Walton v. Huron Regional Medical Center

#31052-aff in pt & rev in pt-SRJ
2026 S.D. 3

IN THE SUPREME COURT
OF THE
STATE OF SOUTH DAKOTA

****

KEVIN WALTON and
JULIE WALTON, Plaintiffs and Appellants,

v.

HURON REGIONAL MEDICAL CENTER,
INC., WILLIAM J. MINER, M.D., and
JOHN AND JANE DOES, Defendants and Appellees.

****

APPEAL FROM THE CIRCUIT COURT OF
THE THIRD JUDICIAL CIRCUIT
BEADLE COUNTY, SOUTH DAKOTA

****

THE HONORABLE PATRICK T. PARDY
Judge

****

DANIEL K. BRENDTRO of
Hovland Rasmus & Brendtro, Prof. LLC
Sioux Falls, South Dakota Attorneys for plaintiffs and
appellants.

MARK W. HAIGH of
Evans, Haigh & Arndt, L.L.P.
Sioux Falls, South Dakota Attorneys for defendant and
appellee Huron Regional
Medical Center, Inc.

****

ARGUED
NOVEMBER 17, 2025
OPINION FILED 01/28/26
****

GREGORY J. BERNARD
COREY J. QUINTON of
Thomas, Braun, Bernard & Burke, LLP
Rapid City, South Dakota Attorneys for defendant and
appellee William J. Miner, M.D.
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JENSEN, Chief Justice

[¶1.] Kevin Walton and his wife, Julie Walton, sued Huron Regional Medical

Center (HRMC) and Dr. William Miner for medical malpractice, alleging Kevin

suffered a hypoxic brain injury 1 from the administration of high dosages of opiates
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and the failure to properly monitor him while being treated for testicular pain.

Following discovery, HRMC moved to exclude the testimony of Dr. Richard Adler, a

causation expert witness designated by the Waltons, arguing his testimony was not

reliable under SDCL 19-19-702. Dr. Miner joined the motion. The circuit court

granted the motion and subsequently granted the motions for summary judgment

filed by HRMC and Dr. Miner, concluding the Waltons could not generate a genuine

issue of material fact on causation without expert testimony. The Waltons

appealed. We reverse in part and affirm in part.

Factual and Procedural History

[¶2.] A brief history of Kevin’s medical care is necessary to provide context

for the Waltons’ claims. At age 26, Kevin began reporting complaints of physical

weakness. From 2005 to 2009, Kevin received medical tests and treatment related

to these complaints, including two MRI brain scans, lab work, physical therapy, an

evaluation for multiple sclerosis, a speech and language evaluation, an

electroencephalogram (EEG), cardiac event monitoring, and two echocardiograms.

1. A hypoxic brain injury is a type of brain injury “characterized by a lack of
oxygen to the brain” that can result in “severe physical, cognitive, and
emotional changes[.]” Anoxic and Hypoxic Brain Injuries, Shepard Center,
https://shepherd.org/treatment/conditions/brain-injury/types/anoxic-hypoxic/
(last visited Jan. 26, 2026).
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Kevin was also diagnosed with Guillain-Barré syndrome during this time. 2 Kevin
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reported no similar issues until October 2013, when Kevin’s medical records showed

complaints of insomnia and other physical symptoms that continued through 2016.

During this time, Kevin also underwent a psychiatric evaluation, clinic visits for

neurology issues and insomnia, an echocardiogram, cardiac monitoring, a nuclear

stress test, and a nuclear medicine cardiac study.

[¶3.] Kevin did not present with other medical issues until January 2018,

when he began complaining of severe testicular pain. Kevin saw a urologist for his

complaints, but no significant physical abnormalities were found. A bilateral

spermatic anesthesia block was performed to treat the pain and determine the

possible source of the pain.

[¶4.] On April 3, 2018, Kevin was admitted to HRMC by Dr. Miner,

complaining of 10/10 testicular pain. Dr. Miner believed Kevin may have

epididymitis, an infection of the tube at the back of each testicle carrying the sperm.

Dr. Miner treated Kevin with antibiotics and steroids and placed orders to

administer frequent dosing of hydromorphone, oxycodone, anti-inflammatories, and

muscle relaxants for pain. The hydromorphone prescription contained the following

note: “**HIGH ALERT DRUG** HR/BP/RR MONITOR[.]” Kevin was also

prescribed trazadone at night, which he had been taking prior to his hospitalization

for insomnia. Physician orders were entered to contact a physician if Kevin’s

2. Guillain-Barré syndrome “is a condition in which the body’s immune system
attacks the nerves. It can cause weakness, numbness or paralysis.”
Guillain-Barre Syndrome, Mayo Clinic (June 7, 2024),
https://www.mayoclinic.org/diseases-conditions/guillain-barre-
syndrome/symptoms-causes/syc-20362793.
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respiratory rate was greater than 26 and to administer supplemental oxygen to

Kevin as needed to maintain an oxygen saturation above 90%. Periodic oxygen

saturations were recorded during Kevin’s three-day stay and registered between 92

and 98%. Kevin was discharged on April 5.

[¶5.] On the night of April 8, 2018, Kevin again presented to HRMC with

complaints of 10/10 right testicular pain and mild left testicular pain. It is during

this three-day stay at HRMC that the Waltons claim Kevin suffered a hypoxic brain

injury due to the large dosages of opiates administered to treat his pain. The initial

admission orders were entered by physician assistant Jacob Lyngaas and included

an order that the physician should be notified for a respiratory rate greater than 26.

Kevin’s respiratory and oxygen saturation rates were monitored periodically during

this three-day stay as well. Lyngaas also entered an order for the administration of

1 milligram of hydromorphone IV every 30 minutes as needed for pain. This order

contained the same “HIGH ALERT DRUG” warning as was included in the order

during his previous admission to HRMC. Pain-relieving and anti-inflammatory

medications were also ordered. The orders were reviewed and co-signed by Dr.

Gregory Wiedel on the morning of April 9. Dr. Wiedel also telephonically ordered

that the hydromorphone dose be increased to 2 milligrams every 15 minutes as

needed for pain and added other pain and muscle relaxant medication orders. Dr.

Miner assumed care for Kevin later on the morning of April 9.

[¶6.] At 7:20 am on April 11, Kevin was noted to have an abnormally low

respiratory rate of 9 breaths per minute. A nurse documented that Kevin “was

awakened from sound sleep to apply oxygen saturation monitor. Patient upon

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awakening states he has level 5 pain and requests pain medicine. Patient educated

about respiratory rate and narcotic use. Will repeat a narcotic as soon as safe to do

so.” The nurse documented that Kevin was “frequently drowsy, arousable, drifts off

to sleep during conversation.” Julie claims that the nurse told her that Kevin “was

breathing like a man taking his last breaths” during this time.

[¶7.] At 8:38 am, Dr. Miner entered an order adding 10 milligrams of

hydrocodone and 325 milligrams of acetaminophen every four hours as needed—

with no parameters regarding when to give this medication in comparison to the

previously ordered medications. Kevin was given two additional dosages of

hydrocodone before he asked to go home and was discharged from HRMC at 2:30

pm.

[¶8.] Immediately after his discharge, Kevin began exhibiting new and

unusual symptoms that Julie began to log. She reported that Kevin acted childlike,

spoke with a stutter, and engaged in unconventional conversations. She also

reported that Kevin displayed memory problems and confusion and appeared to be

“choking all the time.”

[¶9.] On April 16, 2018, Kevin attempted to return to work. His employer

reported that Kevin had a stutter, blank eyes, and lack of balance and asked Julie

to pick Kevin up. Julie logged similar problems almost every day for the following

month. On May 12, Kevin and Julie attempted to go camping. Julie reported that

Kevin was very unstable in the camper, could not cut his steak at supper, almost

got lost walking to another camper, and choked badly that evening.

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[¶10.] Kevin underwent numerous diagnostic tests and evaluations for these

symptoms. An MRI brain scan taken on April 20 showed some fluid behind the left

ear and mild sinus inflammation, but no abnormalities in the brain structure. On

May 23, Kevin presented to Dr. William Rossing for a neurological evaluation. He

described Kevin’s condition as “atypical syndrome of encephalopathy, 3 fatigability,
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gait imbalance and some coordination deficits that also incorporate peculiar speech

and language changes.” An EEG of the brain, measuring electrical activity within

the brain, did not show any abnormalities. On May 31, Kevin had a brain PET

scan, providing detailed images of brain function and metabolism, which was also

read as unremarkable.

[¶11.] Sometime in May or June, Julie noticed that Kevin was speaking in a

foreign accent, which she described as similar to a Hutterite accent. On July 9,

Kevin had another PET scan of his entire body and an MRI brain scan. Both were

read as normal. An EEG taken on July 25 was also read as normal.

[¶12.] On September 26, Kevin presented to Dr. Lyle Christopherson, a

psychiatrist, for a psychiatric evaluation. Due to the absence of any physiological or

observable structural brain abnormalities in any of the diagnostic testing, Dr.

Christopherson believed Kevin had conversion disorder, also known as functional

3. “Encephalopathy is a group of conditions that cause brain dysfunction.”
Encephalopathy, Cleveland Clinic, https://my.clevelandclinic.org/health/
diseases/encephalopathy (last updated Oct. 2, 2023). There are different
types of encephalopathy, including hypoxic-ischemic encephalopathy (HIE) (a
brain injury that occurs when the brain does not get enough blood and
oxygen) and toxic encephalopathy (brain dysfunction caused by medications,
street drugs, or poisons). See id.; Hypoxic-Ischemic Encephalopathy (HIE),
Cleveland Clinic, https://my.clevelandclinic.org/health/diseases/hypoxic-
ischemic-encephalopathy-hie (last updated Sept. 8, 2023).
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neurological disorder, 4 but did not reach a definitive diagnosis.
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[¶13.] On November 14, Kevin presented to Dr. Joseph Matsumoto, a

professor of neurology and movement disorder specialist, for a comprehensive

neurological examination. Dr. Matsumoto diagnosed Kevin with functional

neurological deficits, functional right leg weakness, and a functional speech

disorder. Dr. Matsumoto described these conditions as “functional” because there

were no observable structural or physiological changes to the brain explaining

Kevin’s symptoms.

[¶14.] On January 18, 2019, Kevin followed up with Dr. Rossing, who

concluded that Kevin was likely suffering from a functional movement disorder. At

a subsequent follow-up visit, Dr. Rossing diagnosed Kevin with “[f]unctional

movement/neurologic disorder.” Kevin also presented for follow-up medical

treatment for ongoing testicular pain, various nerve blocks, another neurology

evaluation, weekly psychotherapy visits, and a CT scan of the abdomen and pelvis.

[¶15.] On August 12, 2019, Kevin began rehabilitation at The Brain Injury

Rehabilitation Center (the Center) in Rapid City. A progress report from the Center

listed Kevin’s cause of trauma as hypoxia, primarily based on the history provided

by the Waltons. Kevin underwent a neurological evaluation at the Center and was

diagnosed with mild neurocognitive disorder and unspecified adjustment disorder.

On November 4, Kevin was discharged from his weekly psychotherapy visits

4. Dr. Adler agreed with defense counsel that conversion disorder is a “mental
health condition that causes physical symptoms because the brain converts
the effects of a mental health condition into disruptions of the brain or
nervous system” and typically a patient will “complain of physical symptoms
for which a medical provider cannot determine the cause[.]”
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against professional advice. On November 11, Kevin underwent a surgical

procedure for the removal of his left testicle.

[¶16.] The Waltons commenced this action against HRMC and Dr. Miner,

alleging that HRMC and Dr. Miner were negligent in overprescribing opiates to

Kevin and failing to monitor him, resulting in Kevin suffering a hypoxic brain

injury during his hospitalization. HRMC and Dr. Miner denied any negligence,

further denied that Kevin suffered a hypoxic brain injury, and alleged that Kevin

suffers from conversion disorder.

[¶17.] The Waltons designated, among others, Dr. Kenneth Stein, a board

certified physician in internal and emergency medicine, and Dr. Joseph Wu, a

psychiatrist, as expert witnesses. The Waltons later withdrew Dr. Wu as a

testifying expert.

[¶18.] Dr. Stein prepared a report stating, “The amount of opiate medications

that were ordered (by Dr. Weidel and then continued by Dr. Miner) and that were

administered by the nursing staff at HRMC [w]ould best be described as massive.”

Dr. Stein also opined that it was a breach of the standard of care for Dr. Miner to

administer massive dosages of hydromorphone to Kevin; for HRMC nursing staff to

fail to inquire whether the dosages of hydromorphone were ordered correctly; for Dr.

Miner and HRMC to administer these high dosages “on a regular medical/surgical

ward without continuous monitoring of oxygen saturation and respiratory rate[;]”

for HRMC nursing staff to fail to recognize that Kevin was suffering from toxicity

related to the high dosages and combination of hydromorphone and other sedative

medications; and for HRMC nursing staff to administer additional sedating

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medications after Kevin had been noted to have a low sedation score and a

respiratory rate as low as 9 breaths per minute.

[¶19.] The Waltons later retained Dr. Adler, a psychiatrist, as a testifying

causation expert. Dr. Wesley Center, a psychologist, was also retained to read a

quantitative electroencephalography (qEEG) test that was considered by Dr. Adler

in arriving at his opinions. As discussed in more detail later, the Daubert motions

filed by the defendants to exclude both doctors’ opinions focused primarily on the

qEEG, as well as other quantitative analysis testing conducted by Dr. Adler.

[¶20.] A qEEG quantitative analysis test digitally quantifies the raw EEG

signals from the brain’s cortex and compares this information to statistically

normative population groups to identify patterns of dysfunction in the subject’s

brain functioning. As Dr. Center explained in a deposition:

QEEG is when we take the EEG data, we quantify it, filter it,
digitally process it, create displays, spectral analyses, database
comparisons, so it’s the use of the EEG in a digitized form to
more easily be able to depict that activity, localized activity, and
to make some statements about what may or may not be
happening.

The qEEG is peer reviewed and used in clinical settings to understand and confirm

certain diagnoses, but is not considered a primary diagnostic tool. Dr. Adler also

used Neurocloud-VOL and Neurocloud-PET tests in his work on Kevin’s case.

These quantitative analysis tests quantify the MRI and PET brain scans, comparing

them to statistical data to provide information about the brain structure and

function.

[¶21.] Before preparing his report, Dr. Adler met with Kevin and Julie to

collect various information about Kevin, including a social history, developmental

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history, family of origin, educational history, marital history, occupational history,

financial status, legal history, psychiatric history, medical history, and current

medication use. In addition to the quantitative analysis tests, Dr. Adler conducted

several screening and psychological tests on Kevin, including the Draw a Clock

Test, Gudjonsson Suggestibility Scale, CNS Vital Signs (CNS-VS) neurocognitive

assessment, 5 Personality Assessment Inventory, Impact of Events Scale, Behavior
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Rating Inventory of Executive Function, Adult Behavior Checklist, a symptom

screen, and a mental status examination.

[¶22.] Dr. Center conducted the qEEG assessment based upon another EEG

taken by a neurologist. Kevin completed a questionnaire and was given a CNS-VS

by Dr. Center. In conducting the qEEG assessment, Dr. Adler asked Dr. Center to

consider whether the qEEG showed any indications of either hypoxic brain injury or

a traumatic brain injury from a 2003 or 2004 snowmobile accident—from which

Kevin self-reported he was hospitalized and had jaw surgery. Dr. Center opined

that Kevin’s qEEG revealed patterns suggesting a traumatic brain injury and that

Kevin’s inability to control or regulate his emotions were “consistent with his CNS

VS results, self-reported symptoms, and history of hypoxemia.” However, Dr.

Center noted that he was unable to determine, from the qEEG results which were

suggestive of a trauma-based injury, whether the snowmobile accident or the

alleged hypoxic event at HRMC may have caused the injury.

5. The CNS-VS test is used to “assess a broad spectrum of brain function
performance or domains[,]” including, among others, verbal memory, visual
memory, psychomotor speed, motor speed, reaction time, and reasoning.
Clinical Practice, CNS Vital Signs,
https://www.cnsvs.com/ClinicalPractice.html (last visited Jan. 26, 2026).
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[¶23.] After reviewing Dr. Center’s report, including his analysis of the

qEEG, Dr. Adler utilized the quantitative analysis tests, along with other data and

information, to arrive at a differential diagnosis of mild neurocognitive disorder due

to drug-induced hypoxemia. Dr. Adler testified in a deposition that he did not use

the quantitative testing to diagnose hypoxia, but rather to determine whether there

was a biological basis for the neurological deficits Kevin presented. He stated:

[C]onversion disorder says, the diagnostic criteria -- there is no
physiologic basis. There is no organic basis. There is no
evidence that would account for the clinical presentation of these
deficits.
...
[The quantitative analysis testing] shows us that in terms of
neurocognitive functioning, not structure, functioning that
something is amiss.
...
This is the qEEG, without a doubt, of somebody who is quite
afflicted [with a biologic abnormality in the brain].

Regarding his differential diagnosis method, Dr. Adler explained that the two

possible explanations offered for Kevin’s condition were hypoxia or conversion

disorder. Based upon all of the information available to him, he had ruled out

conversion disorder and ruled in hypoxia to a reasonable degree of medical

certainty.

[¶24.] In their motion to exclude the opinions of Dr. Adler and Dr. Center,

HRMC argued that the doctors’ methodology and conclusions were unreliable under

SDCL 19-19-702 and the Daubert standard. The motion focused on the unreliability

of the quantitative analysis testing considered by Dr. Adler in arriving at his

opinions. The Waltons resisted the motion as to Dr. Adler, but withdrew Dr. Center

as a testifying expert.

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[¶25.] Following a hearing, the court issued a memorandum decision

granting the motion to exclude the entirety of Dr. Adler’s opinions. HRMC and Dr.

Miner subsequently filed separate motions for summary judgment, arguing the

Waltons could not present the necessary causation evidence on their claims for

malpractice in the absence of Dr. Adler’s opinions. The Waltons resisted the

motions and filed a motion for reconsideration of the court’s Daubert ruling.

[¶26.] At a hearing on the motions, the circuit court initially considered the

Waltons’ motion for reconsideration and denied the motion. 6 The circuit court also
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heard argument on the summary judgment motions and subsequently granted

summary judgment in favor of both defendants.

[¶27.] The Waltons appeal, raising several issues, which we restate as

follows:

1. Whether the circuit court abused its discretion when it
granted the motion to exclude the testimony of Dr.
Adler.

2. Whether the circuit court erred when it granted
summary judgment to the defendants.

6. HRMC and Dr. Miner argue the circuit court properly denied the Waltons’
motion for reconsideration, without considering the merits, because the
Waltons sought to introduce new evidence that could have been initially
presented in resisting the Daubert motion. Our review of the circuit court’s
Daubert ruling is based entirely on the initial motion and the Waltons’
resistance to that motion. As such, we decline to consider any of the
additional submissions from the Waltons in the motion for reconsideration.
We need not consider the propriety of circuit court’s decision denying the
motion for reconsideration based upon our resolution of the Daubert issue.
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Standard of Review

[¶28.] “We review a trial court’s ‘decision to admit or deny an expert’s

testimony under the abuse of discretion standard.’” State v. Fisher, 2011 S.D. 74,

¶ 42, 805 N.W.2d 571, 580 (citations omitted). An abuse of discretion “is a

fundamental error of judgment, a choice outside the range of permissible choices, a

decision, which, on full consideration, is arbitrary or unreasonable.” State v. Pretty

Weasel, 2023 S.D. 41, ¶ 28, 994 N.W.2d 435, 441 (citation omitted). We review a

circuit court’s decision on “a motion for summary judgment under the de novo

standard of review.” North Star Mut. Ins. v. Korzan, 2015 S.D. 97, ¶ 12, 873

N.W.2d 57, 61 (citation omitted). “Summary judgment is appropriate ‘if the

pleadings, depositions, answers to interrogatories, and admissions on file, together

with the affidavits, if any, show that there is no genuine issue as to any material

fact and that the moving party is entitled to a judgment as a matter of law.’” Id.

(citation omitted).

1. Exclusion of Dr. Adler’s opinions.

[¶29.] The Waltons argue the circuit court misapplied SDCL 19-19-702 to the

testimony of Dr. Adler. Specifically, the Waltons assert the circuit court conducted

too narrow of an analysis by excluding all of Dr. Adler’s opinions based solely upon

the quantitative analysis testing. They argue the court failed to consider whether

Dr. Adler’s causation opinions, formed through a differential diagnosis methodology,

were reliable. They further contend that Dr. Adler’s use of the quantitative

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analysis testing, along with other information to support his differential diagnosis

analysis, was both relevant and reliable. 76F

[¶30.] SDCL 19-19-702 provides:

A witness who is qualified as an expert by knowledge, skill,
experience, training, or education may testify in the form of an
opinion or otherwise if:

(a) The expert’s scientific, technical, or other specialized
knowledge will help the trier of fact to understand the
evidence or to determine a fact in issue;

(b) The testimony is based on sufficient facts or data;

(c) The testimony is the product of reliable principles and
methods; and

(d) The expert has reliably applied the principles and
methods to the facts of the case.

[¶31.] “The burden of demonstrating that the testimony is competent,

relevant, and reliable rests with the proponent of the testimony. The proponent of

the expert testimony must prove its admissibility by a preponderance of the

evidence.” Tosh v. Schwab, 2007 S.D. 132, ¶ 18, 743 N.W.2d 422, 428 (citation

omitted). The defendants’ Daubert motion did not challenge Dr. Adler’s competence

or the relevance of his opinions. Instead, they argued Dr. Alder’s methodology in

relying upon the quantitative analysis testing was unreliable.

[¶32.] This Court determines the admissibility of expert testimony in

accordance with Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).

7. The Waltons also argue the circuit court abused its discretion by relying upon
certain erroneous factual findings in granting the motion to exclude the
testimony of Dr. Adler, but we need not address these arguments given our
determination under Daubert.
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State v. Lemler, 2009 S.D. 86, ¶ 22, 774 N.W.2d 272, 280 (citation omitted). “The

Daubert standard requires that the trial court ensure an expert’s testimony ‘rests

on a reliable foundation and is relevant to the task at hand.’” Id. (citations

omitted). We have stated that “an expert’s opinion is reliable if it is derived from

the foundations of science rather than subjective belief.” State v. Guthrie, 2001 S.D.

61, ¶ 36, 627 N.W.2d 401, 416–17 (citing Daubert, 509 U.S. at 589–90).

[¶33.] In applying the Daubert standard, “the trial court must function as a

gatekeeper.” Kostel v. Schwartz, 2008 S.D. 85, ¶ 79, 756 N.W.2d 363, 387 (citations

omitted). “[T]he district court’s gatekeeping role separates expert opinion evidence

based on ‘good grounds’ from subjective speculation that masquerades as scientific

knowledge.” Glastetter v. Novartis Pharms. Corp., 252 F.3d 986, 989 (8th Cir. 2001)

(citation omitted). In this role, the court must “‘screen the jury from unreliable

nonsense opinions, but not exclude opinions merely because they are impeachable.’”

City of Pomona v. SQM N. Am. Corp., 750 F.3d 1036, 1044 (9th Cir. 2014) (citation

omitted).

[¶34.] In considering reliability,

[a] circuit court may consider the following nonexclusive
guidelines for assessing an expert’s methodology: “(1) whether
the method is testable or falsifiable; (2) whether the method was
subjected to peer review; (3) the known or potential error rate;
(4) whether standards exist to control procedures for the
method; (5) whether the method is generally accepted; (6) the
relationship of the technique to methods that have been
established as reliable; (7) the qualifications of the expert; and
(8) the non-judicial uses to which the method has been put.”

State v. Huber, 2010 S.D. 63, ¶ 25, 789 N.W.2d 283, 290–91 (citation omitted).

These factors are flexible and are “neither necessarily nor exclusively appli[cable] to

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all experts or in every case.” Lemler, 2009 S.D. 86, ¶ 24, 774 N.W.2d at 280

(quoting Kumho Tire Co., Ltd. v. Carmichael, 526 U.S. 137, 141 (1999)).

[¶35.] In its memorandum decision, the circuit court aptly described the data

and information Dr. Adler relied on and the differential diagnosis he conducted to

arrive at his opinions:

Dr. Adler, when approached with this matter, used a diagnostic
method that is typically used in medicine. Dr. Adler (a)
gathered some of the patient’s history and symptoms; (b)
performed physical examinations; (c) conducted diagnostic tests;
(d) analyzed the results; (e) formed a differential diagnosis; (f)
ruled out alternative explanations; and (g) arrived at a final
diagnosis. Dr. Adler viewed Mr. Walton’s medical history,
including any pre-existing conditions and previous cognitive or
emotional issues, witness statements from family members or
caregivers, medical records from the alleged overdose on opioids,
clinical observations, neuropsychological evaluations, and
imaging studies.

[¶36.] However, rather than applying the Daubert reliability standards to

this methodology, the circuit court considered only the reliability of the three

quantitative analysis tests utilized by Dr. Adler as a part of his differential

diagnosis. By considering only the reliability of the quantitative analysis testing,

the court failed to apply Daubert to the differential diagnosis utilized by Dr. Adler

to rule out conversion disorder, rule in hypoxia, and ultimately arrive at his

causation opinions. Moreover, in considering the reliability of the quantitative

analysis tests, the circuit court only analyzed whether these tests were reliable to

diagnose hypoxia, not whether the tests provided reliable information for Dr. Adler

to consider in making his differential diagnosis.

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[¶37.] In his deposition, Dr. Adler explained his use of the quantitative

analysis testing, particularly the qEEG, as part of his differential diagnosis to

arrive at his causation opinions:

Q: And just to be clear, you’re not using, like, for instance,
the qEEG as a way to establish definitive proof or
objective proof that there’s hypoxia, but you’re just using
it to show that there is some organic brain injury to rule
out and to discredit conversion disorder and to show
there’s symmetry to -- to rule out that it’s a -- just a TBI
that is affecting Mr. Walton; is that correct?

A: Yeah, plain and simple. Right, that’s a good way of
saying it. That’s right. These are tools within the
totality. They’re never, never, no matter how fancy, a
standalone tool. That’s not how doctors do things.
Doctors look at all the evidence, right. And you
ultimately reach a diagnosis. That’s how I’ve always done
it and hope to always do it.

[¶38.] Although we have not explicitly considered whether a physician’s use

of a differential diagnosis methodology is reliable under Daubert, there is

considerable case law on this issue in the federal courts. “Differential diagnosis, or

differential etiology, is a standard scientific technique of identifying the cause of a

medical problem by eliminating the likely causes until the most probable one is

isolated.” Westberry v. Gislaved Gummi AB, 178 F.3d 257, 262 (8th Cir. 1999)

(citation omitted). “Most circuits have held that a reliable differential diagnosis

satisfies Daubert and provides a valid foundation for admitting an expert opinion.”

Turner v. Iowa Fire Equip. Co., 229 F.3d 1202, 1208 (8th Cir. 2000). “The circuits

reason that a differential diagnosis is a tested methodology, has been subjected to

peer review/publication, does not frequently lead to incorrect results, and is

generally accepted in the medical community.” Id. (citations omitted).

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[¶39.] “A reliable differential diagnosis typically, though not invariably, is

performed after ‘physical examinations, the taking of medical histories, and the

review of clinical tests, including laboratory tests,’ and generally is accomplished by

determining the possible causes for the patient’s symptoms and then eliminating

each of these potential causes until reaching one that cannot be ruled out or

determining which of those that cannot be excluded is the most likely.” Westberry,

178 F.3d at 262 (citations omitted). The Eighth Circuit has consistently held “that

experts are not required to rule out all possible causes when performing the

differential etiology analysis” and that “a differential expert opinion can be reliable

even ‘with less than full information.’” Johnson v. Mead Johnson & Co., LLC, 754

F.3d 557, 563–64 (8th Cir. 2014) (citations omitted). However, “[t]he conclusion

that the opinion of a doctor who has engaged in few standard diagnostic techniques

should be excluded unless the doctor offers a good justification for his or her

conclusion is supported by the case law.” In re Paoli R.R. Yard PCB Litig., 35 F.3d

717, 761 (3d Cir. 1994).

[¶40.] In arriving at his causation opinions, Dr. Adler began his analysis with

two primary diagnoses in mind—conversion disorder and hypoxic brain injury—

because those were the two diagnoses of the medical professionals who reviewed

Kevin’s case. However, Dr. Adler also addressed and considered the possibility of a

traumatic brain injury from the prior snowmobile accident. 8 From this starting
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8. Dr. Center concluded the qEEG test was demonstrative of biologically-
induced brain trauma. However, he was unable to differentiate whether this
trauma was drug induced or the result of the 2003 snowmobile accident. Dr.
Center was not asked to, and acknowledged that he was unable to, make a
(continued . . .)
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point, Dr. Adler’s report identified a variety of data sources he considered to arrive

at his opinions on causation, such as an extensive medical history; direct

observation; the records and information from Kevin’s hospital stay; his before and

after symptoms; and the psychological testing conducted by Dr. Adler, including

interviews, self-report measures, performance measures, and “objective scans

addressing both structural (e.g., MRI) and functional (e.g., QEEG, PET) aspects of

brain functioning which were submitted for quantitative analyses using databases

from suitable comparison groups.” 9 8F

[¶41.] Dr. Adler’s methodology in arriving at his differential diagnosis began

with Kevin’s medical history at HRMC. Dr. Adler believed based upon this history

that the symptoms were indicative of a hypoxic brain injury as new symptoms

(. . . continued)
medical diagnosis as to either cause based upon his limited role in Kevin’s
case. Dr. Adler addressed the possibility of a traumatic brain injury as part
of his differential diagnosis and ruled out traumatic brain injury as a cause of
his current neurological deficits based upon Kevin’s medical history, the
symptoms that arose immediately following his hospitalization at HRMC,
and the psychological testing. As to Kevin’s diagnosis of Guillain-Barré
syndrome in 2005, there was no similar diagnosis after Kevin was admitted
to HRMC in 2018, and Dr. Adler and Dr. Center testified that such a
diagnosis typically lasts months rather than years and would not show up on
a qEEG.

9. The defendants emphasize that Dr. Adler admitted he did not review all of
Kevin’s medical records before forming his causation opinions. While
“performance of physical examinations, taking of medical histories, and
employment of reliable laboratory tests all provide significant evidence of a
reliable differential diagnosis, . . . a doctor does not always have to employ all
of these techniques in order for the doctor’s differential diagnosis to be
reliable.” In re Paoli, 35 F.3d at 758–59 (emphasis added). This is because
“differential diagnosis is an ongoing process of making judgments about
causation and then adapting those judgments as new information is
acquired.” Id. at 759.
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developed immediately after his hospitalization. Dr. Adler relied upon both the

hospital notes and history from Kevin’s stay at HRMC that he considered as part of

his diagnosis:

So in short he was in [the] hospital. He was being given a
number of different narcotics, that he was noted in particular at
a certain point in the morning to have respirations of 9 per
minute, that he did however at that moment have a[n oxygen]
saturation of 93 percent, but that it was noted that his mental
status and the nature of his breathing seemed to be altered.

Despite the fact that he was in pain and requested additional
medication, the nurse indicated that she was not going to give
him additional medicine. And that he was noted sometime later
still to let’s say be impaired in some way in terms of his speech,
his general appearance. And that later that day -- or when he
was discharged, he had unusual aberrant, peculiar behavior.

[¶42.] Dr. Adler also testified that he considered Kevin’s psychological

testing, particularly CNS-VS test results, which showed cognitive performance

deficits consistent with a hypoxic brain injury. Dr. Adler explained that the

“considerable ‘scatter’ among the domain scores” from this test and the fact that

Kevin’s “notable areas of weakness include[d] Visual Memory, Psychomotor and

MotorSpeed” were indicative of a mild traumatic brain injury.

[¶43.] Additionally, Dr. Adler explained that Kevin’s symptoms did not meet

the criteria under the Diagnostic and Statistical Manual of Mental Disorders, 5TR

edition (DSM-5TR) for conversion disorder:

1. One or more symptoms of altered voluntary motor or
sensory function.

2. Clinical findings can provide evidence of incompatibility
between the symptom and recognized neurological or
medical conditions.

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3. Another medical or mental disorder does not better
explain the symptom or deficit.

4. The symptom or deficit results in clinically significant
distress or impairment in social, occupational, or other
vital areas of functioning or warrants medical evaluation.

Jessica L. Peeling & Maria R. Muzio, Functional Neurologic Disorder, National

Library of Medicine, https://www.ncbi.nlm.nih.gov/books/NBK551567/ (last updated

May 8, 2023).

[¶44.] Dr. Adler acknowledged that Kevin meets the first and fourth criteria

because of his “leg trouble” and the limitations that prevent him from working and

engaging in vital areas of life. Dr. Adler ruled out conversion disorder, however,

because, in his view, Kevin does not meet the second and third criteria for a

conversion disorder diagnosis. Relying on the psychological testing and Kevin’s

history, Dr. Adler opined that Kevin does not meet the second diagnostic criterion

because conversion disorder is “well-known to be associated with a history of

psychiatric problems and also co-occurring psychiatric disorders, which [Kevin] does

not have” and that the psychological testing shows “the absence of a preoccupation

of vast somatic symptoms . . . typical of conversation disorder; anxiety; depression --

none of it’s there.” Additionally, Dr. Adler explained Kevin’s foreign accent

syndrome was incompatible with conversion-based foreign accent syndrome because

the latter is most often functional rather than biologically based. He explained that

conversion-based foreign accent syndrome is uncommon in men, and there were no

known conversion-based foreign accent syndrome cases prior to 2005, and only

fifteen such cases since 2005.

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[¶45.] As to the third criterion under the DSM-5TR, Dr. Adler explained that

another medical or mental disorder, hypoxia, better explains the symptoms. Dr.

Adler testified that most of the other providers primarily relied upon the absence of

abnormalities shown on the brain scans but failed to conduct the battery of

psychological testing that he carried out. He further testified that the absence of

past similar symptomology in kind and degree, before the large dosages of opiates

were administered to Kevin in 2018, supports hypoxia as a better explanation for

Kevin’s symptoms.

[¶46.] Dr. Adler also noted that the abnormalities identified by Dr. Center in

a reading of the qEEG were suggestive of a physical cause for Kevin’s symptoms

rather than an unexplained conversion disorder. He testified these abnormalities

did not establish a diagnosis of hypoxia, but rather were useful to provide

information about brain function and brain abnormalities that may not be

observable in the various brain scans. Dr. Adler explained that the qEEG report

was created by uploading an EEG to a computer program for analysis of the brain’s

electrical activity and comparison to a normalized control group and was

subsequently analyzed by Dr. Center, who is certified in reading qEEG reports.

[¶47.] Dr. Center testified at his deposition that qEEG has been tested and

used extensively in clinical settings to identify mild traumatic brain injuries. He

also referred to many peer-reviewed articles discussing the use of qEEG in a clinical

setting for mild traumatic brain injuries and the known error rates for using qEEG

to demonstrate brain abnormalities. The Waltons also submitted a 2020 peer-

reviewed article, which provides that “[q]EEG is used for the following conditions:

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post-concussion syndrome, mild or moderate traumatic brain injury, attention

deficit disorder, schizophrenia, depression, alcoholism, tinnitus and for monitoring

the therapeutic response to psychotropic drugs.” 10
9F

[¶48.] The defendants highlight the seeming inconsistencies between the

qEEG and EEGs conducted on Kevin during the months following his

hospitalization at HRMC. Specifically, the EEGs were all read to be normal, while

the qEEG was suggestive of some biologically-based trauma. In this regard, Dr.

Center testified that the standard of care to test for signs of hypoxia through an

EEG would require it to be conducted within hours or days after the toxic exposure.

He explained that the medical literature is clear that a hypoxic exposure would not

likely show up on an EEG after this time.

[¶49.] Although the circuit court addressed the reliability of the qEEG testing

considered by Dr. Adler, the court did so in the context of considering its reliability

to diagnose hypoxia. But the record clearly establishes that neither Dr. Adler nor

Dr. Center used the qEEG testing to diagnose Kevin with hypoxia, and they both

specifically rejected the qEEG as a tool to provide a specific diagnosis. Dr. Adler

testified that in considering the qEEG he was not using it to diagnose hypoxia, but

10. HRMC cites to several decisions from other jurisdictions, which have
excluded expert opinions relying upon qEEG testing. However, the cases are
distinguishable from the present case because the experts in those cases
solely used a qEEG to diagnose certain conditions. Additionally, many of the
cited cases applied the “general acceptance” standard from Frye v. United
States, 293 F. 1013 (D.C. Cir. 1923). This Court previously applied the Frye
standard. See State v. Wimberly, 467 N.W.2d 499, 505 (S.D. 1991). However,
in State v. Hofer, we expressly adopted the Supreme Court’s Daubert
standard and held that general acceptance in the scientific community is no
longer required. 512 N.W.2d 482, 484 (S.D. 1994); see also State v. Moeller,
1996 S.D. 60, ¶ 52, 548 N.W.2d 465, 479.
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to consider whether there were brain wave patterns suggestive of a biological cause

of Kevin’s neurological deficits. Dr. Center acknowledged the absence of any known

error rates, peer reviews, or proven reliability for qEEG testing as the sole

diagnostic tool for hypoxia, but stated that studies show the qEEG testing provides

valid, reliable, and clinical applications, meeting peer review standards, to identify

abnormalities in brain function, such as those existing in this case.

[¶50.] In addition to the qEEG testing from Dr. Center, Dr. Adler also relied

upon the Neurocloud-VOL and Neurocloud-PET quantitative testing as part of his

differential diagnosis. Dr. Adler testified that the Neurocloud tests did not provide

any new information but were consistent with the information in the qEEG report

from Dr. Center.

[¶51.] In terms of the reliability, the Waltons did not present evidence to

meet their burden that Neurocloud-VOL and Neurocloud-PET meet the Daubert

reliability standard. In his deposition, Dr. Adler testified that he did not know

whether Neurocloud-VOL and Neurocloud-PET had been tested for accuracy or

reliability, had been subjected to peer review and publication, or had a known rate

of error. Further, the Waltons could only point to three European hospitals where

Neurocloud-PET has been validated in clinical environments. The circuit court also

noted discrepancies between the results of the various diagnostic tests conducted on

Kevin that are known to be reliable and the results of the Neurocloud tests. Based

upon the record, we cannot say the circuit court abused its discretion in determining

the Waltons had not presented evidence of the reliability of these Neurocloud tests

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and in excluding Dr. Adler’s testimony concerning these two quantitative analysis

tests.

[¶52.] Nonetheless, given the other reliable methodology Dr. Adler utilized to

arrive at a differential diagnosis of hypoxic brain injury, including the qEEG, the

circuit court abused its discretion in excluding his opinions. In particular, the court

failed to apply the Daubert reliability standards to the differential diagnosis

methodology, including all of the information and data relied upon by Dr. Adler, to

arrive at his opinions. “When a trial court misapplies a rule of evidence, as opposed

to merely allowing or refusing questionable evidence, it abuses its discretion.”

Guthrie, 2001 S.D. 61, ¶ 30, 627 N.W.2d at 415 (citation omitted). We reverse the

circuit court’s decision excluding Dr. Adler’s opinions and testimony, including the

qEEG evidence, but affirm the circuit court’s decision excluding his testimony

concerning the Neurocloud-VOL and Neurocloud-PET tests.

2. Grant of summary judgment to the defendants.

[¶53.] “In order to prevail in a suit based on negligence, a plaintiff must prove

duty, breach of that duty, proximate and factual causation, and actual injury.”

Hanson v. Big Stone Therapies, Inc., 2018 S.D. 60, ¶ 25, 916 N.W.2d 151, 158

(citations omitted). “‘[I]n medical malpractice cases[,] . . . negligence must be

established by the testimony of medical experts,’ because a verdict in a malpractice

case cannot be based on ‘speculation and conjecture.’” Kostel, 2008 S.D. 85, ¶ 61,

756 N.W.2d at 383 (citation omitted). The element of negligence at issue in the

summary judgment motions below was causation.

In negligence cases and especially in malpractice cases, proof of
causal connection must be something more than consistent with

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the plaintiff’s theory of how the claimed injury was caused. The
burden is on plaintiff to show that it is more probable that the
harm resulted from some negligence for which defendant was
responsible than in consequence of something for which he was
not responsible.

Hanson, 2018 S.D. 60, ¶ 34, 916 N.W.2d at 160 (citation modified) (citations

omitted). “Causation is generally a question of fact for the jury except when there

can be no difference of opinion in the interpretation of the facts.” Id. (citation

omitted).

[¶54.] After excluding the opinions of Dr. Adler, the circuit court determined

the Waltons could not present the necessary expert testimony to create a genuine

issue of material fact on causation. Having reversed the circuit court’s Daubert

ruling, we conclude the opinions of Dr. Stein and Dr. Adler create a genuine issue of

material fact on causation.

[¶55.] In his report, which has not been challenged, Dr. Stein testified to

several breaches of the standard of care, as well as a general statement that the

combination of the high dose opioids given to Kevin greatly increased his risk for

hypoventilation, hypoxemia, respiratory arrest, and death. Additionally, Dr. Stein

stated, to a reasonable degree of medical certainty, the breaches of the standard of

care on behalf of HRMC and Dr. Miner were the direct cause of Kevin’s injuries.

Further, Dr. Adler opined that Kevin has a hypoxic brain injury and that “[t]his

disorder is the direct and proximate result of the subject events which are the focus

of the pending lawsuit.” (Emphasis added.) Therefore, we reverse the circuit

court’s entry of summary judgment in favor of HRMC and Dr. Miner.

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[¶56.] For the reasons discussed, we affirm in part and reverse in part and

remand for further proceedings consistent with this opinion.

[¶57.] SALTER, DEVANEY, and MYREN, Justices, and KERN, Retired

Justice, concur.

[¶58.] GUSINSKY, Justice, not having been a member of the Court at the

time this action was considered by the Court, did not participate.

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