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Complex Regional Pain Syndrome as a Central Nervous System Disorder

November 28, 2014 (9 min read)

A case study from California

A case handled by this author involved the diagnosis of Complex Regional Pain Syndrome (CRPS) from a lower extremity industrial injury. The WCAB upheld a trial judge’s decision that a WPI rating can exceed the maximum value of an amputation and the medical reporting that formed the basis of the WCJ’s decision is a model of a medical doctor writing a report that constitutes substantial medical evidence. The facts of the case are as follows:

A 49-year-old retail clothing store manager sustained admitted injuries to her right foot, right toes, right hip (trochanteric bursitis), right lower extremity (iliotibial band tendonitis), hypertension and CRPS when a display case fell on her foot and she had unsuccessful foot surgeries. The parties agreed to two AME physicians, internal medicine and orthopedic surgery. Defendant did not dispute the AME in internal medicine diagnosis or WPI for hypertension:

> No prior history of HTN

> No family history of HTN

> No known risk factors that became causative during the period of onset, e.g., no smoking history, no obesity (her BMI was 25)

> Onset of HTN was well documented by PTP pain medicine physician and correlated with her post injury orthopedic conditions

> AME concluded Class 1 Table 4-2, 9% WPI with no apportionment

Combining the hypertension and the orthopedic ratings, defendant claimed the case rated 66% PD while applicant claimed the case rated 72% PD. The WCJ adopted the orthopedic and internal medicine AME conclusions and found that the applicant had a 72% PD.

Defendant appealed and contended that all of the applicant’s right lower extremity conditions when combined using the Combined Values Chart exceeded the WPI value of an amputated leg (40% WPI) in violation of the instructions in the AMA Guides and on page 1-11 of the 2005 Permanent Disability Rating Schedule.

Page 1-11 of the 2005 PDRS limits the permanent disability rating (after adjustment of the WPI ratings for DFEC, age, occupation) to the value of an amputated limb:

The composite rating for an extremity (after adjustment) may not exceed the amputation value of the extremity adjusted for earning capacity, occupation and age…

In his response to the appeal, the WCJ relied entirely on the orthopedic AME’s discussion of how he arrived at the ratings for each lower extremity rating and the CRPS. The orthopedic AME assigned a 39% WPI for the CRPS (right leg), 7% for the iliotibial band tendonitis (right lower extremity), 3% WPI for the trochanteric bursitis (right hip), which after adjustment is 45% WPI (40% for a leg amputation).

After assessing all objective findings on exam, the AME stated:

The patient’s right foot remained with a constant deformity of inversion. Upon standing, she continued to remain in an external rotation deformity of the right leg and knee. Her gait was affected. She was unable to perform full weight bearing and continued to ambulate with antalgia. She has lost the normal rhythm and cadence of her gait as previously documented and again has progressed. The exam was characterized by findings consistent with CRPS including allodynia and hyperpathia as well as loss of active motion in the toes on manual muscle and ROM testing. Diagnosis: S/P crush injury right foot, varus deformity, secondary right hemipelvis, thigh and leg pain consistent with RSD; S/P (status post) right forefoot reconstructive surgery with post-operative complications including infection requiring multiple I&D; history of postoperative forefoot infection and cellulitis.

The abnormal positioning of the leg secondary to her right foot deformity was as a result of fatigue and overuse of the right lower extremity from the pelvis to the foot culminating in the disorder characterized by pain involving the entire foot, hindfoot, right leg, knee and thigh, trochanteric region consistent with trochanteric bursitis and iliotibial band tendonitis. There was evidence of peroneal nerve injury as well as diffuse tenderness of the ankle joint in the dorsum of the mid foot and plantar aspect of the right foot.

Counsel should note the detailed description of the applicant’s anatomic loss and objective medical findings. You should always start with the operative medical reports to determine whether a physician has properly and completely assessed all objective findings in a given case since those objective findings form the basis of many WPI ratings directly or indirectly. In addition to reviewing all operative reports, counsel should also focus on all physical examination sections in evaluating and treating physician reports because, again, those findings often form the basis of an impairment rating and are sometimes overlooked by the physician who writes an MMI report.

In this case, the AME thoroughly listed all objective medical findings based on the history of multiple surgeries and based on his own physical findings on examination of the applicant.

The AME assigned a 45% WPI impairment after using the CVC:

> 3% WPI Table 17-33 for trochanteric bursitis (a strict rating)

> 7% WPI Table 17-33 for iliotibial band tendonitis (The AME cited Guzman III: “There is no actual classification system for iliotibial band tendonitis included in the AMA Guides. Considering that the injury is similar to a cruciate or collateral ligament laxity, given that the iliotibial band is ligamentous in nature as are cruciate and collateral ligaments.”)

> The AME assigned a 45% WPI impairment after using the Combined Values Chart

> 39% WPI for the CRPS using Table 13-15. (The AME stated: “The pathology of CRPS occurs in the central nervous system. Therefore, as recommended by the Guides, the evaluation should utilize the station and gait impairment criteria from Table 13-15 in order to rate lower extremity impairments due to lesions in the central nervous system ‘such as brain and/or spinal cord.’”)

> No apportionment to non-industrial factors.

In this case, the AME properly and completely applied the AMA Guides 5th Edition to the objective medical findings and based on his own physical examination of the patient. Notice how he took two unlisted medical conditions (iliotibial band tendonitis and trochanteric bursitis) and found analogous WPI ratings for each within the four corners of the AMA Guides. This case demonstrates the depth of knowledge the AME has of both the AMA Guides and the requirements for a thorough compliant medical report as set forth in Section 2.6 of the Guides and 8 Cal. Code Reg. § 10606.

The WCAB upheld the WCJ’s decision based on the substantial evidence consisting of the AME reports [see Porter v. Coldwater Creek, 2014 Cal. Wrk. Comp. P.D. LEXIS 178 (Appeals Board noteworthy panel decision)].

The AME referred to and quoted AMA Guides Sec. 17.2m, page 553:

[CRPS] makes an impairment evaluation based on the traditional physical examination impossible…no single peripheral nerve has been injured, and the pain involves the entire limb. Thus, trying to rate this as a peripheral nerve injury is inappropriate. No specific method described in the lower extremity or upper extremity chapters adequately covers this unique circumstance.

The AME also referred to and quoted another section of the AMA Guides Sec. 17.2m, page 553:

The pathology in CRPS is currently believed to occur in the central nervous system so the evaluator should use the station and gait impairment criteria in Table 13-15 to rate lower extremity impairments due to lesions in the central nervous system.

Notice here how the AME quoted actual sections of the text in the AMA Guides supporting his position that CRPS is primarily a central nervous system disorder and is not simply a lower or upper extremity condition even though the triggering event that led to the diagnosis of CRPS was, in this case, a lower extremity injury. Again, we encounter the issue of the difference between causation of the injury and causation of impairment. Here, causation of the injury was a heavy display case falling on the applicant’s foot, and causation of the impairment is the CRPS and associated lower extremity impairments that relate back to the original injury and unsuccessful treatment.

In the AMA Guides, Table 13-15 Station and Gait, provides for WPI ratings up to 60%, which is greater than the value of an amputated leg (which is 40% WPI). Since the WPI value of an amputated leg is 40% WPI, it is clear that the AMA Guides recognizes CRPS as a central nervous system disorder that can result in an impairment greater than the loss of a lower extremity. Do not be confused by the different nomenclature in the AMA Guides for causalgia, RSD, CRPS. The AMA Guides 5th Edition was published in 2000 and some of the terminology is obsolete.

The International Association of the Study of Pain changed the names and diagnostic criteria for CRPS in 2006. The DCA in Almaraz-Guzman III allows you to use current diagnostic criteria and then apply the AMA Guides 5th Ed. for WPI ratings [see Milpitas Unified School Dist. v. Workers’ Comp. Appeals Bd. (Guzman) (2010) 187 Cal. App. 4th 808, 115 Cal. Rptr. 3d 112, 75 Cal. Comp. Cases 837].

As explained in the WCJ’s Report and Recommendation on Reconsideration [see Porter v. Coldwater Creek, 2014 Cal. Wrk. Comp. P.D. LEXIS 178 (Appeals Board noteworthy panel decision)]:

…It is the court’s opinion that the instructions on page 1-11 [of the 2005 PDRS] regarding the composite rating for an extremity not exceeding the amputation value of that extremity are meant to apply to impairments within the extremity category; that is, several combined impairments within the [lower extremity] category should not exceed the amputation value of the lower extremity. As a central nervous system disorder which is recognized as a different body system by the AMA Guides that could also result in greater impairment than the loss of an extremity, a rating for CRPS should not be included in the composite rating for an extremity….

The WCJ, in footnote 3 of his Report, stated [see Porter v. Coldwater Creek, 2014 Cal. Wrk. Comp. P.D. LEXIS 178 (Appeals Board noteworthy panel decision)]:

An impairment in a peripheral nerve of the lower extremity would be a lower extremity impairment and could be rated using the appropriate sections of Chapter 17 (lower extremities). However, as a central nervous system impairment, CRPS is rated using a completely different chapter and methodology.

The WCJ continued:

Therefore, the court believes it was correct to first combine the lower extremity ratings for the iliotibial band tendinitis and trochanteric bursitis pursuant to the instructions on page 1-11 of the Schedule, and then combine the ratings for the CRPS, hypertension and lower extremity per the CVC to arrive at the final rating of 72% permanent disability.

Regardless of the technical requirements of the 2005 PDRS, the AME in orthopedic surgery rebutted the PDRS by explaining how and why page 1-11 does not apply in this case.

COMMENTARY: The case illustrates the thorough analysis conducted by the AME of the medical and medical-legal issues in this case. In addition, an outside disability evaluator had been hired by the defendant to rate the AME reports and in doing so, erroneously reported that the AME rating of the injury exceeded the amputation value of the lower extremity in violation of the 2005 PDRS. This misinformation given to the defendants by an outside disability rater turned out to force this case to trial and reconsideration. A word of caution to the defense community—check your outside rating specialist’s work or don’t use them at all and obtain a consultative rating from the DEU instead.

© Copyright 2014 LexisNexis. All rights reserved. This article was excerpted from The Lawyer’s Guide to the AMA Guides and California Workers’ Compensation, 2015 Edition (to be published late December 2014).