The MAA Permanent Impairment Guidelines
28The MAA Permanent Impairment Guidelines are issued under s 44(1)(d) of the Motor Accidents Compensation Act and are used for the assessment of permanent impairment of a person injured as a result of a motor vehicle accident. They apply in the review of an assessment made by a Review Panel under s 63 of the Act.
29Chapters 1.1 and 1.2 of the MAA Guidelines read:
"1.1 These MAA Guidelines have been developed for the purpose of assessing the degree of permanent impairment arising from the injury caused by a motor accident, in accordance with section 133(2)(a) of the New South Wales Motor Accidents Compensation Act 1999.
1.2 The MAA Guidelines are based on the American Medical Association publication "Guides to the Evaluation of Permanent Impairment", 4th Edition, 3rd Printing (1995) (AMA 4 Guides). However, in these Guidelines there are some very significant departures from that document. Persons undertaking impairment assessments for the purposes of the NSW Motor Accidents Compensation Act 1999 must read these MAA Guidelines in conjunction with the AMA 4 Guides. These MAA Guidelines are definitive with regard to the matters they address. Where they are silent on an issue, the AMA 4 Guides should be followed. In particular, Chapters 1 and 2 of the AMA 4 Guides should be read carefully in conjunction with this Chapter of the MAA Guidelines. Some of the examples in AMA 4 are not valid for the assessment of impairment under the Motor Accidents Compensation Act 1999. It may be helpful for assessors to mark their working copy of the AMA 4 Guides with the changes required by these MAA Guidelines."
30The convention used in the Guidelines is that if the test is in bold type, it is a directive as to how the assessment should be performed (see Chapter 1.3). I shall adopt this convention in my judgment where referring to the Guidelines.
31Not all injuries lead to an assessment of permanent impairment, for example, an uncomplicated healed sternal and rib fracture or an uncomplicated skull fracture do not. It is important to define the term "impairment" and distinguish it from the "disability" that may result. Impairment is defined as an alteration to a person's health status. It is a deviation from normality in a body part or organ system and its functioning. Hence, impairment is a medical issue and is assessed by medical means (Guidelines 1.10 and 1.11).
32In Ackling v QBE Insurance (Australia) Limited [2009] NSWSC 881 at [83] Johnson J had this to say about the role of the Permanent Impairment Guidelines in relation to the Motor Accidents Compensation Act.
"[83] Although the limits of jurisdiction to be exercised by Medical Assessors are to be determined by the construction of the MAC Act itself, the Permanent Impairment Guidelines are not irrelevant to this task. Those Guidelines may be characterised as delegated legislation under s 44(1)(c) MAC Act. As delegated legislation, the Guidelines cannot affect the proper construction of the MAC Act, and they exist to indicate how relevant assessments are generally carried out: Allianz Australia Insurance Ltd v Crazzi (2006) 68 NSWLR 266 at 274 [17]; Paice v Hill [2009] NSWCA 156 at [2]-[3], [59]-[60]. With these qualifications in mind, I observe, nevertheless, that cl 1.4-1.6 of the Permanent Impairment Guidelines fortify the conclusion that the determination as to whether an injury is caused by the relevant motor accident lies within the medical assessment jurisdiction provided for in Pt 3.4 MAC Act."
33Chapter 5 sets out the approach to the assessment of permanent neurological impairment. In the introduction, Guideline 5.1 states that Chapter 4 in the AMA 4 Guides (pp 139-152) provides guidelines on methods of assessing permanent impairment involving the central nervous system. Elements of the assessment of permanent impairment involving the peripheral nervous system can be found in relevant parts of the Upper Extremity, Lower Extremity and Spine sections.
34I briefly digress to include the relevant part of Chapter 4 of the AMA Guidelines (referred to above). It is similar to Chapter 5 of the Permanent Impairment Guidelines:
"The forebrain or cerebrum is that portion of the nervous system located within the skull and above the tentorium of the posterior fossa of the skull. The most complex cerebral processes and integrative functions are only partially understood.
The more common categories of impairment resulting from disorders of the forebrain are as follows: (1) disturbances of consciousness and awareness; (2) aphasia or communication disturbances; (3) mental status and integrative functioning abnormalities; (4) emotional or behavioural disturbances; (5) special types of preoccupation or obsession; (6) major motor or sensory abnormalities; (7) movement disorders; (8) episodic neurological disorders; and (9) sleep and arousal disorders. Sleep and arousal disorders are considered in the Guides' chapter on the respiratory system (p 153).
A patient may have more than one of the types of cerebral dysfunction listed above. The most severe of the first five categories shown above should be used to represent the cerebral impairment. Any impairments in the last four categories may be combined with the most severe of the first five by means of the Combined Values Chart (p 322); the result would represent the estimate of total cerebral impairment."
35Some of AMA 4 Guides (above) are picked up in Guideline 5.5 of the Permanent Impairment Guidelines for the central nervous system. Under the heading "The approach to assessment of permanent neurological impairment", Guideline 5.5 reads:
"5.5 The introduction to Chapter 4 (the Nervous System) of the AMA 4 Guides is ambiguous in its statement about combining nervous system impairments. The most severe impairment in the categories of (1) disturbances of consciousness and awareness (permanent and episodic), (2) aphasia or communication disorders, (3) mental status and integrative functioning abnormalities, or (4) emotional and behavioural disturbances only should be assessed. Select the highest rating from categories 1 to 4. This rating can then be combined with ratings from other body regions."
36The relevant Guidelines for the central nervous system - cerebrum or forebrain are as follows.
"The central nervous system - cerebrum or forebrain
5.9 For an assessment of Mental Status Impairments and Emotional and Behavioural Impairments there should be:
(i) evidence of a significant impact to the head, or a cerebral insult, or that the motor accident involved a high velocity vehicle impact; and
(ii) one or more significant medically verified abnormalities such as an abnormal initial post-injury Glasgow Coma Scale score, or Post Traumatic Amnesia, or brain imaging abnormality.
5.10 The results of psychometric testing, if available, should be taken into consideration.
5.11 Assessment of disturbances of Mental Status and Integrative Functioning
The assessor should use Table 5.1 of these MAA Guidelines, the Clinical Dementia Rating (CDR) which combines cognitive skills and function.
5.12 When using the CDR the individual's cognitive function for each category should be scored 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 the 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 and two secondary categories are scored In this case CDR = M. Similarly if two secondary categories are greater than M, two are less than M and one is the same as M, CDR=M.
5.13 Corresponding impairment ratings for CDR scores are listed in Table 5.2 below.
5.14 Assessment of Emotional or Behavioural Disturbances is done using Table 3 of the AMA 4 Guides (p 142)."
37The two specific Guidelines that apply and that are in dispute are Guidelines 5.9 and 5.10.