The employee appeals from the judge’s order dismissing his medical request with prejudice.  We reverse.

The employee sustained an admitted work injury to his left leg on August 6, 2008, while employed by Wells Concrete Products Co. [the employer].  He subsequently filed a claim petition on August 31, 2010, alleging that he had developed RSD^[2] and seeking, in part, payment for a trial and implantation of a neurostimulator, also referred to as a spinal cord stimulator.  In findings and order filed on June 13, 2011, the compensation judge found that the employee had failed to show that the neurostimulator work-up, implantation, and follow-ups qualified as reasonable medical treatment for the employee’s work injury.  The compensation judge explained that internet research had led the employee to believe that a neurostimulator would help his chronic pain and that the employee had then sought out a doctor with whom to discuss this option.  That doctor, Dr. Andrew Will, concluded that the employee was a good candidate for a neurostimulator implant.^[3]  The compensation judge also found that the employee had “failed to show through Dr. Will’s deposition testimony of April 5, 2011, and the records taken as a whole, that he suffers from a complex regional pain syndrome,” and the judge accordingly concluded that the disputed treatment “was not reasonable or necessitated by the work injury of Aug. 6, 2008.”  The judge’s decision was appealed to this court where, on March 7, 2012, it was affirmed.

On October 7, 2013, the employee filed a medical request, seeking payment for removal and replacement of the spinal cord stimulator.  Submitted with the medical request was a July 23, 2012, letter from Dr. Paul J. Vollmar, stating that he had been treating the employee since January 16, 2012, when the employee presented with a diagnosis of CRPS, which he opined was still the employee’s diagnosis.  It was his opinion that the employee’s medical treatment to date of his letter had been reasonable and necessary and that future treatment would include periodically having the manufacturer (Medtronics) reprogram the stimulator.^[4]  He went on to state that, because it was a battery-operated electronic unit, the stimulator would at some time need revision or replacement.

The employer and insurer filed a medical response, contending that a compensation judge had already determined that the employee had failed to establish that he suffered from CRPS and that the employer and insurer were not liable for the stimulator.  It was their contention that the issues presented in the medical request had already been decided and that the employee’s claim was barred by the doctrines of res judicata and collateral estoppel.

The employer and insurer accordingly filed a motion to dismiss the employee’s medical request, which came before the original compensation judge on a special term conference, by telephone, on March 10, 2014.  At the beginning of the telephone conference, the compensation judge identified some exhibits that he proposed be marked and received “for purpose of this motion.”  The two attorneys made their arguments.  On March 31, 2014, the judge issued his findings and order, concluding that the employee’s claim for treatment described in the October 2013 medical request was barred by the doctrines of collateral estoppel and res judicata, and the judge dismissed the medical request with prejudice.  The employee appeals.

“[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).

The employee contends that res judicata and collateral estoppel do not bar his claim for medical treatment rendered by Dr. Vollmar, including implantation of a new neurostimulator, as those issues were not previously litigated.  We agree.

The principles of res judicata are applicable in workers’ compensation proceedings.  Fischer v. Saga Corp., 498 N.W.2d 449, 48 W.C.D. 368 (Minn. 1993).  Collateral estoppel, or issue preclusion, is a form of res judicata in which a prior judgment is conclusive in a later suit between the same parties as to determinative issues resolved in the first action.  Travelers Ins. Co. v. Thompson, 163 N.W.2d 289 (Minn. 1969).  Collateral estoppel may apply in the following circumstances:  (1) the issue is identical to one in a prior adjudication; (2) there was a final judgment on the merits; (3) the estopped party was a party or in privity with a party to the prior adjudication; and (4) the estopped party was given a full and fair opportunity to be heard on the adjudicated issue.  Nelson v. American Family Ins. Group, 651 N.W.2d 499, 511 (Minn. 2001).  The Minnesota Supreme Court has also held that neither res judicata nor collateral estoppel should be “rigidly applied,” and the focus is on whether its application would work an injustice on the party against whom estoppel is urged.  Johnson v. Consolidated Freightways, 420 N.W.2d 608, 613-614 (Minn. 1988).

In his 2011 findings and order, the compensation judge found that the employee had “failed to show that he suffers from complex regional pain syndrome” and had failed to show that the neurostimulator trial, work-up, implant, and follow-ups were reasonable and necessary to treat the work injury.  He also found that the neurostimulator implant “was not reasonable or necessitated by the work injury.”

In his March 31, 2014, findings and order on motion to dismiss, the same compensation judge found that removal and replacement of the stimulator “represents maintenance and/or a continuation of treatment” found non-compensable in 2011.  At oral argument, counsel for the employee admitted that the 2011 decision was a final determination as to the neurostimulator implanted by Dr. Will on May 17, 2010.  The employee, however, did not begin treatment with Dr. Vollmar until January of 2012, and the employee’s medical request, filed in October of 2013, seeks payment for treatment by Dr. Vollmar, including the implantation of a new stimulator on April 18, 2012.  Dr. Vollmar’s bills were not before the judge in 2011 and are therefore not precluded by the previous decision.

At oral argument, counsel for the employer and insurer contended that their argument at the 2011 hearing was that the employee had fully recovered from his 2008 work injury and that he required no further medical treatment.  However, the compensation judge made no such finding in 2011.  Rather, he found that the employee had sustained an admitted work injury to his left leg, that the employee did not prove that he had CRPS, and that the employee did not prove that a neurostimulator was reasonable or necessary treatment for or “necessitated by” the work injury.  Nothing in those findings establishes that the employee’s work injury was temporary, had healed, or had resolved.  “A finding that the employee’s claims were denied for lack of proof does not equate to a finding that his work injuries were temporary or that he is foreclosed from claiming benefits thereafter.”  Vick v. Northern Engraving Corp., 70 W.C.D. 348, 357 (W.C.C.A. 2010).

There has never been a finding that the 2008 work injury was temporary, has resolved, or has healed.  The 2011 findings and order covered only claims for medical expenses prior to January 5, 2011, and the current claim is for medical expenses from and after January of 2012.  Under these circumstances, the current claim is not barred by res judicata or collateral estoppel, and we therefore reverse the compensation judge’s dismissal of the employee’s 2013 medical request.  That medical request should be determined on the merits.