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                     HYNES v. GOOD SAMARITAN HOSP.
                            Cite as 291 Neb. 757




                   K imberly L. Hynes, appellee, v.
                      Good Samaritan Hospital,
                        a Nebraska nonprofit
                       corporation, appellant.
                                ___ N.W.2d ___

                    Filed September 4, 2015.   No. S-15-002.

 1.	 Workers’ Compensation: Appeal and Error. Pursuant to Neb. Rev.
     Stat. § 48-185 (Cum. Supp. 2014), an appellate court may modify,
     reverse, or set aside a Workers’ Compensation Court decision only when
     (1) the compensation court acted without or in excess of its powers; (2)
     the judgment, order, or award was procured by fraud; (3) there is not
     sufficient competent evidence in the record to warrant the making of the
     order, judgment, or award; or (4) the findings of fact by the compensa-
     tion court do not support the order or award.
 2.	____: ____. Determinations by a trial judge of the Workers’
     Compensation Court will not be disturbed on appeal unless they are
     contrary to law or depend on findings of fact which are clearly wrong in
     light of the evidence.
 3.	 Workers’ Compensation: Evidence: Appeal and Error. Admission of
     evidence is within the discretion of the Workers’ Compensation Court,
     whose determination in this regard will not be reversed upon appeal
     absent an abuse of discretion.
 4.	 Expert Witnesses. Expert testimony should not be received if it appears
     the witness is not in possession of such facts as will enable him or her to
     express a reasonably accurate conclusion, as distinguished from a mere
     guess or conjecture.
 5.	 Trial: Expert Witnesses. It is within the trial court’s discretion to deter-
     mine whether there is sufficient foundation for an expert witness to give
     his or her opinion about an issue in question.
 6.	 Workers’ Compensation: Proof. In order to recover under the
     Nebraska Workers’ Compensation Act, a claimant has the burden of
     proving by a preponderance of the evidence that an accident or occupa-
     tional disease arising out of and occurring in the course of employment
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                    HYNES v. GOOD SAMARITAN HOSP.
                           Cite as 291 Neb. 757

      proximately caused an injury which resulted in disability compensable
      under the act.
 7.	 Workers’ Compensation: Mental Health. A worker is entitled to
      recover compensation for a mental illness if it is a proximate result of
      the worker’s injury and results in disability.
 8.	 ____: ____. A claim for a psychological or mental condition requires
      that the mental condition must be related to or caused by the physi-
      cal injury.
  9.	 ____: ____. An injury caused by a mental stimulus does not meet the
      requirement that a compensable accidental injury involve violence to the
      physical structure of the body.
10.	 Workers’ Compensation: Appeal and Error. On appellate review
      of a workers’ compensation award, the trial judge’s factual findings
      have the effect of a jury verdict and will not be disturbed unless
      clearly wrong.
11.	 Workers’ Compensation. As the trier of fact, the Workers’ Compensation
      Court is the sole judge of the credibility of witnesses and the weight to
      be given their testimony.
12.	 Trial: Proximate Cause. The determination of causation is ordinarily a
      matter for the trier of fact.
13.	 Workers’ Compensation: Words and Phrases. When the question is
      whether compensability should be extended to a subsequent injury or
      aggravation related in some way to the primary injury, the rules that
      come into play are essentially based upon the concepts of “direct and
      natural results.”
14.	 Proximate Cause. A cause of an injury may be a proximate cause,
      notwithstanding that it acted through successive instruments of a series
      of events, if the instruments or events were combined in one con-
      tinuous chain through which the force of the cause operated to produce
      the disaster.
15.	 Workers’ Compensation: Evidence: Appeal and Error. In testing
      the sufficiency of evidence to support findings of fact made by the
      compensation court after rehearing, the evidence must be considered in
      the light most favorable to the successful party and the successful party
      will have the benefit of every inference reasonably deducible from
      the evidence.
16.	 ____: ____: ____. If the record contains evidence to substantiate the
      factual conclusions reached by the trial judge in workers’ compensation
      cases, an appellate court is precluded from substituting its view of the
      facts for that of the compensation court.
17.	 Workers’ Compensation: Expert Witnesses. It is the role of the
      Workers’ Compensation Court as the trier of fact to determine which, if
      any, expert witnesses to believe.
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                        Nebraska A dvance Sheets
                         291 Nebraska R eports
                     HYNES v. GOOD SAMARITAN HOSP.
                            Cite as 291 Neb. 757

18.	 Workers’ Compensation: Mental Health: Evidence. Where the evi-
     dence is sufficient to permit the trier of fact to find that a psychological
     injury is directly related to an accident and the employee is unable to
     work, the employee is entitled to be compensated.

  Appeal from the Workers’ Compensation Court: Michael K.
High, Judge. Affirmed.
   Thomas D. Wulff, of Wulff & Freeman, L.L.C., for appellant.
  John C. Fowles, of Fowles Law Office, P.C., L.L.O., for
appellee.
  Heavican, C.J., Wright, Connolly, McCormack, Miller-
Lerman, and Cassel, JJ.
   Wright, J.
                      NATURE OF CASE
   Good Samaritan Hospital (Good Samaritan) appeals from
an award entered by the Nebraska Workers’ Compensation
Court on November 24, 2014. The court found the claimant,
Kimberly L. Hynes, sustained a 100-percent loss of earn-
ing power due to psychological injuries resulting from three
assaults that occurred in the course of her employment at a
hospital. Good Samaritan contends that Hynes failed to pro-
duce sufficient evidence to sustain the award, that the Workers’
Compensation Court improperly connected noncompensable
injuries to the compensable injury, and that the compensation
court should have excluded the psychiatric report of Hynes’
expert from evidence.
   For the reasons discussed below, we affirm the findings and
award of the Workers’ Compensation Court.
                     SCOPE OF REVIEW
   [1-3] Pursuant to Neb. Rev. Stat. § 48-185 (Cum. Supp.
2014), an appellate court may modify, reverse, or set aside a
Workers’ Compensation Court decision only when (1) the com-
pensation court acted without or in excess of its powers; (2)
the judgment, order, or award was procured by fraud; (3) there
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                HYNES v. GOOD SAMARITAN HOSP.
                       Cite as 291 Neb. 757

is not sufficient competent evidence in the record to warrant
the making of the order, judgment, or award; or (4) the find-
ings of fact by the compensation court do not support the order
or award. Lagemann v. Nebraska Methodist Hosp., 277 Neb.
335, 762 N.W.2d 51 (2009). Determinations by a trial judge
of the Workers’ Compensation Court will not be disturbed on
appeal unless they are contrary to law or depend on findings of
fact which are clearly wrong in light of the evidence. Giboo v.
Certified Transmission Rebuilders, 275 Neb. 369, 746 N.W.2d
362 (2008). Admission of evidence is within the discretion of
the Workers’ Compensation Court, whose determination in this
regard will not be reversed upon appeal absent an abuse of
discretion. Olivotto v. DeMarco Bros. Co., 273 Neb. 672, 732
N.W.2d 354 (2007).

                            FACTS
   This is the second time the case has been before this court.
In Hynes v. Good Samaritan Hosp., 285 Neb. 985, 830 N.W.2d
499 (2013), we vacated the award because the testimony of the
employer’s witnesses had been lost due to no fault of either
party and, therefore, the record was insufficient to undertake
a meaningful appellate review of the case. We remanded the
cause for a new trial.
   On remand, the parties stipulated that Hynes had been
employed as a registered nurse by Good Samaritan in Kearney,
Nebraska, and also stipulated to her average weekly wage.
Hynes alleged that she suffered from posttraumatic stress dis-
order (PTSD) and depression as a result of three incidents
which occurred in the course of her employment as a nurse in
the mental health unit of Good Samaritan and that these inci-
dents left her unable to work.
   On April 16, 2008, a patient “whipped” Hynes several times
with a large vacuum cleaner cord and punched her in the jaw.
Hynes suffered bruising and substantial pain as a result of the
assault. This was the only incident for which Hynes sought
medical treatment for a physical injury.
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                 HYNES v. GOOD SAMARITAN HOSP.
                        Cite as 291 Neb. 757

   Following this incident, Hynes tearfully discussed the
assault with an employee assistance program counselor, Roni
Norman. She reported having difficulty eating and sleeping
following the assault and stated she did not feel safe return-
ing to the adolescent unit. On April 23, 2008, Hynes again
visited Norman. Hynes was tearful and described experiencing
feelings of extreme hypervigilance and sensitivity to noises
and movement, as well as nightmares and disturbing dreams.
Followup meetings between Hynes and Norman on May 22,
May 28, and June 2, revealed Hynes’ increasing feelings
of hopelessness and helplessness, flashbacks, dreams of the
assault, strained communication problems, and difficulty func-
tioning in her professional, social, and personal life.
   In the meeting with Norman on June 2, 2008, Hynes
described a second incident, where she was assaulted by a
patient the previous week. Hynes was kicked and was bitten
on the arm by a patient. She did not seek medical treatment for
the alleged physical injuries.
   Following these assaults, Hynes’ symptoms worsened
severely. On June 11, 2008, Hynes reported to Norman that she
had been experiencing panic attacks, hypersensitivity to loud
noises, loss of appetite, social withdrawal, and general feelings
of anxiety and depression.
   On July 6, 2008, Hynes reported a third incident to Norman
which occurred while Hynes was working in the male portion
of the adolescent/youth unit of the hospital. A male adolescent
grabbed Hynes and made “extremely aggressive” sexual com-
ments to her. Hynes did not receive treatment for physical inju-
ries associated with this assault.
   On July 20, 2008, Norman received a late night “crisis
call” from Hynes, who expressed suicidal thoughts and feel-
ings of hopelessness. Concerned with Hynes’ safety, Norman
facilitated Hynes’ admission to a medical center in North
Platte, Nebraska, for treatment relating to anxiety and suicidal
thoughts, eating and sleeping disorders, and depression. She
was diagnosed with an adjustment disorder with depressed
mood and anxiety.
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                HYNES v. GOOD SAMARITAN HOSP.
                       Cite as 291 Neb. 757

   Five days later, Hynes was transferred to Two Rivers
Psychiatric Hospital (Two Rivers)—an inpatient treatment
facility in Kansas City, Missouri—in order to receive more
specialized trauma care. While at Two Rivers, Hynes under-
went psychiatric evaluations by two separate doctors and was
diagnosed with major depressive disorder and PTSD. She
remained hospitalized at Two Rivers until August 8, 2008.
   Hynes was admitted to Two Rivers a second time several
weeks later for major depressive disorder and PTSD. A psy-
chiatric evaluation was performed by a doctor who had not
previously evaluated Hynes. She was diagnosed with major
depressive disorder and PTSD with “suicidal ideas and plan.”
She was discharged on September 12, 2008, but was subse-
quently readmitted on September 16 and then discharged on
October 3.
   Later in October 2008, Hynes began treatment at a medical
center in Lincoln, Nebraska, for PTSD and depressive disorder.
From November 2008 through March 2009, Hynes had mul-
tiple hospitalizations for her psychiatric injuries.
   Subsequently, Hynes began treatment with a psychiatric
group in Lincoln. During the course of this treatment, she
was given high doses of numerous medications which ulti-
mately proved ineffective at treating her psychiatric episodes.
In March 2009, Hynes began electroconvulsive therapy to
treat her depression and PTSD. These treatments were initially
administered three times a week. The frequency of the treat-
ments was gradually reduced, but at the time of trial, Hynes
was still receiving treatments.
   In April 2009, Hynes commenced this action in the Workers’
Compensation Court. She alleged that her mental injuries
occurred in the course of her employment at Good Samaritan
and that the injuries rendered her unable to work. Good
Samaritan denied the occurrence of the second and third inci-
dents and alleged Hynes suffered no injury beyond slight bruis-
ing from being whipped by a vacuum cleaner cord. It claimed
there was insufficient medical causation for the alleged men-
tal injuries of PTSD or depression, for which Hynes sought
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                 HYNES v. GOOD SAMARITAN HOSP.
                        Cite as 291 Neb. 757

compensation. The compensation court found in favor of
Hynes. On appeal, we remanded the cause for a new trial based
on insufficiency of the record. See Hynes v. Good Samaritan
Hosp., 285 Neb. 985, 830 N.W.2d 499 (2013).
   Hynes, Hynes’ husband, and Norman testified at the second
trial. Hynes testified about the three incidents, her subsequent
therapy and treatment, and her psychological condition after
the incidents. The court also received Hynes’ medical records
and evaluations.
   Good Samaritan conceded that the initial assault on April
16, 2008, involved a physical injury during the scope of
Hynes’ employment and therefore was compensable under the
Nebraska Workers’ Compensation Act. However, it claimed that
there was no medical evidence of a physical injury in either the
second or third incident and that, therefore, any psychologi-
cal injuries that resulted from them were not compensable. It
sought to exclude any evidence relating to the second and third
incidents, arguing that neither the second nor third incident was
compensable under the Nebraska Workers’ Compensation Act
and that the evidence was, therefore, irrelevant.
   Good Samaritan sought to exclude the report of Paula
Malin, M.D., Hynes’ expert psychiatric witness. Hynes
retained Malin to provide an expert opinion regarding the
causation and extent of Hynes’ injuries. In her report, Malin
opined that Hynes suffered psychological and physical inju-
ries in the April 16, 2008, assault and that the second and
third assaults caused cumulative trauma. She also opined that
Hynes had been unable to work since July 2008. Malin based
her opinions on an in-­person evaluation of Hynes and a review
of the records of Hynes’ psychiatric treatment following the
assaults. Good Samaritan claimed that Malin’s opinions were
not relevant, because they were based in part upon the cumu-
lative effect of the second and third incidents, which Good
Samaritan claimed were not compensable under the Nebraska
Workers’ Compensation Act and therefore irrelevant. The
compensation court overruled all of Good Samaritan’s rel-
evancy objections.
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                  Nebraska A dvance Sheets
                   291 Nebraska R eports
                HYNES v. GOOD SAMARITAN HOSP.
                       Cite as 291 Neb. 757

   Good Samaritan also sought to exclude Malin’s opinions for
lack of foundation. Good Samaritan claimed that Malin lacked
the necessary facts to form a reliable opinion, because Hynes
was allegedly untruthful about her personal and psychiatric
history during her face-to-face interview with Malin. The court
overruled Good Samaritan’s foundational objection, finding
the deficiencies claimed by Good Samaritan went only to the
weight and credibility of the opinion.
   Good Samaritan offered the testimony of Terry Davis, M.D.
Davis, a psychiatrist, opined that Malin’s report lacked foun-
dation because it did not specifically reference past trauma—
including instances of sexual assault, rape, physical and mental
abuse, sexual promiscuity, and counseling for past physical and
substance abuse. Davis opined that such trauma was significant
in conducting psychiatric evaluations and forming opinions.
The court received a report from Howard Entin, M.D., the
court-appointed psychiatrist from Colorado. Entin opined that
while Hynes had a major depressive disorder, she did not meet
the criteria for PTSD and “did not experience an event that
was a significant threat to her life at work.” Entin suggested
that Hynes might have PTSD related to significant preexist-
ing stressors.
   The Workers’ Compensation Court found that Hynes was a
credible witness and generally accepted her testimony regard-
ing the three incidents. The court found that the first inci-
dent was an “accident” within the meaning of the Nebraska
Workers’ Compensation Act, that it left Hynes temporarily
totally disabled, and that she subsequently sustained a per-
manent partial disability to the body as a whole with com-
plete loss of earning power. The court accepted the opinion
of Hynes’ expert, Malin. It found that Hynes’ psychological
injury began with the first incident on April 16, 2008, and
that the second and third assaults aggravated or cumulatively
added to the injury. The court reasoned that the three assaults
created “one continuous chain through which . . . the cause
operated to produce the totality of mental illness [Hynes] is
suffering from.”
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                 HYNES v. GOOD SAMARITAN HOSP.
                        Cite as 291 Neb. 757

   The compensation court expressly rejected the opinion of
Good Samaritan’s expert, Davis, and that of Entin, the court-
appointed expert. It found that Davis’ opinion placed too much
emphasis on Hynes’ past trauma, much of which occurred
10 to 20 years prior to the incidents in the case at bar. The
court noted that Hynes was consistently employed from 1992
through 2008 without significant or relevant physical or men-
tal incident and that during this time, she married and had a
family. The court rejected Entin’s opinions, partially because
he “seemed to be using the burden’s [sic] placed upon [a
plaintiff in Colorado,] which is a burden not applicable to
[t]his case.”
   The compensation court ordered Good Samaritan to pay
Hynes the sum of $578.14 per week for 1425⁄ 7 weeks for tem-
porary total disability, and $644 per week for so long as Hynes
remained permanently and totally disabled. Good Samaritan
was also ordered to pay past and future medical bills.

                 ASSIGNMENTS OF ERROR
   Good Samaritan asserts that (1) the trial court erred in find-
ing Hynes suffered physical injury in the second and third
incidents, (2) the trial court erred in tying the three alleged
incidents together and finding that Hynes’ psychological inju-
ries flowed from some combination of them, and (3) the trial
court erred in overruling Good Samaritan’s objections to the
medical report of Hynes’ expert witness, Malin.

                          ANALYSIS
   When considered together, Good Samaritan’s assignments
of error present two issues. The first issue is whether Malin’s
opinions had sufficient foundation. Good Samaritan claims that
Malin did not possess sufficient facts to form a reliable opinion
regarding Hynes’ condition.
   The second issue is whether the compensation court erred
in considering the second and third incidents in its determina-
tion of Hynes’ disability. Good Samaritan asserts that there
was no proof Hynes suffered a physical injury in either the
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                HYNES v. GOOD SAMARITAN HOSP.
                       Cite as 291 Neb. 757

second or third incident and that, therefore, neither was inde-
pendently compensable. Consequently, Good Samaritan con-
tends that the court should not have considered these incidents
in its analysis and that Malin’s inclusion of such incidents in
her report makes her opinions irrelevant. This argument sug-
gests that each incident must be independently compensable
under the Nebraska Workers’ Compensation Act in order to
be relevant.
                         Foundation for
                         M alin’s R eport
   We first address Good Samaritan’s foundational objec-
tion to Malin’s opinions. The compensation court found that
Malin’s opinions had sufficient foundation and were credible
and reliable. The court adopted the opinions as carrying the
greater weight of evidential probability with respect to causa-
tion, diagnosis, and need for medical care. Good Samaritan
claims Malin was unaware of various pertinent facts, such
as previous psychological counseling, supposed visual and
auditory hallucinations, past work in psychiatric units at hos-
pitals, a past sexual assault, sexual promiscuity, physical and
mental abuse by a former fiance, a terminated pregnancy,
and Hynes’ continued work at Good Samaritan after the first
assault. It argues that because Malin did not consider these
facts, her opinions were based on insufficient information and,
therefore, lacked sufficient foundation and should have been
excluded. Good Samaritan claims that without Malin’s opin-
ions, Hynes has no evidence of causation and failed to meet
her burden of proof.
   [4,5] Admission of evidence is within the discretion of the
Workers’ Compensation Court, whose determination in this
regard will not be reversed upon appeal absent an abuse of
discretion. Olivotto v. DeMarco Bros. Co., 273 Neb. 672, 732
N.W.2d 354 (2007). Expert testimony should not be received
if it appears the witness is not in possession of such facts as
will enable him or her to express a reasonably accurate conclu-
sion, as distinguished from a mere guess or conjecture. City
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                 HYNES v. GOOD SAMARITAN HOSP.
                        Cite as 291 Neb. 757

of Lincoln v. Realty Trust Group, 270 Neb. 587, 705 N.W.2d
432 (2005). It is within the trial court’s discretion to determine
whether there is sufficient foundation for an expert witness to
give his or her opinion about an issue in question. American
Central City v. Joint Antelope Valley Auth., 281 Neb. 742, 807
N.W.2d 170 (2011).
   We conclude that the Workers’ Compensation Court did
not abuse its discretion in finding Malin’s opinions had suf-
ficient foundation. We reach this conclusion for several rea-
sons. First, Good Samaritan makes some factually incorrect
allegations regarding Malin’s report. It claims Malin stated
that Hynes did not experience hallucinations in her discus-
sion of symptomology, but Malin’s report notes that Hynes
exhibited “an increase in intensity of symptoms of Major
Depressive Disorder that featured frequent suicidality as well
as emergence of psychotic symptoms, including hallucina-
tions.” Malin later states: “She continues to have fluctuating
suicidality and intermittent hallucinations.” Good Samaritan
also alleges Malin was unaware that Hynes continued to work
after the first incident, which occurred on April 16, 2008, but
this is contradicted by the fact that Malin considered the sec-
ond and third assaults that occurred while Hynes worked at
Good Samaritan.
   Another basis for our conclusion is Malin’s statement that
she formed her opinions following a detailed review of Hynes’
psychiatric records. Those records detailed Hynes’ personal
and psychological history that Good Samaritan alleges was
not considered by Malin. We have previously held that for
purposes of determining whether a medical expert’s testimony
is admissible, it is acceptable, in arriving at a diagnosis, for
a physician to rely on examinations and tests performed by
other medical practitioners. Carlson v. Okerstrom, 267 Neb.
397, 675 N.W.2d 89 (2004). The defense expert, Davis, con-
ceded that he used many—if not all—of Hynes’ records as a
basis for his opinion. Regardless of whether the information
was disclosed in an in-person examination of Hynes or noted
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                 HYNES v. GOOD SAMARITAN HOSP.
                        Cite as 291 Neb. 757

in a report, we find that Malin possessed the relevant informa-
tion by virtue of her review of Hynes’ records.
   Whether Malin possessed or considered the entirety of
Hynes’ personal or psychological history in forming her opin-
ion ultimately concerns the weight to be given to Malin’s
opinions by a trier of fact, rather than the admissibility of
the opinions. An appellate court is not a superexpert and
will not lay down categorically which factors and principles
an expert may or may not consider; such matters go to the
weight and credibility of the opinion itself and not to its
admissibility. State v. Davlin, 263 Neb. 283, 639 N.W.2d 631
(2002). Malin’s opinions had sufficient foundation based on
her review of Hynes’ medical records and her in-person evalu-
ation of Hynes.

                            Causation
   We next consider Good Samaritan’s challenges to both
the compensation court’s and Malin’s consideration of the
second and third incidents in their analyses of Hynes’ inju-
ries. At trial, Good Samaritan conceded that the first incident
resulted in physical injury and was compensable. At oral argu-
ments, it conceded that the second and third incidents occurred.
However, Good Samaritan claims that Hynes failed to present
any evidence to demonstrate she suffered physical injuries
associated with the second and third incidents and that, there-
fore, neither incident is compensable. Based upon this premise,
it asserts that the second and third incidents were irrelevant to
the determination of the causation of Hynes’ injuries.
   Good Samaritan’s relevancy objection to Malin’s report was
based on Malin’s consideration of the second and third inci-
dents in forming her opinions regarding Hynes’ injuries. These
incidents were the basis of Malin’s opinion that the injury sus-
tained by Hynes in the first incident was exacerbated or aggra-
vated by those incidents. As discussed in detail below, each
incident was not required to be independently compensable to
be considered by either Malin or the court.
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   [6,7] In order to recover under the Nebraska Workers’
Compensation Act, a claimant has the burden of proving by
a preponderance of the evidence that an accident or occupa-
tional disease arising out of and occurring in the course of
employment proximately caused an injury which resulted in
disability compensable under the act. Manchester v. Drivers
Mgmt., 278 Neb. 776, 775 N.W.2d 179 (2009). A worker is
entitled to recover compensation for a mental illness if it is
a proximate result of the worker’s injury and results in dis-
ability. Id.
   [8,9] A claim for a psychological or mental condition
requires that the mental condition must be related to or caused
by the physical injury. See Zach v. Nebraska State Patrol, 273
Neb. 1, 727 N.W.2d 206 (2007). An injury caused by a mental
stimulus does not meet the requirement that a compensable
accidental injury involve violence to the physical structure of
the body. Id.
   [10] On appellate review of a workers’ compensation award,
the trial judge’s factual findings have the effect of a jury ver-
dict and will not be disturbed unless clearly wrong. Visoso
v. Cargill Meat Solutions, 285 Neb. 272, 826 N.W.2d 845
(2013). Using this standard, we first review the compensa-
tion court’s findings regarding the second incident. The court
stated: “This Court finds that [Hynes] was a credible witness
at this second trial. This Court finds the three incidents in this
case happened as [Hynes] described.” It also determined that
“[t]here is evidence that the first and second assaults involved
physical injury with psychological injury.”
   Good Samaritan argues that the compensation court erred
in finding that Hynes suffered a physical injury in the second
incident, because she did not present evidence of such injury.
We disagree. Evidence was provided by Hynes’ testimony
and the notes of her employee assistance program counselor.
Hynes testified that an assault occurred in which a patient
bit her on her forearm, causing a welt and bruises, and then
kicked her several times. The incident was reported to the
counselor, who recorded the incident and symptomology in
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her medical notes. The incident report noted bruising to
Hynes’ right forearm. That Hynes did not receive immediate
medical treatment for a physical injury does not negate the
fact that she sustained one.
   [11] Good Samaritan claims that Hynes’ testimony regarding
the assault was self-serving, suggesting that the compensation
court should not have accepted it. But this is a matter of wit-
ness credibility. As the trier of fact, the Workers’ Compensation
Court is the sole judge of the credibility of witnesses and the
weight to be given their testimony. Manchester v. Drivers
Mgmt., supra. We decline to second-guess the Workers’
Compensation Court’s acceptance of Hynes’ testimony. Good
Samaritan has not shown that the compensation court was
clearly wrong in finding that Hynes suffered a physical injury
during the second incident.
   [12-14] Next, we consider the compensation court’s inclu-
sion of the third incident in its causation analysis. The issue is
whether the court erred in considering the incident in its cau-
sation analysis notwithstanding the fact that the incident was
not independently compensable. Good Samaritan claims that
the court erred in “tying the three alleged incidents together
and finding that [Hynes’] psychiatric issues flowed from some
combination of them.” The determination of causation is ordi-
narily a matter for the trier of fact. Mendoza v. Omaha Meat
Processors, 225 Neb. 771, 408 N.W.2d 280 (1987). When the
question is whether compensability should be extended to a
subsequent injury or aggravation related in some way to the
primary injury, the rules that come into play are essentially
based upon the concepts of “direct and natural results.” Stacy
v. Great Lakes Agri Mktg., 276 Neb. 236, 753 N.W.2d 785
(2008). A cause of an injury may be a proximate cause, not-
withstanding that it acted through successive instruments of a
series of events, if the instruments or events were combined
in one continuous chain through which the force of the cause
operated to produce the disaster. Id.
   The compensation court found that “[t]he first (with physi-
cal injury) and the second and third incidents can combine in
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one continuous chain through which the force of the cause
operated to produce the totality of mental illness [Hynes] is
suffering from.” It further reasoned:
         Although the third incident may not be an accident
     within the meaning of the Nebraska Worker’s [sic]
     Compensation Act (if it were the only incident and not the
     third this would be an issue) the result of the continued
     abuse which happened in the workplace on the underlying
     compensable mental injury is compensable.
         ....
         . . . The Court does not view [Hynes’] claim to be
     for three separate accidents but rather . . . as an initial
     accident with two subsequent incidents which aggravated
     or cumulatively added to the damage and injury to [her]
     mental health which began with the first accident. In this
     regard there is clear evidence that the first assault with
     physical injury caused immediate mental difficulties for
     which [Hynes] sought treatment. There is evidence that
     the first and second assaults involved physical injury
     with psychological injury. . . . There is evidence in the
     record to support a finding that the third assault aggra-
     vated the preceding compensable injuries all of which
     injuries are compensable under the Nebraska Workers’
     Compensation Act.
   The parties stipulated that the April 16, 2008, assault
involved a physical injury and was independently compen-
sable. In its analysis, the Workers’ Compensation Court found
that Hynes was not mentally stable or healthy after the first and
second incidents and that her mental health deteriorated. This
determination was not clearly wrong. A separate compensable
injury for each and every work aggravation is not required if
the initial cause of the injuries is a direct and natural result
of the compensable injury. See Stacy v. Great Lakes Agri
Mktg., supra.
   Good Samaritan claims the facts of the present case are
similar to Sweeney v. Kerstens & Lee, Inc., 268 Neb. 752, 688
N.W.2d 350 (2004). We disagree. In Sweeney, the employee’s
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                 HYNES v. GOOD SAMARITAN HOSP.
                        Cite as 291 Neb. 757

depression was entirely attributable to a loss of earning capac-
ity report that the employee believed would have a negative
impact on the litigation. There was no physical injury that
was related to the employee’s depression. We found that the
worker’s litigation stress was an intervening event which broke
the causal connection between his depression and the original
work-related accident and that, therefore, the psychological
injury was unconnected to a physical injury. We distinguished
Sweeney from our decision in Kraft v. Paul Reed Constr. &
Supply, 239 Neb. 257, 475 N.W.2d 513 (1991), in which we
affirmed an award of workers’ compensation benefits to a
worker whose traumatic neurosis was attributed to both his
physical injury and the psychological loss resulting from the
worker’s immobility and inability to work.
   In the case at bar, the psychological injuries resulted directly
from an assault in which Hynes suffered a physical injury. The
causation opinion was that Hynes’ psychological injuries were
the result of the physical injuries sustained during the assaults.
In Malin’s report, she stated:
      It is my opinion beyond a reasonable degree of medi-
      cal and psychiatric certainty that . . . Hynes sustained
      both physical and psychological injury as a proximate
      result of the work-related assaults detailed in medical
      records. . . .
         The first assault on April 16, 2008, . . . resulted in both
      physical and psychological injury. . . .
         ....
         . . . Hynes went on to experience two other assaults by
      patients in May and June 2008 . . . . These caused cumu-
      lative trauma to her already fragile [PTSD] as had been
      rendered with the April assault.
   Malin noted that “[t]he psychological injury that . . . Hynes
sustained from this first assault . . . was apparent almost
immediately.” Hynes reported difficulty sleeping and eating
and having fear of returning to the unit where the assault
occurred. The symptoms worsened with persistent flashbacks
and greatly affected her personal, occupational, and social
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                HYNES v. GOOD SAMARITAN HOSP.
                       Cite as 291 Neb. 757

functioning. Malin determined those symptoms were consist­
ent with acute stress disorder and PTSD, which eventually led
to a major depressive disorder requiring several hospitaliza-
tions. She opined that Hynes was extremely cooperative with
the evaluation and did not exhibit any common features of
malingering. She further opined that Hynes has been unable to
work since July 2008 and that all of Hynes’ medical treatment
and therapy needs were caused as a result of the injuries—both
physical and psychological—that she sustained in the course of
her employment.
   [15,16] Good Samaritan argues, “At issue is whether there
was sufficient competent evidence to support [Hynes’] alleged
mental injuries . . . .” Brief for appellant at 1-2. In testing
the sufficiency of evidence to support findings of fact made
by the compensation court after rehearing, the evidence must
be considered in the light most favorable to the successful
party and the successful party will have the benefit of every
inference reasonably deducible from the evidence. Miller v.
E.M.C. Ins. Cos., 259 Neb. 433, 610 N.W.2d 398 (2000). If
the record contains evidence to substantiate the factual con-
clusions reached by the trial judge in workers’ compensation
cases, we are precluded from substituting our view of the
facts for that of the compensation court. Pearson v. Archer-
Daniels-Midland Milling Co., 285 Neb. 568, 828 N.W.2d
154 (2013).
   The record contains ample evidence to support the Workers’
Compensation Court’s findings. This includes Hynes’ testi-
mony as to the facts surrounding her injuries. The court
found that “[Hynes] was consistently employed from 1992
through 2008 without significant or relevant incident either
physical or mental. During this time she worked, was mar-
ried and had a family.” There is no indication that Hynes
experienced symptoms of PTSD, major depressive disorder,
or any other significant psychiatric problems in the 15 years
prior to the initial assault in April 2008. Nor did she have
any issues related to substance abuse in the decade prior to
her injuries. Hynes required extensive treatment following the
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                 HYNES v. GOOD SAMARITAN HOSP.
                        Cite as 291 Neb. 757

three incidents, including electroconvulsive therapy, which
Malin stated is “a treatment option of last resort for Major
Depressive Disorders.” We find sufficient evidence to support
the court’s determination that Hynes’ injuries arose as a result
of her work-related accident.
   [17] Regarding the medical evidence, the compensation
court found that Malin’s evaluation was credible and reliable,
and it adopted and relied upon her opinions. Malin opined
that the treatment Hynes received was directly related to the
assaults, that she has been incapable of working since the
assaults, and that she will require future treatment. It is the
role of the Workers’ Compensation Court as the trier of fact to
determine which, if any, expert witnesses to believe. Ludwick
v. TriWest Healthcare Alliance, 267 Neb. 887, 678 N.W.2d
517 (2004).
   [18] The Workers’ Compensation Court was not clearly
wrong in finding that Hynes’ injuries were the result of the
initial “accident” which occurred on April 16, 2008, with two
subsequent incidents that aggravated or cumulatively added to
the injury. Where the evidence is sufficient to permit the trier
of fact to find that a psychological injury is directly related to
the accident and the employee is unable to work, the employee
is entitled to be compensated. Worline v. ABB/Alstom Power
Int. CE Servs., 272 Neb. 797, 725 N.W.2d 148 (2006).
                         CONCLUSION
   The Workers’ Compensation Court was not clearly wrong
in finding that Hynes suffered from major depressive disorder
and PTSD as a result of her injury while working for Good
Samaritan and that she was left permanently and totally dis-
abled as a result. For the reasons stated above, we affirm the
award of the compensation court.
                                                   A ffirmed.
   Stephan, J., not participating.
