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LUMBAR RADICULOPATHY ASSESSMENTS WITH AMA 4 & 5 : COMPLEX DIFFERENCES BY A CIME.5 October at 20:28 from atlas
Lumbar radiculopathy is defined as lower limb neurological symptoms & signs due to compression/irritation of one ,or more lumbar nerve roots comprising the femoral or sciatic nerves.
The spine physical examination should focus on objective findings such as: ROM with plurimeter,Reflexes,muscle strength,atrophy,sensory deficits,root tension signs,gait and the need for assistive devices.If pain is dis[roportionate for the condition, use the pain chapter for determining whether a qualitative and additional amount(1-3%) should be considered with the DRE or ROm rating.
In AMA 4 'models' were referred to, in AMA 5 'methods' are referred to.The DRE method is the principal method of use-please read my other article on selection :Dre versus ROM.The word 'differentiators' in AMA 4 is replaced by 'objective findings' in AMA 5.
For re-evaluation if ROM was used initially, it must be used again.If the DRE method was used initially, the DRE or ROM method may be subsequently used.
The DRE method is used if the impairment is well characterised and when there is cortico-spinal involvement with depression and multi-level fusion within the same spinal region.Impairments within a DRE category can carry a range ,with adjustments of up to 3% to account for treatment effects and changes in ADL activity capacity.
The ROM Method is used for(i) recurrent conditions, when conditions occur within a single spine region.ROM is also used for(ii) multiple events or pathologies in a single region e.g. L4& L5 radiculopathy; (iii)multiple recurrences or episodes ;(iv) multi-level segment alteration ;(v) multiple fractures; (vi)spinal stenosis with radiculopathy , and (vii) conditions not well represented by the DRE method.
Radiculopathy would quickly place the case within DRE category II 9if resolved0 or III or higher (if still present) when MMI is reached.Sciatic nerve tension signs , such as the SLR manoeuvre (with multiple validation tests to be certain of accuracy), can be used to clinically support a diagnosis of radiculopathy but are not always synonymous.The SLR manoeuvre MUST be performed properly to differentiate between hamstring tightness and sciatic nerve stretch. if feasible , test the patient in both the supine and sitting positions and compare results.Reverse SLR tests femoral nerve tension (L2-4).
Validation testing includes: symptomatic response to supine & sitting should be similar, although the angle at which pain is elicited may vary;ankle plantar flexion and hip external rotation decrease sciatica and gentle ankle dorsiflexion with hip internal rotation increase pain.Check and comment on medical reports, and records , that use SLR signs to ensure they describe description of technique, testing in multiple positions, location of pain and any validation manoeuvres.
The SLR test in disc herniation has acceptable sensitivity (72-97%) but is non-specific (11-45%).SLR of the asymptomatic limb (crossed SLR) that produces sciatica in the index limb increases specificity (85-100%) but is less sensitive (23-42%) in detecting disc herniation.Note that in spinal stenosis , sciatic nerve tension signs are often absent, even when there is nerve root compression clinically or on imaging.
Imaging studies are of greatest value for rating purpose when they are consistent with the clinical symptoms and signs.A herniated disc can be detected on asymptomatic individuals and does not necessarily explain the symptoms.EMG studies that are clearly positive and performed by a well trained and qualified electromyography may qualify the case for DRE CategoryII.
In AMA 4 ,Section 3.3 (pp 94-138) , the injury model assigns cases to one of eight categories on the basis of objective clinical findings.As discussed in AMA 4 (p 100) and in the Guides Newsletter(july/August 1997 and September/October 1997), with the AMA 4 Injury Model, surgery to treat an impairment does not modify the original impairment.The model bases impairment on the result of the injury : minor injury, radiculopathy, loss of motion segment integrity, paraplegia etc, NOT THE TREATMENT ( conservative, surgery without fusion, fusion etc.
In AMA 5 , with the DRE Method, the rating is based on the findings when the case has reached MMI. This accounts for the difference between the % of impairment determined with AMA 4 and AMA 5. This is not well known and is a source of confusion amongst assessors.AMA 5 DRE allows for differential ratings for those with spine surgery, since surgery alters anatomy and produces a functionally different spine.
AMA 4 Summary: Section 3.3 pp 94-138, Table 70: NB. Assesses individual at injury, not with surgery-hence NEED for records ab initio, THAT I REPEATEDLY REQUEST!
AMA 5: Section 15.2 , pp 379-381, Section 15.4 pp 384-388, Box 15-1 p 382 and table 15-3 p 384: assesses case at MMI with effects of surgery , if performed.
AMA 4 is difficult as the assessor MUST 'look back in time' to the effect of the injury (records are needed) whereas AMA 5 looks at the case at MMI and does NOT require elimination of (adverse or beneficial) effects of surgery. I as a Senior CIME PI Assessor believe that AMA 5 is not only easier, but is more meaningful as the injured is assessed at MMI , as he is, syrgery (benefits and complications). AMA 6 is superior again. In Queensland the Q-comp Schedule for Pi is aligned to AMA 4.
ASSISTANT PROFESSOR MICHAEL CORONEOS CIME MASE
SENIOR NEUROSURGEON & PI ASSESSOR
NATIONAL RACS EXAMINER
SENIOR RACS MORTALITY ASSESSOR RACS(QASM)
MEMBER of ACADEMY of SURGICAL EDUCATORS (RACS) :MASE
FAIM CIME MASE FRACS FACS FRCSI FRCS(EDIN)SN MB BS(1ST CLASS HONOURS) MNSA MNSQ MAPS MANZSOM
Please always follow the advice of your treating doctor.