5.9 In assessing disturbances of mental status and integrative functioning; and emotional or behavioural disturbances; disturbances in the level of consciousness and awareness; disturbances of sleep and arousal function; and disorders of communication (AMA5 sections 13.3a, 13.3c, 13.3d, 13.3e and 13.3f; pp 309–311 and 317–327), the assessor should make ratings based on clinical assessment and the results of neuropsychometric testing, where available.
For traumatic brain injury, there should be evidence of a severe impact to the head, or that the injury involved a high-energy impact.
Clinical assessment must include at least one of the following:
- significant medically verified abnormalities in the Glasgow Coma Scale score
- significant medically verified duration of post-traumatic amnesia
- significant intracranial pathology on CT scan or MRI.
Neuropsychological testing should be conducted by a registered clinical neuropsychologist who is a member, or is eligible for membership, of the Australian Psychological Society’s College of Clinical Neuropsychology. Neuropsychological test data is to be considered in the context of the overall clinical history, examination and radiological findings, and not in isolation.
5.10 Assessment of arousal and sleep disorders (AMA5 Section 13.3c, pp 317–319): refers to assessment of primary sleep disorders following neurological injury. The assessor should make ratings of arousal and sleep disorders based on the clinical assessment that would normally have been done for clinically significant disorders of this type (ie sleep studies or similar tests).
5.11 Olfaction and taste: The assessor should use AMA5 Chapter 11, Section 11.4c (p 262) to assess olfaction and taste, for which a maximum of 5% WPI is allowable for total loss of either sense. The effect on activities of daily living should be considered.
5.12 Visual impairment assessment (AMA4 Chapter 8, pp 209–22): An ophthalmologist should assess all impairments of visual acuity, visual fields, extra-ocular movements or diplopia.
5.13 Trigeminal nerve assessment (AMA5, p 331): Sensory impairments of the trigeminal nerve should be assessed with reference to AMA5 Table 13-11 (p 331). The words ‘sensory loss or dysaesthesia’ should be added to the table after the words ‘neuralgic pain’ in each instance. Lesions of the ophthalmic division of the trigeminal nerve with impairment of corneal sensation should be apportioned with extra weighting.
If present, motor loss for the trigeminal nerve should be assessed in terms of its impact on mastication and deglutition (AMA5, p 262).
For bilateral injury to the trigeminal nerves, assess each side separately and combine the assessed WPIs.
5.14 Spinal accessory nerve: AMA5 provides insufficient reference to the spinal accessory nerve (cranial nerve XI). This nerve supplies the trapezius and sternomastoid muscles. For loss of use of the nerve to trapezius, the assessor should refer to AMA5 Chapter 16 on upper limb assessment, and a maximum of 10% impairment of the upper limb may be assigned. For additional loss of use of sternomastoid, a maximum of 3% upper limb impairment may be added.
5.15 Impairment of sexual function caused by severe traumatic brain injury is to be assessed using AMA5 Table 13-21 (p 342). For spinal cord, nerve root or more peripheral nerve injury, sexual impairment should only be assessed where there is appropriate objective evidence of spinal cord, cauda equina or bilateral nerve root dysfunction, or lumbosacral plexopathy.
5.16 Impairment due to miscellaneous peripheral nerves should be evaluated with reference to the following table.
Table 5.1 Criteria for rating miscellaneous peripheral nerves