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  DOLORES WILSON v. MAEFAIR HEALTH CARE
             CENTERS ET AL.
                (AC 35976)
                   Alvord, Mullins and Bear, Js.
   Argued November 13, 2014—officially released February 10, 2015

  (Appeal from the Workers’ Compensation Review
                     Board)
  Timothy D. Ward, for the appellant (defendant Gal-
lagher Bassett Services).
  Vincent Di Palma, for the appellee (defendant Lib-
erty Mutual Insurance Company).
                          Opinion

   ALVORD, J. This workers’ compensation appeal
arises out of a dispute between two defendant insurers,
Liberty Mutual Insurance Company (Liberty Mutual)
and Gallagher Bassett Services (Gallagher Bassett), as
to which of them is responsible for surgical expenses
and disability benefits arising from an injury sustained
by the plaintiff, Dolores Wilson, on March 22, 2011,
while she was employed as a certified nursing assistant
with the defendant Maefair Health Care Centers (Mae-
fair).1 Gallagher Bassett appeals from the decision of
the Workers’ Compensation Review Board (board)
affirming the findings and award of the Workers’ Com-
pensation Commissioner for the Fourth District (com-
missioner), who determined that Gallagher Bassett was
solely responsible for Wilson’s expenses and benefits.
On appeal, Gallagher Bassett claims that the board
improperly affirmed the decision of the commissioner
because the commissioner (1) made findings of fact
that were not supported by the medical evidence, (2)
erroneously determined that Wilson’s March 22, 2011
injury ‘‘was causative of [Wilson’s] need for surgery,’’
and (3) made factual findings that were inconsistent
with the evidence in the record.2 We affirm the decision
of the board.
   The record reveals the following facts, either undis-
puted or as found by the commissioner, and procedural
history. Wilson commenced employment with Maefair
as a certified nursing assistant in October, 2000. In 2006,
Wilson sustained a work related injury to her neck.
After a brief period of medical treatment, she resumed
her duties without any restrictions. On April 4, 2010,
she sustained a second work related injury to her neck.
Wilson sought medical treatment, and the doctor who
treated her noted that her pain radiated into her left
hand and finger. Wilson initially was unable to work
after the April 4, 2010 incident, but subsequently
returned to her position several days later without any
restrictions. She continued to receive chiropractic treat-
ment from April 9, 2010 through August 4, 2010, at which
time she reported that her condition had significantly
improved and that she no longer had pain in her neck
or arm. She did note that she continued to experience
numbness from her left elbow to her first three fingers,
but she reported that she was not taking any medi-
cation.
  Wilson, at her doctor’s request, underwent an MRI
on August 7, 2010, which revealed multiple levels of
degenerative cervical disc disease. She was referred
to Mark E. Wilchinsky, a board certified physician in
orthopedic surgery. Dr. Wilchinsky noted that Wilson
was experiencing pain that radiated from her neck
down to the radial three digits of her left hand, and that
Wilson reported that she was beginning to experience
similar symptoms with respect to her right hand. Dr.
Wilchinsky noted that Wilson’s reflexes were symmetri-
cally decreased; he did not note hyperflexia3 or clonus4
at that time. He believed Wilson was a surgical candi-
date and referred her to Abraham Mintz, a neurosur-
geon, for a second opinion, but he indicated that she
could continue with her present job duties. Liberty
Mutual, then Maefair’s workers’ compensation insur-
ance carrier, did not authorize Wilson’s appointment
with Dr. Mintz, and, therefore, she did not meet with
him in 2010.5 After August, 2010, she received no further
medical treatment for her neck injury until she reinjured
her neck in March, 2011.
  Despite ongoing symptoms that extended from her
neck into her left arm and fingers, Wilson continued
to perform her duties at Maefair, although with some
difficulty, without work restrictions. On March 22, 2011,
while assisting a patient, Wilson sustained another work
related injury to her neck. At this point, Gallagher Bas-
sett was Maefair’s workers’ compensation insurance
carrier. Wilson immediately sought medical treatment,
was diagnosed with a cervical sprain, and was restricted
to light duty work. On April 5, 2011, Wilson returned
to Dr. Wilchinsky, who found that her reflexes were
symmetrically increased. He stated that she needed cer-
vical disc surgery6 and again referred her to Dr. Mintz
for a neurological evaluation. Although Dr. Wilchinsky
continued Wilson’s light duty work restrictions, Maefair
was unable to accommodate Wilson’s needs after a
short period of time, and, thus, she ceased employment
with it. She has made diligent efforts to secure employ-
ment elsewhere, but has been unsuccessful in finding
work within her physical limitations.
   Dr. Mintz met with Wilson on August 12, 2011. At
that time, he recommended a multilevel anterior cervi-
cal disc excision and fusion. Dr. Mintz opined that Wil-
son had ‘‘additional findings’’ that were not noted to
have existed in 2010. He specifically found that she had
weakness in her left upper extremity, that her reflexes
were diffusely hyperactive, and that she had Hoffman
signs7 bilaterally. He additionally opined that, based on
the MRI scan of August, 2010, Wilson had been a surgical
candidate prior to the March 22, 2011 incident.
   At the request of Liberty Mutual, Wilson underwent
an examination with John G. Strugar, a board certified
neurosurgeon, on January 11, 2012. Dr. Strugar opined,
as did Dr. Wilchinsky and Dr. Mintz, that Wilson had
been a surgical candidate prior to the March 22, 2011
incident. Although Wilson had underlying cervical disc
disease, Dr. Strugar believed that the injuries she sus-
tained in the April 4, 2010 and March 22, 2011 incidents
both were substantial factors in causing her need for
surgery much sooner than would otherwise have been
necessary. Dr. Strugar opined that the April 4, 2010
incident was 30 percent responsible for Wilson’s need
for surgery, the March 22, 2011 incident was 10 percent
responsible for her need for surgery, and Wilson’s
underlying cervical disc disease was 60 percent respon-
sible for her need for surgery.
   The hearing before the commissioner was held on
February 15, 2012. In addition to medical evaluations
by Dr. Wilchinsky, Dr. Mintz, and Dr. Strugar,8 the com-
missioner heard testimony from Wilson. Wilson testi-
fied that the 2006 injury to her neck did not debilitate
her in any way. She further testified that the April 4,
2010 injury caused her to miss a few days of work, but
that she returned to her position without any restric-
tions until the March 22, 2011 incident. After the April
4, 2010 incident, Wilson stated that she had had some
symptoms in her right arm that became worse after
the March 22, 2011 incident. After the March 22, 2011
incident, Wilson testified that her new symptoms
included constant numbness in her right arm and
cramping of her hand. Additionally, Wilson stated that
she was given light duty work restrictions after the
March 22, 2011 incident, and that she had had no work
restrictions prior to the March 22, 2011 incident.
   The commissioner issued her findings and award on
August 7, 2012. In addition to making the factual find-
ings as previously discussed, the commissioner stated
that she found Wilson to be ‘‘credible and persuasive.’’
The commissioner further found: (1) Wilson’s work
related injuries sustained in the April 4, 2010 and March
22, 2011 incidents were responsible for her need for
cervical surgery; (2) the surgery proposed by Dr. Mintz
was reasonable and necessary; (3) Wilson had ‘‘addi-
tional findings’’ in August, 2011, that were not noted to
have existed in 2010; (4) the March 22, 2011 incident
probably aggravated Wilson’s preexisting condition; (5)
the March 22, 2011 incident ‘‘was an identifiable second
injury that worsened [Wilson’s] condition and adversely
affected her ability to work’’; (6) ‘‘despite the fact that
[Wilson] may have been a surgical candidate prior to
the March 22, 2011 incident, the totality of the circum-
stances indicate that that incident caused [Wilson’s]
condition to worsen in a material and substantial way’’;
and (7) ‘‘Gallagher Bassett is responsible for [Wilson’s]
injuries after March 22, 2011.’’ The commissioner
ordered Gallagher Bassett ‘‘to accept liability for [Wil-
son’s] injury of March 22, 2011 and . . . to authorize
surgery and pay [Wilson] temporary partial disability
benefits commencing June 27, 2011, and continuing pur-
suant to job searches.’’
  Gallagher Bassett filed a motion to correct the com-
missioner’s findings, which was denied on August 30,
2012. Gallagher Bassett then filed a petition for review
with the board. A hearing was held on January 18, 2013.
The gravamen of its claim was that the March 22, 2011
incident was not a substantial contributing factor with
respect to Wilson’s need for surgery. Counsel for Gal-
lagher Bassett argued that all three physicians testified
that the March 22, 2011 incident was less than a substan-
tial contributing factor, and that, therefore, the commis-
sioner could not find contrary to their expert opinions.
The board’s chairman inquired whether the substantial
factor standard was a medical or a legal determination,
and counsel for Gallagher Bassett responded that it
was both.
   The board issued its decision on August 8, 2013, in
which it concluded: ‘‘The precedent in Hatt [v. Burl-
ington Coat Factory, 263 Conn. 279, 819 A.2d 260
(2003)] places the burden of the claimant’s medical
condition on the more recent compensable injury when
it renders the claimant’s disability materially and sub-
stantially greater than prior to the injury. We believe a
reasonable fact finder could reach this conclusion from
the evidence on the record. As an appellate panel, we
cannot revisit this decision.’’ Accordingly, the board
affirmed the commissioner’s decision. This appeal
followed.
   The principles that govern our standard of review in
workers’ compensation appeals are well established.
‘‘The commissioner is the sole trier of fact and [t]he
conclusions drawn by [the commissioner] from the
facts found must stand unless they result from an incor-
rect application of the law to the subordinate facts or
from an inference illegally or unreasonably drawn from
them. . . . The review [board’s] hearing of an appeal
from the commissioner is not a de novo hearing of the
facts. . . . [I]t is [obligated] to hear the appeal on the
record and not retry the facts. . . . On appeal, the
board must determine whether there is any evidence
in the record to support the commissioner’s findings
and award. . . . Our scope of review of [the] actions
of the [board] is [similarly] . . . limited. . . . [How-
ever] [t]he decision of the [board] must be correct in
law, and it must not include facts found without evi-
dence or fail to include material facts which are admit-
ted or undisputed.’’ (Internal quotation marks omitted.)
Sierra v. C & S Wholesale Grocers, Inc., 128 Conn. App.
78, 81–82, 16 A.3d 1240, cert. denied, 301 Conn. 924, 22
A.3d 1279 (2011).
   As correctly determined by the board in this case,
the responsibility for the payment of Wilson’s surgical
expenses and disability benefits is controlled by the
language of General Statutes § 31-349, as construed by
our Supreme Court in Hatt v. Burlington Coat Factory,
supra, 263 Conn. 279. Section 31-349 (a) provides in
relevant part: ‘‘The fact that an employee has suffered
a previous disability, shall not preclude him from com-
pensation for a second injury . . . . If an employee
having a previous disability incurs a second disability
from a second injury resulting in a permanent disability
caused by both the previous disability and the second
injury which is materially and substantially greater than
the disability that would have resulted from the second
injury alone, he shall receive compensation for (1) the
entire amount of disability, including total disability,
less any compensation payable or paid with respect to
the previous disability, and (2) necessary medical care
. . . notwithstanding the fact that part of the disability
was due to a previous disability . . . .’’ Section 31-349
(d) provides: ‘‘Notwithstanding the provisions of this
section, no injury which occurs on or after July 1, 1995,
shall serve as a basis for transfer of a claim to the
Second Injury Fund under this section. All such claims
shall remain the responsibility of the employer or its
insurer under the provisions of this section.’’
   In Hatt, our Supreme Court was asked to determine
whether § 31-349 abrogated common-law apportion-
ment in cases involving a separate and distinct second
injury and whether the insurer at the time of the second
injury retained sole liability for the second injury claim.
Hatt v. Burlington Coat Factory, supra, 263 Conn. 289.
The facts in Hatt are similar to the facts in the present
case. The claimant in Hatt had suffered two distinct
injuries to her left foot while working for the same
employer. Id., 284–85. The employer, however, had
changed workers’ compensation insurance carriers dur-
ing the time between the first and second injuries, and
the question arose as to whether there could be appor-
tionment between the two insurers whose coverage did
not overlap. Id., 285–86. The court held that apportion-
ment was not appropriate when there was a second
distinct injury and that the second insurer retained sole
liability for the second injury. Id., 312.
   Gallagher Bassett argues that the commissioner and
the board erroneously applied the holding in Hatt to
the facts in the present case because Wilson’s current
condition (1) was not caused by both the April 4, 2010
and March 22, 2011 injuries, and (2) was not ‘‘materially
and substantially greater than the disability that would
have resulted’’ from the March 22, 2011 injury alone.
Because Dr. Wilchinsky, Dr. Mintz, and Dr. Strugar all
agreed that Wilson was a surgical candidate prior to
the March 22, 2011 incident, Gallagher Bassett claims
that the March 22, 2011 injury could not have been a
substantial factor in her need for cervical disc surgery.
To conclude otherwise, it claims, goes against the evi-
dence presented and is contrary to expert opinion.
Moreover, Gallagher Bassett argues that ‘‘all three phy-
sicians in this case testified that the [March 22] 2011
injury was not a substantial factor in bringing about
the need for surgery.’’ (Emphasis added.) We are not
persuaded.
   As a threshold matter, we note that the determination
of whether the substantial factor test has been satisfied
is a question of fact. ‘‘[T]raditional concepts of proxi-
mate cause furnish the appropriate analysis for
determining causation in workers’ compensation cases.
. . . [T]he test for determining whether particular con-
duct is the proximate cause of an injury [is] whether
it was a substantial factor in producing the result.’’
(Internal quotation marks omitted.) Marandino v. Pro-
metheus Pharmacy, 105 Conn. App. 669, 678, 939 A.2d
591 (2008), rev’d in part on other grounds, 294 Conn.
564, 986 A.2d 1023 (2010). ‘‘[C]onsidering that what
constitutes a substantial factor will . . . vary with the
circumstances of each case, an attempt to articulate a
more precise standard may, in practice, be unnecessar-
ily restrictive, and may inadvertently foreclose a claim-
ant’s right to compensation. . . . The criticism . . .
usually leveled at the [substantial factor] test . . . is
that . . . it is too general. . . . The answer is that the
formula cannot be reduced to any lower terms. . . . It
presents a question of fact. . . . The answer to any
such [question] when proposed to [the commissioner]
must be found by the [commissioner] after a consider-
ation of all the facts that bear upon it. . . . If reason-
able minds can disagree as to whether the [claimant]
has satisfied her burden of establishing proximate cause
. . . we will not disturb the commissioner’s finding
even if we might reach a different conclusion.’’ (Cita-
tions omitted; internal quotation marks omitted.) Sapko
v. State, 305 Conn. 360, 392, 44 A.3d 827 (2012).
   In the present case, tracking the express language of
§ 31-349 (a), the commissioner concluded that the
March 22, 2011 incident ‘‘caused [Wilson’s] condition to
worsen in a material and substantial way.’’ (Emphasis
added.) The evidence in the record supports the com-
missioner’s determination: (1) Wilson received no medi-
cal treatment for her neck from August, 2010, until
the March 22, 2011 incident; (2) after the April 4, 2010
incident, Wilson returned to work without restrictions;
(3) after the March 22, 2011 incident, Wilson was given
light duty restrictions; (4) Dr. Wilchinsky testified that
the March 22, 2011 injury aggravated her preexisting
condition and ‘‘made it worse’’; (5) Dr. Wilchinsky
opined that the March 22, 2011 injury probably was 10
percent responsible for Wilson’s current condition; (6)
Dr. Mintz noted that Wilson had additional symptoms
in August, 2011, that had not been observed in 2010,
including hyperreflexia and Hoffman signs; (7) Dr. Stru-
gar testified that the April 4, 2010 and March 22, 2011
injuries both were substantial factors in the treatment
required for her current condition; (8) Dr. Strugar testi-
fied that Wilson exhibited symptoms of hyperreflexia,
clonus, and Hoffman signs after March 22, 2011; (9) Dr.
Strugar opined that the March 22, 2011 incident was 10
percent responsible for Wilson’s need for surgery;9 (10)
Wilson testified that she had had some symptoms in
her right arm prior to the March 22, 2011 incident, but
that those symptoms became worse after that incident;
(11) Wilson testified that she was constantly experienc-
ing numbness down her arm and cramping in her hand
after the March 22, 2011 incident, which she had not
experienced prior to that incident; and (12) Wilson
explained that she was limited to five pounds of lifting
after the March 22, 2011 incident, which precluded her
from lifting, pulling, or pushing patients.
    The evidence presented was sufficient for the com-
missioner to conclude that the March 22, 2011 incident
caused Wilson’s condition to worsen in a material and
substantial way. As correctly summarized by the board,
‘‘[t]he evidence herein is that [Wilson] had a work capac-
ity prior to the 2011 injury and subsequent to that injury,
was unable to continue to perform the job that she
had been performing after her 2010 injury.’’ Although
Gallagher Bassett argues that the March 22, 2011 injury
was not as serious or severe as the April 4, 2010 injury,
thereby precluding the finding that it was a substantial
factor in her need for surgery, we agree with the board
that ‘‘[n]either § 31-349 nor the language of the Hatt
decision makes an exception for cases in which the
first injury is much more serious than the second
injury.’’ Kelly v. Dunkin Donuts, No. 4621, CRB 4-03-2
(April 5, 2004).
   Gallagher Bassett also argues that the commissioner
substituted her own opinion for the opinions of the
medical experts because ‘‘all three physicians in this
case testified that the [March 22] 2011 injury was not
a substantial factor in bringing about the need for sur-
gery.’’ This argument fails. At the outset, we do not
find that this assertion is totally accurate when the
testimony of Dr. Wilchinsky, Dr. Mintz, and Dr. Strugar
is read as a whole.10
  During Dr. Wilchinsky’s deposition, he was asked by
counsel for Gallagher Bassett whether it was fair to
describe the March 22, 2011 incident ‘‘as a factor, but
not a substantial contributing factor, to the necessity
of surgery in this case, given that [Wilson] was already
a surgical candidate?’’ Dr. Wilchinsky responded that
he did not ‘‘know how to quantify that,’’ although he
did acknowledge that he would have recommended
surgery prior to the March 22, 2011 incident. After sev-
eral more questions, Dr. Wilchinsky agreed with coun-
sel’s statement that the March 22, 2011 injury was a
factor, but not a substantial contributing factor given
the fact that she already was a surgical candidate.
   During the deposition of Dr. Mintz, counsel for Gal-
lagher Bassett asked: ‘‘[Y]our initial opinion was that
the March 22, 2011 incident was not a substantial factor
in bringing about the need for surgery?’’ Dr. Mintz
responded: ‘‘I did not say that.’’ After several additional
attempts to have Dr. Mintz characterize the March 22,
2011 injury as a factor but not a substantial factor in
bringing about the need for surgery, Dr. Mintz said:
‘‘Look, you’re playing with words.’’ Eventually, he
responded ‘‘correct’’ to counsel’s characterization of the
March 22, 2011 incident as being ‘‘somewhere between a
factor and a substantial factor.’’ When further pressed
as to whether the March 22, 2011 incident could be
deemed a ‘‘substantial factor,’’ Dr. Mintz responded:
‘‘So again, I feel somewhat uncomfortable because I
am being caught in a war of words.’’
   When Dr. Strugar was asked during his deposition
whether the April 4, 2010 and March 22, 2011 injuries
aggravated Wilson’s preexisting condition, he testified
that ‘‘[b]oth injuries are substantial factors in her requir-
ing treatment of her current condition . . . .’’ When
counsel for Gallagher Bassett questioned whether the
latter injury could be placed somewhere between a
factor and a substantial factor, Dr. Strugar acquiesced
in counsel’s characterization. Later, however, he opined
that the April 4, 2010 and the March 22, 2011 incidents
were 40 percent responsible for Wilson’s need for sur-
gery, and that the March 22, 2011 incident alone was
10 percent responsible for her need for surgery. Dr.
Strugar finally questioned counsel: ‘‘Is that substantial
enough? Is 40 percent substantial?’’
  A review of the depositions in their entirety reveals
that the physicians were uncomfortable in being forced
to characterize the March 22, 2011 injury as either a
factor or a substantial factor in Wilson’s need for sur-
gery. Moreover, counsel for Gallagher Bassett did not
offer a definition of ‘‘substantial factor’’ for the physi-
cians to use in proffering their opinions. All three physi-
cians clearly opined that the March 22, 2011 incident
played a part in Wilson’s current condition, worsening
the symptoms that she had suffered prior to the latter
incident. As to whether it was a ‘‘substantial factor,’’ that
determination properly was left to the commissioner to
make after hearing and weighing all of the evidence pre-
sented.11
  Accordingly, for all of the foregoing reasons, we con-
clude that the commissioner’s determination finds sup-
port in the record, and, therefore, the board did not err
in affirming the commissioner’s findings and award.
  The decision of the Workers’ Compensation Review
Board is affirmed.
      In this opinion the other judges concurred.
  1
     Wilson, did not file a brief in this appeal, which centers on the dispute
between Liberty Mutual and Gallagher Bassett, the workers’ compensation
insurance carriers for Maefair at the time of Wilson’s various injuries.
   2
     Because these three claims are interrelated, we address them together.
   3
     John G. Strugar, a board certified neurosurgeon who testified in this case,
defined hyperflexia, also referred to as hyperreflexia, as unusual reflexes that
are indicative of spinal cord compression in some patients.
   4
     Dr. Strugar; see footnote 3 of this opinion; defined clonus as an abnormal
finding that is indicative of spinal cord compression.
   5
     As part of the commissioner’s decision, she made the following order:
‘‘Further hearings will be held regarding the appropriate sanctions for . . .
Liberty Mutual’s undue and unreasonable delay in failing to authorize the
recommended evaluation with Dr. Mintz.’’
   6
     Although Dr. Wilchinsky maintained that it was difficult to quantify, he
indicated that he would probably attribute 10 percent of her condition at
that time to the March 22, 2011 incident.
   7
     Dr. Strugar; see footnote 3 of this opinion; defined a Hoffman sign as
an abnormal reflex in the upper extremities, which is indicative of spinal
cord compression above the level of the fifth cervical vertebrae.
   8
     Prior to the issuance of the commissioner’s findings and award on August
7, 2012, the commissioner received Wilson’s medical records, information
relative to Wilson’s search for employment opportunities, the deposition
transcript of Dr. Wilchinsky, the deposition transcript of Dr. Mintz, and the
deposition transcript of Dr. Strugar as exhibits.
   9
     As previously noted, Dr. Strugar opined that Wilson’s underlying cervical
disc disease was 60 percent responsible for her need for surgery. The com-
missioner credited his testimony. Her preexisting condition, however, does
not negate the finding that her March 22, 2011 injury was a substantial factor
in her need for surgery. It is well established that ‘‘an employer takes the
employee in the state of health in which it finds the employee. . . . [A]n
injury received in the course of the employment does not cease to be one
arising out of the employment merely because some infirmity due to disease
has originally set in action the final and proximate cause of the injury.’’
(Citation omitted; internal quotation marks omitted.) Blakeslee v. Platt
Bros. & Co., 279 Conn. 239, 245–46, 902 A.2d 620 (2006). ‘‘If the injury is
the cause of the disability, it is compensable even though such an injury
might not have caused the disability if occurring to a healthy employee or
even an average employee.’’ Mages v. Alfred Brown, Inc., 123 Conn. 188,
192, 193 A. 780 (1937).
   10
      ‘‘Whether an expert’s testimony is expressed in terms of a reasonable
probability that an event has occurred does not depend [on] the semantics
of the expert or his use of any particular term or phrase, but rather, is
determined by looking at the entire substance of the expert’s testimony.’’
(Internal quotation marks omitted.) Marroquin v. F. Monarca Masonry, 121
Conn. App. 400, 419, 994 A.2d 727 (2010).
   11
      We agree with the board’s position that it was the responsibility of the
commissioner to make the determination whether the substantial factor test
had been satisfied. The commissioner, after reviewing the expert testimony
and all of the other evidence presented in this matter, concluded that the
March 22, 2011 incident had caused Wilson’s condition to ‘‘worsen in a
material and substantial way.’’ The commissioner’s determination was a
legal determination based upon the medical evidence that she credited.
   It is also important to note that ‘‘[i]t [is] within the commissioner’s discre-
tion to credit all, part or none of the expert testimony presented at the
hearing.’’ Dixon v. United Illuminating Co., 57 Conn. App. 51, 59, 748 A.2d
300, cert. denied, 253 Conn. 908, 753 A.2d 940 (2000).
