Evaluation Of Permanent Impairment Research Articles

Evaluating Impairment from Allergic Disorders

Abstract More than 15 million Americans have allergic rhinitis alone, and approximately 12 million have other allergic manifestations such as urticaria, angioedema, eczema, or sensitivity to food, drugs, or insect bites. Almost 10% of patients who seek care at a physician's office do so for one of the common allergic diseases, but rating impairment for allergic disorders is uncommon because typically they do not produce “permanent” impairment and are not work- or liability-related. Section 9.3a, Respiration in Chapter 9, Ear, Nose, Throat, and Related Structures, of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) addresses the process of assessing impairment due to allergic rhinitis, the first type of allergy. Because allergic rhinitis is seasonal, the examiner must determine if permanent impairment is present and if the patient is at maximum medical improvement. The second major manifestation of allergy is allergic skin disease, including urticaria-angioedema and is discussed in Chapter 13, The Skin, where a table classifies skin disorder impairments. The third primary manifestation of allergic disease is eczema, also called atopic dermatitis, which also is discussed in Chapter 13. Allergic diseases are common but generally are quite treatable. Evaluators should ensure that the patient has had an appropriate trial of therapeutic agents before assigning a permanent partial impairment; because of treatment options, the latter should be rare.

Quick Reference: Motion at the Wrist, Elbow, and Shoulder

Abstract Apportionment estimates the degree to which each of various occupational or nonoccupational factors may have caused or contributed to a particular impairment. Apportioning spinal impairment among different injuries often is challenging. The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Third Edition, relied on the Range of Motion (ROM) Model, which is included in the Fourth Edition for use only in 2 circumstances: first, if the spine has a disease and no injury has occurred (eg, ankylosing spondylitis) and, second, as a tie breaker. The AMA Guides, Fourth Edition, introduced a new approach, the Injury Model or Diagnosis-related estimates (DRE) Model. The Injury Model is different from other approaches in the AMA Guides because when the individual reaches Maximal Medical Improvement (MMI), the degree of persisting anatomic or physiologic loss is rated. In contrast, the Injury Model rates the severity of the original injury, not the degree of recovery. Recurrence is common after significant back injury, so even if the individual seems to be doing well when rated, years later the functional result may be different; these concerns explain the instructions to rate soft-tissue back injury using objective findings and true radiculopathy using the Injury Model.

Measurement in Rehabilitation — Lies, damned lies and statistics

Measurement in Rehabilitation Medicine commences with clear definitions of the terms used and clear ideas about the nature of the entity being measured. In this lecture, issues such as goal based measurement, the difficulties of comparison, weighting systems, different types of scales, and the mathematical problems they present are discussed. Scales discussed include the American Medical Association Guides to the Evaluation of Permanent Impairment, and the Functional Independence Measure (FIM). Caution is necessary when drawing conclusions from statistics generated from ordinal scales, especially when comparisons are being made. The Australasian Faculty of Rehabilitation Medicine supports the use of standard measures and has developed an Australian Standard Data Set for Rehabilitation Medicine. The functional measure used in this data set is the FIM.

Tools and Resources: Lower Extremity Impairment Checklist and Worksheet

Abstract The North Dakota Supreme Court has ruled that the “most current” and “most recent” edition of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) is the Third Edition (McCabe v North Dakota Workers’ Compensation Bureau). This counterintuitive holding involved a claimant who injured his back and neck at work and who reached maximum medical improvement in 1994. At issue was which edition of the AMA Guides to use to measure the claimant's permanent partial impairment (PPI). Specifically, the question was whether to evaluate the impairment according to the Range of Motion (ROM) Model from the Third Edition or the Diagnosis-related estimates (DRE) of the Fourth Edition. The relevant statutory language required use of the “most current” or “most recent” edition of the AMA Guides. The court held that the language must be construed to mean the most recent edition at the time of the statute's enactment. At the time of enactment, the AMA Guides, Fourth Edition, (with the DRE Model) had not been published. The court held that the claimant's impairment must be evaluated using the ROM Model. The interpretation of the North Dakota Supreme Court is not consistent with the philosophy of the AMA Guides, and legal interpretations regarding use of the AMA Guides are not always consistent with specific directions therein.

Lower Extremity Impairments—Knee and Hip

Abstract The process of assessing lower extremity impairment described in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fourth Edition, differs from that in previous editions. This article addresses common questions that arise in knee and hip impairment rating according to the new edition. Anatomic, diagnostic, or functional methods can be used to estimate lower extremity impairments. Functional methods include ratings based on diminished range of motion, weakness, or gait derangement. In general, only one method should be used to rate impairment associated with an injury or illness. Section 3.2i, Diagnosis-related Estimates, in the AMA Guides lists impairment ratings for many knee conditions and operative procedures. Decreased range of motion, ankylosis, diminished muscle function, and joint space narrowing are some rating methods for the knee. Similar anatomic, diagnostic, and functional methods may be used to rate impairment due to hip pathology, but most hip impairments are estimated by range-of-motion deficits. Assessing lower extremity impairments requires a thorough medical evaluation, careful analysis, experience, and clear judgment; evaluators must determine the applicable rating methods, use the methods to rate the impairment, and then decide which method or combination best describes the impairment, without overlooking or duplicating ratings. [A related Lower Extremity Impairment Checklist and Worksheet appears on page 4 of this issue of The Guides Newsletter. A related Quick Reference, Motion at the Wrist, Elbow, and Shoulder, appears on page 5.]

Impairment Tutorial: The Combined Values Chart

Abstract Impairment values are more often combined than added, and the Combined Values Chart in the AMA Guides to the Evaluation of Permanent Impairment can be used to calculate the combined value of two numbers. The values are derived from the formula A + B(1 – A) = the combined value of A and B, where A and B are the decimal equivalents of the impairment ratings. This mathematically prevents an estimate of impairment greater than 100%. With smaller numbers, the combined value may equal the arithmetic sum of the 2 numbers. Impairments of different organ systems are converted to whole person impairment ratings before combining. In most lower extremity impairment cases only one evaluation method is used, but certain circumstances justify combining impairments. Examples in the lower extremity include diagnosis-based estimates with short leg, degenerative joint disease (in the case of fractures in and about joints), and neurologic loss. Combining vs adding can be confusing, but one can nearly always combine, with the following exceptions for the musculoskeletal system: range of motion (ROM) deficits within an upper extremity; ROM deficits of the thumb; total hand impairment; rating hip or knee replacement results; and ROM deficits of the spine at a specific level.

Clinical Update: Tinnitus

Abstract Momentary or intermittent tinnitus—perceived sounds that originate within a person's head rather than in the outside world—is common; continuous tinnitus is abnormal but not unusual. According to the National Center for Health Statistics, 32% of US adults acknowledge having experienced tinnitus at some time; 6.4% characterize the condition as debilitating or severe; and prevalence increases with age to approximately 70 years and declines thereafter. A patient with tinnitus is assessed initially using a comprehensive otologic and neurotologic history, a physical examination, and selected tests of otologic function. Current tests can evaluate hearing and balance, but no good, comprehensive, objective methods exist to determine the presence of tinnitus, quantify the symptoms, or assess its severity. For these reasons, there are no scientific data on which to base a judgment regarding impairment or disability, and tinnitus alone generally is not considered compensable. The AMA Guides to the Evaluation of Permanent Impairment allows some adjustment for unilateral, but not bilateral, tinnitus that may impair speech discrimination. No scientific justification supports this policy, and there is no defensible basis for this disparity. Thus, additional research is necessary before this subjective symptom can be used reliably in impairment and disability determinations.

Evaluating Shoulder Impairment

Abstract The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fourth Edition, offers several categories to describe impairment in the shoulder, including shoulder amputation, abnormal shoulder motion, peripheral nerve disorders, subluxation/dislocation, and joint arthroplasty. This article clarifies appropriate methods for rating shoulder impairment in a specific patient, particularly with reference to the AMA Guides, Section 3.1j, Shoulder, Section 3.1k, Impairment of the Upper Extremity Due to Peripheral Nerve Disorders, and Section 3.1m, Impairment Due to Other Disorders of the Upper Extremity. A table shows shoulder motions and associated degrees of motion and can be used in assessing abnormal range of motion. Assessments of shoulder impairment due to peripheral nerve lesion also requires assessment of sensory loss (or presence of nerve pain) or motor deficits, and these may be categorized to the level of the spinal nerves (C5 to T1). Table 23 is useful regarding impairment from persistent joint subluxation or dislocation, and Table 27 can be helpful in assessing impairment of the upper extremity after arthroplasty of specific bones of joints. Although inter-rater reliability has been reasonably good, the validity of the upper extremity impairment rating has been questioned, and further research in industrial medicine and physical disability is required.

Tools and Resources

Abstract The editor and associate editor of The Guides Newsletter respond to and comment on a letter by Knobler and Mandel and the response by Ensalada in this issue. Knobler and Mandel raise interesting issues, including the importance of a thorough medical evaluation and analysis in which the physician must differentiate, on the one hand, symptoms associated with a physical disease process and, on the other hand, illness behavior (symptom magnification) and somatization. Probable relationships must be differentiated from those that are only possible. For example Knobler and Mandel note that RSD can change, but permanent impairment is rated as the individual is, not as he or she will be in the future. The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) states that the degree of disability in the social and vocational contexts is not necessarily the same as the degree of impairment, and loss of function may be greater or less than the impairment might imply. Further, many factors can confound the relationships between impairment and disability, including motivation and illness behavior. The AMA Guides also states that the complexities of secondary gain and motivation complicate the assessment process. Finally, the AMA Guides is used to assess impairment; it was not designed to define disability.

Questions and Answers

Abstract The authors respond to the two-part article by Ensalada in the November/December 1997 and January/February 1998 issues of The Guides Newsletter. Disability determination in the AMA Guides to the Evaluation of Permanent Impairment often is based on formulations that use a scaled ranking of the impaired function(s) that approximates the impact on the individual's ability to perform specific tasks. The method, although imperfect, generates a percentage impairment score for rating the disability. This method breaks down when applied to disorders with far-reaching effects, such as reflex sympathetic dystrophy (RSD), because it tends to focus only on the affected extremity. The AMA Guides also identifies five factors can affect disability in individuals with RSD: First, RSD spreads in an unpredictable temporal manner. Second, RSD is associated with global effects on cognitive processes (eg, constant pain leads to impairment of sleep, decreased alertness, and altered attention). Third, depression often is a reactive consequence to impaired function. Fourth, RSD may change over time yet may remain quite disabling. Fifth, RSD can significantly affect remote systems (eg, bladder disturbance). For these reasons, during the evaluation of people affected by RSD, physicians should be aware of additional issues besides the percentage loss of function of the affected injured extremity.

Impairment Tutorial: Dermatological Impairment Assessment

Abstract The main function of the skin is to protect the body that it encloses. Anatomically and physiologically, the skin's regions differ to the extent that skin is not one organ but a combination of multiple systems. The skin has a limited range of reaction patterns, but these may express a wide range of clinical syndromes. The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) states that the morphology of the lesion and the pattern of distribution suggest the differential diagnosis. Skin lesions can be characterized as macule, papule, change in pigmentation, plaque, erythema, or eczema. The evaluating physician should consider relevant characteristics, including: Is the condition localized or generalized? Does in involve the face or spare it? Does the condition involve or spare the palms and soles? Approximately 95% of occupational skin disease involves contact dermatitis from irritation, contact allergy, or both. The remaining instances usually arise from biological, physical, mechanical, or other miscellaneous causes. The AMA Guides directs the evaluating physician to complete a detailed work description and conduct a physical examination with biopsy or patch testing as needed. Because most cases of occupational contact dermatitis involve irritants, a systematic approach to examination of the skin and use of good dermatology tests can pinpoint the diagnosis in the majority of cases.

Letter to the Editor: The Continuing Challenge of Evaluating RSD Impairment and Disability

Abstract The author of the two-part article about evaluating reflex sympathetic dystrophy (RSD) responds to criticisms that a percentage impairment score may not adequately reflect the disability of an individual with RSD. The author highlights the importance of recognizing the difference between impairment and disability in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides): impairment is the loss, loss of use, or derangement of any body part, system, or function; disability is a decrease in or the loss or absence of the capacity to meet personal, social, or occupational demands or to meet statutory or regulatory requirements because of an impairment. The disparity between impairment and disability can be encountered in diverse clinical scenarios. For example, a person's ability to resume occupational activities following a major cardiac event depends on medical, social, and psychological factors, but nonmedical factors appear to present the greatest impediment and many persons do not resume work despite significant improvements in functional capacity. A key requirement according to the AMA Guides is objective documentation, and the author agrees that when physicians consider the disability evaluation of people, more issues than those relating to the percentage loss of function should be considered. More study of the relationships among impairment, disability, and quality of life in patients with RSD are required.

Impairment Tutorial: Rating Facial Disfigurement After an Injury

Abstract This article discusses two important cases that involve the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides). First, in Vargas v Industrial Com’n of Arizona, a claimant had a pre-existing non–work-related injury to his right knee as well as a work-related injury, and the issue was apportionment of the pre-existing injury. The court held that, under Arizona's statute, the impairment from the pre-existing injury should be subtracted from the current work-related impairment. In the second case, Colorado courts addressed the issue of apportionment in a workers’ compensation claim in which the pre-existing injury was asymptomatic at the time of the work-related injury (Askey v Industrial Claim Appeals Office). In this case, the court held that the worker's benefits should not be reduced to account for an asymptomatic pre-existing condition that could not be rated accurately using the AMA Guides. The AMA Guides bases impairment ratings on anatomic or physiologic loss of function, and if an examinee presents with two or more sequential injuries and calculable impairments, the AMA Guides can be used to apportion between pre-existing and subsequent impairments. Courts often use the AMA Guides to decide statutorily determined benefits and are subject to interpretation by courts and administrative bodies whose interpretations may vary from state to state.

Performing Quality Impairment Evaluations

Abstract An impairment evaluation aims to produce a report that is clear and consistent with the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fourth Edition, which outlines the three-step process of medical evaluation, analysis of the findings, and comparison of the results with the impairment criteria. This article reviews common errors that can occur in each of these steps. Medical evaluation is the basis for the evaluation of impairment and relies on the patient's medical history; the latter must include adequate background information, specify data sources, document pre-existing status and specifics of the injury, and document history from onset to current status. The medical evaluation should support a report that explains the effects of the medical condition on life activities; whether the medical condition is stable; whether the individual is likely to suffer incapacitation, injury, harm, or further impairment; and whether restrictions or accommodations are warranted. Common errors in this step include determinations of permanency and stability, and raters should be aware that the AMA Guides is used to assess impairment, not disability. Forms from the AMA Guides are appropriate and help mitigate errors. An audit form is included and can help physicians produce consistent, efficient reports.

Tools and Resources: Impairment Evaluation Report Audit

Abstract Dysphagia refers to the feeling of difficulty in passing food or liquid from the mouth to the stomach and requires rapid neuromuscular coordination not only of the esophagus but also structures in the oral cavity, pharynx, and larynx during a brief cessation of respiration. The swallowing mechanism can be separated into three stages: oral, pharyngeal, and esophageal. Disabilities resulting directly from dysphagia may arise secondary to aspiration, and the ongoing risk of aspiration has several consequences: limited oral intake of solid food and liquids, restriction of the diet (eg, to foods of a certain consistency), need for assistance when eating, and discomfort associated with eating. Evaluation usually includes assessment by a speech-language pathologist and often is supplemented by a modified barium swallow or a fiberoptic endoscopic evaluation of swallowing. The AMA Guides to the Evaluation of Permanent Impairment describes the process for evaluating impairment for dysphagia in Chapter 4, The Nervous System, Chapter 9, Ear, Nose, Throat, and Related Structures, and Chapter 10, The Digestive System. Section 9.3b, Mastication and Deglutition, includes information about the relationship of dietary restrictions to permanent impairment. Impairment for dysphagia is determined by considering the underlying cause for the dysphagia, dietary restrictions, feeding requirements, and complications.

Clinical Update: Dysphagia

Abstract Physicians are infrequently asked to evaluate an individual with facial disfigurement following an injury because, when the face is injured, typically it heals without any ratable impairment. When a permanent facial disfigurement must be rated, physicians can use Section 9.2 of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides). Chapter 9 of the AMA Guides is unique because it deals only with permanent impairment related to the face's structural integrity, which may be only one aspect of a patient's condition that requires an impairment rating. Facial disfigurement may be the result of a complicated process, for example, a burn that involves multiple organ systems, each with a loss of function that requires an impairment rating. These ratings fall into one of four classes: Class 1 is used when the disorder is limited to the cutaneous structures and may involve a scar or abnormal pigmentation in the cutaneous structures of the face. Class 2 involves loss of some significant underlying supporting structure of the face without significant functional loss or major disfigurement such as a depressed orbital rim, frontal bone, or nasal bone. Class 3 indicates loss of a normal anatomic part or area of the face, eg, an eye. A facial disfigurement so severe that it precludes social acceptance is a Class 4 impairment.

Impairment Update: Illness Behavior

Abstract The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) notes that many methods used to report medical impairments rely on the completeness, accuracy, and honesty of the patient's self-presentations. Symptom exaggeration is best understood in the context of clinical phenomena that lie along a continuum from unconscious and unintentional to conscious and intentional. Illness behavior refers to the ways in which given symptoms may be perceived, evaluated, and acted upon by different persons, and such behavior can be appropriate or inappropriate, depending on context, and can be learned and reinforced. Further, certain illness behaviors potentially confound the association between illness or injury, on the one hand, and impairment or disability, on the other hand. For example, any deficit can be exaggerated, including neuropsychological deficits, pain, and loss of sensation. Specialized assessments include symptom validity testing to assess memory or sensory deficits, and maximum voluntary effort testing assesses strength deficits. In their assessment of illness behavior, physicians should employ the same degree of thoroughness as they would with any condition. Written reports should include not only the conclusion that symptom exaggeration is present but also the basis for this determination. A table shows the characteristics of symptom magnification syndromes and other related conditions vs the presence of symptoms such as seeking gain or deception.

Instability of the Wrist

Abstract Wrist trauma can disrupt the ligamentous support between the carpal bones, leading to instability of the carpus and pain, loss of motion, and loss of function. The most common patter of wrist instability is scapholunate instability that results from a fall on the outstretched hand, possibly with twisting motion. The second most common carpal instability pattern is that between the triquetrum and the lunate, termed lunotriquetral instability. The AMA Guides to the Evaluation of Permanent Impairment directs physicians to use frontal and lateral roentgenographic projections of the wrist to evaluate carpal instabilities and to rate impairment as mild, moderate, or severe. Carpal height can be used to assess impairment. Carpal translation is a medial or lateral translation of the entire carpus on the forearm (radius and ulna). Arthritic changes also can impair wrist stability and are seen roentgenographically as loss of joint space in the wrist. The degree of carpal instability lies on a continuum of loss of carpal bone support and amount of collapse, and, although little absolute difference exists between a 28-degree radiolunate angle and a 31-degree measurement, these two measurements yield different impairment ratings. Also, some forms of instability (eg, dynamic carpal instability) appear roentgenographically if the wrist is stressed, and examiners have freedom to assign impairment without reproducible, objective measures.

Clinical Update: Functional Capacity Evaluations and Disability

Abstract According to the AMA Guides to the Evaluation of Permanent Impairment, a functional capacity evaluation (FCE) measures an individual's physical abilities via a set of activities in a structured setting and provides objective data about the relationship between an impairment and maximal ability to perform work activities. A key distinction between FCEs and self-reported activities of daily living is that the former involve direct observation by professional evaluators. Numerous devices can quantify the physical function of a specific part of the musculoskeletal system but do not address the performance of whole body tasks in the workplace, and these devices have not been shown to predict accurately the ability to perform all but the simplest job tasks. Information about reliability has been proposed as a way to identify magnification and malingering, but variability due to pain and poor comprehension of instructions may cause variations in assessments. Structured work capacity evaluations involve a set of activities but likely underestimate the individual's ability to do jobs that involve complex or varying activities. Job simulations involve direct observation of an individual performing actual job tasks, require a skilled and experienced evaluator, and raise questions about expense, time, objectivity and validity of results, and interpretation of results in terms of the ability to perform specific jobs. To understand the barriers to return to work, examiners must supplement FCEs with information regarding workplace environment, accommodations, and demotivators.

Tools and Resources: Lower Extremity Conditions: Combination vs Duplication

Abstract This article discusses uses of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) in Australia and New Zealand. In addition to its use in the United States, the AMA Guides also is used in Australia, New Zealand, Canada, and some European countries such as Ireland, the Netherlands, and Norway. Use of the AMA Guides varies from country to country, depending on local workers’ compensation or personal injury legislation. In Australia, the AMA Guides is used in various state systems, but the editions used or recommended may differ. Often, cases in which the impairment predates December 1988 (when the current Commonwealth Workers’ Compensation Act became effective) are assessed in terms of the AMA Guides, Fourth Edition. Although many physicians use the Fourth Edition, others refer to the Table of Disabilities (Div 4/S66 of the New South Wales Workers’ Compensation Act) and Victoria prefers the AMA Guides, Second Edition. At the federal level, Australia has adopted the Guide to the Assessment of the Degree of Permanent Impairment (1989 but under revision at the time of writing). In New Zealand, the Accident Compensation Commission officially adopted use of the AMA Guides, Fourth Edition, in 1997.