  United States Court of Appeals
      for the Federal Circuit
                ______________________

DOUG PALUCK, RHONDA PALUCK, AS PARENTS
 AND NATURAL GUARDIANS, ON BEHALF OF
         THEIR MINOR SON, K.P.,
           Petitioners-Appellees

                           v.

      SECRETARY OF HEALTH AND HUMAN
                  SERVICES,
              Respondent-Appellant
             ______________________

                      2014-5080
                ______________________

    Appeal from the United States Court of Federal
Claims in No. 1:07-vv-00889-CFL, Judge Charles F.
Lettow.
               ______________________

                Decided: May 20, 2015
                ______________________

    SHEILA A. BJORKLUND, Lommen, Nelson, Cole &
Stageberg, P.A., Minneapolis, MN, argued for petitioners-
appellees.

    PATRICK NEMEROFF, Commercial Litigation Branch,
Civil Division, United States Department of Justice,
Washington, DC, argued for respondent-appellant. Also
represented by JOYCE R. BRANDA; ALEXIS B. BABCOCK,
Vaccine/Torts Branch, Civil Division, United States
2                                             PALUCK   v. HHS



Department of Justice, Washington, DC; MICHAEL S.
RAAB, Appellate Staff, Civil Division, United States
Department of Justice, Washington, DC.
                ______________________

      Before REYNA, MAYER, and CHEN, Circuit Judges.
MAYER, Circuit Judge.
    The Secretary of Health and Human Services appeals
a final judgment of the United States Court of Federal
Claims setting aside the special master’s findings of fact
and conclusions of law and granting entitlement to com-
pensation under the National Childhood Vaccine Injury
Act of 1986, 42 U.S.C. §§ 300aa–1 to –34. (“Vaccine Act”).
See Paluck ex rel. Paluck v. Sec’y of Health & Human
Servs., 113 Fed. Cl. 210 (2013) (“Court of Federal Claims
Decision II”). We affirm.
                       BACKGROUND
    The Court of Federal Claims provided a comprehen-
sive account of the relevant facts and they need only be
briefly summarized here. K.P. was born on January 15,
2004. He exhibited no apparent signs of disability during
the first six to eight months of his life, but in October
2004 K.P.’s daycare provider referred him to K.I.D.S., an
infant development service, for evaluation. Id. at 213.
After extensive testing, K.I.D.S. determined that K.P.
suffered from significant delays in his gross motor skills
and some delays in his fine motor skills. Id. at 214.
Evaluation conducted using the Bayley Scales of Infant
Development protocol, however, determined that K.P.’s
“cognitive skills (i.e., ability to remember, problem solve,
use and understand language, and identify early number
concepts)” were “within normal limits.” The evaluators
from K.I.D.S. noted that K.P. was “a social boy with a
bright smile” who made “a nice variety of sounds while
babbling using both consonants and vowels.” The evalua-
tors ultimately concluded that K.P. presented a “mixed
PALUCK   v. HHS                                            3



picture,” and that his “gross motor delays [were] impact-
ing his ability to achieve age-level skills in other areas of
development.”
     K.P. experienced recurrent rashes, which were later
identified as a symptom of erythema multiforme. He also
suffered from repeated ear infections. On December 27,
2004, K.P. saw Stephen L. McDonough, M.D., his pedia-
trician, for a check of his ears. McDonough evaluated
K.P. as having normal muscle tone, noting that he had
“good head control and fairly good truncal control.”
McDonough stated, however, that K.P. was “not pulling
himself to stand or crawling yet.” Although McDonough
indicated that K.P. might have “possible mild gross motor
delay,” he also noted that K.P. was rolling over, trying to
crawl, and had “several words.”
    McDonough saw K.P. on January 19, 2005 for his one-
year well baby visit. At this appointment, K.P. received
doses of the measles-mumps-rubella (“MMR”), pneumo-
coccal, and varicella vaccines. After examining K.P.,
McDonough described K.P.’s neuromuscular condition as
“abnormal,” noting increased tone 1 in his upper extremi-
ties and the presence of ankle clonus, an abnormal reflex
movement. Although K.P. could “bang [two] cubes held
[in his] hands,” “play ball with [the] examiner,” “pull to
stand,” “stand holding on,” “say single syllables,” and “say
dada/mama,” he could not “get to sitting” or “stand alone.”
    On January 21, 2005, two days after he was vaccinat-
ed, K.P. had a temperature of 101.5 degrees. Seven days
later, on January 28, 2005, K.P. had a recorded tempera-
ture of 101.3 degrees. In the two weeks following the



    1   As Richard Frye, M.D., the Palucks’ expert, ex-
plained, “tone” is a measurement of the ability of the
muscles to maintain the body in proper posture in differ-
ent positions, such as sitting or standing.
4                                           PALUCK   v. HHS



vaccinations, K.P. was generally fussy and did not nap or
eat well.
    In February 2005, Rhonda and Doug Paluck (the
“Palucks”), K.P.’s parents, took him to the Pokorny Chiro-
practic Clinic, hoping to address his gross motor prob-
lems. On February 11, 2005, the chiropractor reported
that K.P. was “spastic.” On March 24, 2005, McDonough
referred K.P. to Siriwan Kriengkrairut, M.D., a pediatric
neurologist. In making the referral, McDonough noted
that K.P. suffered from “gross motor delay, global devel-
opmental delay, and hypertonicity.”
    After evaluating K.P., Kriengkrairut concluded that
he suffered from “marked spasticity of the extremities”
and “[g]lobal delayed development.” Kriengkrairut sug-
gested to the Palucks that K.P.’s muscular abnormalities
and developmental delays were possibly the result of a
“central nervous system pathology.”
    On April 27, 2005, K.P. had a magnetic resonance im-
aging (“MRI”) exam of his brain. The results of this MRI
exam were initially deemed to be normal. Subsequently,
however, the MRI results were reexamined, and it was
determined that they evidenced a thinning of the corporal
callosum. In May 2005, K.P. was evaluated by a speech
therapist who determined that he possessed fewer lan-
guage skills than he did in October 2004, and that his
total language score was in the first percentile.
    In July 2005, K.P. suffered a series of seizures and
was hospitalized for three weeks. While in the hospital,
he underwent another MRI exam, which showed further
thinning of the corporal callosum. Theodore J. Passe,
M.D., a radiologist who reviewed K.P.’s April and July
2005 MRI results, concluded that they were “consistent
with a progressing leukodystrophy” which could have a
“hereditary, toxic or metabolic etiolog[y].”
PALUCK   v. HHS                                           5



    On October 27, 2005, K.P. had another MRI exam.
Michael Frost, M.D., a physician who began treating K.P.
in the summer of 2005, determined that this exam showed
no significant changes in K.P.’s brain since the July 2005
MRI exam. Frost concluded that “the progression of a
signal change” in K.P.’s brain “between 4/27/05 and
07/22/05 may have represented evolution of [one] tox-
ic/metabolic event, which is now stable.”
    K.P. was subsequently diagnosed with an unspecified
mitochondrial disorder. All parties agree that this mito-
chondrial disorder was most likely present from the time
of K.P.’s birth. K.P. now lives in a state of severe neuro-
logical disability. He has “no purposeful movements” and
“no specific smiling or distinctive eye contact.” K.P. has a
tracheotomy tube and breathes with the assistance of a
ventilator.
    In December 2007, the Palucks filed a petition for
compensation under the Vaccine Act. They alleged that
K.P. sustained a permanent injury to his brain as a result
of the MMR, pneumococcal, and varicella vaccines he
received on January 19, 2005. Frye, the Palucks’ expert,
testified that K.P.’s underlying mitochondrial disorder
prevented him from coping with the oxidative stress from
the vaccines he received. According to Frye, this led to
“metabolic decompensation,” and eventually caused
neurodegeneration and developmental regression. The
special master, however, rejected the Palucks’ claim,
concluding that Frye failed to provide a plausible medical
theory causally connecting K.P.’s injury to the vaccines he
received. See Paluck ex rel. Paluck v. Sec’y of Health &
Human Servs., No. 07-889V, 2011 WL 6949326, at *16
(Fed. Cl. Dec. 14, 2011) (“Special Master Decision I”). The
special master determined, moreover, that K.P.’s neuro-
logical symptoms emerged too late to be causally linked to
the vaccinations he received. Id. at *24–27. In the special
master’s view, if K.P.’s neurodegeneration was vaccine-
induced, he would have exhibited symptoms of neurologi-
6                                             PALUCK   v. HHS



cal injury within two weeks of the date of his vaccina-
tions. Id. at *27.
    On appeal, the Court of Federal Claims concluded
that the special master had “required a higher level of
proof . . . than the Vaccine Act demands.” Paluck ex rel.
Paluck v. Sec’y of Health & Human Servs., 104 Fed. Cl.
457, 473 (2012) (“Court of Federal Claims Decision I”).
According to the court, the special master had no reason-
able basis for rejecting Frye’s theory of causation. Id. at
474. The court further determined that “[i]t was arbitrary
and capricious for the special master to set a hard and
fast limit of two weeks” between vaccination and the
onset of symptoms of vaccine-induced neurological injury.
Id. at 482. Because the special master “misapprehend[ed]
the testimony of Dr. Frye and ignor[ed] salient medical-
record evidence of [K.P.’s] symptoms during the relevant
time period,” id. at 483, the court vacated the special
master’s decision and remanded for further proceedings.
    On remand, the special master accepted the govern-
ment’s apparent concession that Frye had presented a plausi-
ble medical theory explaining how vaccination could
aggravate an underlying mitochondrial disorder.2 See Paluck
ex rel. Paluck v. Sec’y of Health & Human Servs., No. 07-
889V, 2013 WL 2453747, at *42 (Fed. Cl. May 10, 2013)
(“Special Master Decision II”). The special master deter-
mined, however, that K.P.’s condition did not deteriorate in
the manner predicted by Frye’s theory. In the special mas-


    2   The special master determined that K.P.’s claim
should be treated not as a new injury claim, but instead
as a claim for the significant aggravation of his pre-
existing mitochondrial disorder. See 42 U.S.C. § 300aa–
33(4) (“The term ‘significant aggravation’ means any
change for the worse in a preexisting condition which
results in markedly greater disability, pain, or illness
accompanied by substantial deterioration of health.”).
PALUCK   v. HHS                                             7



ter’s view, Frye’s theory predicted “a dramatic and continual
deterioration, beginning within two to three weeks after”
vaccination. Id. at *49. The special master concluded, how-
ever, that K.P. did not manifest any symptoms of neurological
injury within three weeks of his vaccinations, id. at *55–62,
and did not experience the type of “linear” deterioration that
Frye’s theory of causation required, id. at *49.
    On appeal, the Court of Federal Claims held that the
special master had misconstrued Frye’s theory of causation.
Court of Federal Claims Decision II, 113 Fed. Cl. at 234–
35. According to the court, “[t]o fall within Dr. Frye’s
theory and the applicable medical literature, it [was]
sufficient if [K.P.’s] medical records show[ed] a decline in
condition over time, notwithstanding periods of remission
or modest improvement.” Id. The court determined,
moreover, that it was arbitrary and capricious for the
special master to disregard probative medical record
evidence showing that K.P. experienced progressive
neurological deterioration in the months following his
vaccinations. Id. at 235–39. Because the Palucks had
demonstrated, “by a preponderance of the evidence, that
[K.P.’s] existing medical setbacks were significantly
aggravated by his receipt of the vaccinations within a
medically acceptable time,” the Court of Federal Claims
vacated the special master’s decision and remanded the
case for a determination of the amount of compensation
the Palucks were due. Id. at 241.
    The government then filed a timely appeal to this
court. 3 We have jurisdiction under 42 U.S.C. § 300aa–
12(f).



    3  Contrary to the Palucks’ assertions, the govern-
ment’s appeal to this court was not untimely filed. The
government filed its notice of appeal on April 25, 2014,
which was within sixty days of the Court of Federal
8                                            PALUCK   v. HHS



                        DISCUSSION
A. Standard of Review
    “In reviewing an appeal from a judgment of the Court
of Federal Claims in a Vaccine Act case, we apply the
same standard of review as the Court of Federal Claims
applied to the special master’s decision.” Andreu ex rel.
Andreu v. Sec’y of Dep’t of Health & Human Servs., 569
F.3d 1367, 1373 (Fed. Cir. 2009); see also Koehn ex rel.
Koehn v. Sec’y of Health & Human Servs., 773 F.3d 1239,
1243 (Fed. Cir. 2014). Although we review legal determi-


Claims’ entry of judgment on February 28, 2014. See id.
§ 300aa–12(f) (providing that an appeal to this court must
be filed “within 60 days of the date” the Court of Federal
Claims enters judgment).
    The Palucks contend that the Court of Federal
Claims’ October 29, 2013, decision—which set aside the
special master’s decision denying entitlement and re-
manded for a determination of compensation—was a
“final judgment” that triggered the running of the sixty-
day appeal period. This argument is without merit.
Because the Court of Federal Claims’ October 29, 2013,
decision determined entitlement, but remanded to the
special master for consideration of the appropriate
amount of compensation to be awarded, see Court of
Federal Claims Decision II, 113 Fed. Cl. at 241, it was not
an appealable final judgment. See Flanagan v. United
States, 465 U.S. 259, 263 (1984) (The “final judgment rule
requires that a party must ordinarily raise all claims of
error in a single appeal following final judgment on the
merits.” (citations and internal quotation marks omit-
ted)); Teledyne Cont’l Motors v. United States, 906 F.2d
1579, 1582 (Fed. Cir. 1990) (emphasizing that “a judg-
ment limited to the issue of liability, where the assess-
ment of damages or other relief remains open, is not
final”).
PALUCK   v. HHS                                             9



nations without deference, we review findings of fact
under the arbitrary and capricious standard. Griglock v.
Sec’y of Health & Human Servs., 687 F.3d 1371, 1374
(Fed. Cir. 2012); see also Moberly ex rel. Moberly v. Sec’y of
Health & Human Servs., 592 F.3d 1315, 1321 (Fed. Cir.
2010).
B. The Vaccine Act
    “Childhood vaccinations, though an important part of
the public health program, are not without risk.” Terran
ex rel. Terran v. Sec’y of Health & Human Servs., 195 F.3d
1302, 1306 (Fed. Cir. 1999). Recognizing that “a small
but significant number” of individuals will be “gravely
injured” as a result of inoculation, H.R. Rep. No. 99–908,
99th Cong., 2d Sess. 4 (1986), reprinted in 1986
U.S.C.C.A.N. 6345, Congress created a federal no-fault
compensation scheme under which awards were to “be
made to vaccine-injured persons quickly, easily, and with
certainty and generosity.” H.R. Rep. No. 99–908, at 3,
1986 U.S.C.C.A.N. at 6344; see Shalala v. Whitecotton,
514 U.S. 268, 269 (1995) (explaining that the Vaccine Act
compensation system was “designed to work faster and
with greater ease than the civil tort system”).
    A petitioner seeking compensation under the Vaccine
Act must establish, by a preponderance of the evidence,
that a covered vaccine caused the claimed injury. See
Moberly, 592 F.3d at 1321. Where, as here, the claimed
injury is not listed in the Vaccine Injury Table, see 42
U.S.C. § 300aa–14, a claimant may obtain compensation
by showing that his injury was “caused in fact” by the
vaccine or vaccines he received. See Andreu, 569 F.3d at
1374. In order to prove causation in fact, a petitioner
must: (1) provide a medical theory causally connecting the
vaccination to the injury; (2) demonstrate a logical se-
quence of cause and effect showing that the vaccination
was the reason for the injury; and (3) establish a proxi-
mate temporal relationship between the vaccination and
10                                            PALUCK   v. HHS



the injury. Althen v. Sec’y of Health & Human Servs., 418
F.3d 1274, 1278 (Fed. Cir. 2005). If the petitioner satis-
fies this burden, he is entitled to compensation unless the
government demonstrates by a preponderance of the
evidence that the injury was in fact caused by factors
unrelated to the vaccine. 42 U.S.C. § 300aa–13(a)(1)(B).
    The Palucks assert that their son suffered severe
neurodegeneration as a result of the vaccines he received
on January 19, 2005. They contend that these vaccines
caused a significant aggravation of K.P.’s underlying
mitochondrial disorder, leading to alterations in his brain
development and subsequent neurodevelopmental regres-
sion. In support of their claim, the Palucks proffered
several medical articles, including: (1) an article discuss-
ing four children suffering from both a mitochondrial
disorder and autism who experienced developmental
regression following vaccination, see John Shoffner et al.,
Fever Plus Mitochondrial Disease Could Be Risk Factors
for Autistic Regression, J. Child Neurology 3 (2009)
(“Shoffner”); (2) an article discussing a link between
infection and subsequent neurodegenerative events in
persons with mitochondrial disorders, see Joseph L.
Edmonds et al., The Otolaryngological Manifestations of
Mitochondrial Disease & the Risk of Neurodegeneration
with Infection, 128 Archives of Otolaryngology-Head &
Neck Surgery 30 (2002) (“Edmonds”); and (3) a case study
of Hannah Poling, a child with a mitochondrial disorder,
who experienced fever and severe developmental regres-
sion shortly after vaccination, see Jon S. Poling et al.,
Developmental Regression and Mitochondrial Dysfunction
in a Child with Autism, 21(2) J. Child Neurology 170
(2006) (the “Poling case study”). The Palucks also relied
upon reports and testimony from Frye, a pediatric neurol-
ogist, who explained that in a child with an underlying
mitochondrial disorder, vaccination can lead to an “over-
whelming immune response” and subsequent neuro-
degeneration. Frye explained that “vaccines, by intention,
PALUCK   v. HHS                                            11



activate the immune system,” leading to “potentially
toxic” reactive oxygen species and reactive nitrogen
species. In an individual with a mitochondrial disorder,
these potentially toxic elements can accumulate, causing
oxidative stress, and setting off “a cascade of intracellular
events” that leads to “apoptosis or cellular death.” Frye
asserted that because cells in the brain are particularly
vulnerable to oxidative stress, vaccination can cause
persons with underlying mitochondrial disorders to expe-
rience neurodegeneration and developmental regression.
Frye emphasized, moreover, that “the interaction between
oxidative stress and mitochondria [is] something that’s
progressive over time.”
    On appeal, the government does not meaningfully
dispute that Frye’s theory of causation is medically plau-
sible. Indeed, before the special master the government
conceded that vaccination could have, in theory, exacer-
bated K.P.’s underlying mitochondrial disorder.         See
Special Master Decision II, 2013 WL 2453747, at *42. The
government contends, however, that the Court of Federal
Claims erred in setting aside the special master’s finding
that K.P.’s health did not deteriorate as quickly or as
consistently as anticipated by Frye’s medical theory. In
the government’s view, because the special master had a
“rational basis” for “concluding that K.P.’s condition did
not change following his vaccinations in the manner
predicted by [Frye’s] medical theory,” the Court of Federal
Claims exceeded its authority by reweighing the evidence
and “second guess[ing]” the special master’s “fact-
intensive conclusions.”
    We do not find this argument persuasive. By statute,
the Court of Federal Claims is empowered to “set aside
any findings of fact or conclusion of law of the special
master found to be arbitrary, capricious, an abuse of
discretion, or otherwise not in accordance with law and
issue its own findings of fact and conclusions of law . . . .”
42 U.S.C. § 300aa–12(e)(2)(B). Where, as here, a special
12                                            PALUCK   v. HHS



master misapprehends a petitioner’s theory of causation,
misconstrues his medical records, and makes factual
inferences wholly unsupported by the record, the Court of
Federal Claims is not only authorized, but obliged, to set
aside the special master’s findings of fact and conclusions
of law. See Andreu, 569 F.3d at 1375 (concluding that a
special master erred in disregarding probative testimony
from a petitioner’s treating physicians); Capizzano v. Sec’y
of Health & Human Servs., 440 F.3d 1317, 1325 (Fed. Cir.
2006) (concluding that a special master “impermissibly
raise[d] a claimant’s burden under the Vaccine Act”);
Althen, 418 F.3d at 1280–81 (concluding that a special
master improperly required medical literature linking a
particular vaccine to the claimant’s injury). While review
of the factual findings made by a special master is highly
deferential, see Porter v. Sec’y of Health & Human Servs.,
663 F.3d 1242, 1249 (Fed. Cir. 2011), both this court and
the Court of Federal Claims have a duty to ensure that
the special master has properly applied Vaccine Act
evidentiary standards, “considered the relevant evidence
of record, drawn plausible inferences and articulated a
rational basis for [his] decision.” Hines ex rel. Sevier v.
Sec’y of Dep’t of Health & Human Servs., 940 F.2d 1518,
1528 (Fed. Cir. 1991).
C. Progressive Neurological Decline
    The special master acknowledged that K.P. experi-
enced significant neurodevelopmental regression between
January 19, 2005, the date he was vaccinated, and July
30, 2005, the date he was discharged from the hospital.
See Special Master Decision II, 2013 WL 2453747, at *42
(“By virtually any metric, [K.P.] was worse.”). He con-
cluded, however, that K.P.’s post-vaccination deteriora-
tion did not align with Frye’s medical theory because that
deterioration was not “linear,” id. at *49, and K.P. did not
manifest identifiable symptoms of neurologic injury
within three weeks of his vaccinations, id. at *62. In an
exceptionally thorough and well-reasoned opinion, the
PALUCK   v. HHS                                         13



Court of Federal Claims correctly determined that the
special master misapprehended Frye’s medical theory and
acted arbitrarily and capriciously in disregarding signifi-
cant probative evidence showing that K.P. experienced
rapid and progressive neurological deterioration within a
medically acceptable interval following his vaccinations.
     Frye testified that in a person suffering from a mito-
chondrial disorder, vaccine-induced neurodegeneration
would proceed in two phases. In the first phase, “an
inciting event,” such as an immunization, activates the
immune system and causes it “to get to the point where it
initiate[s] the cascade of events that cause[s] dysfunction
between the mitochondria and oxidative stress.” Accord-
ing to Frye, in a child with a mitochondrial defect, an
“adverse reaction” to a vaccine would be expected to
appear within a week of vaccination. K.P. exhibited
symptoms of an adverse reaction to inoculation shortly
after his January 2005 vaccinations. Within forty-eight
hours of being vaccinated, K.P. “showed signs of irritabil-
ity, fever, and fatigue.” Court of Federal Claims Decision
II, 113 Fed. Cl. at 216. K.P. had a recorded temperature
of 101.5 degrees two days after being vaccinated and a
recorded temperature of 101.3 degrees seven days later.
As experts for both sides agreed, fever is evidence of
immune activation. 4
    The second phase of vaccine-induced neurodegenera-
tion, Frye explained, is “something that’s progressive over
time,” occurring over a period of “weeks and months.” In
this phase, there is a “downward spiral of activity be-
tween the mitochondria and oxidative stress,” leading to


   4   Although S. Robert Snodgrass, M.D., the govern-
ment’s expert, acknowledged that K.P.’s fever was evi-
dence of immune activation, he suggested that the fever
could have been caused by an infection rather than the
vaccines K.P. received.
14                                          PALUCK   v. HHS



the death of brain cells and neurodegeneration. Frye
emphasized that there was no rigid timeframe for when
the clinical symptoms of vaccine-induced neurodegenera-
tion would be expected to appear, explaining that the
progression of neurological deterioration would “depend
on the severity and type of mitochondrial disorder.”
    As the Court of Federal Claims correctly determined,
the rapid and devastating neurological regression K.P.
experienced in the wake of his vaccinations was fully
consistent with Frye’s medical theory. See id. at 238–39.
Although K.P. “was not a completely healthy child when
he received the vaccinations,” id. at 228, there was no
credible evidence that he suffered from any significant
problems in his central nervous system. At the time of
the January 2005 vaccinations, McDonough observed that
K.P. had some gross motor delays and exhibited some
increased tone in his upper extremities. McDonough also
reported, however, that K.P. was able to “play ball with
[the] examiner,” “bang [two] cubes held by [the] hands,”
“pull to stand,” “stand holding on,” and say “dada/mama.”
Significantly, there was no persuasive evidence that
K.P.’s increased tone and gross motor delays were caused
by a central nervous system problem rather than by his
underlying mitochondrial disorder. See id. at 222 (“The
parties agreed that [K.P.’s] mitochondrial defect was
likely affecting his health before the vaccinations.”). To
the contrary, given Frye’s unrebutted testimony that
mitochondrial disorders can impair muscle function and
development, and the fact that K.P. did not exhibit any
pronounced pre-vaccination language or cognitive delays,
the Court of Federal Claims had ample support for its
conclusion that K.P. had no significant neurological
problems in the pre-vaccination period. Id. at 228 (“If
[K.P.’s] problems prior to the vaccinations on January 19,
2005, were neurological, the impairment was small and
not evident to the treating physicians.”).
PALUCK   v. HHS                                          15



    In the wake of his January 2005 vaccinations, K.P.
experienced a precipitous and well-documented neurologi-
cal decline. By February 11, 2005, twenty-three days
after the date of the vaccinations, K.P.’s chiropractor
determined that he was “spastic.” As the special master
acknowledged, “‘[s]pasticity’ means that the muscles are
so hypertonic (that is, rigid) that movements are limited.”
Special Master Decision I, 2011 WL 6949326, at *21. The
February 11, 2005, chiropractic report was the first time
that any therapist or medical professional had found that
K.P. suffered from spasticity, and, as Frye correctly noted,
showed “that there was a very rapid change in [K.P.’s]
central nervous system.” According to Frye, the fact that
K.P. developed spasticity within a month of vaccination
indicated that the neurons in the motor cortex of his brain
had been “severely damaged and [were] no longer control-
ling the neurons in the spinal cord.” Thus, as the Court of
Federal Claims properly concluded, “the chiropractor’s
notation that [K.P.] was ‘spastic’ on February 11, 2005,”
was “an identifiable neurodegenerative event” showing
that “the neurodegenerative process [had] begun.” Court
of Federal Claims Decision II, 113 Fed. Cl. at 240.
    K.P.’s pronounced neurodevelopmental regression was
confirmed by both McDonough and Kriengkrairut, K.P.’s
neurologist. On March 24, 2005, McDonough reported
that K.P. was “hypertonic[]” and suffered from “global
developmental delay.” When Kriengkrairut evaluated
K.P. in April 2005, she confirmed that he suffered from
global developmental delay, noting that he was “unable to
sit alone” and did “not babble.” She determined, moreo-
ver, that K.P. suffered from “marked spasticity of the
extremities,” which was likely due to a “central nervous
system pathology.” By May 2005, K.P.’s speech therapist
concluded that he had fewer language skills than he
displayed in October 2004, and that his total language
score was in the first percentile. By October 2005, K.P.
had “no purposeful movements” and “no specific smiling
16                                            PALUCK   v. HHS



or distinctive eye contact.” MRI exams—conducted in
April and July 2005—showed thinning of the corporal
callosum of K.P.’s brain and were consistent with progres-
sive brain degeneration.
     In the face of this compelling evidence of post-
vaccination neurodevelopmental regression, the special
master had no reasonable basis for concluding that K.P.
did not experience the progressive neurodegeneration
predicted by Frye’s medical theory. As noted previously,
Frye asserted that a child experiencing vaccine-induced
neurodegeneration would decline in a manner that was
“progressive over time.” Contrary to the special master’s
assertions, nothing in Frye’s testimony mandated a
“linear” deterioration with no instances of slight or tem-
porary improvement in symptoms. See 113 Fed. Cl. at
234 (explaining that neither the relevant medical litera-
ture nor Frye’s theory required “a linear, downward slope”
of injury). In concluding that K.P. did not experience the
progressive decline predicted by Frye’s theory, the special
master noted that K.P.’s February 2005 chiropractic
records indicated that he was “less rigid” on some days
than on others. Special Master Decision II, 2013 WL
2453747, at *44. In focusing on the fact that K.P.’s mus-
cle tone fluctuated somewhat in February 2005, the
special master failed in his duty to consider “the record as
a whole.” 42 U.S.C. § 300aa–13(a)(1). Although K.P.’s
chiropractic records indicate that he was “less rigid” on
some days than on others, those records, when viewed as
a whole, do not reflect any sustained improvement in his
condition. To the contrary, the chiropractor evaluated
K.P. as “spastic” on February 11, 2005, and he “never
appeared to improve above his initial assessment.” Court
of Federal Claims Decision II, 113 Fed. Cl. at 236; see also
id. at 241 (emphasizing that K.P. “did not continue to
develop in any way after the vaccinations”). It was arbi-
trary and capricious for the special master to give short
shrift to the evidence of K.P.’s sudden neurological regres-
PALUCK   v. HHS                                           17



sion—reflected in the chiropractor’s finding of spasticity—
and to place undue emphasis on the relatively insignifi-
cant variations in muscle tone recorded in the February
2005 chiropractic records.      Indeed, because physical
therapy can stretch muscles, the fact that K.P.’s muscle
tone fluctuated during the period when he was receiving
chiropractic therapy was “expected,” and did not mean
that his overall condition was improving. Id.
    Significantly, moreover, the special master misread
the handwritten notes from K.P.’s chiropractor. Accord-
ing to the special master, “[t]he chiropractor’s opinion was
that [K.P.] did not have an adverse reaction to a vaccine.”
Special Master Decision II, 2013 WL 2453747, at *46. As
the government now acknowledges, the special master
misread the chiropractor’s notes and nothing they contain
suggests that he had concluded that K.P.’s spasticity was
not caused by the vaccines he received on January 19,
2005. Instead, the chiropractor had only concluded that
K.P.’s injury was not the result of child abuse. K.P.’s
chiropractic records are very significant in that they are
“the most comprehensive contemporaneous records of
[K.P.’s] condition in the several months after the vaccina-
tions.” Court of Federal Claims Decision I, 104 Fed. Cl. at
480; see Cucuras ex rel. Cucuras v. Sec’y of Dep’t of Health
& Human Servs., 993 F.2d 1525, 1528 (Fed. Cir. 1993)
(emphasizing the importance of contemporaneous medical
records in evaluating Vaccine Act cases). The fact that
the special master misconstrued those records undercuts
his analysis and buttresses the Court of Federal Claims’
decision to set aside his findings of fact and conclusions of
law.
D. Timeframe for the Onset of Neurological Symptoms
    The special master further erred in setting a hard and
fast deadline of three weeks between vaccination and the
onset of clinically apparent symptoms of neurological
injury. See Special Master Decision II, 2013 WL 2453747,
18                                            PALUCK   v. HHS



at *55 (“The important time is within three weeks of
January 19, 2005 . . . . Thus, for the Palucks to meet their
burden of proof they must show that [K.P.] manifested
signs or symptoms of neurodegeneration within this
timeframe.”). As the Court of Federal Claims correctly
determined, the special master had no reasonable basis
for concluding that an individual suffering from vaccine-
induced neurodegeneration would necessarily manifest
clinical symptoms of neurologic injury within three weeks
of vaccination. See Court of Federal Claims Decision II,
113 Fed. Cl. at 240 (“Neither the medical literature nor
the expert testimony stated with any certainty when
neurodegeneration can be expected to begin in all cases.”).
The Shoffner study described twelve patients with both
autism and a mitochondrial disorder who experienced
developmental regression within two weeks of the onset of
a fever. In four of those patients, the elevated tempera-
ture was determined to be “a febrile response to vaccina-
tion.” The Edmonds article collected information about
thirteen patients with mitochondrial disease who experi-
enced “neurodegenerative events” following an infection.
In most patients, the neurodegenerative event occurred
within three to seven days after the onset of the infection,
but in at least one patient it did not occur until nineteen
days after infection. The Poling case study described a
young girl with a mitochondrial disorder who developed a
fever and lost the ability to climb stairs a few days after
being vaccinated. Over the next three months, she lost
the ability to communicate and developed autistic behav-
iors.
    The Shoffner article, the Edmonds article, and the
Poling case study—which collectively discuss only a very
small number of patients—do not purport to establish any
definitive timeframe for the onset of clinical symptoms of
neurological regression in individuals afflicted with
mitochondrial disorders. There is a wide variety of mito-
chondrial disorders and those disorders are as yet poorly
PALUCK   v. HHS                                         19



understood by the medical community. See id. at 238–41.
Indeed, as the special master properly acknowledged,
“mitochondrial disorders are variegated. What happens
in one mitochondrial disorder may not happen in the next
person with a mitochondrial disorder.” Special Master
Decision I, 2011 WL 6949326, at *13. Given the hetero-
geneity of mitochondrial defects and the paucity of scien-
tific literature discussing the impact that vaccination has
on persons suffering from such defects, the special master
had no reasonable basis for setting a hard and fast dead-
line of three weeks for the onset of neurological symp-
toms. See Althen, 418 F.3d at 1280 (emphasizing that
“the purpose of the Vaccine Act’s preponderance standard
is to allow the finding of causation in a field bereft of
complete and direct proof of how vaccines affect the
human body”). Accordingly, the fact that K.P.’s first
clinically evident sign of neurodegeneration—spasticity—
was documented twenty-three days, rather than twenty-
one days, after vaccination does not preclude a finding
that it was a symptom of vaccine-induced neurologic
injury. See Andreu, 569 F.3d at 1380 (emphasizing that
relevant medical “evidence must be viewed . . . not
through the lens of the laboratorian, but instead from the
vantage point of the Vaccine Act’s preponderant evidence
standard”).
E. Unsupported Inferences
    As the Court of Federal Claims correctly determined,
moreover, the special master made inferences unsupport-
ed by the record when he concluded that K.P. did not
experience progressive neurological deterioration in the
immediate aftermath of his January 19, 2005 vaccina-
tions. First, the special master reasoned that if K.P.’s
condition had been significantly deteriorating in February
2005, the Palucks would have taken him to a medical
doctor more frequently. See Special Master Decision II,
2013 WL 2453747, at *60 (“The Palucks have . . . not
provided any evidence to explain why, if [K.P.] was as sick
20                                            PALUCK   v. HHS



as they claim, they did not take him to a medical doctor in
February.”). As the Court of Federal Claims correctly
noted, however, K.P.’s “parents actually were taking him
frequently to a medical provider, i.e., the chiropractor” in
February 2005. Court of Federal Claims Decision II, 113
Fed. Cl. at 236. Indeed, the Palucks took K.P. to the
chiropractor nine times in three weeks during February
2005, apparently believing that his developmental prob-
lems were caused by a pinched nerve. Id. It was arbi-
trary and capricious for the special master to infer that
K.P.’s condition did not deteriorate in February 2005
simply because his parents were attempting to ameliorate
their son’s symptoms through chiropractic therapy.
    It was also arbitrary and capricious for the special
master to infer that McDonough referred K.P. to a pediat-
ric neurologist in March 2005 only because he was “frus-
trated” with the Palucks.      In making the referral,
McDonough stated that K.P. was “hypertonic[]” and
suffered from “global developmental delay.” The special
master’s suggestion that McDonough made the referral
not because he believed K.P. was getting worse, but
instead because he was “frustrated that the Palucks were
not following his recommendations for physical therapy
[and] occupational therapy,” Special Master Decision II,
2013 WL 2453747, at *47, is devoid of any credible sup-
port in the record.
F. MRI Evidence and Contemporaneous Physician State-
ments
    The special master also had no reasonable basis for
disregarding MRI evidence indicating that K.P. experi-
enced progressive post-vaccination neurological deteriora-
tion. An April 2005 MRI exam of K.P.’s brain showed a
subtle thinning of the corporal callosum. An MRI exam
conducted three months later, in July 2005, showed
further thinning of the corporal callosum. Passe, the
radiologist who evaluated these MRIs, concluded that
PALUCK   v. HHS                                         21



they were “consistent with a progressing leukodystrophy,”
i.e., consistent with progressive neurodegeneration. 5
Frost, a physician who began treating K.P. in the summer
of 2005, likewise concluded that K.P.’s April and July
MRI exams evidenced “neurodegenerative disease,” which
was “likely progressing leukodystrophy.” As the Court of
Federal Claims correctly concluded, moreover, the fact
that K.P.’s April 2005 MRI exam showed only a very
“subtle” thinning of the corporal callosum suggested that
the thinning had only recently begun. Court of Federal
Claims Decision II, 113 Fed. Cl. at 238. K.P.’s MRI rec-
ords are consistent with a finding that his neurological
decline began at the time of his vaccinations, and the
special master provided no reasonable justification for
discounting their significance. 6
    Finally, the special master erred in disregarding con-
temporaneous statements from K.P.’s treating physicians
regarding the cause of his neurodegeneration. As we
explained in Andreu, “treating physicians are likely to be
in the best position to determine whether a logical se-
quence of cause and effect show[s] that the vaccination
was the reason for the injury.” 569 F.3d at 1375 (citations



   5    “Leukodystrophy” refers to a group of disorders
characterized by degeneration of the white matter of the
brain. See Dorland’s Illustrated Med. Dictionary 1029
(32nd ed. 2012).
    6   Snodgrass contended that the thinning of K.P.’s
corporal callosum may have begun even prior to the date
of his vaccinations. See Special Master Decision II, 2013
WL 2453747, at *48. In support, he suggested that the
thinning of the corporal callosum shown in the April 2005
MRI exam could have been the result of a prenatal infec-
tion. Id. There is, however, no credible evidence in the
record demonstrating that any type of prenatal infection
might have caused an injury to K.P.’s brain.
22                                           PALUCK   v. HHS



and internal quotation marks omitted). After reviewing
the results of K.P.’s April and July 2005 MRI exams,
Passe stated that K.P.’s neurodegeneration could have a
“hereditary, toxic or metabolic etiolog[y].” Frost, after
reviewing the April and July exams—as well as the
results from a third MRI exam conducted in October 2005
which showed no further significant changes in K.P.’s
brain—agreed that K.P.’s condition could have a “toxic”
etiology. Frost concluded that “the progression of a signal
change” in K.P.’s brain “between 4/27/05 and 07/22/05
may have represented evolution of [one] toxic/metabolic
event, which is now stable.”
      As the special master acknowledged, “the term ‘toxic’
is broad enough to include an injury caused by a vaccine
. . . . ” Special Master Decision II, 2013 WL 2453747, at
*48. Thus, the Palucks were entitled to rely on the
statements from K.P.’s physicians that his condition could
be due to a “toxic . . . event” as evidence supporting a
causal nexus between K.P.’s vaccinations and his subse-
quent neurological regression. It was arbitrary and
capricious for the special master to wholly discount the
probative value of these statements simply because K.P.’s
physicians suggested that his condition could also poten-
tially be due to alternative causes. See id. at *49 (“While
the Palucks have cited Dr. Passe’s July 22, 2005 report as
a statement of a treating doctor showing that the reason
for [K.P.’s] decline was the vaccination . . . [this] argu-
ment is not persuasive because the Palucks have not
addressed the other possible causes listed by Dr. Passe.”).
The Palucks’ burden was to show, by a preponderance of
the evidence, that K.P.’s mitochondrial disorder was
significantly aggravated by the vaccines he received, not
to rule out every other potential cause of his injury. See
de Bazan v. Sec’y of Health & Human Servs., 539 F.3d
1347, 1352 (Fed. Cir. 2008) (“So long as the petitioner has
satisfied all three prongs of the Althen test, she bears no
burden to rule out possible alternative causes.” (footnote
PALUCK   v. HHS                                       23



omitted)); Walther v. Sec’y of Health & Human Servs., 485
F.3d 1146, 1151 (Fed. Cir. 2007) (emphasizing that “the
government bears the burden of establishing alternative
causation by a preponderance of the evidence once the
petitioner has established a prima facie case”).
                      CONCLUSION
    Accordingly, the judgment of the United States Court
of Federal Claims is affirmed.
                      AFFIRMED
