clinical testing (Imaging studies, Electrodiagnostic, etc.) as it attempts to document anatomical and physiological impairment relating to an injury, rather than congenital developmental or age-related conditions. (AMA Guides Newsletter- May/June 2004).

Master the AMA Guides (page 197) states that in the case of multiple injuries or conditions, if the pathology affects different spinal regions, the DRE method is applied to each region. Only when the pathology reoccurs or repeats in the same spinal level or region is the ROM method use. Spinal level refers to an area bounded by two vertebrae, a single spinal disk and associate nerve roots and nerves.

1. DRE Evaluation Criteria: - AMA 5th Ed, page 379 & 398 & - AMA 5th Ed., pages 405 & 406.

1.1. Clinical findings must be correlated to the imaging studies, which have been used to confirm a diagnosis. Without clinical correlation, a 'positive' imaging study in itself does not make the diagnosis or cannot be used as the sole support for an impairment rating.

1.2. The P&S report must clearly outline physician's evaluating criteria and its support.

1.3. For determining impairment based on the clinical diagnosis related findings refer to pages 381 to 398 (Chapter 15) AMA Guides -5th Edition.

2. Box 15-1 provides the necessary definitions evaluating physician can use to assign an individual to DRE categories I, II or III. (AMA Guides, page 382).

Definitions of Clinical Findings Used to Place an Individual in DRE Category

Muscle Spasm
Muscle spasm is a sudden, involuntary contraction of a muscle or group of muscles. Paravertebral muscle spasm is common after acute spinal injury but is rare in chronic back pain. It is occasionally visible as a contracted paraspinal muscle but is more often diagnosed by palpation (a hard muscle). To differentiate true muscle spasm from voluntary muscle contraction, the individual should not be able to relax the contractions. The spasm should be present standing as well as in the supine position and frequently causes a scoliosis. The physician can sometimes differentiate spasm from voluntary contraction by asking the individual to place all his or her weight first on one foot and then the other while the physician gently palpates the paraspinous muscles. With this maneuver, the individual normally relaxes the paraspinal muscles on the weight-bearing side. If the examiner witnesses this relaxation, it usually means that true muscle spasm is not present.

Muscle Guarding
Guarding is a contraction of muscle to minimize motion or agitation of the injured or diseased tissue. It is not true muscle spasm because the contraction can be relaxed. In the lumbar spine, the contraction frequently results in loss of the normal lumbar lordosis, and it may be associated with reproducible loss of spinal motion.

Asymmetry of Spinal Motion
Asymmetric motion of the spine in one of the three principal planes is sometimes caused by muscle spasm or guarding. That is, if an individual attempts to flex the spine, he or she is unable to do so moving symmetrically; rather, the head or trunk leans to one side. To qualify as true asymmetric motion, the finding must be reproducible and consistent and the examiner must be convinced that the individual is cooperative and giving full effort.

Non-verifiable Radicular Root Pain
Non-verifiable pain is pain that is in the distribution of a nerve root but has no identifiable origin; i.e., there are no objective physical, imaging, or electromyographic findings. For dermatomal distributions, see Figures 15-1 and 15-2.

Reflexes
Reflexes may be normal, increased, reduced, or absent. For reflex abnormalities to be considered valid, the involved and normal limb(s) should show marked asymmetry between arms or legs on repeated testing. Once lost because of previous radiculopathy, a reflex rarely returns. Abnormal reflexes such as Babinski signs or clonus may be signs of corticospinal tract involvement.

Weakness and Loss of Sensation
To be valid, the sensory findings must be in a strict anatomic distribution, i.e., follow dermatomal patterns (see Figures 15-1 and 15-2). Motor findings should also be consistent with the affected nerve structure(s). Significant, long-standing weakness is usually accompanied by atrophy.

Atrophy
Atrophy is measured with a tape measure at identical levels on both limbs. For reasons of reproducibility, the difference in circumference should be 2 cm or greater in the thigh and 1 cm or greater in the arm, forearm, or leg. The evaluator can address asymmetry due to extremity dominance in the report.

Radiculopathy
Radiculopathy for the purposes of the Guides is defined as significant alteration in the function of a nerve root or nerve roots and is usually caused by pressure on one or several nerve roots. The diagnosis requires a dermatomal distribution of pain, numbness, and/or paresthesias in a dermatomal distribution. A root tension sign is usually positive. An appropriate finding on an imaging study must substantiate the diagnosis of herniated disk. The presence of findings on an imaging study in and of itself does not make the diagnosis of radiculopathy. There must also be clinical evidence as described above.

Electrodiagnostic Verification of Radiculopathy
Unequivocal electrodiagnostic evidence of acute nerve root pathology includes the presence of multiple positive sharp waves or fibrillation potentials in muscles innervated by one nerve root. However, the quality of the person performing and interpreting the study is critical.

AMA Guides, Section 15.1a, page 374 requires that evaluating physician's history taking and reporting describe in detail the chief complaints and the quality, severity, anatomic location, frequency, and duration of symptoms. Employee's description of complaints (including pain, numbness, paresthesias, weakness) and how these factors interfere with activities of daily living (ADL), can further assist evaluating physician to pinpoint a specific WPI% within a given DRE category.

In deciding where to place an individual's impairment rating within a range, the physician needs to consider all the criteria applicable to the condition, which includes performing activities of daily living (ADL), and estimate the degree to which the medical impairment interferes with these activities. AMA Guides, page 20.

On page 204 of Master The AMA Guides, Dr. Cocchiarella states:
* Use the DRE method as the method of choice (for rating spinal impairment).
* When determining what end of the range to use, determine whether the condition and its impact on ADL is consistent with that condition, or if the impairment has led to worse functioning. If ADL are more severely impacted than expected for the condition, use the upper end of the scale.

For a table of Clinical Findings That Indicate Corresponding DRE Categories, click here.

The DRE Tables: (1) Cervical Spine: AMA 5th Ed., Table 15-5, page 392, (2) Thoracic Spine: AMA 5th Ed., Table 15-4, page 389, and (3) Lumbar Spine: AMA 5th Ed., Table 15-3, page 384.

The third and final part of this series will review the spinal ROM rating method.

Article by Luis Perez-Cordero & Craig Andrew Lange, Impairment & Disability Rating Specialists. They can be reached at pdrating@pacbell.net.

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