Stowell v. Dandade ( 2017 )


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    1        IN THE COURT OF APPEALS OF THE STATE OF NEW MEXICO
    2 R.R., a minor child, by and through
    3 HEATHER STOWELL, as parent
    4 and next friend,
    5          Plaintiff-Appellant,
    6 v.                                                                                   No. 34,998
    7 TUSHAR DANDADE, M.D.,
    8          Defendant-Appellee.
    9 APPEAL FROM THE DISTRICT COURT OF SANDOVAL COUNTY
    10 Valerie A. Huling, District Judge
    11 Law Offices of James P. Lyle, P.C.
    12 James P. Lyle
    13 Albuquerque, NM
    14 for Appellant
    15   Rodey, Dickason, Sloan, Akin & Robb, P.A.
    16   Jocelyn Drennan
    17   Edward Ricco
    18   Albuquerque, NM
    19   Hinkle Shanor LLP
    20   Kathleen Wilson
    21   Hari-Amrit Khalsa
    22   Albuquerque, NM
    1 for Appellee
    2                             MEMORANDUM OPINION
    3 VARGAS, Judge.
    4   {1}   This is an appeal from the district court’s decision to exclude the opinion
    5 testimony of Plaintiff Heather Stowell’s only expert witness, a pharmacologist, as to
    6 the cause of her minor child’s neurodegenerative disorder. Plaintiff also appeals the
    7 district court’s entry of summary judgment in favor of Defendant Tushar Dandade,
    8 M.D., following the exclusion of Plaintiff’s expert. As discussed below, we conclude
    9 that the district court did not err by excluding the testimony of Plaintiff’s expert
    10 pharmacologist; and, absent other expert medical testimony on causation, the district
    11 court’s entry of summary judgment for Defendant was proper.
    12 BACKGROUND
    13   {2}   After becoming pregnant with her first child in 2008, Plaintiff sought prenatal
    14 treatment from Defendant. During the course of her pregnancy, Defendant prescribed
    15 Zoloft to Plaintiff. Zoloft is a selective serotonin reuptake inhibitor (SSRI) used to
    16 treat disorders such as depression and anxiety.
    17   {3}   Plaintiff gave birth to a baby girl, (R.R.) in April 2009. At birth, R.R. appeared
    18 to be a normal, healthy child with no apparent medical problems. Around age one,
    19 however, R.R. began displaying symptoms of neurodegeneration, which have steadily
    2
    1 continued. Genetic and metabolic testing have failed to identify a cause for R.R.’s
    2 condition.
    3   {4}   Plaintiff filed suit against Defendant, claiming that the Zoloft he prescribed and
    4 she took during her pregnancy was the cause of R.R.’s neurodegenerative disorder.
    5 In support of her claim, Plaintiff named Dr. Patrick Ronaldson, Ph.D., as her only
    6 expert witness to testify about the medical causation of R.R.’s condition and damages.
    7   {5}   Dr. Ronaldson holds a Ph.D. in pharmacology, but is not a medical doctor and
    8 is not licensed to diagnose medical conditions. As part of his testimony, Dr.
    9 Ronaldson explained that he did not intend to offer opinions on the medical diagnosis
    10 of R.R. Instead, his testimony was limited to the etiology of R.R.’s neurodegenerative
    11 condition, specifically, the biological mechanisms that could have caused the
    12 symptoms that are apparent in R.R.
    13   {6}   In support of his theory that Zoloft was the cause of R.R.’s neurodegenerative
    14 disorder, Dr. Ronaldson explained, “[T]here is evidence in the scientific literature that
    15 hypoxia, including fetal hypoxia, can be caused by in utero exposure to SSRIs
    16 including [Zoloft].” According to Dr. Ronaldson, hypoxia can cause neurological
    17 damage; periventricular leukomalacia (PVL) is an established biomarker of hypoxia;
    18 and there are three references in R.R.’s very substantial medical records to PVL.
    19 These three references, along with Dr. Ronaldson’s understanding that board-certified
    3
    1 geneticists who had examined R.R. had ruled out a genetic cause for R.R.’s condition,
    2 form the basis of Dr. Ronaldson’s opinion. In arriving at his conclusion, Dr.
    3 Ronaldson did not review R.R.’s testing images or actual lab results. Instead, he
    4 reviewed reports from the geneticists and radiologists who treated R.R.
    5   {7}   Dr. Ronaldson conceded that none of the studies on which he relied to reach his
    6 opinion demonstrate that Zoloft can cause a neurodegenerative disorder with the
    7 symptoms of those exhibited by R.R. He further admitted that no study to date
    8 supports his exact hypothesis.
    9   {8}   In support of his motion to exclude Dr. Ronaldson’s testimony, Defendant
    10 presented evidence from R.R.’s treating pediatric geneticist and from his own expert
    11 geneticist and teratologist that a genetic explanation for R.R.’s neurodegenerative
    12 condition had not been ruled out and was the likely cause of R.R.’s condition. Dr.
    13 Randall Heidenreich, Chief of the Division of Pediatric Genetics at the University of
    14 New Mexico, evaluated R.R. in an attempt to identify a genetic cause for her
    15 condition. He was unable to identify a specific genetic basis for her
    16 neurodegeneration; however, Dr. Heidenreich continues to strongly believe that R.R.
    17 suffers from a genetic alteration that might be identified using exome or genome
    18 sequencing that has not yet been performed on R.R.
    4
    1   {9}    Dr. Margaret Adam, M.D., a clinical geneticist and teratologist who testified on
    2 behalf of Defendant, agreed with the assessment of Dr. Heidenreich. Dr. Adam
    3 testified that, in her opinion, to a reasonable degree of medical probability, the cause
    4 of R.R.’s neurodegenerative condition was genetic. According to Dr. Adam, that R.R.
    5 was normal at birth but began exhibiting degenerative features around one year of age,
    6 that the degenerative features continued to progress, and that R.R.’s whole brain was
    7 affected all support her and Dr. Heidenreich’s conclusions that the cause of R.R.’s
    8 condition is genetic. Dr. Adam confirmed Dr. Ronaldson’s testimony that there were
    9 no studies in the field of genetics, teratology, or pediatrics that support the conclusion
    10 that prenatal exposure to Zoloft can cause a neurodegenerative condition such as
    11 R.R.’s. Further, Dr. Adam testified that the well-described effects of Zoloft on a fetus
    12 in utero are typically in the form of autonomic dysfunction and respiratory issues,
    13 none of which were present in R.R.
    14   {10}   Finally, Defendant submitted evidence from at least three separate sources,
    15 concluding that R.R. did not suffer from hypoxia or PVL, the conditions relied upon
    16 by Dr. Ronaldson to reach his conclusion. Dr. Adam testified that nowhere in R.R.’s
    17 medical records had any physician made a diagnosis of PVL in R.R. Another of
    18 Defendant’s expert witnesses, Gail McCarver, M.D., a board certified pediatrician,
    19 neonatologist, and clinical pharmacologist, submitted an affidavit refuting Dr.
    5
    1 Ronaldson’s assumption that hypoxia is the medical cause of R.R.’s condition, instead
    2 concluding that R.R.’s “clinical presentation does not correlate with chronic hypoxia
    3 in utero.” Finally, Dr. Marvin Nelson, M.D., a pediatric neuroradiologist submitted
    4 his affidavit, concluding “that the head imaging findings [for R.R.] do not suggest
    5 hypoxia during the perinatal period and this is not HIE (hypoxic-ischemic
    6 encephalopathy) or PVL (periventricular leukomalacia).”
    7 STANDARD OF REVIEW
    8   {11}   The admissibility of expert testimony lies in the sound discretion of the district
    9 court. Loper v. JMAR, 
    2013-NMCA-098
    , ¶ 18, 
    311 P.3d 1184
    .
    10          An abuse of discretion standard of review, however, is not tantamount
    11          to rubber-stamping the trial judge’s decision, and we are not prevented
    12          from conducting a meaningful analysis of the admission of the expert
    13          testimony to ensure that the trial judge’s decision was in accordance with
    14          the Rules of Evidence and the evidence in the case.
    15 
    Id.
     (internal quotation marks and citation omitted); see State v. Alberico, 1993-NMSC-
    16 047, ¶ 63, 
    116 N.M. 156
    , 
    861 P.2d 192
    . We resolve doubts regarding the admissibility
    17 of an expert opinion in favor of admission rather than exclusion of the evidence.
    18 Parkhill v. Alderman-Cave Milling & Grain Co. of N.M., 
    2010-NMCA-110
    , ¶ 60, 149
    
    19 N.M. 140
    , 
    245 P.3d 585
     (Vigil, J., specially concurring).
    6
    1 DISCUSSION
    2 A.       Admissibility of Expert Testimony
    3   {12}   Whether testimony of an expert witness is admissible depends on three
    4 requirements: “(1) that the expert be qualified; (2) that the testimony be of assistance
    5 to the trier of fact; and (3) that the expert’s testimony be about scientific, technical,
    6 or other specialized knowledge with a reliable basis.” State v. Downey, 2008-NMSC-
    7 061, ¶ 25, 
    145 N.M. 232
    , 
    195 P.3d 1244
    .
    8   {13}   To be admissible, testimony of a medical expert must explain both “how and
    9 why [the expert] arrives at an opinion that a defendant physician’s conduct has been
    10 substandard.” Sewell v. Wilson, 
    1982-NMCA-017
    , ¶ 23, 
    97 N.M. 523
    , 
    641 P.2d 1070
    .
    11 The qualifications required of a medical expert turn on “the type of negligence
    12 claimed and the medical complexity involved.” Lopez v. Reddy, 
    2005-NMCA-054
    , ¶
    13 16, 
    137 N.M. 554
    , 
    113 P.3d 377
    . Testimony from a medical professional who does not
    14 specialize in the area of medicine at issue may be admitted if the professional is
    15 qualified and competent to do so. See Sewell, 
    1982-NMCA-017
    , ¶ 23. “[T]he mere
    16 fact that a medical witness is not a specialist goes to the weight, not to admissibility,
    17 of the witness’ expert testimony.” 
    Id.
     “Nevertheless, to give scientific or specialized
    18 opinion testimony, an expert witness must be qualified to do so by knowledge, skill,
    19 training or education.” 
    Id.
    7
    1   {14}   On appeal, Plaintiff first argues that the district court wrongfully usurped the
    2 function of the jury by resolving the divergent opinions regarding medical causation
    3 in favor of Defendant’s experts. Plaintiff further argues that the district court
    4 committed error when it rejected Dr. Ronaldson’s opinion as untested and
    5 unsupported. We reject Plaintiff’s arguments for two reasons and affirm the decision
    6 of the district court.
    7 1.       Dr. Ronaldson’s Opinion Was Based on a Misunderstanding of R.R.’s
    8          Medical Diagnosis and He Is Not Qualified to Offer an Alternative
    9          Diagnosis
    10   {15}   Both in his expert report and in his testimony before the district court,
    11 Plaintiff’s expert contended that there was no dispute between the parties regarding
    12 R.R.’s medical diagnosis. This is not the case. Dr. Ronaldson is correct that Plaintiff
    13 and Defendant agree that R.R. suffers from a neurodegenerative medical condition of
    14 unknown etiology, however, the parties do not agree on the manner in which R.R.’s
    15 condition manifested itself. In reaching his conclusion, Dr. Ronaldson relied on two
    16 premises that have been refuted by Defendant’s medical experts.
    17   {16}   In forming his opinion, Dr. Ronaldson relied on his understanding that R.R. had
    18 been diagnosed with PVL, a biomarker of hypoxia. Hypoxia, Dr. Ronaldson
    19 concluded, can cause neurological damage. Dr. Ronaldson’s understanding that R.R.
    20 had been diagnosed with PVL was based on three references to PVL in R.R.’s medical
    8
    1 records. However, notwithstanding that R.R.’s medical records mention PVL on three
    2 instances, we note that Defendant’s medical experts testified that R.R. was never
    3 diagnosed with PVL or hypoxia and did not suffer from either condition.
    4   {17}   Dr. Adam testified that nowhere in her medical records was R.R. diagnosed
    5 with PVL. Dr. Nelson, a pediatric neuroradiologist, agreed that R.R.’s head imaging
    6 revealed neither PVL nor hypoxia. Finally, Dr. McCarver, Defendant’s expert
    7 pediatrician, neonatologist, and clinical pharmacologist, concluded that R.R.’s
    8 “clinical presentation did not correlate with chronic hypoxia in utero.” As Dr.
    9 Ronaldson is not a medical doctor, did not review R.R.’s testing images and lab
    10 results, and admitted he is not qualified to diagnose medical conditions, he is not
    11 qualified to refute the conclusions of Defendant’s three medical experts that R.R.
    12 suffers from neither PVL nor hypoxia. Without diagnoses of PVL and hypoxia, the
    13 foundational basis of Dr. Ronaldson’s opinion—that Zoloft caused hypoxia
    14 (evidenced by PVL) in R.R., which resulted in her neurodegenerative
    15 condition—lacks any factual or medical support. See Downey, 
    2008-NMSC-061
    , ¶ 30
    16 (“[T]he reasoning or methodology underlying the testimony must not only be
    17 scientifically valid, it also must be properly applied to the facts in issue.” (omission,
    18 alteration, internal quotation marks, and citation omitted)).
    9
    1   {18}   Further compromising Dr. Ronaldson’s opinion is his exclusion of any possible
    2 genetic cause for R.R.’s condition. Among the factors cited by Dr. Ronaldson in
    3 support of his conclusion was the fact that a genetic cause had not been identified for
    4 R.R.’s condition. The absence of a genetic cause, Dr. Ronaldson surmised, made it
    5 more likely that the harm to R.R. was caused by Plaintiff’s ingestion of Zoloft during
    6 pregnancy. Both Dr. Adam and Dr. Heidenreich, however, provided testimony that the
    7 cause of R.R.’s condition was genetic. Dr. Adam testified that it was her opinion to
    8 a reasonable degree of medical probability that the cause of R.R.’s neurodegenerative
    9 condition was genetic, pointing to the delay in the onset of her degenerative condition,
    10 as support. Dr. Heidenreich opined that R.R.’s specific genetic alteration might be
    11 identified using exome or genome sequencing that has not yet been performed. Dr.
    12 Ronaldson has no background, training, or experience in genetics that qualifies him
    13 to contradict the conclusions of Dr. Adam and Dr. Heidenreich that the cause of R.R.’s
    14 condition was genetic. As Dr. Ronaldson admits he is not qualified to offer a contrary
    15 diagnosis of R.R.’s medical condition, we are unpersuaded by Plaintiff’s argument
    16 that the district court improperly weighed the opinions of the experts in excluding Dr.
    17 Ronaldson’s testimony.
    10
    1 2.       Plaintiff Failed to Show That Dr. Ronaldson’s Opinion Was Reliable
    2   {19}   Plaintiff also argues on appeal that the district court improperly rejected Dr.
    3 Ronaldson’s opinion as untested and unsupported. However, Plaintiff failed to
    4 establish that the science that forms the basis of Dr. Ronaldson’s conclusion is reliable
    5 and therefore admissible. To be admissible, expert testimony that is scientific or
    6 technical in nature, or that requires specialized knowledge must have a reliable basis.
    7 See id. ¶ 25. “[T]he determination of the external cause of a patient’s disease is a
    8 complex process that is unrelated to diagnosis and treatment, and which requires
    9 specialized, scientific knowledge regarding the external agents involved.” Parkhill,
    10 
    2010-NMCA-110
    , ¶ 23. Dr. Ronaldson’s testimony as to the causation of R.R.’s
    11 condition is admissible only if it is reliable. We have adopted several factors,
    12 frequently referred to as the Daubert-Alberico factors, to determine whether scientific
    13 testimony is reliable. Those factors are:
    14          (1) whether a theory or technique can be (and has been) tested; (2)
    15          whether the theory or technique has been subjected to peer review and
    16          publication; (3) the known potential rate of error in using a particular
    17          scientific technique and the existence and maintenance of standards
    18          controlling the technique’s operation; . . . (4) whether the theory or
    19          technique has been generally accepted in the particular scientific field[;
    20          and (5)] whether the scientific technique is based upon well-recognized
    21          scientific principle and whether it is capable of supporting opinions
    22          based upon reasonable probability rather than conjecture.
    11
    1 State v. Anderson, 
    1994-NMSC-089
    , ¶ 15, 
    118 N.M. 284
    , 
    881 P.2d 29
     (internal
    2 quotation marks and citation omitted).
    3   {20}   Following an evidentiary hearing to determine whether Dr. Ronaldson’s
    4 testimony should be excluded, the district court found that there was no literature in
    5 the fields of genetics, teratology, or pediatrics that concludes that the ingestion of
    6 Zoloft can cause a neurodegenerative condition such as R.R.’s. The court further
    7 found that there were no cases or other reports of Zoloft exposure during pregnancy
    8 causing later neurodegeneration after birth in humans or animals. Finally, the court
    9 found that there are no studies demonstrating that Zoloft can cause a
    10 neurodegenerative disorder such as that of R.R. or that support Dr. Ronaldson’s
    11 opinions that the ingestion of Zoloft by pregnant women can cause the type of
    12 condition seen in R.R.
    13   {21}   In his report and at the hearing on Defendant’s motion to exclude his testimony,
    14 Dr. Ronaldson relied on two scientific articles. The first, referred to by the parties as
    15 the Rurak article, considered the effects of fetal exposure to different types of SSRI
    16 medications. See Dan Rurak, et al., Third Trimester Fetal Heart Rate and Doppler
    17 Middle Cerebral Artery Blood Flow Velocity Characteristics During Prenatal
    18 Selective Serotonin Reuptake Inhibitor Exposure, 70 Pediatric Res. J. 96 (2011),
    19 http:///www.nature.com/pr/journal/v70/n1/pdf/pr2011139a.pdf. Included in the results
    12
    1 reported in the Rurak article were four cases of fetal exposure to Zoloft.
    2 Acknowledging that, “[t]o date, very little is known about SSRI effects on the human
    3 fetal physiologic functions[,]” the Rurak article concluded, after studying the effects
    4 of different SSRIs on twenty-nine subjects, that the observed results suggest possible
    5 fetal hypoxia. Rurak, et al., supra, at 96 (emphasis added). While the Rurak article
    6 opined that it was “conceivable that [SSRIs] alter early brain development[,]” the
    7 study neither discussed nor concluded that SSRIs caused neurodegenerative disorders
    8 such as the one seen in R.R. Rurak, et al., supra, at 96. In addition to the Rurak article,
    9 the only other peer-reviewed article on which Dr. Ronaldson relied was an article
    10 reporting the results of a study of the effects of high serotonin levels in mouse
    11 embryos. See Chi Chiu Wang, et al., Serotonin Receptor 6 Mediates Defective Brain
    12 Development in Monoamine Oxidase A-deficient Mouse Embryos, 289 J. Biological
    13 Chemistry 8252 (2014), http://www.jbc.org/content/289/12/8252.full.pdf. While the
    14 Wang study concluded that the presence of an SSRI in mouse embryos can initiate a
    15 series of events that impairs the central nervous system of the embryos, the study did
    16 not determine the manner in which the impairment manifested itself, as the embryo
    17 cultures did not go to term.
    18   {22}   Rather than support a conclusion that Dr. Ronaldson’s opinion is based on well-
    19 recognized scientific principles, see Anderson, 
    1994-NMSC-089
    , ¶ 15, the
    13
    1 peer-reviewed articles on which he relies fail to connect the use of Zoloft with R.R.’s
    2 neurodegenerative condition. Dr. Ronaldson provided no other peer-reviewed
    3 information to support his hypothesis that R.R.’s condition was caused by in utero
    4 ingestion of Zoloft, and Dr. Ronaldson admitted that there are no other studies that
    5 support his exact hypothesis. Defendant’s expert, Dr. Adam, confirmed this, testifying
    6 there is no medical literature to support the proposition that Zoloft or any prescription
    7 medication causes a neurodegenerative condition such as the one suffered by R.R.,
    8 either in humans or animals. Dr. Adam further testified that studies and case reports
    9 she has examined demonstrate that there does not appear to be any significant
    10 neurological effects to individuals exposed to Zoloft. In the absence of additional
    11 research, Dr. Ronaldson’s testimony and opinion are merely conjecture and do not
    12 satisfy any of the Daubert-Alberico factors utilized to determine scientific reliability.
    13 See Anderson, 
    1994-NMSC-089
    , ¶ 15.
    14   {23}   Dr. Ronaldson testified and Plaintiff argues on appeal that his education,
    15 training, and experience as a pharmacologist render him qualified to testify about the
    16 biological mechanisms associated with this case that could have caused the symptoms
    17 that are apparent in R.R. According to Plaintiff, his opinions are sound,
    18 notwithstanding that he does not diagnose patients. See Sewell, 
    1982-NMCA-017
    ,
    19 ¶ 23.
    14
    1   {24}   Plaintiff urges that our Supreme Court’s ruling in Acosta v. Shell Western
    2 Exploration & Production, Inc., 
    2016-NMSC-012
    , 
    370 P.3d 761
    , supports the
    3 admissibility of Dr. Ronaldson’s testimony. In Acosta, a toxic tort case, our Supreme
    4 Court declined to adopt the ruling of the United States Supreme Court in General
    5 Electric Co. v. Joiner, 
    522 U.S. 136
    , 146 (1997), which allows a judge to “reject
    6 expert testimony where the ‘analytical gap’ between the underlying evidence and the
    7 expert’s conclusion is ‘too great[.]’ ” Acosta, 
    2016-NMSC-012
    , ¶ 27. In declining to
    8 adopt the Joiner rule, Acosta determined it was inconsistent with the policy of our
    9 courts to leave credibility determinations and weighing of evidence to the trier of fact.
    10 Acosta, 
    2016-NMSC-012
    , ¶ 28. Reasoning that it would be unfair to bar the claims of
    11 the first several victims of a new toxic tort “simply because scientific analysis on a
    12 particular chemical cause has not yet been fully developed[,]” the Court utilized the
    13 nonformulaic guidelines of Sir Austin Bradford Hill to assess whether the plaintiff’s
    14 epidemiological study finding an association between exposure to a mixture of
    15 benzene and other organic solvents and autoimmune disease supported an inference
    16 of causation. Id. ¶¶ 31-32. The Bradford Hill factors, the Court reasoned, “measure
    17 the ability of an epidemiological study to determine whether an association found by
    18 the study is sufficient to satisfy an ultimate question of fact regarding causation or
    19 whether the association is merely spurious.” Id. ¶ 33.
    15
    1   {25}   Initially, we note that unlike Acosta, Plaintiff’s expert, Dr. Ronaldson, has not
    2 conducted or participated in any epidemiological or other studies or done any work
    3 on the effects of Zoloft on pregnant women or their fetuses. Cf. Parkhill, 2010-
    4 NMCA-110, ¶ 45 (“ ‘One very significant fact to be considered is whether the experts
    5 are proposing to testify about matters growing naturally and directly out of research
    6 they have conducted independent of the litigation, or whether they have developed
    7 their opinions expressly for the purpose of testifying[.]’ ” (quoting Daubert v. Merrell
    8 Dow Pharms., Inc., 
    43 F.3d 1311
    , 1317 (9th Cir. 1995))). Plaintiff does not ask us to
    9 conclude the results of Dr. Ronaldson’s scientific study to be sufficiently reliable
    10 evidence to prove causation in this case. There is no study to consider. Instead,
    11 Plaintiff offers Dr. Ronaldson’s conclusions with regard to a single patient based on
    12 the two scientific articles he cites along with his pharmacology education, training,
    13 and experience in studying how drugs cross biological membranes and accumulate in
    14 the body.
    15   {26}   This case is not akin to Acosta, as the effects of SSRI medications, such as
    16 Zoloft have been scientifically studied on pregnant women. Dr. McCarver explained
    17 that Defendant’s prescription of Zoloft to Plaintiff is consistent with its use within the
    18 medical community, and the drug is commonly used in pregnancy. Dr. Adam testified
    19 that several studies of the effects of Zoloft have been conducted, and the effects on
    16
    1 fetuses, if any, manifest themselves in the form of autonomic dysfunction and
    2 respiratory issues, neither of which afflicted R.R. Notwithstanding Dr. Ronaldson’s
    3 significant pharmacology credentials, these deficiencies, coupled with the inability to
    4 satisfy any of the Daubert-Alberico factors, render his opinion unreliable, and
    5 therefore inadmissible. The district court did not abuse its discretion by excluding Dr.
    6 Ronaldson’s testimony.
    7 B.       Grant of Summary Judgment
    8   {27}   Concluding that Plaintiff had not disclosed a medical expert qualified to
    9 establish a causal connection between Defendant’s conduct and R.R.’s injuries, the
    10 district court granted Defendant’s motion for summary judgment. We review, de
    11 novo, whether the district court properly granted summary judgment, viewing the facts
    12 in the light most favorable to the party opposing summary judgment and indulging all
    13 reasonable inferences in favor of a trial on the merits. Acosta, 
    2016-NMSC-012
    , ¶ 20.
    14   {28}   “In any medical malpractice action, the plaintiff has the burden of proving that
    15 . . . [the defendant’s] actions complained of were the proximate cause of [the]
    16 plaintiff’s injuries.” Schmidt v. St. Joseph’s Hosp., 
    1987-NMCA-046
    , ¶ 8, 
    105 N.M. 17
     681, 
    736 P.2d 135
    . As we noted in Parkhill, a determination of the external cause of
    18 a patient’s condition requires specialized, scientific knowledge regarding those
    19 external agents involved. 
    2010-NMCA-110
    , ¶ 23. Dr. Ronaldson was Plaintiff’s only
    17
    1 expert to testify about the medical causation of R.R.’s condition and damages. With
    2 the exclusion of his testimony, Plaintiff has no medical expert to testify about the
    3 cause of R.R.’s harm and cannot prove the elements of her medical malpractice claim
    4 against Defendant. The district court properly granted summary judgment.
    5 CONCLUSION
    6   {29}   We affirm the district court’s exclusion of Dr. Ronaldson’s expert causation
    7 testimony, as well as summary judgment granted on the basis of that exclusion.
    8   {30}   IT IS SO ORDERED.
    9
    10                                         JULIE J. VARGAS, Judge
    11 WE CONCUR:
    12
    13 JONATHAN B. SUTIN, Judge
    14
    15 TIMOTHY L. GARCIA, Judge
    18