Abstract

We present a case involving a catastrophic injury that resulted from a completely obstructed airway when an examinee choked on food. She had cardiopulmonary arrest and developed a hypoxic-ischemic encephalopathy associated with profound neurological losses. The evaluation of the consequences of severe central nervous system injury necessitates evaluation and rating of all the sequelae of that injury. The first step is clinical assessment, followed by thoughtful application of these data to the processes and criteria provided in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides). The approaches discussed in the fifth and sixth editions of the AMA Guides are similar.

Introduction

The evaluation of a severe central nervous system (CNS) injury necessitates evaluation and rating of all the sequelae of an injury. It requires careful clinical assessment and thoughtful application of these data to the processes and criteria provided in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides). Accurate usage of the AMA Guides for complex neurological issues can be difficult. For example, an individual who has a CNS injury has visual problems following the injury. Is this rated using Chapter 12 (The Visual System) or Chapter 13 (The Central and Peripheral Nervous System) in the AMA Guides, Fifth and Sixth Editions ? How is urinary or fecal incontinence rated following a CNS injury? A case involving a catastrophic accident in which an examinee's airway was completely obstructed, causing a cardiopulmonary arrest and subsequent hypoxic-ischemic encephalopathy, is presented that exemplifies many of the problems that can occur to the reader and/or rater.

This article explains, in detail, the methodology for rating multiple impairments caused by central nervous system injuries. It is intended to allow the reader to be more mindful of the nuances found in the AMA Guides when rating catastrophic CNS injuries, whether it's using the fifth or sixth edition of the AMA Guides.

Case Example

The examinee is now a 50-year-old female, who choked on a donut while eating at work in April 2016. She completely obstructed her airway. A Heimlich maneuver was unsuccessful in dislodging the food. After transport to the emergency room (ER), she underwent an emergency cricothyrotomy and was resuscitated. Her injury was deemed compensable as a work-related injury.

Her prior history was unremarkable, except for a remote history of minor head injury without evidence of sequelae, and she was a two-pack-per-day smoker. Secondary to the airway obstruction, she had experienced cardiopulmonary arrest and hypoxic-ischemic encephalopathy. She was hospitalized for 3 weeks.

A magnetic resonance imaging (MRI) scan of the brain revealed bilateral cortical restricted diffusion consistent with hypoxic-ischemic brain injury, as well as an acute left temporal lobe stroke. An echocardiogram was suspicious for stress-induced cardiomyopathy, an apical thrombus, global hypokinesis, grade 2/4 diastolic dysfunction, and an ejection fraction (EF) of 35%. There was normal right ventricular function. Anti-coagulants were administered.

On discharge, the primary diagnosis was cardiopulmo-nary arrest with airway obstruction from food impaction. Secondary diagnoses included hypoxic-ischemic encephalopathy, acute followed by chronic respiratory failure, tracheostomy, dysphagia with percutaneous endoscopic gastrostomy (PEG) tube, spastic quadriplegia, ischemic cardiomyopathy, hypertension, normocytic anemia, and fever of unknown origin.

The examinee was transferred to a rehabilitation facility for 2 months, during which time her condition improved, and she was discharged home with 24-hour care. Discharge diagnoses included sequelae of severe hypoxic-ischemic encephalopathy with radiological evidence of basal ganglia and bilateral posterior frontal, parietal, and occipital/cortical involvement.

An echocardiogram performed 3 months later showed globally normal left ventricular size and systolic function with a calculated EF of 56%. The PEG and tracheostomy tubes were removed. Her mentation slowly improved. Following discharge, the examinee met criteria for major depressive disorder.

Two years post-incident, the examinee was seen for an IME. She was living at home with 24/7 assistance. She required total assistance for all activities of daily living (ADL), such as dressing, grooming, bathing, and toileting. She was unable to read or write but was able to listen to audiobooks. She was able to eat and swallow but was unable to feed herself due to profound visual loss and arm weakness. She has urinary urge incontinence three times nightly resulting in urinary incontinence and necessitating diapers. She has no sensation of impending bowel movements and no control over bowel function (full fecal incontinence).

She reported difficulty with thinking, memory, concentration, and problem solving, as well as feelings of sadness and anger. Other complaints included problems with balance, coordination, weakness, difficulty swallowing and speaking, and diffuse numbness. She did not complain of headache or dizziness. She had no focal sensory deficit. She felt she has good strength in the lower extremities but is weak in the upper extremities. She was reported to be able to walk short distances with a quad walker.

On examination, she was found to be cortically blind. Extraocular movements were full without nystagmus. She was in a wheelchair but was able to walk short distances with a quad walker in the examining room. There was spasticity in all extremities. Reflexes were brisk throughout and plantar responses were upgoing bilaterally. She recalled three of three objects on immediate recall but could only remember one object after 5 minutes.

At maximum medical improvement, diagnoses that applied included:

  1. Hypoxic-ischemic encephalopathy secondary to food-related asphyxiation on 4/18/16 with subsequent cardiac arrest.

  2. Status post-acute and chronic respiratory failure'resolved.

  3. Cortical blindness secondary to anoxic-ischemic encephalopathy.

  4. Spastic quadriparesis.

  5. Status post-percutaneous endoscopic gastrectomy'removed.

  6. Status post-tracheostomy'removed.

  7. Status post-percutaneous suprapubic catheter'removed.

  8. Major depressive disorder'improved.

Neuropsychological testing was subsequently performed. In brief, this revealed mild to moderate cognitive deficits. However, the physician evaluating impairment did not have access to the neurophysiological testing, only to this summary conclusion. A psychiatric IME was also performed. Her global assessment of functioning (GAF) score was 55.

Impairment Assessment Using AMA Guides, Fifth Edition

Multiple impairments need to be rated in this examinee's case. The examinee will be rated with reference to the following chapters in the fifth edition of the AMA Guides: Chapter 13, The Central and Peripheral Nervous System; Chapter 3, The Cardiovascular System: Heart and Aorta; and Chapter 5, The Respiratory System.

The AMA Guides (5th ed, 306) states, “If impairments involve several nervous system areas (eg, the brain, spinal cord, and/or peripheral nerves), calculate separate whole person impairment ratings for each area and combine them using the Combined Values Chart (p. 604). As discussed in the following text, impairment of the brain is assessed differently. Because brain dysfunction will likely affect many overlapping functions, identify the most severe cerebral impairment. The impairment rating is based on the neurologic condition that causes the most severe impairment. Examples are provided later in this chapter.1 

The current data do not show evidence of permanent impairment affecting the cardiovascular and pulmonary systems.

Section 13.2 of the AMA Guides (5th ed, 308) discusses “Criteria for Rating Impairment Due to Central Nervous System Disorders.” The fifth edition notes:

The central nervous system (CNS) consists of the brain and spinal cord. When injury or illness affects the CNS, several areas of function may be impaired. Therefore, the most severe category of impairment is based on the neurologic evaluation and relevant clinical investigations in four categories: (1) state of consciousness and level of awareness, whether permanent or episodic; (2) mental status evaluation and integrative functioning; (3) use and understanding of language; and (4) influence of behavior and mood. The motor and sensory systems, gait, and coordination are evaluated once the four categories of cerebral impairment have been determined.

The most severe of these four categories should be used to determine a cerebral impairment rating.

  • Step 1. The initial step in assessing cerebral function is to determine whether disturbance is present in the level of consciousness or awareness. This may be a permanent alteration or an intermittent alteration in consciousness, awareness, or arousal. See Table 13-2 (Criteria for Rating Impairment of Consciousness and Awareness); Table 13-3 (Criteria for Rating Impairment Due to Episodic Loss of Consciousness or Awareness); and Table 13-4 (Criteria for Rating Impairment Due to Sleep and Arousal Disorders).

  • Step 2. Evaluate mental status and highest integrative functioning (see Table 13-6, Criteria for Rating Impairment Related to Mental Status).

  • Step 3. Identify any difficulty with understanding and use of language (see Table 13-7, Criteria for Rating Impairment Due to Aphasia or Dysphasia).

  • Step 4. Evaluate any emotional or behavioral disturbances such as depression that can modify cerebral function (Table 13-8, Criteria for Rating Impairment Due to Emotional or Behavioral Disorders).

  • Step 5. Identify the most severe cerebral impairment listed above. Combine the most severe impairment from categories 1 through 4 with any, or multiple, distinct neurologic impairments listed in Table 13-1 using the Combined Values Chart (p. 604).1 

Each of these five steps were reviewed based on this case.

  1. Assess disturbance in the level of consciousness or awareness. In this case, there were no ratable deficits according to Tables 13-2, 13-3, and 13-4 (5th ed, 309, 312, and 317, respectively).

  2. Evaluate mental status and highest integrative function. As explained in Section 13.3d, Mental Status, Cognition and Highest Integrative Function (5th ed, 319-322), Table 13-5, Clinical Dementia Rating (CDR) (5th ed, 320) was used to quantify deficits. Based on the neurologic examination, neuropsychological testing, and reported difficulties with ADL, the following determinations were made.

AreaDescriptionScore
Memory (M) Some difficulties with memory documented by neuropsychological testing. Moderate: 2.0 
Orientation (O) Fully oriented in all spheres. None: 0 
Judgment and Problem Solving (JPS) Difficulties with problem solving documented by neuropsychological testing. Mild: 1.0 
Community Affairs (CA) Primarily home-bound, although able to be taken to the store. Moderate: 2.0 
Home and Hobbies (HH) The records provided support “only simple chores preserved; very restricted inter-ests, poorly maintained.” Moderate: 2.0 
Personal Care (PC) The records document that she needs help with personal care due to her cognitive impairment. She has bowel and bladder incontinence. Left on her own, she would not be capable of rising from bed, making meals, feeding herself, caring for her bowel and bladder functions, or havin n ocial interactions. Severe: 3.0 
AreaDescriptionScore
Memory (M) Some difficulties with memory documented by neuropsychological testing. Moderate: 2.0 
Orientation (O) Fully oriented in all spheres. None: 0 
Judgment and Problem Solving (JPS) Difficulties with problem solving documented by neuropsychological testing. Mild: 1.0 
Community Affairs (CA) Primarily home-bound, although able to be taken to the store. Moderate: 2.0 
Home and Hobbies (HH) The records provided support “only simple chores preserved; very restricted inter-ests, poorly maintained.” Moderate: 2.0 
Personal Care (PC) The records document that she needs help with personal care due to her cognitive impairment. She has bowel and bladder incontinence. Left on her own, she would not be capable of rising from bed, making meals, feeding herself, caring for her bowel and bladder functions, or havin n ocial interactions. Severe: 3.0 

The fifth edition of the AMA Guides (p 319) notes:

The criteria for evaluating mental status and cognitive impairment are based on the amount of interference with the ability to perform activities of daily living [ADL]. This information can be obtained from someone who has close and continual contact with the individual and can be documented using any one of numerous ADL indices that determine changes in activities of activities of daily living (eg, Barthel ADL Index and Blessed Dementia Scale). A tool that combines both cognitive skills and function is the Clinical Dementia Rating (CDR), which covers memory, orientation, judgment and problem solving, home and hobbies, community affairs, and personal care. This validated clinical assessment tool is reproduced in Table 13-5 to serve as an example of how to evaluate cognitive change in light of ADL impairment. One of the standardized mental status tests'the short Blessed, NCSE [Neurobehavioral Cognitive Status Examination], or MMSE [Mini-Mental State Examination]'can be used in conjunction with the CDR to rate the impairment. To use the CDR, score the individual's cognitive function for each category (M, O, JPS, CA, HH, and PC) independently. The maximum CDR score is 3. Memory is considered the primary category; the other categories are secondary. If at least three secondary categories are given the same numeric score as memory, then CDR = M. If three or more secondary categories are given a score greater or less than the memory score, CDR = the score of the majority of secondary categories unless three secondary categories are scored on one side of M and two secondary categories are scored on the other side of M. In this case, CDR = M.1 

Corresponding impairment ratings for CDR scores are listed in Table 13-6 (5th ed, 320). A CDR score of 0.5 equals class 1 impairment; CDR score of 1 equals class 2 impairment; CDR score of 2 equals class 3 impairment; and CDR score of 3 equals class 4 impairment.

In this case, there were two scores less than the score of memory (O and JPS), two scores the same (CA and HH), and one score greater (PC). Because at least three secondary categories that have been given the same numeric score as memory, CDR equals M.

A CDR score of 2 was rated under class 3 with reference to Table 13-6 (5th ed, 320). A rating under class 3 ranges between 30% and 49% whole person impairment (WPI). Rating under this category applies when impairments require assistance and supervision for most ADL.

Considering all of the currently available data, including clinical assessment and the results of neuropsychological testing, a rating of 40% WPI was recommended in this case.

  • 3. Identify any difficulty with understanding and use of language. This was not applicable in this case. This process is described in Section 13.3e, Communication Impairments: Dysphasia and Aphasia (5th ed, 322-325).

  • 4. Evaluate any emotional or behavioral disturbances that reflects cerebral dysfunction. This process is explained in Section 13.3f, Emotional or Behavioral Impairments (5th ed, 325-327), and is based on Table 13-8, Criteria for Rating Impairment Due to Emotional or Behavioral Disorders (5th ed, 325).

On the basis of what was described in the records provided (including a GAF score of 55), it was reasonable to assign the examinee to class 2, ie, moderate limitation of some ADL and some daily social and interpersonal functioning. Although class 1 was also considered in the evaluation, in view of all of the available information, the examinee was assigned to class 2. Rating within this class ranges between 15% and 29% WPI. A rating of 20% WPI was determined with reference to this component of the symptom complex.

The depression rating was performed with reference to Section 13.3f because the problem with depression occurred in the context of documented neurologic (cerebral) impairment.

As noted in the AMA Guides (5th ed, 325), “Psychiatric manifestations and impairments that do not have documented neurologic impairments are evaluated using the criteria in the chapter on mental and behavioral impairments (see Table 13-8 and Chapter 14, Mental and Behavioral Disorders).”1  It could be argued that problems with depression were not solely related to the direct physiologic effects of the encephalopathy, but were because of the cognitive reaction to the encephalopathy.

  • 5. Identify the most severe cerebral impairment listed above and combine the most severe impairment from categories 1 through 4 “with any or multiple neurologic impairments listed in Table 13-1 using the Combined Values Chart” (5th ed, 308 and 604-606, respectively).

The most severe impairment in this case was the mental status cognition and highest integrative function deficits, resulting in 40% WPI. The AMA Guides explicitly states that the other impairments “that are combined with the most severe cerebral impairment” are the cranial nerve impairments; station, gait, and movement disorders; extremity disorders related to central impairment (in other words, these deficits are to be evaluated using Chapter 13, not Chapter 15, The Spine; Chapter 16, The Upper Extremities; or Chapter 17, The Lower Extremities); spinal cord impairments; chronic pain; and peripheral nerve, motor, and sensory impairments (see Table 13-1, 5th ed, 308).

Visual Impairment

Visual impairment was assessed using Section 13.4, Criteria for Rating Impairments of the Cranial Nerves (5th ed, 327-335). Although there was no cranial nerve injury, per se, using this as a proxy provided a reasonable basis for assessing the visual impairment. Therefore, impairment was rated as if there was dysfunction of cranial nerve II, the optic nerve. The instructions for determining impairment for this nerve are found in Section 13.4b, Table 13-9: Examples of Whole Person Impairment Due to Visual Acuity Loss, and Table 13-10: Examples of Whole Person Impairment (WPI) Due to Visual Field Loss (5th ed, 328-329). The examinee does not have total loss (her vision is severely pixilated; she occasionally sees colors). However, testing did reveal a profound bilateral vision loss that was most closely identified as class 5 in Table 13-9. A rating within class 5 represents between 62% and 73% WPI. A mid-range value of 68% WPI was assigned for this examinee.

Station, Gait, and Movement Impairment

Ambulatory difficulties were assessed using Section 13.5, Criteria for Rating Impairments of Station, Gait, and Movement Disorders (5th ed, 336-337). The examinee has difficulties with ambulation, is essentially wheel-chair-bound, requires help to transfer, and is reportedly able to walk only short distances using a quad walker.

Referring to Table 13-15 of the AMA Guides (5th ed, 336), the examinee was assigned to class 3. A rating within class 3 applies when an individual “[r]ises and maintains standing position with difficulty; cannot walk without assistance.” A rating within class 3 ranges between 20% and 39% WPI. A mid-range value of 30% WPI was assigned.

Upper Extremities Impairment

The examinee has marked difficulty with her upper extremities. This was assessed using Section 13.6, Criteria for Rating Impairments of Upper Extremities Related to Central Impairment (5th ed, 338-340). She has significant difficulty with the use of her hands, related to spasticity and weakness. Referring to Table 13-17, Criteria for Rating Impairment of Two Upper Extremities (5th ed, 340), she was assigned to a rating within class 3. A rating within this class applies when an individual can use both upper extremities but has difficulty with self-care activities. A rating within this class ranges between 40% and 79% WPI. On the basis of information provided in the records, a value of 75% WPI was assigned.

Urinary Incontinence Impairment

Urinary incontinence may be related to various factors, including neurologic injury, or may be secondary to other conditions affecting the bladder. In this examinee's case, reference was made to an inability to get to the bathroom at night in time due to the underlying neurologic condition.

In view of this, rating for urinary incontinence with reference to Table 15-6d of the Guides (5th ed, 397) was recommended. In this case, a rating within class 1 applies, because the individual has some degree of voluntary control but is impaired by urgency or intermittent incontinence. A rating within class 1 ranges between 1% and 9% WPI. A rating of 9% WPI was recommended in this case.

Neurogenic Bowel Function

At maximal medical improvemen (MMI), the examinee has complete incontinence of bowel function. She is managed with diapers that need to be changed twice a day, on average. In the past 2 years, she has had no skin breakdown. This assessment was rated using Section 13.7c, Anorectal System Neurologic Impairment (5th ed, 342), and Table 13-20 (5th ed, 342). Based on the total incontinence, she merited a class 3 rating. Based on the infrequency of diaper changes and the lack of skin breakdown, she was rated at the lowest level in this class, 40% WPI.

Neurogenic Sexual Function

Sexual dysfunction, caused by CNS conditions, was rated using Section 13-7d, Sexual System Neurologic Impairments, and Table 13-21 (5th ed, 342). She has not desired to have sexual intercourse or stimulation since her injury. Accordingly, no impairment rating for sexual dysfunction on a neurological basis was recommended.

Chronic Pain Impairment

Chronic pain caused by central or peripheral system conditions was rated using Section 13.8, Criteria for Rating Impairments Related to Chronic Pain (5th ed, 343-344). This section includes ratings for causalgia and reflex sympathetic dystrophy (RSD). This woman has had no chronic pain that needs to be evaluated/rated using this section of the AMA Guides.

Peripheral Nerve, Motor, and Sensory Impairments

These conditions were rated using Section 13-9, Criteria for Rating Impairments of the Peripheral Nervous System, Neuromuscular Junction, and Muscular System (5th ed, 344-351). Based on lack of complaints and relatively normal examination, there was no ratable condition for this examinee using this section of the AMA Guides.

Combined Impairment

Combined impairment was performed using the Combined Values Chart (5th ed, 604-606). The whole person components that must be combined were:

1. Cardiac impairment 0% 
2. Pulmonary impairment 0% 
3. CNS disorders 40% 
4. Cranial nerve impairments: vision (optic nerve) 68% 
5. Station, gait, and movement disorders 30% 
6. Upper extremity related to central impairment 75% 
7. Bladder incontinence 9% 
8. Bowel incontinence 40% 
1. Cardiac impairment 0% 
2. Pulmonary impairment 0% 
3. CNS disorders 40% 
4. Cranial nerve impairments: vision (optic nerve) 68% 
5. Station, gait, and movement disorders 30% 
6. Upper extremity related to central impairment 75% 
7. Bladder incontinence 9% 
8. Bowel incontinence 40% 

Using the Combined Values Chart, the combined impairment was 98% WPI. The AMA Guides explains:

A 90% to 100% WP impairment indicates a very severe organ or body system impairment requiring the individual to be fully dependent on others for self-care, approaching death (5th ed, 5).1 

Based on the facts in this case and the criteria provided in the AMA Guides, a rating of 98% WPI was supportable and appropriate.

Impairment Assessment Using the AMA Guides, Sixth Edition

Impairment was based on Chapter 13, The Central and Peripheral Nervous System, and Chapter 12, The Visual System. The current data do not show evidence of permanent impairment affecting the cardiovascular and pulmonary systems.

Disorders of cerebral function were assessed using Chapter 13, The Central and Peripheral Nervous Systems, Section 13.2, Criteria for Rating Cerebral Impairments (6th ed, 326), and Section 13.3, Criteria for Rating Cerebral Impairments (6th ed, 326-333) Section 13.2 states:

The first step in assessing CNS impairment is to assess the most severe category of cerebral impairment, if any, from 4 categories:

  1. State of consciousness and level of awareness, whether permanent or episodic.

  2. Mental status evaluation and integrative functioning.

  3. Use and understanding of language.

  4. Influence of behavior and mood.

Next, the rater assesses impairment (if any) of the cranial nerves, upper and lower extremities, bowel and bladder (due to neurogenic problems), sexual function, neurologic respiratory impairment, and peripheral nervous system. These are then combined with the single most severe category of cerebral impairment, using the Combined Values Chart in the Appendix [in the AMA Guides].2 

This is seen most clearly in Table 13-3 (6th ed, 326).

TABLE 13-3
Neurologic Impairments That Are Combined With the Most Severe Cerebral Impairment 
Cranial nerve impairments
Upper extremity function
Lower extremity function
Neurogenic bladder function
Neurogenic bowel function
Neurogenic sexual function
Neurogenic respiratory function
Peripheral nervous system disorders
Migraine headaches and craniocephalic pain 
Neurologic Impairments That Are Combined With the Most Severe Cerebral Impairment 
Cranial nerve impairments
Upper extremity function
Lower extremity function
Neurogenic bladder function
Neurogenic bowel function
Neurogenic sexual function
Neurogenic respiratory function
Peripheral nervous system disorders
Migraine headaches and craniocephalic pain 

Section 13-3, Criteria for Rating Cerebral Impairments, provides the following instructions on page 326:

Step 1. The initial step in assessing cerebral function is to determine whether disturbance is present in the level of consciousness or awareness. This may be a permanent alteration or an intermittent alteration in consciousness, awareness, or arousal (Tables 13-4 through 13-6).

Step 2. Evaluate mental status and highest integrative functioning (Tables 13-7 and 13-8).

Step 3. Identify any difficulty with understanding and use of language (Table 13-9).

Step 4. Evaluate any emotional or behavioral disturbances, such as depression, that can modify cerebral function (Table 13-10).

Step 5. Identify the most severe cerebral impairment listed above. Combine the most severe impairment from categories 1 through 4 with any or multiple distinct neurologic impairments listed in Table 13-3 using the Combined Values Chart in the Appendix.2 

Each of these five steps were reviewed based on this case.

  1. Assess disturbance in the level of consciousness, awareness, or arousal. In this case, there were no ratable deficits according to Tables 13-4, 13-5, and 13-6 (6th ed, 327-329).

  2. Evaluate mental status and highest integrative function. As explained in Section 13.3d, Mental Status, Cognition, and Highest Integrative Function (6th ed, 330-331):

Mental status and integrative function deficits include the general effects of organic brain syndrome; dementia; and some specific, focal, and neurologic deficiencies. Mental status tests are used to screen and follow up individuals, frequently with repeated testing. They usually cover measures of orientation, attention, immediate recall, calculations, abstraction, construction, information, and recall. Diagnosis should be based on a detailed mental status examination, often in concert with neuropsychological assessment and testing. The mental status exam for the neurologically impaired patient is outlined in Table 13-7.2 

TABLE 13-7
Mental Status Exam for the Neurologically Impaired Patient
1. Level of consciousness 
2. Attention 
3. Memory 
4. Intellectual function 
5. Language function 
6. Psychosensory function 
7. Psychomotor function 
8. Constructional ability 
9. Higher cognitive function 
10. Thought content 
11. Behavioral observations 
12. Mood and general emotional status 
13. Emotional reactions 
1. Level of consciousness 
2. Attention 
3. Memory 
4. Intellectual function 
5. Language function 
6. Psychosensory function 
7. Psychomotor function 
8. Constructional ability 
9. Higher cognitive function 
10. Thought content 
11. Behavioral observations 
12. Mood and general emotional status 
13. Emotional reactions 

Table 13-8, Criteria for Rating Neurologic Impairment due to Alteration in Mental Status, Cognition, and Highest Integrative Function (MSCHIF) (6th ed, 331), was used to quantify deficits based on the extended mental status examination, the neuro-psychological assessment and testing, and the reported difficulties with ADL (Description).

The criteria for evaluating mental status and cognitive impairment are based on the amount of interference with the ability to perform ADLs (Table 13-8). This information can be obtained from someone who has close and continual contact with the individual.2 

In this case, the alterations in MSCHIF were:

AreaDescriptionScore
Extended mental status exam Reported some difficulties with memory, documented by mental status testing. Class 1: Mild alterations 
Neuropsychological assessment and testing Found to be fully oriented in all spheres; documented difficulties with problem solving based on the results of neuropsychological testing. Class 1: Mild alterations 
Difficulties with ADL (Description) Primarily home-bound, although able to be taken to the store. The records provided support that “only simple chores preserved; very restricted interests, poorly maintained.” The provided records document that she needs help with personal care and experiences incontinence. Class 4: Severe alterations 
AreaDescriptionScore
Extended mental status exam Reported some difficulties with memory, documented by mental status testing. Class 1: Mild alterations 
Neuropsychological assessment and testing Found to be fully oriented in all spheres; documented difficulties with problem solving based on the results of neuropsychological testing. Class 1: Mild alterations 
Difficulties with ADL (Description) Primarily home-bound, although able to be taken to the store. The records provided support that “only simple chores preserved; very restricted interests, poorly maintained.” The provided records document that she needs help with personal care and experiences incontinence. Class 4: Severe alterations 

As evident from an inspection of Table 13-8, this table does not fit the pattern of the generic template as described in Section 1.8c, Generic Template for Uniformity and Ease of Application, wherein the first step is to find the “key factor.” Barth discusses the proper application of the MSCHIF table in the article “Rating Cognitive Impairment, Part 1: Case Example Illustrates Need for Adherence to AMA Guides, Sixth Edition Methodology” in the AMA Guides Newsletter:

[Step]11.b.i. If the class for the Extended Mental Status Exam line is lower than (further to the left of Table 13-8) than the class for the Description line (and the rating process did not use neuropsycho-logical assessment and testing), then the evaluator should document that the clinical findings were not supportive of the claims of impairment and assign an impairment rating from the class that was assigned for the Extended Mental Status Exam line. The class from the Extended Mental Status Exam line is used for the creation of the impairment rating (even when the Description line involved a class that would have produced a higher rating) because of the following considerations:

  • Section 13.1 (6th ed, 322-323) explains that “the physician should note whether the patient's report of ADL loss is consistent with the neurologic impairment evident in the physician's office.”

  • The Sixth Edition methodology involves a fundamental principle that impairment rating is based on objective findings and an axiom that calls for impairment rating to be diagnosis based and evidence based.

  • The Sixth Edition methodology involves an emphasis on validity.

  • If the clinical findings regarding “the neurologic impairment evident in the physician's office,” classified on the Extended Mental Status Exam line of Table 13-8, indicate a lower impairment rating than what is indicated by inherently biased reports of ADLs, then the impairment rating must be based on the clinical findings in order to comply with the Sixth Edition issues that were listed in the preceding bullet points. In contrast, an impairment rating that is based on the inherently biased reports of “ADL loss” that are obtained from the examinee and his/her collateral would violate Sixth Edition considerations and, in fact, would involve an abandonment of clinical and scientific expertise altogether (it would allow the impairment rating to be based solely on the inherently biased reports from the examinee and his/her collateral).

[Step]11.b.ii. If the class for the Extended Mental Status Exam line is consistent with or higher (further to the right of Table 13-8) than the class from the Description line, then the impairment rating should come from the class that has been assigned to the case from the Description line. The impairment rating is based on the class from the Description line (even when the class for the Extended Mental Status Exam line might have produced a higher impairment rating) because impairment rating is to be “based on the amount of interference with the ability to perform ADLs” (6th ed, 330) (for any case that otherwise satisfies the general Sixth Edition requirements for impairment rating to be diagnosis based, evidence based, justified by objective verification, and valid).

[Step]11.c. The evaluator should comply with the Sixth Edition axiom that calls for simplicity and ease of application by avoiding use of both neuro-psychological assessment and testing and mental status tests within a single rating process. This will prevent a scenario in which the Neuropsychological Assessment and Testing line of Table 13-8 contradicts the Extended Mental Status Exam line. If an evaluator faces such a contradiction, the discrepancy should be resolved by giving preference to the type of assessment (mental status tests or neuropsychological assessment and testing), which allows the evaluator to maximize compliance with the Sixth Edition emphases on diagnosis-based rating, evidence-based rating, objectivity, and validity. Neuropsychological assessment and testing will usually be the option that maximizes such compliance with an evidence-based approach.3 

Based on the information available, a 10% impairment rating was recommended (the range is 1% to 10% WPI and the highest level was chosen based on the higher class for the description). If one assigned the examinee to class 4, this would have been associated with a rating between 36% and 50% WPI.

  1. Identify any difficulty with understanding and use of language. These difficulties were rated using Section 13-3e, Communication Impairments: Dysphasia and Aphasia (6th ed, 331-332). This section was not applicable in this case.

  2. Evaluate any emotional or behavioral disturbances that reflects cerebral dysfunction. This process is explained in Section 13.3f, Emotional or Behavioral Impairments (6th ed, 332-333), and is based on Table 13-10, Global Assessment of Functioning (GAF) Impairment Score (6th ed, 334). On the basis of the records reviewed and assuming the results of the GAF report (score of 55) were reliable, it was reasonable to assign a rating of 10% WPI.

  3. Identify the most severe cerebral impairment listed above. Combine the most severe impairment from categories 1 through 4 with any or multiple distinct neurologic impairments listed in Table 13-3 using the Combined Values Chart in the Appendix (6th ed, 604-606).

There was a rating of 10% WPI for neurological impairment caused by alteration in mental status, cognition, and highest integrated function, and there was a rating of 10% WPI for emotional or behavioral disturbances. Therefore, there was a rating of 10% WPI for cerebral impairment. This needs to be combined with any additional neurological impairments as found in Table 13-3. These will be described as follows, individually.

Upper Extremities Impairment Caused by CNS Dysfunction

Section 13-5, Criteria for Rating Impairments of Upper Extremities due to CNS Dysfunction (6th ed, 335), states:

The basic tasks of everyday living depend on dexterous use of the dominant upper extremity. Loss of use of that extremity results, in most instances, in greater impairment than would be the case with impairment of the limb on the nondominant side. Table 13-11 is used to rate upper extremity dysfunction from any lesion in the brain or spinal cord. Use this table for rating upper extremity dysfunction (manifested by weakness, tremor, or pain) that affects ADLs. The upper extremity impairment may result from, but is not limited to, traumatic brain injury, stroke, neurodegenerative diseases (eg, Parkinson's disease, progressive supranuclear palsy), multiple sclerosis, spinal cord injury, and sequelae of CNS infection.

When the spinal cord disorder affects both upper extremities, combine the ratings for the dominant and nondominant upper extremity.2 

Using Table 13-11, Criteria for Rating Impairments of Upper Extremities due to CNS Dysfunction (6th ed, 335), based on the spasticity noted in both upper extremities, and based on the significant interferences in ADL, the examinee merited class 3 impairment of both upper extremities (“Individual can use the involved extremity only as a gross assist in ADLs”). For the nondominant side, based on the severity of the interferences in the ADL, there was 30% WPI. For the dominant side, based on the same factors, there was 40% WPI. (Also note, the ratings found in this chapter for upper and lower extremity impairments are provided in WPI values, not upper or lower extremity impairment values as found in Chapters 15 and 16.) When combined, there was 58% WPI.

Lower Extremities Impairment Caused by CNS Dysfunction

Lower extremity problems were rated using Section 13-6, Criteria for Rating Impairments of Station, Gait, and Movement Disorders (6th ed, 336), and Table 13-12, Station and Gait Disorders, (6th ed, 336). The examinee has difficulties with ambulation, is essentially wheel-chair-bound, requires help to transfer, and is reported able to walk short distances but only with a quad walker. Using Table 13-12, she was assigned class 4, ie, “Cannot stand without help, mechanical support, and/or an assistive device.” This is associated with 40% to 60% WPI. She was assigned a mid-range value of 50%.

Neurogenic Bladder and Bowel Dysfunction

Section 13-7, Criteria for Rating Neurogenic Bowel, Bladder, and Sexual Dysfunction (6th ed, 336-337), rates abnormalities related to incontinence and sexual dysfunction.

At MMI, the examinee has partial incontinence of bladder function. She manages with diapers for nocturnal incontinence. In the past 2 years, she has only had two urinary tract infections, so there was no rating for upper urinary tract disease. This was rated using Section 13.7b, Neurogenic Bladder (6th ed, 336), and Table 13-14 (6th ed, 337). Based on the nocturnal incontinence, she could be rated in either class 1 (less than normal control) or class 3 (incontinent once a day). A factor in her incontinence is delay in going to the bathroom at night due to limited mobility, which is a non-genitourinary reason for her incontinence. Her cystometrogram shows a small capacity “spastic” bladder, so she was best placed in class 3 and 18% WPI.

Neurogenic Bowel Function

At MMI, the examinee has complete incontinence of bowel function. She manages with diapers that need to be changed twice a day, on average. In the past 2 years, she has had no skin breakdown. This was rated using Section 13.7a, Neurogenic Bowel (6th ed, 336), and Table 13-13 (6th ed, 337). Based on the total incontinence, she merited class 4. Based on the infrequency of diaper changes and the lack of skin breakdown, she was rated at the lowest level in this class, 21% WPI.

Neurogenic Sexual Function

Sexual dysfunction, caused by CNS conditions, was rated using Section 13-7c, Criteria for Rating Neurogenic Sexual Dysfunction (6th ed, 336) and Table 13-15 (6th ed, 338). She has no desire to have sexual intercourse or stimulation since her injury. Accordingly, no impairment rating for sexual dysfunction on a neurological basis was recommended.

Neurogenic Respiratory Function

Respiratory dysfunction caused by CNS conditions was rated using Section 13-8, Criteria for Rating Neurogenic Respiratory Dysfunction (6th ed, 337-339). At MMI, there was no evidence of disturbance of respiratory function based on a neurological dysfunction.

Peripheral Nervous System Disorders

Peripheral neuropathies were rated using Section 13.9, Criteria for Rating Peripheral Neuropathy, Neuromuscular Junction Disorders, and Myopathies (6th ed, 339-341). This section rates peripheral neuropathies, dysesthetic pain, neuromuscular junction disorders, myopathies, and autonomic nervous system disorders.

Peripheral neuropathies are also covered in Section 13-12 (6th ed, 343). This section states:

In recent editions of the AMA Guides, certain peripheral nerves have been inadvertently omitted …. Most focal neuropathies are rated in the chapters on upper and lower extremity disorders. The purpose of the following table is to rate miscellaneous peripheral nerves that are not ratable in other places in the Guides.2 

Table 13-20 (6th ed, 343) includes dysfunction of the greater occipital nerve, the lesser occipital nerve, the greater auricular nerve, the intercostal nerves, the genitofemoral nerves, the ilioinguinal nerves, the iliohypogastric nerves, and the pudendal nerves.

At MMI, there was no evidence of a neuropathic problem using either of these sections.

Migraine Headaches and Craniocephalic Pain

Migraine headaches and craniocephalic pain were rated using Section 13-11, Criteria for Rating Impairments Related to Craniocephalic Pain (6th ed, 341-342). At MMI, there were no complaints of migraine headaches or craniocephalic pain.

Cranial Nerve Impairments

There is no direct correlation between the cranial nerve impairments section in the fifth and the sixth editions. In the CNS chapter, the sixth edition only addresses cranial nerves 5 and 9 in Section 13-11b, Trigeminal and Glossopharyngeal Neuralgia (6th ed, 343). Regarding the remainder of the cranial nerves, Section 13-12 (6th ed, 343) states, “Most cranial neuropathies (whether central or peripheral) are rated in the ENT or individual disorders chapters.”2 

Section 13-13, Nervous System Impairment Evaluation Summary (6th ed, 344), also states, “Rate neurologic impairments from other chapters: …Cranial neuropathies other than trigeminal/glossopharyngeal neuralgia (Chapter 11); dysarthria and dysphonia (Chapter 11); vestibular disorders (Chapter 11); and visual disorders (Chapter 12)”2 

Visual Impairment

Accordingly, this individual's visual problems will need to be rated using Chapter 12, The Visual System (6th ed, 281-319).

Impairment was assessed using Chapter 12, The Visual System. The examinee is reported to be “nearly totally blind.” Using Table 12-2, Impairment of Visual Acuity (6th ed, 288), and assuming that this correlates with a visual acuity score (VAS) of 5 for both eyes, and applying Table 12-3, Calculation of the Acuity-Related Impairment Rating (6th ed, 289), the functional acuity score (FAS) is 5 and, therefore, the acuity-related impairment rating was 95. Per Figure 12-8, Conversion From VSI to WPI, this converts to 82% WPI (impairment rating of the visual system [VSI] of 90 converts to 78 and 100 converts to 85). Per Table 12-10, Classification of Impairment of the Visual System and of the Whole Person (5th ed, 307), this is class 4, “(Near-) Total Vision Loss.”

Combined Impairment

Combined impairment was performed using the Combined Values Chart (6th ed, 604-606). The whole person components that must be combined were:

1. CNS impairment 10% 
2. Upper extremities impairment 58% 
3. Lower extremities impairment 50% 
4. Neurogenic bladder impairment 18% 
5. Neurogenic bowel impairment 21% 
6. Visual impairment 82% 
1. CNS impairment 10% 
2. Upper extremities impairment 58% 
3. Lower extremities impairment 50% 
4. Neurogenic bladder impairment 18% 
5. Neurogenic bowel impairment 21% 
6. Visual impairment 82% 

The combined impairment for this examinee per the sixth edition of the AMA Guides was 98% WPI.

Conclusion

In summary, the combined impairment rating of 98% WPI is the same using the fifth and the sixth editions of the AMA Guides. Similar approaches were used in this comparison. The clinician performs a detailed evaluation, identifies the ratable conditions, and applies the processes and criteria provided in the AMA Guides to determine the combined impairment.

References

References
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AMA Guides to the Evaluation of Permanent Impairment,
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AMA Guides to the Evaluation of Permanent Impairment,
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Chicago
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3.
Barth
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Rating cognitive impairment, part 1: case example illustrates need for adherence to AMA Guides, Sixth Edition, methodology.
AMA Guides Newsletter.
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