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Richard T. Katz

Abstract

Hand arm vibration syndrome (HAVS) has been defined as a constellation of vascular, neurological, and musculoskeletal signs and symptoms in workers who use hand-held vibrating tools (eg, drills, grinders, saws, or jackhammers); pathological features affect primarily vascular, neurological, and muscle tissues. Researchers have hypothesized changes in central nervous system processing, but no significant somatotopic cortical changes have been found using functional magnetic resonance imaging. Differential diagnosis of HAVS includes a variety of anatomical, circulatory, and vasospastic disorders and was standardized in the Stockholm Workshop classification scale (1987). Available laboratory tests generally are incapable of grading the severity of individual cases, and no protocol reliably distinguishes between psychogenic and organic abnormalities. Some proposed tests are impractical, and multimodality testing is confounded by statistical fallacies. Vascular tests, including the cold provocation tests, correlate poorly with disease staging according to the Stockholm Scale, and plethysmography before and after cold provocation, were found to be unsatisfactory. Job tasks that involve vibrating machines are associated with musculoskeletal symptoms but sorting out the roles and latency periods of vibration, repetitive movements, grip and push factors, and worker postures is imprecise. The AMA Guides to the Evaluation of Permanent Impairment, does not provide directions about rating impairment associated with HAVS, but evaluators can use Chapter 16 The Upper Extremities, basing the rating on motion, neurological, and/or vascular deficits.

in AMA Guides® Newsletter
Richard T. Katz

Abstract

Repetitive strain injury (RSI), also known as cumulative trauma disorder, implies that an injury exists and was caused by repetitive strain, but both implications are debatable. Ulnar neuropathy at the elbow (UNE), also known as cubital tunnel syndrome, is the second most common upper extremity compression neuropathy (after carpal tunnel syndrome). This article examines one particular aspect of the RSI debate: Is there scientific evidence to support a causal relationship between UNE and repetitive elbow flexion and extension in the workplace? The authors extensively searched published articles, books, and federal task force publications to look for evidence supporting a causal relationship between UNE and RSI. This included a literature review followed by a study of pertinent review articles, bibliographies, national task force reports related to musculoskeletal problems in the workplace, and relevant case reports. In brief, after extensive searches the authors found no credible medical literature to support a causal relationship between RSI and UNE. Case reports and cadaver studies provide tenuous support for causation of UNE by high-force activities such as pitching in baseball. The only prospective study that systematically assessed any causal relationship between RSI and UNE showed there is none. This article includes a three-page Feature Companion, “Rating Guidance: Ulnar Neuropathy,” that identifies common errors and provides an example rating report.

in AMA Guides® Newsletter
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Richard T. Katz

Abstract

The author, who is the editor of the Mental and Behavioral Disorders chapter of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Sixth Edition, comments on the previous article, Assessing Mental and Behavioral Disorder Impairment: Overview of Sixth Edition Approaches in this issue of The Guides Newsletter. The new Mental and Behavioral Disorders (M&BD) chapter, like others in the AMA Guides, is a consensus opinion of many authors and thus reflects diverse points of view. Psychiatrists and psychologists continue to struggle with diagnostic taxonomies within the Diagnostic and Statistical Manual of Mental Disorders, but anxiety, depression, and psychosis are three unequivocal areas of mental illness for which the sixth edition of the AMA Guides provides M&BD impairment rating. Two particular challenges faced the authors of the chapter: how could M&BD disorders be rated (and yet avoid an onslaught of attorney requests for an M&BD rating in conjunction with every physical impairment), and what should be the maximal impairment rating for a mental illness. The sixth edition uses three scales—the Psychiatric Impairment Rating Scale, the Global Assessment of Function, and the Brief Psychiatric Rating Scale—after careful review of a wide variety of indices. The AMA Guides remains a work in progress, but the authors of the M&BD chapter have taken an important step toward providing a reasonable method for estimating impairment.

in AMA Guides® Newsletter
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Richard T. Katz

Abstract

Patients may complain of daytime drowsiness associated with a painful musculoskeletal disorder, but these complaints regard an activity of daily living (ADL) and do not result in a separate sleep impairment rating. This article focuses on sleep impairment resulting from documented nervous system dysfunction or sleep apnea. Because the accuracy and reliability of sleep testing are critical for the proper diagnosis and impairment rating of a sleep disorder, sleep testing should be completed at a center certified by the American Academy of Sleep Medicine. In both the fifth and sixth editions of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), neurologically based sleep disorders are rated using Chapter 13, and sleep apnea is rated using Chapter 5. The AMA Guides, Sixth Edition, does provide a rating value of up to 3% whole person impairment for sleep apnea related impairment, but the fifth edition does not provide any numerical rating value. A sleep disturbance not related to neurologically based dysfunction or apnea should be considered according to its effects on ADLs for the primary pathology identified or diagnosed. Expert understanding of sleep disorders is crucial, as is the specialized experience of a credentialed sleep laboratory. Subjective questionnaires can be used to screen for sleep disorders or excessive daytime sleepiness, but formal sleep studies are necessary to confirm any diagnosis and to provide an objective basis to assess permanent impairment.

in AMA Guides® Newsletter
Richard T. Katz

Abstract

This article addresses some criticisms of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) by comparing previously published outcome data from a group of complete spinal cord injury (SCI) persons with impairment ratings for a corresponding level of injury calculated using the AMA Guides, Sixth Edition. Results of the comparison show that impairment ratings using the sixth edition scale poorly with the level of impairments of activities of daily living (ADL) in SCI patients as assessed by the Functional Independence Measure (FIM) motor scale and the extended FIM motor scale. Because of the combinations of multiple impairments, the AMA Guides potentially overrates the impairment of paraplegics compared with that of quadriplegics. The use and applicability of the Combined Values formula should be further investigated, and complete loss of function of two upper extremities seems consistent with levels of quadriplegia using the SCI model. Some aspects of the AMA Guides contain inconsistencies. The concept of diminishing impairment values is not easily translated between specific losses of function per organ system and “overall” loss of ADLs involving multiple organ systems, and the notion of “catastrophic thresholds” involving multiple organ systems may support the understanding that variations in rating may exist in higher rating cases such as those that involve an SCI.

in AMA Guides® Newsletter
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Richard T. Katz

Abstract

In catastrophic injury cases, attorneys may request that a budget, often called a life care plan (LCP), be created to estimate expenses that a client will have in the future. The LCP is a budgeting process that requires a thorough understanding of a patient's condition, rehabilitation, and future needs to estimate what services and costs are likely to be needed in the future. The physician determines the extent and sequelae of the patient's physical and cognitive impairments; estimates a prognosis; estimates the need for and benefit of further medical and rehabilitative interventions; and then calculates the costs of future personal needs. Such a model first requires an accurate prognostication of the patient's life expectancy. Various costs projections are evaluated to estimate costs related to supplies, medications, physician and therapist services, and home and transportation modifications. Finally, such costs must be placed in an economic model in order to determine how the costs of inflation will modify the LCP. A competently formulated LCP can be a useful tool in estimating the future costs in catastrophic patient care. The article also presents a case example using a spinal cord injury to demonstrate how an LCP can be constructed.

in AMA Guides® Newsletter
Richard T. Katz

Abstract

This article is an introduction to electrodiagnosis of the peripheral nervous system, including electromyography, electroneurography (nerve conduction studies), and somatosensory evoked potentials. Electromyography involves the introduction of a special recording needle into a muscle body in search of spontaneous activity (electrical potentials that occur while the muscle is at rest). Three types of spontaneous activity are of greatest relevance: positive sharp waves, fibrillation potentials, and fasciculations. Electromyography can help assess the status of nerve fibers indirectly, but the integrity of large myelinated sensory and motor neurons can be evaluated directly by nerve conduction studies (NCS), also known as electroneurography. NCS involves the introduction of an electrical stimulus, either by surface electrode or needle, and recording an evoked response. NCS can assess motor neurons, sensory neurons, or mixed nerve trunks, depending on the strategy employed. Somatosensory evoked potentials (SSEP) sometimes are useful as an adjunct to EMG and NCS in the diagnosis of peripheral nervous system pathology and are obtained by stimulating a peripheral mixed nerve at a frequency of approximately 2-5 Hz. Several manufacturers have created automated, hand-held units for performing nerve conduction studies, and neuromuscular ultrasound is noninvasive and painless, and ultrasound of nerve entrapment has identified nerve enlargement just proximal to the site of entrapment. Physicians should know or learn the qualifications of the physician to whom they refer their patients for electrodiagnostic assessment.

in AMA Guides® Newsletter