DALE LARSON, Employee/Appellant, v. STATE OF MINN., DEP’T OF MNSCU, RIDGEWATER COLLEGE-WILLMAR and SELF-INSURED/DEP’T OF RISK MGMT., Employer/Respondent.

The employee appeals the compensation judge’s denial of his claim for permanent partial disability benefits for his admitted low back injury.  We affirm.

The employee, Dale Larson, began working as a janitor and truck driver for the self-insured employer, Ridgewater College, in the summer of 2015.  On January 13, 2017, he sustained an admitted low back injury during a motor vehicle accident that occurred in the course and scope of his work activities.  He did not notice symptoms at that time, but within a few days he developed low back symptoms along with cramping in his right leg down to his right knee.

The employee sought treatment from his family practitioner on January 19, 2017, when he reported significant back pain.  An x-ray failed to show acute trauma but indicated mild multilevel degenerative disc disease and mild disc space narrowing throughout the lumbar spine.  The employee was prescribed medications and initially placed on light-duty work restrictions.  He subsequently reported his back pain was improving and was released to work without restrictions by his family practitioner on February 2, 2017.  He was later placed back on work restrictions but has been able to continue working in his pre-injury job within those restrictions.

The employee was seen at the Rice Memorial Hospital emergency room on March 14, 2017, for right-sided low back pain.  On examination, he was normal neurologically.  He was provided with pain medications.  On March 20, 2017, the employee saw Dr. Timothy Mulder at the Family Practice Medical Center for his right-sided low back pain and was noted to show tenderness in the right low back.  Dr. Mulder recommended an MRI of the employee’s lumbar spine.

The MRI was performed on March 21, 2017, and showed disc bulges at several levels.  At L1-2, a small protrusion abutted the exiting left L1 nerve root, but without distortion.  At L3-4, there was minimal annular bulging at both foraminal locations.  The right foraminal protrusion abutted the exiting right L3 nerve root but did not distort it.  At L4-5, a broad-based right paracentral and right foraminal disc protrusion abutted and slightly distorted the exiting right L4 and L5 nerve roots.  The interpreting radiologist noted that some of these bulges could potentially result in right L3, L4, or L5 radiculopathy, but that such a determination required clinical correlation.

The employee underwent an epidural injection at L4-5 on the right on March 27, 2017.  He reported a dramatic improvement to his symptoms over the next several medical visits and on November 15, 2017, one of his physicians filled out a Health Care Provider Report indicating that the employee had reached maximum medical improvement (MMI) without permanent partial disability (PPD) and that no further treatment was planned.

When the employee saw Dr. Mulder on December 5, 2017, he reported a gradual return of discomfort in his right thigh along with intermittent muscle spasms.  On February 12, 2018, another MRI scan of the lumbar spine was performed, which showed a small right-sided disc herniation at L4-5 with impingement on the right L5 nerve root.  No significant abnormalities were reported at any other lumbar level.

The employee was seen at Summit Orthopaedics for low back and right leg pain on March 29, 2018.  He showed limited motion in the low back and decreased sensation in the right thigh.  Straight leg raising was negative.  Physical therapy, facet injections and an EMG of the right leg were recommended.  The employee underwent facet injections at L4-5 and L5-S1 on April 24, 2018.  The employee later reported that he had obtained just a few days’ relief of pain from these injections.

On April 25, 2018, the employee underwent an EMG of the right leg.  The EMG was read as normal, showing no evidence for a right L5 radiculopathy or other electrodiagnostic evidence for nerve conditions involving the right lower extremity.  The employee was treated with medial branch blocks from L3 to L5 bilaterally on June 21, 2018, and again five days later.  On July 19, 2018, the employee returned to Dr. Mulder, who noted that the employee had received multiple facet and epidural steroid injections without significant change to his pain.  Dr. Mulder stated that the employee did not display radiculopathy, which was confirmed by the EMG.

On November 1, 2018, the employee saw Dr. Timothy Lindley for a neurosurgical consultation.  Dr. Lindley reviewed the employee’s MRI and concluded that it did not show clear nerve root compression.  Dr. Lindley advised the employee that a residual nerve injury was likely the cause of his ongoing numbness.  He felt that the employee’s back pain was likely be due to a muscle-ligament injury along with degenerative disc disease and that surgery likely would not improve his symptoms.  He suggested lumbar radiofrequency ablation as a treatment option, along with non-operative management including additional physical therapy and injections.

On May 30, 2019, the employee was examined by Dr. Robert Wengler at the suggestion of his attorney.  The employee’s concern on that date was back pain with pain into his right groin and the medial aspect of his right thigh.  On examination, straight leg raising produced low back pain but no radicular symptoms.  Dr. Wengler noted that the employee “has documented disc herniations at L3-4 and L4-5 on the right.”  He opined that the employee’s right groin pain indicated a significant pathology at L4-5, and that the pain into his right thigh indicated pathology at L4-5.  Accordingly, Dr. Wengler considered the employee to be a candidate for surgical decompression at L3-4 and L4-5.  He rated the employee with 21 percent PPD pursuant to Minn. R. 5223.0390, subps. 4D, 4D(1) and 4D(4).

The employee was seen by Dr. Anthony Gabriel Bottini at the Fairview Southdale Neurosurgery Center on October 7, 2019.  At that time, the employee reported that he had low back pain and pain going into his right leg since the accident on January 13, 2017, despite five epidural injections and a variety of other treatments.  The employee’s predominant symptom at this appointment was muscle spasm into the anterior right thigh with intermittent pain and a burning sensation into the medial aspect of his leg.  On examination, he was found to be neurologically intact.  Dr. Bottini noted that the February 2018 MRI had shown degenerative changes largely isolated to the L4-5 level with a small focal disc protrusion producing lateral stenosis on the right and apparently slightly impinging the right L5 nerve root.  Dr. Bottini stated that he was not certain that the pattern of the employee’s symptoms related to the findings at the L4-5 level from two years earlier and suggested a repeat MRI to determine whether there had been any significant interval changes.

The repeat MRI was performed on October 14, 2019, and showed multilevel small disc bulges with no impingement of the descending nerves.  There was no compression fracture, spondylolisthesis, or significant facet arthropathy.  At L4-5, there was still a circumferential disc bulge with a right foraminal annular tear and mild narrowing of the right neural foramen, but no ganglion impingement.  The left foramen was patent and the spinal canal was capacious throughout the lumbar levels.  There was no acute or subacute vertebral compression fracture and no spondylolisthesis.

The employee returned to Dr. Bottini on October 21, 2019, following the MRI scan.  Dr. Bottini noted that the new study showed improvement in the disc bulge previously seen at the right L4-5 level, in that there was now no evidence of a focal disc protrusion.  He told the employee that he believed the radiographic findings did not constitute a likely cause for the nature, distribution or severity of his symptoms and that surgical intervention was unlikely to be effective. Dr. Bottini suggested that the employee undergo medial branch blocks at L4-5 to determine whether the pain in his right lumbar region was facet mediated, in which case facet rhizotomies could be considered.  In the alternative, the doctor suggested right L4-5 foraminal steroid injections for both diagnostic and therapeutic purposes.  The employee elected to undergo the injections.

The employee was evaluated on behalf of the employer by Dr. Paul Wicklund on February 9, 2021.  Dr. Wicklund diagnosed multilevel degenerative disc disease along with a small right-sided disc herniation that was currently neurologically silent.  He opined that MMI had been reached from the employee’s work injury following a radiofrequency procedure on December 20, 2019, which provided only a month of relief.  He rated the employee with a zero percent permanency under Minn. R. 5223.0390, subp. 3A.  He disagreed with Dr. Wengler’s rating on the basis that such a rating required a disc herniation accompanied by “persistent” objective clinical findings, which he did not consider present in the employee’s case.  For that reason, he similarly did not consider the employee to be a surgical candidate.

In an addendum to his report on June 3, 2021, Dr. Wengler acknowledged that the 2019 MRI had shown a capacious spinal canal and that the only suspicious area on that MRI was mild narrowing of the right neuroforamen at L4, which did not appear to impinge on the nerves.  He stated that the employee’s herniated discs had apparently become desiccated and had shrunk, which would be the desired outcome in conservative management.  However, he continued to rate the employee’s PPD at 21 percent because of the prior MRI evidence of herniation with possible impingement at two levels, despite the improvement of those conditions.  He believed that his rating remained appropriate because, in his view, the employee’s ongoing symptoms were best explained by instability of the motion segments at those levels.  He now thought the best surgical option would be fusion surgery.

Dr. Wicklund issued a supplemental report on June 22, 2021, in which he discussed the reasons why he disagreed with Dr. Wengler’s rating.  He noted that the employee’s complaints were not substantiated by persistent clinical findings.  He disagreed with Dr. Wengler’s assessment of instability at L3-4 and L4-5, finding an absence of supporting diagnostic studies or objective neurologic findings.  He continued to rate the employee with a zero percent PPD pursuant to Minn. R. 5223.0390, subp. 3A, specifically noting that the employee had symmetrical reflexes, strength, no muscle atrophy, and negative straight leg raising.

Following the hearing below, the compensation judge adopted the views of Dr. Wicklund over those of Dr. Wengler and found that the employee had failed to show that his work injury had resulted in ratable permanency.  The employee appeals.

On appeal, the Workers’ Compensation Court of Appeals must determine whether “the findings of fact and order [are] clearly erroneous and unsupported by substantial evidence in view of the entire record as submitted.”  Minn. Stat. § 176.421, subd. 1(3).  Substantial evidence supports the findings if, in the context of the entire record, “they are supported by evidence that a reasonable mind might accept as adequate.”  Hengemuhle v. Long Prairie Jaycees, 358 N.W.2d 54, 59, 37 W.C.D. 235, 239 (Minn. 1984).  Where evidence conflicts or more than one inference may reasonably be drawn from the evidence, the findings are to be affirmed.  Id. at 60, 37 W.C.D. at 240.  Similarly, findings of fact should not be disturbed, even though the reviewing court might disagree with them, “unless they are clearly erroneous in the sense that they are manifestly contrary to the weight of evidence or not reasonably supported by the evidence as a whole.”  Northern States Power Co. v. Lyon Food Prods., Inc., 304 Minn. 196, 201, 229 N.W.2d 521, 524 (1975).

A decision which rests upon the application of a statute or rule to essentially undisputed facts generally involves a question of law which the Workers’ Compensation Court of Appeals may consider de novo.  Krovchuk v. Koch Oil Refinery, 48 W.C.D. 607, 608 (W.C.C.A. 1993), summarily aff’d (Minn. June 3, 1993).

The compensation judge denied the employee’s claim for permanent partial disability compensation, relying upon the most recent MRI findings and the opinion of Dr. Wicklund.  The finding of permanent partial disability is one of “ultimate fact” for the compensation judge.  The interpretation of medical evidence and the determination of the level of permanent partial disability is for the compensation judge.^[1]  The compensation judge must base an award of permanent partial disability benefits on objective medical evidence which meets the requirements of the disability schedules.^[2]

As a preliminary matter, the employee argues that the compensation judge violated due process by failing to write a memorandum that discusses in detail the arguments raised in the employee’s trial brief and which explains more fully the reasons for the judge’s decision.  This court does not have jurisdiction over questions of constitutional interpretation, and thus cannot address the question of what the due process clause requires with respect to the extent of the discussion of the issues in a compensation judge’s decision.^[3]

The employee claimed 21 percent permanent partial disability under subparts 4D, 4D(1) and 4D(4) of Minn. R. 5223.0390, consistent with the opinion of his medical expert, Dr. Wengler.  The compensation judge found that the requirements of this provision were not met, consistent with the opinion of Dr. Wicklund, and accepted that physician’s opinion that the employee’s condition was instead most appropriately rated pursuant to Minn. R. 5223,0390, subp. 3A, which provides for a zero percent rating for a lumbar pain syndrome not substantiated by persistent objective clinical findings.  The relevant portions of Minn. R. 5223.0390, subp. 4D, provide:

A rating pursuant to Minn. R. 5223.0390, subp. 4D, thus requires three elements: (1) “radicular pain or radicular paresthesia . . .with objective radicular findings;” (2) “evidence [from specific forms of medical imaging] of intervertebral disc bulging, protrusion, or herniation that impinges on a lumbar nerve root;” and (3) “the medical imaging findings correlate anatomically with the findings on neurologic examination.”  All of these elements must be met.  There was conflicting evidence in this case with respect to each of these criteria.

With respect to the first element, Dr. Wicklund examined the employee, reviewed the records of the other providers and experts, and opined that there was no objective evidence of radiculopathy.  We note, also, that the medical records of many of the employee’s treating physicians similarly found negative straight leg testing or specifically noted an absence of radiculopathy.  The employee underwent an EMG to assess possible radiculopathy, and the results were read as normal.  There was, on the other hand, some support for the employee’s claim in the opinion of Dr. Wengler and in the initial MRI results, which were seen as suggestive of potential causes for radiculopathy, if clinically correlated with the employee’s symptoms.  In Finding 20, the compensation judge explicitly adopted Dr. Wicklund’s opinions as findings of fact, thereby finding that the employee has no objective evidence of radiculopathy and no nerve root involvement.  The employee argues that the compensation judge should instead have adopted the view of Dr. Wengler.

A compensation judge's choice of expert opinion is generally to be affirmed by this court unless the opinion or opinions relied on lack adequate foundation.^[4]   Here, however, we see no foundational defect sufficient to warrant overruling the compensation judge’s reliance on the opinion of Dr. Wicklund.  The finding of an absence of objective evidence of radiculopathy is itself sufficient to defeat the employee’s claimed 21 percent rating under this rule.

The judge also relied upon the most recent MRI findings, which fail to show the necessary evidence of the second element - intervertebral disc bulging, protrusion, or herniation that impinges on a lumbar nerve root.  The employee makes two arguments to address the lack of such findings in that MRI scan.  First, the employee contends that the language of the rule should be interpreted to require nerve impingement on a nerve root only for a herniated disc, and that the mere presence of a disc bulge or protrusion is sufficient to apply the rule even in the absence of nerve root impingement.  This interpretation is directly contrary to well-settled case law.  In Sletten v. American Hoist & Derrick,^[5] and innumerable cases following it, we held that the question of whether a bulging disc could receive the same rating as a herniated disc hinged on the functional effects of the bulge or herniation – which in turn was generally a question of whether the herniation or bulge compressed a nerve root or the spinal cord.  The current language of the rule was adopted after Sletten and essentially incorporates that holding.  In addition, adoption of the employee’s interpretation would be contrary to the purpose of permanent partial disability compensation, which focuses “not on the body part which sustained direct injury but rather on the resultant permanent functional disability.”^[6]

The employee further argues that a rating under subpart 4D of the rule remains appropriate where no impingement is currently present, as long as it was present at some point in time.  The employee likens a disc bulge that has resorbed to a disc that has been surgically removed, arguing that there is no logical reason why these situations should be treated differently.  We disagree.  The surgical removal of a disc is not, in our view, the same as a disc healing sufficiently to become asymptomatic.

Finally, while Dr. Wengler believed that the employee’s symptoms correlated with the MRI findings, Dr. Wicklund did not.  We note that several other physicians over the course of the employee’s treatment expressed the view that the employee’s symptoms were unlikely to be related to the changes shown on the prior MRI scans.  Again, the compensation judge could reasonably conclude that the employee did not manifest symptoms that correlated with the findings on any of the three MRI scans.

Substantial evidence supports the judge’s determination that the employee failed to meet the criteria for a rating under Minn. R. 5223.0390, subp. 4D.  We therefore affirm.