                IN THE SUPREME COURT, STATE OF WYOMING

                                     2015 WY 88

                                                      APRIL TERM, A.D. 2015

                                                              June 19, 2015


IN THE MATTER OF THE WORKER’S
COMPENSATION CLAIM OF:

JAIME GUERRERO,

Appellant
(Petitioner),

v.                                                S-14-0271

STATE OF WYOMING, ex rel.,
DEPARTMENT OF WORKFORCE
SERVICES, WORKERS’
COMPENSATION DIVISION,

Appellee
(Respondent).


                   Appeal from the District Court of Campbell County
                      The Honorable Thomas W. Rumpke, Judge

Representing Appellant:
      Matthew R. Sorenson of Daly, Davidson & Sorenson, LLC, Gillette, Wyoming.

Representing Appellee:
      Peter K. Michael, Wyoming Attorney General; John D. Rossetti, Deputy Attorney
      General; Michael J. Finn, Senior Assistant Attorney General; Kristin M. Nuss, Senior
      Assistant Attorney General.



Before BURKE, C.J., and HILL, KITE, DAVIS, and FOX, JJ.
NOTICE: This opinion is subject to formal revision before publication in Pacific Reporter Third.
Readers are requested to notify the Clerk of the Supreme Court, Supreme Court Building,
Cheyenne, Wyoming 82002, of typographical or other formal errors so correction may be made
before final publication in the permanent volume.
KITE, Justice.

[¶1] The Office of Administrative Hearings (OAH) denied Jaime Guerrero’s worker’s
compensation claim on the grounds he failed to prove a causal relationship between his
lower back problems and a work-related accident on June 8, 2011. The district court
upheld the OAH decision.

[¶2]   We affirm.

                                              ISSUES

[¶3]   The issues for review in this case are:

      1.       Whether the OAH decision that Mr. Guerrero did not meet his burden of
establishing the causal relationship between his back problems and his work-related
accident is supported by substantial evidence.

       2.      Whether the OAH properly applied the second compensable injury rule.

                                               FACTS

[¶4] On June 8, 2011, Mr. Guerrero, who was a welder for Ironarc Welding, LLC,
suffered a work-related injury. He welded a drain-off valve on a pipe at an oil well
pumping station and was watching while the system was restarted, when a thirteen pound
blow-out valve broke loose from the pipe and hit him on the lower left side of the front of
his body. Mr. Guerrero went to the emergency room where he was treated for “blunt
abdominal trauma with a contusion, hematoma and abrasions to the left suprapubic
region.” He underwent surgery a few days later to drain the hemotoma.

[¶5] The Department of Workforce Services, Workers’ Compensation Division (the
Division) approved benefits for the injury to Mr. Guerrero’s left groin, abdomen, upper
leg, and knee. He was unable to work for approximately three months and received
temporary total disability benefits during that time. While he was convalescing, he took
prescription pain medication. Because of continued numbness and pain in his leg, his
treating physician, Sara Hartsaw, M.D., referred him to a neurologist for further
evaluation. He saw neurologist Robert Finley, M.D., on September 8, 2011, who
diagnosed him as suffering from “weakness involving the left lower extremity and
sensory alteration noted in what appears to be likely the distribution of the left lateral
femoral cutaneous nerve consistent with ‘meralgia paresthetica.’” 1 Mr. Guerrero did not
1
  “Meralgia paresthetica occurs when the lateral femoral cutaneous nerve — which supplies sensation to
the surface of [the] outer thigh — becomes compressed, or ‘pinched.’ The lateral femoral cutaneous nerve
is purely a sensory nerve and doesn’t affect [the] ability to use [the] leg muscles.”
http://www.mayoclinic.org/diseases-conditions/meralgia-paresthetica/basics/causes/con-20030852
                                                   1
complain to Dr. Finley of back pain at that time, and his notes indicate that Mr. Guerrero
told him he did not have any significant back pain while in the hospital after the accident.

[¶6] Mr. Guerrero participated in a work hardening program with a physical therapist
to ready him to return to work. He testified that he had some pain in his lower back while
at therapy but he thought it was from “sitting around those three months and not really
being interactive with anybody.” Dr. Hartsaw released Mr. Guerrero to return to work
without restrictions starting September 19, 2011, and he went back to work as a welder.

[¶7] On October 18, 2011, Mr. Guerrero saw Dr. Hartsaw for continued problems with
his left leg and, this time, he also complained of back pain. She referred him to
neurologist and pain management specialist Romer Mosquera, M.D., who addressed Mr.
Guerrero’s back pain even though the written referral was only for the problems with his
leg. Mr. Guerrero saw Dr. Finley and Dr. Mosquera on November 23, 2011, and
complained to both about his back pain.

[¶8] Dr. Mosquera ordered an MRI of Mr. Guerrero’s lumbar spine.                 The MRI
revealed:

                 Lumbar degenerative change at L3-L4 through L5-S1,
                 with findings suggesting disc tear at each of those levels,
                 some central narrowing at L4-L5, and disc protrusion to
                 the right at L5-S1 compromising the right S1 root.

The medical records from Mr. Guerrero’s December 20, 2011, appointment with Dr.
Mosquera indicate that Mr. Guerrero stated his back pain had started acutely “several
months ago;” was severe and radiated down both of his thighs; and was aggravated by
lifting, exercising, carrying heavy objects, and driving, sitting or standing for long
periods. The doctor discussed Mr. Guerrero’s MRI results with him and recommended a
lumbar epidural steroid injection. Mr. Guerrero had the epidural injection on January 5,
2012, and it relieved a great deal of his pain. He did not, however, return to Dr.
Mosquera for a follow-up appointment.

[¶9] The Division denied Mr. Guerrero’s claim for worker’s compensation benefits for
the evaluation and treatment of his back pain, finding “[t]his case is not open for the
lumbar spine” and noting he was referred to Dr. Mosquera “for left lower extremity pain
only, not low back pain.” More specifically, the Division determined that the lumbar




                                             2
spine evaluation and treatment were not related to his original work injury. Mr. Guerrero
objected, and the Division referred the matter to the OAH. 2

[¶10] The OAH held a contested case hearing on March 4, 2013. Transcripts of the
depositions of Dr. Hartsaw and Dr. Mosquera were admitted into evidence, as were the
relevant medical records. Mr. Guerrero was the only witness who testified at the
contested case hearing. The OAH ruled that Mr. Guerrero did not satisfy his burden of
proving his back pain was caused by the work accident and denied his request for
worker’s compensation benefits. Mr. Guerrero petitioned the district court for review,
and that court affirmed the OAH decision. Mr. Guerrero then appealed to this Court.

                                   STANDARD OF REVIEW

[¶11] When an appeal is taken from a district court’s review of an administrative
agency’s decision, we examine the case as if it had come directly from the agency
without giving any deference to the district court’s decision. Dutcher v. State ex rel.
Wyo. Workers’ Safety & Comp. Div., 2010 WY 10, ¶ 9, 223 P.3d 559, 561 (Wyo. 2010);
Dale v. S & S Builders, LLC, 2008 WY 84, ¶ 8, 188 P.3d 554, 557 (Wyo. 2008). Our
review is governed by Wyo. Stat. Ann. § 16-3-114(c) (LexisNexis 2013):

                 (c) To the extent necessary to make a decision and when
               presented, the reviewing court shall decide all relevant
               questions of law, interpret constitutional and statutory
               provisions, and determine the meaning or applicability of the
               terms of an agency action. In making the following
               determinations, the court shall review the whole record or
               those parts of it cited by a party and due account shall be
               taken of the rule of prejudicial error. The reviewing court
               shall:
                    (i) Compel agency action unlawfully withheld or
               unreasonably delayed; and
                    (ii) Hold unlawful and set agency action, findings and
               conclusions found to be:
                         (A) Arbitrary, capricious, an abuse of discretion or
               otherwise not in accordance with law;
                         (B) Contrary to constitutional right, power, privilege
               or immunity;
                         (C) In excess of statutory jurisdiction, authority or
               limitations or lacking statutory right;
2
 The OAH ruled that it did not have jurisdiction over some of the final determinations because Mr.
Guerrero did not object within the deadline set out in Wyo. Stat. Ann. § 27-14-601(k) (LexisNexis 2010).
Mr. Guerrero does not challenge that ruling on appeal.


                                                   3
                        (D) Without observance of procedure required by
              law; or
                       (E) Unsupported by substantial evidence in a case
              reviewed on the record of an agency hearing provided by
              statute.

[¶12] Under § 16-3-114(c), we review the agency’s findings of fact by applying the
substantial evidence standard. Dale, ¶ 22, 188 P.3d at 561. Substantial evidence means
“such relevant evidence as a reasonable mind might accept as adequate to support a
conclusion.” Bush v. State ex rel. Wyo. Workers’ Comp. Div., 2005 WY 120, ¶ 5, 120
P.3d 176, 179 (Wyo. 2005) (citation omitted). See also Kenyon v. State ex rel. Wyo.
Workers’ Safety & Comp. Div., 2011 WY 14, ¶ 11, 247 P.3d 845, 849 (Wyo. 2011).
“Findings of fact are supported by substantial evidence if, from the evidence preserved in
the record, we can discern a rational premise for those findings.” Id., ¶ 11, 247 P.3d at
849 (citation omitted).

[¶13] When an agency rules that the claimant did not satisfy his burden of proof, we
apply the following standard:

              If the hearing examiner determines that the burdened party
              failed to meet his burden of proof, we will decide whether
              there is substantial evidence to support the agency’s decision
              to reject the evidence offered by the burdened party by
              considering whether that conclusion was contrary to the
              overwhelming weight of the evidence in the record as a
              whole. If, in the course of its decision making process, the
              agency disregards certain evidence and explains its reasons
              for doing so based upon determinations of credibility or other
              factors contained in the record, its decision will be sustainable
              under the substantial evidence test. Importantly, our review of
              any particular decision turns not on whether we agree with
              the outcome, but on whether the agency could reasonably
              conclude as it did, based on all the evidence before it.

Dale, ¶ 22, 188 P.3d at 561 (citations omitted).

[¶14] “We review an agency’s conclusions of law de novo, and will affirm only if the
agency’s conclusions are in accordance with the law.” Middlemass v. State ex rel. Wyo.
Workers’ Safety & Comp Div., 2011 WY 118, ¶ 13, 259 P.3d 1161, 1164 (Wyo. 2011),
quoting Kenyon, ¶ 13, 247 P.3d at 849, which quoted Moss v. State ex rel. Wyo. Workers’
Comp. Div., 2010 WY 66, ¶ 11, 232 P.3d 1, 4 (Wyo. 2010).



                                             4
                                      DISCUSSION

   1. Direct Causation

[¶15] “A worker’s compensation claimant has the burden of proving all of the essential
elements of his claim by a preponderance of the evidence.” State ex. rel. Wyo. Workers’
Safety & Comp. Div. v. Slaymaker, 2007 WY 65, ¶ 13, 156 P.3d 977, 981 (Wyo. 2007);
Sanchez v. State ex. rel. Wyo. Workers’ Safety & Comp. Div., 2006 WY 64, ¶ 7, 134 P.3d
1255, 1257 (Wyo. 2006). In order to qualify for worker’s compensation benefits, an
employee must demonstrate he suffered a compensable injury, as defined in Wyo. Stat.
Ann. § 27-14-102(a)(xi) (LexisNexis 2013):

              (xi) “Injury” means any harmful change in the human
              organism other than normal aging and includes damage to or
              loss of any artificial replacement and death, arising out of and
              in the course of employment while at work in or about the
              premises occupied, used or controlled by the employer and
              incurred while at work in places where the employer’s
              business requires an employee’s presence and which subjects
              the employee to extrahazardous duties incident to the
              business.

Under the statutory definition of injury, the claimant has the burden of “establishing the
cause of the condition for which compensation is claimed and proving that the injury
arose out of and in the course of employment.” Hanks v. City of Casper, 2001 WY 4, ¶
6, 16 P.3d 710, 711 (Wyo. 2001). See also State ex rel. Wyo. Workers’ Comp. Div. v.
Espinoza, 924 P.2d 979, 981 (Wyo. 1996). The claimant must show the causal
connection to a reasonable degree of medical probability. Typically this requires expert
medical testimony that it is more probable than not that the work contributed in a material
fashion to the precipitation, aggravation or acceleration of the injury. Stevens v. State ex
rel. Dept. of Workforce Servs., Workers’ Safety & Comp. Div., 2014 WY 153, ¶ 50, n.6,
338 P.3d 921, 932, n.6 (Wyo. 2014).

[¶16] The OAH found:

              Guerrero did not prove his October-November 2011 lumbar
              spine conditions and symptoms were causally connected to
              his June 8, 2011 work-related accident and injury. The
              evidence was confusing and inconsistent regarding the timing
              and development of Guerrero’s low back pain and symptoms.
              The evidence did not demonstrate which of Guerrero’s
              lumbar spine conditions was generating his symptoms. Dr.
              Mosquera’s opinion testimony was not strongly stated and

                                             5
                was based upon the unproven assumption that Guerrero’s low
                back pain arose acutely five months before November 2011.

[¶17] Mr. Guerrero challenges the OAH conclusion that Dr. Mosquera’s testimony was
insufficient to prove his back problem was caused by his work injury. Dr. Mosquera was
deposed and the deposition transcript was admitted into evidence at the contested case
hearing. Dr. Mosquera stated Mr. Guerrero’s MRI showed degenerative changes and
disc tears. Dr. Mosquera testified about the general causes of disc tears:

                Q.      What causes [a disc tear]?

                A.     Usually you can see that from degeneration, okay, in
                elderly people. You can see that from external pressure, like
                if somebody has a bad habit of lifting heavy weights without
                the proper alignment of [the] spine, not following the
                recommendations for hygiene,3 then they’re at higher risk of
                having these type of conditions.
                       People overweight         may have        them even
                spontaneously, because they’re carrying a higher amount of
                pressure, discs carry a higher amount of pressure.
                       High velocity injuries like a motor vehicle accident or
                motorcycle accident just from the shear pressure, shear injury;
                you could have a tear on the disc that could produce
                outpouching of disc material.
                       You could – there’s some – most of the cases,
                especially across the U.S., are caused by occupational, you
                know. It has to do with using improperly devices to lift
                weights or lifting too much weight that the spine is not
                prepared to handle, you know, if you don’t use your spine
                properly.

(footnote added).

[¶18] Dr. Mosquera was then asked about whether Mr. Guerrero’s particular work
accident could have caused disc tears:

                       Q.     With Mr. Guerrero, when he had the -- I guess
                the blunt force trauma on the front half of his body, could that
                have caused a disc tear?


3
 Hygiene is defined as “the conditions or practices that serve to promote or preserve health.” The
American Heritage Stedman’s Medical Dictionary (2002).
                                                    6
                        A.     You know, it’s difficult because I got an initial -
                -- what he told me initially was that he had that very strong
                pressure coming in and produced significant compression,
                contusion in that area.
                        Then we were trying to get more details about the
                injury, and he did mention on the second occasion when I saw
                him that the strength of that pressure actually blew him out I
                think several feet, okay, and he landed on his back.
                        I would say it’s certainly possible, but could we have
                certainty?4 You know, those lesions could have been there
                from before and just been aggravated after the injury. . . .

                      Q.     Was Mr. Guerrero asymptomatic prior to his
                hemotoma injury on the front half of his body, at least that’s
                what he reported to you?

                        A.     Yeah, I think he mentioned that he didn’t ever
                have any back problems before. So he was suspicious of all
                this coming after his injury.
                        But, obviously I didn’t do my – I didn’t do the initial
                evaluation when he actually had the injury. . . . [W]hen time
                elapses there is always this possibility of confusing
                timeframes for symptoms. You know, I would say it is
                possible, but do I have certainty that that was the case? Not
                really.

                        Q.    I mean, do you ever have certainty in those
                situations other than what the patient reports to you, I
                suppose?

                       A.      It’s difficult, yeah. It’s difficult. Unless you
                have somebody that, you know, is 18 years old that, you
                know, never had any injury, and then all of a sudden [has]
                a[n] injury, and you see something that you shouldn’t really
                be seeing in someone that young, then you definitely
                associate it to that injury.
                       But you know, I would say you have to go with what
                the patient tells you and believe that.


4
 Medical certainty is not required to establish causation in a worker’s compensation case. As we stated
above, the standard of proof on causation is “medical probability.” Stevens, ¶ 50, n.6, 338 P.3d at 932,
n.6.
                                                    7
                      Q.    So in the situation with Mr. Guerrero, if he was
              – with the force that had hit him and pushed him back several
              feet, causing him to fall on his back, that could have caused a
              disc tear?

                     A.     Yeah, I think there’s a possibility of that.

(footnote added).

[¶19] Dr. Mosquera was only able to state that it was “possible” Mr. Guerrero’s back
problems were related to the June 2011 work accident. “[O]pinions expressed by medical
experts in terms of ‘can,’ ‘could,’ or ‘possibly’ are not sufficient to meet an employee’s
burden of proof.” Boyce v. State ex rel. Wyo. Workers’ Safety & Comp. Div., 2005 WY
9, ¶ 22, 105 P.3d 451, 458 (Wyo. 2005), citing Thornberg v. State ex rel. Wyo. Workers’
Comp. Div., 913 P.2d 863 (Wyo. 1996). Medical testimony stating the claimant’s work
“contributed to” the injury or the injury was “most likely” or “probably” the product of
the workplace is sufficient to satisfy the requirement. Boyce, ¶ 21, 105 P.3d at 458, citing
Jim’s Water Service v. Eayrs, 590 P.2d 1346, 1349 (Wyo. 1979) and Claim of Vondra,
448 P.2d 313 (Wyo. 1968). See also Salas v. General Chemical, 2003 WY 79, ¶ 10, 71
P.3d 708, 711-12 (Wyo. 2003). Dr. Mosquera’s testimony that it was “possible” or “a
possibility” that Mr. Guerrero’s disc tears were caused by the work accident does not
satisfy the requirement for medical proof of causation.

[¶20] Mr. Guerrero also maintains that the requisite causal connection between the disc
tears and his work accident was established by Dr. Mosquera’s testimony that in a person
without prior back symptoms “the most logical thing is to think that the injury caused
those structural changes.” We have never considered this precise language to determine
whether it is sufficient to meet the “medical probability” standard required for workers’
compensation claims, and we do not need to in this instance because the context of Dr.
Mosquera’s statement clearly shows that he was not stating it was more probable than not
that Mr. Guerrero’s back was injured during the work-related accident. The doctor
testified:

                     Q.    With a disc tear, with Mr. Guerrero’s situation,
              would the pain of a tear of the disc, would that be acute
              immediately upon the injury or could that develop as he came
              back to work later on?

                     A.     You have the two possibilities. A disc tear
              doesn’t tell you that the tear occurred the day you had, you
              know, symptoms. It just tells you about the status of a series
              of structures that are very dynamic, and it’s just taking a
              picture in time. So what you have there is just a picture.

                                             8
                     You don’t know if that tear developed at the time of
             injury or developed six months before the injury or has been
             gradually developing because of wear and tear over a period
             of a year, two years, or five years. So it is difficult.
                     Unless you have – you know, you assume that
             somebody has a normal spine unless they present with
             symptoms. But there is a group of people that are exposed to
             heavy duties that will – you know, you will image their
             spines, and they will have changes, and a lot of them will not
             experience pain.
                     But if that person suffers an injury and those structural
             changes are there, you can see how they can associate, okay,
             this is here, this is abnormal, and you had an injury. So [the]
             most logical thing is to think that the injury caused those
             structural changes.
                     So, again it will be very difficult because unless you
             have documentation that the person had a perfectly normal
             spine before the injury, and then you compare that to a new
             imaging and a new clinical scenario after the injury, and you
             can make that assumption more clearly, there’s always going
             to be a doubt about that.
                     ....
                             Q.     I mean, would Mr. Guerrero, with a disc
             tear, is it possible for him to be asymptomatic for a time
             period and then the symptoms develop as they go on?

                            A.     There is a possibility of that.    As I
             mentioned, you can have – you could have a disc tear that
             didn’t produce symptoms initially.
                            But again, you would expect some of those
             symptoms would develop in the months following the injury,
             especially if he returned back to work, and then he’s back on
             his regular duties. You would expect that to occur within the
             time frame of, you know, within three months, six months.

(emphasis added).

[¶21] When Dr. Mosquera’s testimony about it being logical that an injury causes
structural damage is read in context, it is clear he was providing general information and
was not referring to Mr. Guerrero’s specific situation. When Dr. Mosquera was asked to
opine on Mr. Guerrero’s specific circumstances, he was only able to say there was “a
possibility” that Mr. Guerrero’s lumbar discs were torn in the accident although he
remained asymptomatic for several months afterwards. The medical testimony did not

                                            9
satisfy Mr. Guerrero’s burden of proof.

[¶22] Furthermore, Dr. Mosquera’s initial understanding, based upon his discussions
with Mr. Guerrero, that he suffered an acute injury to his back several months before
when he fell backward, hit a guard and then fell to the ground is not supported by the
other medical records. Mr. Guerrero did not tell the hospital personnel that he fell onto
his back or report to his doctors that he had back pain until months after the accident. A
hearing examiner is not bound by a medical expert’s opinion when it is based “upon an
incomplete and inaccurate medical history provided by the claimant.” Middlemass, ¶ 29,
259 P.3d at 1168¸ quoting Watkins v. State ex rel. Wyo. Medical Comm’n, 2011 WY 49, ¶
25, 250 P.3d 1082, 1091 (Wyo. 2011) (other citations omitted).

[¶23] Mr. Guerrero argues, in the alternative, that the work accident aggravated a
preexisting condition in his back. Preexisting conditions are generally excluded from the
definition of compensable injury. Wyo. Stat. Ann. § 27-14-102(a)(xi)(F). However, an
employee who has a pre-existing condition may still recover if his “employment
aggravated, accelerated, or combined with the disease or infirmity to produce the death or
disability for which compensation is sought.” Dutcher, ¶ 14, 223 P.3d at 562, citing
Lindbloom v. Teton Int’l, 684 P.2d 1388, 1389 (Wyo. 1984) and Larson’s Workmen’s
Compensation Law. “To prove aggravation of a preexisting condition, a claimant must
demonstrate by a preponderance of the evidence that the work contributed to a material
degree to the aggravation of the condition.” Middlemass, ¶ 15, 259 P.3d at 1165, quoting
Dutcher, ¶ 15, 223 P.3d at 562.

[¶24] Mr. Guerrero did not meet his burden of proving the work accident materially
aggravated a preexisting condition in his back because Dr. Mosquera was only able to
say it “could have” aggravated preexisting lesions of the discs, disc bulges or facet
disease in his back. The medical expert was unable to say that it was more probable than
not the work accident caused a material aggravation of a preexisting condition.

[¶25] Mr. Guerrero also asserts that medical evidence was unnecessary and his
testimony that his back was asymptomatic prior to the work accident was sufficient to
establish the causation element of his claim. In Thornberg, 913 P.2d at 867, we analyzed
precedent holding that medical expert testimony is not always required to establish
causation. See, e.g., Forni v. Pathfinder Mines, 834 P.2d 688, 693 (Wyo. 1992); Hansen
v. Mr. D’s Food Center, 827 P.2d 371, 373 (Wyo. 1992); Gray v. State ex rel., Wyo.
Workers’ Safety & Comp. Div., 2008 WY 115, ¶ 17, 193 P.3d 246, 251-52 (Wyo. 2008).
We stated: “Generally, when a single incident is alleged to have caused an injury,
medical testimony is not required if it is not essential to establish a causal connection
between the occurrence and the injury.” Thornberg, 913 P.2d at 867. However, to avoid
the medical testimony requirement, the injury or condition must be “‘immediately and
directly or naturally and probably’” the result of the workplace incident. Id., quoting
Hansen, 827 P.2d at 373. In the absence of an obvious connection between the incident

                                           10
and the medical condition, “medical testimony may be essential to establish a causal
connection.” Id.

[¶26] Mr. Guerrero argues his situation is similar to Murray v. State ex rel., Wyo.
Workers’ Safety & Comp. Div., 993 P.2d 327 (Wyo. 1999). In Murray, we concluded the
employee had shown a sufficient causal connection between his work activities and his
development of urticaria (hives) even though he could not establish the precise trigger of
his symptoms. We stated:

             “Proof of prior good health and change immediately
             following and continuing after an injury may establish that an
             impaired condition was due to the injury.” Waldorf
             Corporation v. Industrial Commission, 303 Ill.App.3d 477,
             236 Ill.Dec. 890, 708 N.E.2d 476, 480 (1999); see also Davis
             v. General Electric Company, 991 S.W.2d 699, 706-707
             (Mo.App. S.D.1999). “[E]vidence of the timing of symptoms
             has been specifically recognized as a competent way of
             studying causation; ‘the manner in which the disease
             developed, with reference to the claimant's medical and work
             history’ is entirely appropriate for the court to consider.”
             Kiczula v. American National Can Company, 310 N.J.Super.
             293, 708 A.2d 742, 746 (1998) (quoting Fiore v.
             Consolidated Freightways, 140 N.J. 452, 659 A.2d 436
             (1995) considering occupational disease).

Id. at 332-33. This is basically the same concept we recognized in Thornberg, i.e.,
medical evidence is not required to establish a causal connection when the injury is
immediately and directly or naturally and probably the result of the work-related incident.

[¶27] Murray does not support Mr. Guerrero’s argument. In that case, Murray’s
symptoms developed immediately after he was exposed to chemicals at work. Mr.
Guerrero, in contrast, did not report his back pain until months after the work accident.
That distinction makes Mr. Guerrero’s situation more akin to Stevens, 2014 WY 153, 338
P.3d 921. There, the question was whether the requisite causal connection was
established when the employee demonstrated that she had no known hip problems before
her work-related fall and then developed a hip problem after the fall. We expressly
rejected application of the Murray rationale in Stevens because the employee made no
documented report of her hip problem for over a month after the fall and did not seek
treatment of her hip condition for more than two months after the fall. Id., ¶ 54, 338 P.3d
at 933.

[¶28] Mr. Guerrero’s report of his back problems was even more remote than Stevens’.
He experienced a distinct injury to the front of his body in June 2011, and even though he

                                            11
was receiving regular medical care for his injury, did not report any back pain to Dr.
Hartsaw until October 2011. Under these circumstances, Mr. Guerrero’s back injury was
not an immediate and direct or natural and probable result of the workplace incident.
Expert medical testimony was critical to establish causation and Dr. Mosquera’s
testimony did not satisfy the “medical probability” standard. The hearing examiner’s
conclusion that Mr. Guerrero did not satisfy his burden of proving his back problem was
caused by the work-related accident is not contrary to the overwhelming weight of the
evidence and is, therefore, supported by substantial evidence.

   2. Second Compensable Injury

[¶29] Mr. Guerrero asserts the OAH erred by failing to properly apply the second
compensable injury rule. “The second compensable injury rule applies when ‘an initial
compensable injury ripens into a condition requiring additional medical intervention.’”
Carabajal v. State ex rel., Wyo. Workers’ Safety & Comp. Div., 2005 WY 119, ¶ 12, 119
P.3d 947, 951 (Wyo. 2005), quoting Yenne–Tully v. State ex rel. Workers’ Safety &
Comp. Div., 12 P.3d 170, 172 (Wyo. 2000). In order to prove a second compensable
injury, “the claimant must show, by a preponderance of the evidence, that it is more
probable than not that there exists a causal connection between the first and second
injuries.” State ex rel. Wyo. Workers’ Safety & Comp. Div. v. Kaczmarek, 2009 WY
110, ¶ 11, 215 P.3d 277, 282-83 (Wyo. 2009). Stated another way, “‘[u]nder the second
compensable injury rule, a subsequent injury or condition is compensable if it is causally
related to the initial compensable injury.’” Hoffman v. State ex rel. Wyo. Workers’ Safety
& Comp. Div., 2012 WY 164, ¶ 9, 291 P.3d 297, 301 (Wyo. 2012), quoting Alvarez v.
State ex rel. Wyo. Workers’ Comp. Div., 2007 WY 126, ¶ 18, 164 P.3d 548, 552 (Wyo.
2007). See also State ex rel. Dep’t of Workforce Services, Workers’ Safety & Comp. Div.
v. Hartmann, 2015 WY 1, ¶ 20, 342 P.3d 377, 382-83 (Wyo. 2015).

[¶30] The OAH has the responsibility to invoke and apply the correct rules of law,
including the second compensable injury rule, to workers’ compensation claims. Pino v.
State ex rel. Wyo. Workers’ Safety & Comp. Div., 996 P.2d 679, 687 (Wyo. 2000).
Contrary to Mr. Guerrero’s assertion, the OAH did identify and apply the second
compensable injury rule to his claim. It concluded that Mr. Guerrero did not meet his
burden of proving he was entitled to benefits under the rule. Thus, Mr. Guerrero’s
argument that the OAH erred by failing to apply the second compensable injury rule is
not correct.

[¶31] Mr. Guerrero also asserts that he was entitled to an award of benefits for his back
under the rule. Pursuant to the second compensable injury rule, Mr. Guerrero had the
burden of proving the injury to the front of his body somehow ripened into an injury to
his back. In order to make the causal connection, a claimant must present evidence
demonstrating that the initial work injury contributed to the second injury. Hoffman, ¶ 9,
291 P.3d at 302. Mr. Guerrero does not direct us to any evidence showing that his June

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2011 injury to his left groin, lower abdomen, leg and knee contributed to his back
problems. Consequently, the hearing examiner correctly ruled that Mr. Guerrero was not
entitled to worker’s compensation benefits under the second compensable injury rule.

[¶32] Affirmed.




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