Evaluation Of Permanent Impairment Research Articles

Case Study: Shoulder Injury

Abstract This issue of The Guides Newsletter introduces a new feature, Case Study, that illustrates some of the challenges encountered in rating shoulder impairment. The history presents the case of a 50-year-old, right-hand dominant white male evaluated for impairment due to left shoulder pain, stiffness, and weakness. His initial injury occurred at work in December 2001 when he used his left arm to prevent himself from falling. After five months of nonoperative treatment, including one subacromial steroid injection, physical therapy, and a second opinion, he underwent open subacromial decompression and acromioplasty and open distal clavicle excision. He returned to work and pain resolved after a year but recurred in September 2003. The patient was examined 19 months after the surgery, and the examining physician evaluated the patient's clinical status at that time, reviewed diagnostic studies performed, diagnosed maximum medical improvement, and, using the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), assessed 11% whole person impairment. Readers are encouraged to use the materials presented to this point to prepare their own rating that they can compare with an analysis (published elsewhere in this issue) that reviews the examining physician's report and finds that it was inconsistent with the AMA Guides and was erroneous in certain key points.

Comparative Analysis: The State of Colorado Study, Part III

Abstract This article concludes the three-part discussion of differences among the editions of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides): Third Edition Revised, Fourth, and Fifth Editions. The discussion begins with a comparison of different editions of the AMA Guides for evaluating lower extremity impairment and spinal impairment. The AMA Guides, Fourth Edition, introduced the Diagnosis related estimates (DRE) model, and in this edition the range-of-motion (ROM) model has only a limited role (ie, primarily as a differentiator). A table summarizes the criteria of spinal impairment criteria by edition of the AMA Guides. The authors summarize differences in the impairment ratings of various body systems based on the use of different editions of the AMA Guides, including differences in ratings of the cardiovascular, pulmonary, digestive, and other systems. Critiquing the AMA Guides, the authors call for improvements, including the following: add a system to rate permanent impairments, including functional limitations; base impairment ratings on scientific evidence and a valid whole person impairment scale; make the AMA Guides reliable, comprehensive, internally consistent, comprehensible, accessible (ie, the AMA Guides are complex and difficult to use, and not all physicians are capable of rating impairment), and acceptable. Despite the shortcomings, no other widely accepted basis to assess impairment is available, and future editions of the AMA Guides will improve the process of providing fair assessments of functional loss.

Comparative Analysis: The State of Colorado Study, Part II

Abstract [Continued from the January/February 2004 issue of The Guides Newsletter.] To understand discrepancies in reviewers’ ratings of impairments based on different editions of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), users can usefully study the history of the revisions as successive editions attempted to provide a comprehensive, valid, reliable, unbiased, and evidence-based system. Some shortcomings of earlier editions have been addressed in the AMA Guides, Fifth Edition, but problems remain with each edition, largely because of the limited scientific evidence available. In the context of the history of the different editions of the AMA Guides and their development, the authors discuss and contextualize a number of key terms and principles including the following: definitions of impairment and normal; activities of daily living; maximum medical improvement; impairment percentages; conversion of regional impairments; combining impairments; pain and other subjective complaints; physician judgment; and causation analysis; finally, the authors note that impairment is not synonymous with disability or work interference. The AMA Guides, Fifth Edition, contrasts impairment evaluations and independent medical evaluations (this was not done in previous editions) and discusses impairment evaluations, rules for evaluations, and report standards. Upper extremity and lower extremity impairment evaluations are discussed in terms of clinical assessments and rating processes, analyzing important changes between editions and problematic areas (eg, complex regional pain syndrome).

Impairment Tutorial: Cervical Fusions: A Paradox in the Fifth Edition

Abstract The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, presents an impairment paradox: Single-level fusions rating using the Diagnosis-related estimates (DRE) method often result in higher impairment values than do multilevel cervical spine fusions. In the AMA Guides, Chapter 15, The Spine, the definition of Cervical Category IV (alteration of motion segment integrity or bilateral or multilevel radiculopathy) changed from the definition in the fourth edition for Cervicothoracic Category IV (loss of motion segment integrity or multilevel neurological compromise) because of changes in the definition of “alteration of motion segment integrity,” which now also includes surgical arthrodesis. This applies only for single-level fusions because the AMA Guides, states the range-of-motion (ROM) method is used in situations when “there is alteration of motion segment integrity (eg, fusions).” The AMA Guides, Fourth Edition, rated impairment on the basis of the injury, not the surgical procedure, and the maximum whole person permanent impairment for a patient with a single-level, single-sided cervical radiculopathy who had a discectomy and fusion would be 15%, but the minimum award for a similar patient rated using the DRE method is 25%. The author reports that, for the reasons outlined, evaluators should rate all cervical fusions, including single-level fusions, using the ROM method.

Impairment Tutorial: Convert, Add, or Combine?

Abstract The presence of multiple ratable entities, including symptoms, physical findings, test results, diagnoses, and/or procedures, complicates impairment evaluation; further, patients may have several findings in the same anatomic area and/or findings unrelated to the condition being rated. In complex cases involving a final extremity or whole person impairment (WPI), the examining physician must consider all possible ratable impairments, discarding duplicative or mutually exclusive ratings and converting, adding, or combining to obtain the final rating. Failure to follow the instructions detailed in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) is a common source of error in impairment rating. The AMA Guides provides multipliers and, for the upper extremity, tables to convert a body part impairment to an extremity and then to a whole person rating. Jurisdictional requirements vary, but rating physicians commonly are asked to provide a single impairment percentage for the limb or whole person; when two or more impairments are involved, the rater must add or combine the percentages, carefully following the specific instructions in the AMA Guides. Adding two ratings is no different than deriving any other arithmetic sum, but impairment percentages much more commonly are combined than added to ensure that, no matter how many impairments are present, the total is never greater than 100% loss of an extremity or 100% WPI.

Clinical Update: Thoracic Outlet Syndrome

Abstract The diagnosis, cause, and treatment of thoracic outlet syndrome (TOS) are challenging, and the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) gives no specific instructions about rating impairments associated with this disorder. TOS is a group of symptoms and signs, including pain, weakness, paresthesias, numbness, swelling, and/or coldness arising at the base of the neck or superior chest but involving the upper limbs. Causes include compression of the brachial plexus (neurogenic TOS) or, less frequently, subclavian vein and/or artery (vascular TOS). Provocative tests for TOS attempt to induce symptoms and/or signs by compressing the subclavian artery or vein or brachial plexus, but palpitation of the radial pulse in various extremity positions is of limited diagnostic value. Diagnostic studies may include radiographs of the cervical spine, upper chest, and/or shoulder; MRI scans of the thoracic outlet; arteriography or venography, and electrodiagnostic testing. The differential diagnosis for TOS is broad and includes cervical radiculopathy, superior sulcus tumor, other peripheral nerve entrapment syndromes, complex regional pain syndrome, and psychiatric disease. The evaluator must determine if the symptoms, physical findings, and diagnostic study results support the diagnosis; the report should list the rating options considered, discuss the rationale for selecting the method(s) used, and explain how the percentage was calculated.

Comparative Analysis of Third Edition, Revised; Fourth; and Fifth Edition Ratings: The State of Colorado Study

Abstract In 2002, the Department of Labor and Employment, the State of Colorado, performed a study to identify changes among the Third Edition, Revised (December 1990); the Fourth Edition (June 1993); and the Fifth Edition (November 2000) of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides). This three-part article summarizes the differences found. The study was based on a random sample of 250 cases identified by the Division of Workers’ Compensation of the State of Colorado and stratified into three broad categories: 40 upper extremity cases, 60 lower extremity cases, and 150 whole person cases. Only case records with adequate documented evidence to enable rating among all three editions of the AMA Guides were included. The average age of the examinee was 42.9 years (SD, 11.1 years, range, 18 to 71 years, 171 [68%] male); equal percentages of men and women were present in the upper extremity impairment ratings (20 men, 20 women), but lower extremity and whole person impairments occurred primarily among males (73% and 71% men, respectively). Interrater reliability was obtained from an independent expert medical review of 20% of the cases. Three figures show percentages of upper extremity, lower extremity, and whole person impairment according to the edition used; ratings generally are lower with more recent editions.

Lumbosacral Corticospinal and Cauda Equina Injuries

Abstract Spinal cord injuries can affect many functions, interfere with the activities of daily living, and result in significant impairment. This article reviews cauda equina and conus medullaris syndromes, examines the process of rating corticospinal tract damage, and provides a case example. In the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), cauda equina syndrome refers to the polyradicular symptomatology resulting from single- or double-level compression of the lumbosacral nerve roots in the dural sac and may include low-back pain, saddle anesthesia, sciatica, motor weakness of the lower extremities, chronic paraplegia, and bladder, bowel, or sexual dysfunction. Conus medullaris syndrome is caused by a compression injury at T12 or L1, and flaccid paralysis of the legs and anal sphincter with variable sensory deficits may be present. The AMA Guides, Fifth Edition, includes Table 15-6, Rating Corticospinal Tract Impairment, which presents criteria for rating the neurological impairment. The physician must determine which systems are impaired, then which categories are appropriate and what value within a range should be selected. This requires the use of judgment because large ranges are provided. Spinal injuries that involve corticospinal tract damage are assessed using the Diagnosis-related estimate (DRE) method, but the range-of-motion method can be used in specified situations. A case example demonstrates how to assess neurological impairment.

Clinical Update: Grip Strength: An Uncommon Impairment

Abstract Upper extremity impairment rarely is assessed using grip strength, according to the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), because results can be influenced by subjective factors that are difficult to control, including sex, age, comorbidities, fatigue, handedness, time of day, pain, and the individual's cooperation. The AMA Guides, Section 16.5b, Impairment Evaluation Methods, discusses the approach used for rating peripheral nerve injuries, but this section applies only to specific nerve lesions with resulting weakness of the muscles supplied or sensory changes. Strength correlates only poorly with performance of the activities of daily living, and grip strength testing using a dynamometer or other types of isometric strength testing has not been shown to reliably discriminate between submaximal and maximal efforts. Grip strength usually is not used in the presence of decreased motion, painful conditions, deformities, or absence of body parts (eg, missing digit), nor is it used to rate weakness from a peripheral nerve lesion. In rare cases, the AMA Guides allows the use of loss of strength (eg, due to a severe muscle tear that healed leaving a palpable muscle defect). Impairment ratings based on objective anatomic findings take precedence, and loss of strength is rarely combined and only if based on unrelated etiologic or pathomechanical causes.

Impairment Tutorial: Functionally Limiting Upper Extremity Pain: Controversies in Impairment Rating

Abstract This article was prompted by the submission of two challenging cases that exemplify the decision processes involved in using the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides). In both cases, the physical examinations were normal with no evidence of illness behavior, but, based on their histories and clinical presentations, the patients reported credible symptoms attributable to specific significant injuries. The dilemma for evaluators was whether to adhere to the AMA Guides, as written, or to attempt to rate impairment in these rare cases. In the first case, the evaluating neurologist used alternative approaches to define impairment based on the presence of thoracic outlet syndrome and upper extremity pain, as if there were a nerve injury. An orthopedic surgeon who evaluated the case did not base impairment on pain and used the upper extremity chapters in the AMA Guides. The impairment ratings determined using either the nervous system or upper extremity chapters of the AMA Guides resulted in almost the same rating (9% vs 8% upper extremity impairment), and either value converted to 5% whole person permanent impairment. In the second case, the neurologist evaluated the individual for neuropathic pain (9% WPI), and the orthopedic surgeon rated the patient as Diagnosis-related estimates Cervical Category II for nonverifiable radicular pain (5% to 8% WPI).

Impairment Rating in Traumatic Brain Injury

Abstract Traumatic brain injury (TBI) usually is described in terms of the severity of the initial neurologic insult and is defined by the Glasgow Coma Scale (GCS) score; the presence and duration of amnesia (retrograde and anterograde); and the presence and duration of alteration in or loss of consciousness. According to the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), the evaluating physician should consider the following: narrative history; most recent clinical evaluation; assessment of current clinical status; plans for future treatment; diagnosis and clinical impressions; and estimated time for full or partial recovery. Individuals who present with brain disease or damage also may experience impairments in several parts of the body or nervous system. Physicians who evaluate TBI must be familiar with numerous relevant sections in Chapter 13, The Central and Peripheral Nervous System, as shown in a table in the article. Individual impairments can be combined using the Combined Values Chart in the AMA Guides. Also, the AMA Guides requires the examiner to grade mental status impairment based on the individual's ability to perform activities of daily living and may require neuropsychological testing. The evaluation of TBI impairment and disability is by no means a simple undertaking for any clinician, and evaluators must familiarize themselves with disability and impairment evaluation protocols and their limitations.

Determining Impairment and Disability for Mental and Behavioral Disorders

Abstract The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Chapter 14, Mental and Behavioral Disorders, focuses on the particularly challenging process of evaluating a person with a mental or behavioral disorder. This chapter is unique: It does not include numeric impairment ratings because no precise methods exist for assessing impairment in mental disorders. This article focuses on the process of gathering qualitative data and relevant information to substantiate the behavioral impairment assessment, for which the Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition–Text Revised (DSM-IV-TR) is used. Impairment ratings in the AMA Guides reflect “consensus-derived estimates that reflect the severity of the impairment and the degree to which the impairment decreases an individual's ability to perform common activities of daily living [ADL]” and designates four relevant areas to consider: ADL; social functioning; concentration, persistence, and pacing; and deterioration or decompensation in complex or work-like settings. The validity of an impairment classification depends on the process used to collect and analyze the data, including clinical treatment records, hospital discharge summaries, community mental health program activity reports, patient and family interviews, reports from work evaluation or rehabilitation centers, supported employment records, and workplace evaluations. Defining maximum medical improvement in patients with mental and behavioral disorders is difficult and, in some instances, may be impossible.

Legal Update: Social Security Disability Insurance

Abstract The US Social Security Disability Insurance (SSDI) system does not use the AMA Guides to the Evaluation of Permanent Impairment, but examinees who are evaluated for permanent impairment frequently also are receiving SSDI benefits. The latter are restricted to workers who have long-term impairments that are so severe they preclude any type of gainful compensable activity, and the impairment must be medically determinable and expected to last at least a year or result in death. Both SSDI and the Supplemental Security Income plan (primarily for workers who have insufficient past work contributions) require the examining physician to provide specific medical information such as the medical history, physical examination, laboratory findings, and impairment, often using standardized forms. Examiners should know that the observations of the treating physician have legal significance, especially in areas of controversy. Social Security may approve additional diagnostic testing in order to conclusively establish the extent and severity of an illness. Based on the patient's history and observations during the examination, physicians also are asked to report any impairments in daily functioning, but examiners are advised not to address work-relatedness and are discouraged from discussing ability to work, which is determined by the state disability agency. Infrequent follow-up reports may be requested because most accepted claims are reviewed on a periodic (yearly) basis.

Clinical Update: Assessing Maximum Medical Improvement in Carpal Tunnel Syndrome

Abstract Permanent impairment cannot be assessed until the patient is at maximum medical improvement (MMI), but the proper time to test following carpal tunnel release often is not clear. The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) states: “Factors affecting nerve recovery in compression lesions include nerve fiber pathology, level of injury, duration of injury, and status of end organs,” but age is not prognostic. The AMA Guides clarifies: “High axonotmesis lesions may take 1 to 2 years for maximum recovery, whereas even lesions at the wrist may take 6 to 9 months for maximal recovery of nerve function.” The authors review 3 studies that followed patients’ long-term recovery of hand function after open carpal tunnel release surgery and found that estimates of MMI ranged from 25 weeks to 24 months (for “significant improvement”) to 18 to 24 months. The authors suggest that if the early results of surgery suggest a patient's improvement in the activities of daily living (ADL) and an examination shows few or no symptoms, the result can be assessed early. If major symptoms and ADL problems persist, the examiner should wait at least 6 to 12 months, until symptoms appear to stop improving. A patient with carpal tunnel syndrome who declines a release can be rated for impairment, and, as appropriate, the physician may wish to make a written note of this in the medical evaluation report.

Impairment Tutorial: Rating Spondylolisthesis

Abstract Spondylolisthesis generally is defined as an anterior or posterior slipping or displacement of one vertebra on another. A unilateral or bilateral defect of the pars interarticularis without displacement of the vertebra is known as spondylolysis or, less frequently, spondyloschisis. The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) notes that the two common types of spondylolisthesis are isthmic (related to the presence of spondylolysis and occurring in the immature spine) and degenerative spondylolisthesis (usually found in older individuals with degenerative changes, usually at the fourth or fifth lumbar vertebra). The AMA Guides classifies spondylolisthesis based on the etiology of the slip: congenital, isthmic, degenerative, traumatic, pathologic, and iatrogenic/postsurgical. In addition, grades ranging from I to V are assessed based on the severity of the displacement of the vertebra above on the vertebra below. Some of the confusion concerning terminology used in the AMA Guides regarding alteration of motion segment integrity arises because multiple different but similar terms exist, eg, those from the American Academy of Orthopaedic Surgeons vs the AMA Guides. The AMA Guides specifies that an x-ray finding of spondylolisthesis alone does not equal alteration of motion segment integrity, and a Diagnosis-related estimate (DRE) is the appropriate method for assessing spondylolisthesis (except in rare occurrences of multilevel spinal involvement, when the range-of-motion method is recommended).

The Independent Medical Evaluation Relationship

Abstract According to the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, an independent medical evaluation (IME) is “an evaluation performed by an independent medical examiner, who evaluates—but does not provide care for—the individual.” In April 2002, the Work Fitness and Disability Evaluation Section of the American College of Occupational and Environmental Medicine (ACOEM) prepared a motion defining the rationale why there is no a priori establishment of a patient–physician relationship during an IME. A figure in the article includes the text of the resolution, which was proposed and debated at the House of Delegates but has not yet been adopted by ACOEM. A table prepared by the College of Physicians and Surgeons of Ontario (CPSO) enumerates differences between the usual doctor–patient relationship and IMEs in terms of duty to provide care, maintaining records, access to records, and fees. CPSO also clarifies that physicians who agree to conduct third-party examinations of individuals whom they are not currently treating have been hired by a third party to perform a particular task, typically to provide an opinion or answer specific questions about the individual. Clear and effective communication with the individual are particularly important because the individual's livelihood or compensation for injury, as well as the person's continuing health, are at stake.

Impairment Tutorial: Impairment Classes and Ranges

Abstract Many chapters in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) provide a range of numbers within four or five impairment classes, and evaluating physicians are required to justify the choice of a class and the impairment rating within the range specified for that class. The process of assigning a class is accomplished by an assessment of the patient's disease process, objective findings, activities of daily living (ADLs), and required continuing medical treatment. A table in the article provides hyperlinks to different scales for measurement of instrumental activities of daily living and ADL; use of these standardized instruments increases the reliability of assessing the impact on ADLs. After describing the patient's ability to perform ADLs, the evaluating physician should ensure that the physical examination and laboratory findings lead to the final diagnosis used for rating. To provide an impairment rating, the evaluator must identify and confirm a physiologic abnormality via physical examination or laboratory or x-ray findings consistent with the diagnosis. Impairment rating must be based on a clearly established diagnosis, not solely on subjective complaints from the patient. As with all impairment evaluations, the rating should be based on a thoughtful evaluation and obtaining the data needed to apply the criteria specified in the AMA Guides.

Questions & Answers

Abstract The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Chapter 3, The Heart and Aorta, is used to rate impairment in patients with coronary disease. Note that the four “functional classes” of the New York Heart Association, which are discussed in the chapter, should not be confused with the four classes used to rate impairment due to coronary heart disease. Treadmill testing of maximal exercise ability is a traditional measurement to help the evaluator place an individual in an impairment rating class. Class 1 impairment rarely is used in rating workers’ compensation impairment, and the presence of small (asymptomatic) coronary artery blockages that may progress is the justification for considering these individuals impaired even in the absence of symptoms. Classes 2, 3, and 4 describe the impairment of individuals with objectively documented symptomatic coronary disease. Class 2 impairment describes individuals who have no symptoms or who manage them with diet or medication and can achieve 90% of predicted maximal heart rate during exercise testing without specific signs of ischemia. Class 3 impairment describes individuals who have symptoms of congestive failure or angina with moderately heavy activity, and Class 4 includes individuals who have symptoms during ordinary activity. To give guidance in this process, a series of clinical examples follows the description of each class.

Impairment Tutorial: Impairment from Coronary Artery Disease: Fifth Edition Approach

Abstract Before the publication of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fourth Edition, each chapter focused on a single organ system and provided a description of the diagnostic and evaluative methods for assessing impairment at the organ system level and functional impairment of the whole person. Beginning with the Fourth and continuing into the Fifth Edition, a new chapter focused not on a single organ system but rather on pain. The author of this article takes issue with others who propose that pain should not only be conceptualized as a disabling factor but also as an impairment. Some have argued that, “[d]espite its stated intent, the [AMA] Guides does not maintain a clear focus on functional impairment … it blurs the line between impairment and disability. The [AMA] Guides defines impairment so broadly as to include disability, effectively confusing the 2 concepts.” For these very reasons, argues the author of this article, pain should not be conceptualized as an impairment, and rating schemes should not promote or reinforce inappropriate behavior, for example, by providing a reward for reporting more pain. The latter will lead to more diagnostic testing, more treatment, and more physician-prescribed work absence, culminating in the reinforcement of perceived illness and incapacity.

Impairment Tutorial: Hearing Impairment

Abstract A 1999 study of adults showed hearing loss was the fifth most common disability in the US population, and almost 50% of workers in carpentry, plumbing, and mining had hearing impairment. Determining hearing impairment according to the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, Section 11.2a, Criteria for Rating Impairment Due to Hearing Loss, is straightforward, if limited. Examiners should be aware that hearing can be temporarily impaired by recent exposure to loud noise and should test only after an extended period without such exposure. Audiometers should be properly calibrated, and technicians must be appropriately trained to obtain accurate measurements. The evaluator should separately test both of the individual's ears at 500 Hz, 1000 Hz, 2000 Hz, and 3000 Hz (the representative or test frequencies) and then identify the total worst ear decibel level using the AMA Guides Table 11-1 or 11-2. The evaluator can use Tale 11-3 to convert hearing impairment to whole person loss. Tinnitus also can be rated if a hearing loss in that ear affects speech discrimination; in such instances, the tinnitus rating is limited to a 5% loss. The article includes a Hearing Impairment Rating Sheet that can be used to record data from the hearing impairment evaluation.