Using the 5th Edition of the AMA Guides to the Evaluation of Permanent Impairment for Evaluating Permanent Impairment of the Lumbar Spine
   
General
  Revisions in evaluation Permanent Impairment of the spine for the American Medical Association Guides to the Evaluation of Permanent Impairment, 5th edition include:
  1. Modifications in the use of the Diagnosis-related Estimate method and the Range of Motion method
  2. Impairment is rated only when the individual has reached maximum medical improvement.
  3. Impairments within a Diagnosis-related Estimate category encompass a range and can be adjusted within a 3% range
  4. Spinal cord injury is evaluated according to the functional approach in the nervous system chapter
  5. The "differentiators" in the 4th edition have been replaced by "objective findings" and are more specifically defined
  6. Alterations of motion segment integrity have been redefined.
As in the 4th edition, the Diagnosis-related Estimate method is the primary method used to evaluate individuals with an injury
The Range of Motion method is used when the impairment is not caused by an injury or when an individual’s condition is not well represented by a Diagnosis-related Estimate category.
The range of motion method is now used to evaluate individuals with an injury at more than one level in the same spinal region and in certain individuals with recurrent pathology.
However, individuals with involvement of the cortico-spinal tracts, who have been treated with decompression and multilevel fusions within the same region, should be rated by the Diagnosis-related Estimates method.
Occasionally the range of motion method is statutorily mandated.
  
Note: an examinee is rated only when their spinal condition is stable (unlikely to change within the next year regardless of treatment, (at maximum medical improvement)), and is based on medical findings that are present when maximum medical improvement has been reached.
  
Principles
As with previous editions of the Guides, the evaluation should include a comprehensive, accurate medical history, a review of all pertinent records, a comprehensive description of the individual’s current symptoms, and their relationship to daily activities, a careful and thorough physical examination, and all findings of relevant laboratory, radiologic, electrodiagnostic, and ancillary tests.
  
History
As with previous editions, the history should be based primarily on the individual’s own statements.
Also as with previous editions, it is not appropriate to question the individual’s integrity.
If the information from the individual is inconsistent with what is known about the medical condition, circumstances, or written records, the inconsistencies should be documented.
  
Examination
The examination should include a targeted neurologic assessment, the examiner needs to have knowledge of the basic neurological exam
Spine related physical findings, including range of motion, reflexes, muscle strength and atrophy, sensory deficits, root tension signs, gait, need for assistive devices all need to be assessed.
Exam must be placed in the context of the examinee’s general health and condition.
Associated system exam (vascular, neurologic) helps sort out other causes of certain symptoms (I.e. vascular claudication masquerading as sciatica).
The examiner should record and discuss any physical findings that are inconsistent with the history.
   
Nerve Tension Signs
While sciatic nerve tension signs are important indicators of irritation of the lumbo sacral spine nerve roots acutely, and most commonly seen in examinees with a herniated disc, chronic nerve root compression often does not show nerve root tension signs, such as with spinal stenosis.
Straight leg raising is most significant when it follows dermatomal distributions.
Crossed straight leg raising is more specific than straight leg raising but is less sensitive. Straight leg raising is sensitive but non specific.
Dorsiflexion of the ankle and internal rotation of the hip can aggravate straight leg raising.
Sitting straight leg raising can verify or undermine recumbent straight leg raising findings.
Femoral stretch is the reverse of straight leg raising and tests for nerve root involvement at higher levels. It has a low sensitivity and specificity.
   
Neurologic Tests
Measurement of knee and ankle reflexes, assessment of motor function and sensory function
L4 involvement can weaken the knee reflex. may be accompanied by sensory changes at the lateral knee, lateral thigh and medial calf and foot with quad weakness, and is usually compressed by the L3-4 disc.
L5 root involvement can produce changes at the medial hamstring reflex, weakness of the extensor hallucis longus, as well as other foot and ankle muscles, difficulty walking on the heel, sensory changes at the lateral thigh, calf and sole of the foot..
S1 involvement can knock out the ankle reflex, cause weakness of plantar flexion at the ankle, and numbness at the lateral ankle and foot.
The Babinski sign and the presence of clonus and hyperreflexia are signs of cortico spinal tract involvement.
Changes in balance and gait pattern may also signify myelopathy.
   
Clinical Studies
It is important to realize that because of a 30% false positive rate, images alone cannot make the diagnosis.
Clinical signs and symptoms must correlate with imaging studies.
EMG and NCS do diagnose radiculopathy.
Motion segment integrity is assessed by flexion and extension x-rays and is defined as anterior posterior motion of one vertebrae over another that is greater than 4.5 mm in the lumbo sacral spine. It is also defined as a difference in the angular motion of two adjacent motion segments greater than 15 degrees at L1-2, L2-3 and L3-4, and greater than 20 degrees at L4-5, and greater than 25 degrees at L5-S1.
   
Determining the Appropriate Method for Assessment
Lumbo sacral spine impairment rating is performed using either the Diagnosis-related Estimates method or the range of motion method.
The Diagnosis-related Estimates method is the principle method in an examinee with a distinct injury.
When the cause of the impairment is not easily determined, and if the impairment can be well characterized by the Diagnosis-related Estimates method, the range of motion method should be used.
The range of motion method may be used when:
  1. An impairment is not caused by an injury
  2. If the cause of the condition is uncertain and the Diagnosis-related Estimates method does not apply
  3. If an individual cannot be easily categorized in a Diagnosis-related Estimates class.
  4. There is multilevel involvement in the same spinal region
  5. There is alteration of motion segment integrity at multiple levels in the same spinal region (if there is cortico spinal tract involvement use the Diagnosis-related Estimates method for cortico spinal tract involvement)
  6. There is recurrent radiculopathy caused by a new (recurrent) disk herniation or injury in the same spinal region
  7. There are multiple episodes of other pathology producing alteration of motion segment integrity and or radiculopathy.
"in the small number of instances in which the range of motion and the Diagnosis-related Estimate method can both be used, evaluate the examinee with both methods, and award the higher rating"!
Permanent impairment to the lumbo sacral spine itself can be derived from the whole body percent impairment referable to the lumbo sacral spine by multiplying the whole body percent impairment by 133% the case of the Diagnosis-related Estimates method and 111% in the case of the range of motion method.
   
Specific Procedures and Directions
  1. Take a careful history, perform a thorough medical examination, review all pertinent records and studies
  2. Consider permanency of the impairment
  3. Select the region involved and identify the most serious objective findings
  4. Determine if there is multilevel involvement or multiple recurrences/occasions?? Use the range of motion model if
  • There are fractures at more than one level in a spinal region
  • There is radiculopathy bilaterally or at multiple levels at the same spinal region
  • There is multilevel motion segment alteration in the same spinal region
  • There is recurrent disc herniation or stenosis with radiculopathy at the same or different level in the same spinal region. In this case combine the ratings using the range of motion method
  1. If the individual does not have multilevel involvement or multiple recurrences/occasions and an injury occurred, determine the proper Diagnosis-related Estimates method category.
  2. If the examinee has been treated with surgery or another modality, evaluate the results, extent of improvement and impact on the ability to perform activities of daily living. If residual symptoms or objective findings impact the ability to perform activities of daily living despite treatment, the higher percentage in each range should be assigned.
  3. If more than one spine region is impaired, determine the impairment of the other region using the Diagnosis-related Estimates method and combine them using the combined values chart
  4. Determine if there was a pre existing impairment
  5. Apportion impairment if requested. Use the same methodology if possible
  6. For examinees with cortico spinal tract involvement refer to table 15-6 for appropriate impairment rating.
   
The Diagnosis-related Estimate method
The examiner can use one of two methods to determine into which of the 5 Diagnosis-related Estimate categories an examinee fits.
The first is based on symptoms, signs, and tests
The second is based on the presence of fractures and or dislocations with or without clinical symptoms.
The symptoms, signs and tests used to categorize an examinee include
  1. Muscle spasm
  2. Muscle guarding
  3. Asymmetry of spinal motion
  4. Non-verifiable radicular root pain
  5. Reflex alteration
  6. Weakness and Loss of Sensation
  7. Atrophy
  8. Radiculopathy
  9. Electrodiagnostic verification of radiculopathy
  10. Alteration of Motion Segment integrity
  11. Cauda Equina syndrome
  12. Urodynamic tests
Remember: permanent impairment is based on the condition once the maximum medical improvement is reached, not on prior symptoms or signs
The Diagnosis-related Estimates method recommends that the examiner document physiologic and structural impairments relating to injuries or diseases other than common developmental findings such as spondylolysis, spondylolisthesis, herniated disc without radiculopathy, and aging changes
   
Diagnosis-related Estimates Categories
I—0%
No significant clinical findings, no observed muscle guarding or spasm, no documented neurologic impairment, no documented alteration in structural integrity, and no other indication of impairment related to injury or illness, no fractures.
II—5-8%
Clinical history and examination findings are compatible with a specific injury, findings may include significant muscle guarding or spasm observed at the time of the examination, asymmetric loss of range of motion, non verifiable radicular complaints, radicular pain without objective finings, no alteration of the structural integrity and no significant radiculopathy
Or
Examinee had a clinically significant radiculopathy and has an imaging study that demonstrates a herniated disc at the level and side that would be expected, but no longer has the radiculopathy following conservative treatment,
Or
Fractures one less than 25% compression fracture of one vertebral body, or posterior element fracture without dislocation that has healed without alteration of motion segment integrity or a spinous or transverse process fracture with displacement without a vertebral body fracture which does not disrupt the spinal canal
III-10-13%
Significant signs of radiculopathy such as dermatomal pain, and or in a dermatomal distribution, sensory loss, loss of relevant reflexes, loss of muscle strength or measured unilateral atrophy above or below the knee compared to the contralateral side at the same location
Or
History of herniated disc at the level and on the side expected by objective clinical findings, associated with radiculopathy, or individuals who had surgery for radiculopathy but are now asymptomatic
Or
Fractures 25-50% compression of one vertebral body, posterior element fracture with displacement disrupting the spinal canal, with fracture healing without alteration of structural integrity
IV—20-23%
Loss of motion segment integrity, or complete loss of motion of a motion segment due to developmental fusion, or surgical arthrodesis (successful or unsuccessful)
Or
Fractures greater than 50% compression of one vertebral body without residual neurologic compromise
V—25-28%
Meets criteria for category III and IV with radiculopathy and alteration of motion segment integrity, with significant lower extremity impairment such as atrophy, or loss of reflexes, pain, and or sensory changes within an anatomic distribution or EMG and NCS findings
Or
Fractures greater than 50% with unilateral neurologic compromise
   
Rating Corticospinal Tract Damage
In the previous edition of the Guides, spinal cord involvement was rated under the Diagnosis-related Estimates categories V, VI, and VII, or using the nervous system chapter.
Those higher Diagnosis-related Estimates method categories no longer exist, and spinal cord impairment is now rated separately, using Table 15-6, on pg. 396 of the American Medical Association Guides to the Evaluation of Permanent Impairment, 5th edition.
Table 15-6 uses a combination of Criteria and classes to rate impairment due to cortico spinal tract involvement.
The criteria include impairment of one upper extremity, impairment of both upper extremities, impairment due to Station and Gait disorders, neurologic impairment of the bladder, neurologic anorectal impairment, neurologic sexual impairment, and neurologic impairment of respiration.
Within each category, the severity of impairment is rated by class.
The neurologic level of involvement is determined by the level of cord involvement, not necessarily the same level as any fracture.
The level of cord involvement is determined by identifying the lowest normally functioning nerve root.
In the 5th edition, it was decided to evaluate spinal cord injuries based on the criteria in the nervous system chapter (13) which are repeated in Chapter 15.
For bilateral neurologic or corticospinal tract damage, neurologic consultation and review of Chapter 13 of the American Medical Association Guides to the Evaluation of Permanent Impairment, 5th edition is recommended.
Impairments of bowel, bladder and sexual function are combined with any impairment of the upper or lower extremities.
Once cortico spinal tract impairment is determined, the total spinal impairment is derived by combining the value with the corresponding additional impairment from Diagnosis-related Estimates method category II, III, IV, or V, as appropriate.
The exact impairment value is based on the degree of impairment of ADL.
   
Range of motion method
The range of motion method is still around.
In addition to assessing and utilizing the range of motion of the lumbo sacral spine, the range of motion method also takes into consideration diagnosis, and spinal nerve deficit.
There must be a medically documented injury or illness, with a permanent anatomic and or physiologic residual dysfunction.
The whole person permanent impairment is obtained by combining ratings from all 3 components, using the combined values chart.
   
The range of motion method should be used only if the Diagnosis-related Estimates method is not applicable (no verifiable Injury), after the physician cannot place the individual within a multi level Diagnosis-related Estimates category, if multilevel involvement and or alteration of motion segment integrity have occurred in the same spinal region, if there is recurrent radiculopathy caused by a new (recurrent) disc herniation or a recurrent injury in the same spinal region, if there are multiple episodes of other pathology producing alteration of motion segment integrity and or radiculopathy, or if statutorily mandated.
   
The evaluation should be performed after the condition has stabilized, and after the completion of all necessary medical, surgical and rehabilitative treatment.
Acute injuries cannot be rated.
The rating should be done when the examinee is at maximum medical improvement.
Reproducibility of range of motion measurements is essential. A warm up period is now recommended.
Inclinometers are most helpful.
Ankylosis is rare and is added to impairments due to range of motion impairments if there are a combination of ankylosis and range of motion impairments using the combined values table.
The steps used in determining impairment using the range of motion method in the 5th edition are essentially the same as those in the 4th edition.
Range of motion and any associated impairment due to motion is assessed using tables 15-8, and 15-9..
Nerve root and spinal cord involvement is assessed using tables 15-15, 15-16, 15-18 and 17-37.
Impairment due to specific spine disorders is determined using Table 15-7.
The combined values chart is used to combine impairment due to range of motion, nerve root and spinal cord involvement, and specific spine disorders.
   
Impairment due to the pelvis is assessed using table 15-19, and can be combined with impairment rating from either the Diagnosis-related Estimates method or the range of motion method for spine impairment.
  
This discussion is based entirely on the American Medical Association Guides to the Evaluation of Permanent Impairment, 5th edition
   

Robert N. Phelps, Jr. MD

Fellow, American Academy of Orthopedic Surgery

Diplomate, American Board of Orthopedic Surgery

1-888-373-6388