The American Medical Association 4th Edition (AMA4) provide information about the spine and assessment of spinal injuries. However, only the diagnosis-related estimate (DRE) method modified by the Motor Accident Guidelines issued by SIRA should be used to evaluate spine impairment. 

DREs are distinguished according to verifiable clinical findings using standard medical procedures. The assessment of spinal impairment is performed during the initial examination of the injured person, taking into account any surgical effects or structural inclusions.  

The Guidelines provides the definitions of clinical findings that are utilized to classify an individual into a DRE category. Please see below a summary of the clinical findings definitions.  


To ensure reproducibility, atrophy is evaluated by measuring the circumference of both limbs at identical levels using a tape measure. A difference of at least 2 cm in the thigh and 1 cm in the arm, forearm, or calf is necessary for consistent results. In the report, the medical assessor can consider asymmetry caused by limb dominance. The measurements should be recorded to the nearest 0.5 cm, and the atrophy should be clinically explainable in relation to the affected nerve root. 

Muscle Guarding

Guarding refers to a muscle contraction that reduces movement or discomfort in damaged or diseased tissue. Unlike a true muscle spasm, the contraction can be released. In the case of the lumbar spine, the contraction can lead to a loss of the normal lumbar lordosis and may be accompanied by a demonstrable decrease in spinal mobility. 

Muscle Spasm

A muscle spasm is a sudden, involuntary contraction of a muscle or group of muscles, and is not to be confused with voluntary muscle contraction. Paravertebral muscle spasm is common after acute spinal injury but is rare in chronic back pain. Although occasionally visible as a contracted paraspinal muscle, it is more often diagnosed by palpation, as the affected muscle is hard. To differentiate between true muscle spasm and voluntary muscle contraction, the affected individual should not be able to relax the contractions. Additionally, the spasm should be present both in the standing and supine positions and frequently causes scoliosis. The medical assessor may distinguish spasm from voluntary contraction by asking the individual to shift their weight between their feet while gently palpating the paraspinal muscles. If the assessor observes relaxation of the paraspinal muscles on the weight-bearing side, it generally indicates the absence of true muscle spasm. 

Non-uniform loss of spinal motion (dysmetria)

Muscle spasm or guarding can sometimes cause non-uniform loss of motion in one of the three main planes of the spine. To be considered as true non-uniform loss of motion, this finding must be consistent and reproducible, and the medical assessor must confirm that the individual is fully cooperative and exerting maximum effort. 

When evaluating non-uniform loss of range of motion (dysmetria), medical assessors must assess all three planes of motion for the cervicothoracic spine (flexion/extension, lateral flexion, and rotation), two planes of motion for the thoracolumbar spine (flexion/extension and rotation), and two planes of motion for the lumbosacral spine (flexion/extension and lateral flexion). The range of spinal motion should be recorded as a fraction or percentage of the normal range, such as cervical flexion being 3/4 or 75% of the normal range. 

Non-verifiable radicular complaints

Non-objective radicular complaints refer to symptoms, such as tingling, burning, or shooting pain, that align with the distribution of a particular nerve root. However, there are no objective clinical findings or signs indicating dysfunction of the nerve root, such as loss or reduced sensation, power, or reflexes. 


Reflexes can present as normal, increased, reduced, or absent. To be considered valid, reflex abnormalities should display significant asymmetry between the involved and normal limbs on repeated testing. Certain reflex abnormalities, like Babinski signs or clonus, may indicate involvement of the corticospinal tract. 

Sciatic nerve root tension signs

Sciatic nerve tension signs are used to detect irritation of the lumbosacral nerve roots, which is often observed in individuals with a herniated lumbar disc, but not always. In chronic nerve root compression due to spinal stenosis, tension signs are often absent. The straight leg raising (SLR) test is the most commonly used nerve tension test, where the hip is flexed with the knee extended in the supine position and with the hip flexed 90 degrees, the knee is extended in the sitting position. A positive SLR test is indicated when thigh and/or leg pain along the appropriate dermatomal distribution is reproduced, and the degree of elevation at which pain occurs is recorded. 

According to research, nerve roots experience maximum movement when the leg is at an angle of 20 degrees to 70 degrees relative to the trunk, but this may vary depending on the individual’s anatomy. Additionally, the L4, L5, and S1 nerve roots primarily change their length during the SLR test. Therefore, pathology at higher levels of the lumbar spine may be associated with a negative SLR test. To be considered reliable, root tension signs must cause pain in a dermatomal distribution. However, back pain on SLR is not a positive test and hamstring tightness must be differentiated from posterior thigh pain due to root tension. 

Weakness and loss of sensation

For sensory findings to be considered valid, they must strictly follow anatomical distribution patterns, such as dermatomes. Similarly, motor findings should be consistent with the affected nerve structure(s), and significant and long-term weakness is often accompanied by atrophy. 

The CTP scheme is a complex one and if you have sustained injuries (physical and/or psychological injuries) from a motor vehicle accident, we highly recommend you seek legal advice. The Head of our NSW team, Jessica Cheung is an Accredited Specialist in Personal Injury Law. Depending on your claim, we can review the liability notice on your behalf, request for an extension of time to lodge internal review, obtain medical evidence to support your injuries and position, and then challenge the insurer’s decision on your behalf.  

If you believe you have sustained a personal injury and would like professional legal advice, reach out to Jessica and her team for a confidential discussion at no costs to you.   

*The intention and purpose of this article is to be used as a guide only. 

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