Opinion
The named plaintiff, Eric Klein, 1 appeals, following our grant of his petition for certification, from the judgment of the Appellate Court affirming the trial court’s judgment, rendered after a jury verdict in a medical malpractice action, in favor of the defendant, Nor-walk Hospital. The plaintiff claims that the Appellate Court, without reaching the merits of his individual claims, improperly concluded that it constituted harmless error when the trial court: (1) on the basis of what it considered to be inadequate disclosure, precluded testimony by one of the plaintiffs expert witnesses to refute the defendant’s theory of causation; and (2) admitted testimony from one of the defendant’s expert witnesses as to this alleged cause without establishing the reliability of the basis of that opinion pursuant to a Porter hearing. 2 We reverse the judgment of the Appellate Court.
The Appellate Court opinion recites the following facts and procedural history pertinent to the plaintiffs appeal. “On February 27, 2003, the plaintiff, a dentist, was admitted [by the defendant] because of aperforated appendix and infectious abscesses. Later that day, he underwent emergency surgery to remove his burst *244 appendix as well as a portion of his large intestine that had a cyst on it. The plaintiff recuperated during the immediate postoperative period as a patient in the hospital. Part of his postoperative treatment was intravenous antibiotic therapy to address the infection that resulted from his appendix bursting. On March 3, 2003, as part of her duties as a registered nurse employed by the [defendant] on its intravenous team, Patricia DePaoli inspected the plaintiffs existing intravenous lines to determine if they required changing or other treatment. Morton Klein, the plaintiffs father, was in the room visiting his son when DePaoli entered. Upon inspection, DePaoli discovered, on the back of the plaintiffs left hand, around an existing intravenous site, an area of low grade phlebitis. 3 She began to replace the existing intravenous line in his left hand with a new intravenous line farther up his arm. During this procedure, Morton Klein testified, his son shouted out in pain on three occasions and that after the third incident, DePaoli terminated her attempt at inserting an intravenous line into the plaintiffs left arm. Morton Klein, however, did not see any of the procedure performed by DePaoli on his son’s left arm.
“The plaintiff testified that during the procedure to place a new intravenous line into his left arm, he felt a distinct and sharp pain shooting down his arm just after DePaoli inserted the needle. He exclaimed in pain but allowed DePaoli to keep going with the procedure. He felt another sharp pain and again exclaimed, telling DePaoli that she had hit a nerve. DePaoli continued with the procedure until the plaintiff exclaimed in pain for a third time, complaining that his entire left hand had gone ‘dead’ and telling DePaoli to remove the needle. After applying a dry sterile dressing to the area of *245 the unsuccessful attempt, DePaoli then, without incident, inserted another intravenous line in the plaintiffs right arm.
“After his release [by the defendant], the plaintiff asserted that he was having ongoing difficulties using his left hand and saw many medical specialists, including neurologists and a hand surgeon. These lingering effects were diagnosed, according to the plaintiff, as anterior interosseous 4 nerve palsy caused by an improper attempted intravenous line insertion and had a negative impact on his dental practice and overall quality of life. He brought this action against the [defendant], alleging medical malpractice on its part for the alleged improper insertion of the intravenous line by its employee, DePaoli, which resulted in the diagnosis of anterior interosseous nerve palsy.
“On January 11, 2006, the plaintiff, pursuant to Practice Book § 13-4 (4), disclosed Clifford Gevirtz, an anesthesiologist specializing in pain management, as an expert witness. According to the disclosure, Gevirtz was to testify on matters concerning the standard of care to which the defendant was held, departures from the standard of care, causation and damages. [The defendant thereafter disclosed Robert Strauch, an orthopedic surgeon, as an expert to testify that the plaintiffs alleged injury was caused by a condition called Parsonage Turner Syndrome.] 5 [Gevirtz] was not specifically disclosed as an expert on Parsonage Turner Syndrome nor was it disclosed that he would be testifying [specifically] about the disease. During his direct *246 examination of Gevirtz, Patrick J. Filan, counsel for the plaintiff, asked [Gevirtz] if he was ‘familiar with the condition known as Parsonage Turner Syndrome.’ The court sustained the defendant’s objection on the ground that the plaintiffs disclosure did not encompass Gevirtz’ testifying on the syndrome because the plaintiff was not ‘in compliance with the Practice Book requirement with respect to disclosure in order to use this expert witness for [that] purpose.’ The court allowed Filan, outside of the jury’s presence, to make a proffer as to what Gevirtz would have testified to in regard to Parsonage Turner Syndrome. [In that proffer, Gevirtz described Parsonage Turner Syndrome, established his familiarity and expertise with that syndrome, stated his opinion that this syndrome was not the cause of the plaintiffs alleged injury, and explained the basis for that conclusion.] 6
*247 * =1=
“Later in the trial, Frank W. Murphy, counsel for the defendant, called [Strauch] ... to testify as an expert witness on the requisite standard of care and causation. The court, upon Filan’s objection, conducted a
Porter
hearing to determine whether, and if so, what scientific methodology would allow [Strauch] to diagnose, within a reasonable degree of medical certainty, without examination, the plaintiffs [alleged] injury as being caused by Parsonage Turner Syndrome. After voir dire examination by both Murphy and Filan, the court allowed Strauch to testify that, on the basis of his review of the plaintiffs medical records and deposition testimony, the plaintiffs alleged injury was caused by Parsonage Turner Syndrome.”
Klein
v.
Norwalk Hospital,
The record reveals the following additional facts. After the conclusion of evidence, closing arguments, and the instructions to the jury, the trial court submitted the case to the jury for deliberation, along with special interrogatories. The jury answered the first interrogatory in the negative: “Did the plaintiff . . . prove by a preponderance of the evidence that [the] defendant ... in its care and treatment of [the plaintiff] breached the standard of care for registered nurses in any of the ways alleged in the complaint?” Along with their answer, the jury returned a verdict for the defendant, *248 which subsequently was accepted by the trial court. The plaintiff thereafter filed a motion to set aside the verdict and a motion for a new trial, both of which were denied by the trial court. The plaintiff thereafter appealed to the Appellate Court from the judgment rendered in accordance with the verdict.
In the Appellate Court, the plaintiff claimed that the trial court improperly had excluded Gevirtz’ testimony about Parsonage Turner Syndrome and that the trial court improperly had permitted Strauch’s testimony about the same subject. The Appellate Court did not reach the propriety of either of the trial court’s rulings, but instead concluded that any impropriety that may have existed was harmless. In doing so, the Appellate Court relied on the standard this court had articulated in
Kalams
v.
Giacchetto,
In the present appeal, the plaintiff claims that: (1) the trial court’s exclusion of Gevirtz’ testimony about Parsonage Turner Syndrome was improper; (2) the trial court’s admission of Strauch’s testimony about the same subject was improper; and (3) the Appellate Court improperly concluded that these decisions, even if they were improper, were harmless. We agree that the evi-dentiary rulings of the trial court were improper and that the plaintiff is entitled to a new trial.
*249 I
The plaintiff first claims that it was both improper and harmful for the trial court to exclude Gevirtz’ testimony regarding Parsonage Turner Syndrome. Specifically, the plaintiff contends that the trial court improperly concluded that his initial disclosure that Gevirtz would testify regarding the cause of the plaintiffs injuries was not adequate to comply with the rules of practice and that, to do so, the plaintiff would have needed to file a supplemental disclosure specifically stating that Gevirtz would offer an opinion that the plaintiffs injuries had not been caused by Parsonage Tinner Syndrome. The plaintiff further contends that his disclosure was sufficient to apprise the defendant in light of the fact that the testimony the plaintiff attempted to elicit from Gevirtz related to its own defense. Finally, the plaintiff contends that the exclusion of this evidence was harmful because it addressed the central issue in the case and undermined the credibility of his key expert witness’ methodology. In response, the defendant claims that the exclusion of Gevirtz’ testimony was proper because he had not been adequately disclosed, or, in the alternative, that any evidentiary impropriety arising from the exclusion of Gevirtz’ testimony was harmless. We agree with the plaintiff.
A
We begin with the appropriate standard for this court’s review for determining whether the exclusion of Gevirtz’ testimony was improper. The trial court’s exclusion of Gevirtz’ testimony was based on that court’s interpretation of the disclosure requirements under Practice Book § 13-4 (4),
8
specifically, the trial
*250
court’s determination that testimony regarding the possible causes that are excluded during differential diagnosis of an alleged injury does not fall within an expert disclosure of “causation.”
9
“[T]he proper construction of a Practice Book section involves a question of law,
*251
[over which] our review ... is plenary.” (Internal quotation marks omitted.)
Wexler
v.
DeMaio,
Practice Book § 13-4 (4) “plainly requires a plaintiff to disclose: (1) the name of the expert witness; (2) the subject matter on which the expert is expected to testify; (3) the substance of the facts and opinions to which the expert is expected to testify; and (4) a summary of the ground for each opinion.” Id., 180. To determine whether the plaintiffs disclosure of Gevirtz was sufficiently detailed to satisfy these requirements and allow him to testify about Parsonage Turner Syndrome, we turn to the content of that disclosure. The disclosure provides in relevant part: “Gevirtz will testify concerning the standard of care to which the defendant and its employees, agents, servants and apparent agents were held, and the departures from the standard of care. In addition, [Gevirtz] will testify concerning proximate causation and damages. ... He will testify that the placement of the intravenous line caused the plaintiff nerve injury .... Without limitation to the foregoing, [Gevirtz] will testify concerning the allegations in the plaintiffs complaint and the plaintiffs medical course in general. ... It is [Gevirtz’] opinion . . . that the aforesaid departures from the standard of care [the needle stick] caused and resulted in the injuries and damages alleged by the plaintiff.” The disclosure also included a list of the various bases for Gevirtz’ opinions.
Our review of the plaintiffs disclosure of Gevirtz leads to the conclusion that it adequately complied with these requirements. The disclosure obviously identifies
*252
Gevirtz’ name and provides, inter alia, that he would be testifying regarding the cause of the plaintiffs nerve injury. Insofar as the plaintiffs disclosure of Gevirtz made clear that he would testify as to what
was
the cause of the plaintiffs alleged injury, the disclosure implicitly indicated that Gevirtz also could be expected to testify about what was
not
the cause of the plaintiffs alleged injury. “Critical to establishing specific causation is exclusion of other possible causes of symptoms.”
Mancuso
v.
Consolidated Edison Co. of New York,
967 F. Sup. 1437, 1446 (S.D.N.Y. 1997). As this court recently acknowledged, “differential diagnosis is a method of diagnosis that involves a determination of which of a variety of possible conditions is the probable cause of an individual’s symptoms, often by a process of elimination.”
DiLieto
v.
County Obstetrics & Gynecology Group, P.C.,
On a more fundamental level, a disclosure generally complies with the requirements of Practice Book § 13-4 (4) so long as it adequately alerts the defendant to
*253
the basic nature of the plaintiffs case. See, e.g.,
Vitone
v.
Waterbury
Hospital,
“Q. Are there any diseases or infections that can impair the functioning of the [anterior interosseous] nerve regardless of the needle stick or aside from the needle stick?
“A. There are a multitude of neurologic diseases that can affect individual nerves.
“Q. Are there any neurological diseases that can occur after surgery that could impair the functioning of the [anterior interosseous] nerve?
“A. Only in the most extreme cases — if a patient has a stroke, or the patient has an embolism, things like *254 that; but there is absolutely, absolutely no indication that that happened here.”
This examination by the defendant’s counsel clearly was designed to elicit Gevirtz’ opinion on the feasibility of neurological diseases, one of which is Parsonage Turner Syndrome, as a possible cause of the plaintiffs alleged injury. Further, in the plaintiffs opening statement to the jury, six days before Gevirtz testified, counsel said: “[Y]ou are going to hear about a condition . . . called Parsonage Turner Syndrome. . . . There will be a claim that this injury is totally unrelated to this needle stick and is due to this Parsonage Turner Syndrome. . . . Gevirtz will tell you . . . that the cause of the nerve injury was the [intravenous] needle stick and nothing else, and specifically not Parsonage Turner Syndrome.” There is no question, considering this evidence, that the defendant was apprised adequately of the details of the plaintiffs claim, the general substance of Gevirtz’ testimony that would be offered to attempt to prove that claim, and his rejection of any neurological diseases, including Parsonage Turner Syndrome, as a cause of the plaintiffs alleged injury. There was, accordingly, no need for the plaintiff to file a supplemental disclosure. Accordingly, the trial court improperly precluded the plaintiff from offering Gevirtz’ testimony as to his exclusion of Parsonage Turner Syndrome as a possible cause of the plaintiffs alleged injury.
B
“[B]efore a party is entitled to a new trial because of an erroneous evidentiary ruling, he or she has the burden of demonstrating that the error was harmful.” (Internal quotation marks omitted.)
Kalams
v.
Giac-chetto,
supra,
In those instances wherein a party claims that the trial court improperly excluded testimony, we undertake a review of the relationship of the excluded evidence to the central issues in the case and whether that evidence would have been merely cumulative of admitted testimony.
Sullivan
v.
Metro-North Commuter Railroad Co.,
In the present case, the first interrogatory asked the jury: “Did the plaintiff . . . prove by a preponderance of the evidence that [the] defendant ... in its care and treatment of [the plaintiff] breached the standard of care for registered nurses in any of the ways alleged in the complaint? ... If you answered ‘No’ complete [the] defendant’s verdicts forms with respect to [the defendant] and proceed no further.” Because the jury answered this interrogatory in the negative, disregarded the other interrogatories and immediately entered a verdict for the defendant, it is clear that the issue of breach was essential to the case, as it was wholly dis-positive of the outcome. See also
Sturm
v.
Harb Development, LLC,
The defendant claims that because Gevirtz’ excluded testimony about Parsonage Turner Syndrome would have been irrelevant to the issue of breach, but instead, would have dealt only with the question of causation, the impropriety was harmless. This argument fails, however, to account for the nature of a differential diagnosis. Because the present case essentially presented a choice as to the causation of the plaintiffs alleged injury between the defendant’s theory of Parsonage Turner Syndrome and the plaintiffs theory of an intravenous needle stick, breach of the standard of care and causation were intertwined not only in Gevirtz’ differential diagnosis, but also in the framing of the case generally. The determination of whether the defendant had breached the standard of care could be reduced to the *257 question of what caused the plaintiffs alleged injury, and the only possible causes presented to the jury were Parsonage Turner Syndrome or the defendant’s alleged breach of the standard of care. Consequently, whether Parsonage Turner Syndrome could have caused the plaintiffs alleged injury was therefore central to the question of not only causation, but breach as well. This centrality was underscored in the jury summations, when the plaintiffs counsel noted that “hitting that [anterior interosseous] nerve is a violation of the standard of care.” 11
Although Gevirtz’ testimony ruling out Parsonage Turner Syndrome as the cause of the plaintiffs injury went to both breach and causation, the central issues in the case, if that evidence would have been merely cumulative of other testimony, its exclusion might well
*258
have been harmless. Gevirtz, however, was the plaintiffs only witness who testified that the defendant’s employee had “deviated from the standard of care,” and his reasons for that conclusion provided the only evidence offered by a physician that the defendant had breached the standard of care. Because that conclusion rested on a differential diagnosis of the plaintiffs alleged injury, that diagnosis and its component exclusions of other possible causes were uniquely important to the issue of breach, and accordingly, were not replicated by any other evidence at trial. The other expert testimony excluding Parsonage Turner Syndrome addressed only causation, and did not address the question of breach.
12
See
Sullivan
v.
Metro-North Commuter Railroad Co.,
supra,
Additionally, it is significant, in our view, to consider that Gevirtz’ excluded testimony also would have aided in establishing his credibility as an expert and the reliability of his ultimate conclusions in the eyes of the jury. In other words, but for the trial court’s improper exclusion, Gevirtz could have explained not only that he had rejected the defense theory of Parsonage Turner Syndrome as a cause, but also why he had done so. See
In re Paoli Railroad Yard PCB Litigation,
II
Although we have concluded that this case must be remanded for a new trial, it is appropriate that we
*260
address issues that are likely to recur on retrial. See
State
v.
Gupta,
The record reveals the following additional facts. During Strauch’s testimony, the plaintiff objected and requested a Porter hearing, which the trial court held to evaluate the reliability of Strauch’s conclusion that, to a reasonable degree of medical certainty, Parsonage Turner Syndrome caused the plaintiffs alleged injury. During the defendant’s voir dire in the Porter hearing, Strauch testified as to his familiarity with Parsonage Turner Syndrome, the nature of that syndrome, his review of the plaintiffs medical records, and his opinion that reviewing such records could allow him to diagnose Parsonage Turner Syndrome. During the plaintiffs voir dire, Strauch acknowledged that diagnosis by review of medical records would not be his normal method of diagnosis, that the only peer review of the method he used was a single article that considered diagnoses made bo th by examination and by consideration of medical records, and that he could not speculate as to the *261 rate of error in diagnoses by this method. Following the Porter hearing, the trial court allowed Strauch to testify that, to a reasonable degree of medical certainty, the plaintiffs alleged injury was caused by Parsonage Turner Syndrome.
“In
Porter,
this court followed the United States Supreme Court’s decision in
Daubert
v.
Merrell Dow Pharmaceuticals, Inc.,
“The factors a trial court will find helpful in determining whether the underlying theories and techniques of
*262
the proffered evidence are scientifically rehable will differ with each particular case.” (Internal quotation marks omitted.)
State
v.
Porter,
supra,
Although the trial court in this case conducted a
Porter
hearing to consider the admissibility of Strauch’s testimony, the defendant did not demonstrate at the hearing the reliability of the methodology upon which Strauch relied. Notably, the defendant made no showing that Strauch’s methodology had been subjected to peer review, nor was Strauch able to identify a likely rate of error for his chosen methodology. While neither of these determinations is a talismanic requirement for satisfaction of the
Porter
requirements, their absence is, in this case, determinative of the inadequacy of the defendant’s proof of the methodology’s reliability. See also
Maher v. Quest Diagnostics, Inc.,
supra,
In response to this claim, the defendant points out that neither
Porter
nor
Daubert
requires courts to determine the reliability of well established methodologies. In support of his claim that Strauch’s testimony was based in well established methodology, the defendant points to Strauch’s concededly extensive experience with treating Parsonage Turner Syndrome. That experience, however, is insufficient to qualify Strauch’s methodology in reaching his conclusions as reliable. It may be sufficient to allow him to testify as to the nature of the syndrome, but it does not provide a basis for concluding that the precise methodology employed by Strauch — namely the ex post review of treating physicians’ records for diagnostic purposes — is itself reliable. As this court noted in
Maher
v.
Quest Diagnostics, Inc.,
supra,
We do not, however, make a determination as to whether Strauch’s potential future testimony and conclusions ultimately may comport with the requirements of Porter. To the contrary, like the trial court, we have insufficient information about the methodology employed by Strauch to enable us to reach such a decision. Some of the information that the defendant could have sought to provide that would have bolstered the reliability of Strauch’s methodology includes: the rate of error of the methodology; the frequency of the medical community’s use of the methodology; the unique applicability of the methodology to the specific characteristics of Parsonage Turner Syndrome; greater information regarding the peer review of the methodology; or even an explanation, beyond Strauch’s ipse dixit, of why he felt that the methodology was sufficiently reliable so as not to require an examination of the plaintiff. 14 Our *265 decision with regard to Strauch’s testimony is limited to our conclusion that, if Strauch’s testimony as to his diagnosis is to be offered again at a new trial, the defendant first must make a showing, not limited to the possibilities we have set forth herein, of the reliability of the methodology that underlies the testimony.
The judgment of the Appellate Court is reversed and the case is remanded to that court with direction to reverse the trial court’s judgment and to remand the case to that court for a new trial.
In this opinion the other justices concurred.
Notes
Jamie Klein, the named plaintiffs wife, also was a plaintiff in the trial court, asserting a claim for loss of consortium. She is not a party to this appeal. For convenience, we refer to Eric Klein as the plaintiff.
See
State
v.
Porter,
“Phlebitis is [defined as] ‘[ijnflammation of a vein.’ Stedman’s Medical Dictionary (27th Ed. 2000) p. 1368.”
Klein
v.
Norwalk Hospital,
“[IJnterosseous” is defined as “lying between or connecting bones; denoting certain muscles and ligaments.” Stedman’s Medical Dictionary (28th Ed. 2006).
Also known as brachial plexopathy, Parsonage Turner Syndrome is “a rare neurological disorder which can cause pain, weakness or numbness in the arm and shoulder.”
Benson
v.
Northwest Airlines, Inc.,
Gevirtz’ direct testimony during the proffer, as questioned by Pilan, was as follows:
“Q. . . . [A]re you familiar with the syndrome called Parsonage Turner Syndrome?
“A. Yes, sir.
“Q. And what is it?
“A. It is a neurologic syndrome comprising pain in — usually abrupt onset of pain in the shoulder. Weakness of the girdle, the muscle girdle of the upper extremity. The pain is very severe, usually described from a pain management point of view as eight over ten or greater. And it gradually decreases over time. You are left with muscle wasting.
“Q. And what role, if any, does an acute injury play in allowing one to make a conclusion that a given neurological condition is Parsonage Turner Syndrome?
“A. It has been — Parsonage Turner Syndrome, the etiology has been attributed to various traumas, to various surgical issues. In other words, it can happen postoperatively and things like that.
“Q. And in this case what opinion do you have concerning whether or not this was due — the plaintiffs injury was due to Parsonage Turner Syndrome?
“A. It is not due to Parsonage Turner Syndrome.
“Q. What is the basis for that opinion?
“A. Because the injury is entirely compatible with a needle injuring the anterior interosseous nerve. The pain that . . . [the plaintiff] experienced the night before is most compatible with either a minor pulmonary embolism or some minor cardiac event.
“Q. What is the significance of having pain as a general matter the night *247 before — prior to Parsonage Turner Syndrome?
“A. Well, that is the heralding event, is that you get shoulder pain.
“Q. Okay. So shoulder pain is the heralding event. Okay. And have you studied Parsonage Turner Syndrome?
“A. Yes, sir.
“Q. Have you treated Parsonage Turner Syndrome?
“A. Yes, sir.
“Q. Have you published on Parsonage Turner Syndrome?
“A. Yes, sir.
“Q. Is this within your area of expertise?
“A. I believe so. Yes, sir.”
We granted the plaintiffs petition for certification to appeal limited to the following issue: “Whether the Appellate Court properly affirmed the judgment on the ground of harmless error?”
Klein
v.
Norwalk Hospital,
At the relevant time of the proceedings in the present case, Practice Book (2006) § 13-4 (4) provided: “In addition to and notwithstanding the provisions of subdivisions (1), (2) and (3) of this rule, any plaintiff expecting to call an expert witness at trial shall disclose the name of that expert, the subject matter on which the expert is expected to testify, the substance of the facts and opinions to which the expert is expected to testify, and a *250 summary of the grounds for each opinion, to all other parties within a reasonable time prior to trial. Each defendant shall disclose the names of his or her experts in like manner within a reasonable time from the date the plaintiff discloses experts, or, if the plaintiff fails to disclose experts, within a reasonable time prior to trial. If disclosure of the name of any expert expected to testify at trial is not made in accordance with this subdivision, or if an expert witness who is expected to testify is retained or specially employed after a reasonable time prior to trial, such expert shall not testify if, upon motion to preclude such testimony, the judicial authority determines that the late disclosure (A) will cause undue prejudice to the moving party; or (B) will cause undue interference with the orderly progress of trial in the case; or (C) involved bad faith delay of disclosure by the disclosing party. Once the substance of any opinion or opinions of an expert witness who is expected to testify at trial becomes available to the party expecting to call that expert witness, disclosure of expert witness information shall be made in a timely fashion in response to interrogatory requests pursuant to subdivision (1) (A) of this rule, and shall be supplemented as required pursuant to Section 13-15. Any expert witness disclosed pursuant to this rule within six months of the trial date shall be made available for the taking of that expert’s deposition within thirty days of the date of such disclosure. In response to any such expert disclosure, any other party may disclose the same categories of information with respect to expert witnesses previously disclosed or a new expert on the same categories of information who are expected to testify at trial on the subject for that party. Any such expert or experts shall similarly be made available for deposition within thirty days of their disclosure. Nothing contained in this rule shall preclude an agreement between the parties on disclosure dates which are part of a joint trial management order.”
While evidentiary determinations are usually reviewed for abuse of discretion; see
State
v.
Popeleski,
Because the Appellate Court did not apply the fair assurance standard in the present case, the plaintiff has urged us to clarify the harmless error requirements, both in terms of the showing required and in terms of who bears the burden of proving harmfulness. We acknowledge that our own jurisprudence and that of the Appellate Court have not been entirely consistent in stating the standard for determining harmlessness of nonconstitutional error. Since we unified our approach to harmlessness in
State
v.
Sawyer,
The plaintiffs claim that, if the intravenous needle struck a nerve, the needle stick was a de facto violation of the standard of care was not disputed by the defendant. To the contrary, the defendant’s trial strategy strongly suggests that the defendant recognized that striking a nerve would constitute a breach of the standard of care, and consequently, the defendant never adduced evidence suggesting that a needle stick could strike a nerve if administered in accordance with the standard of care. Instead, in addition to positing Parsonage Turner Syndrome as a potential alternative explanation for the plaintiffs alleged injury, the defendant’s evidence showed that the needle stick was significantly lower on the plaintiffs arm than the plaintiff claimed. In short, the defendant’s case had two principal prongs: first, that Parsonage Turner Syndrome had caused the alleged injury, and second, that DePaoli, when moving the intravenous line on the plaintiff, complied with the standard of care, which, as described by the defendant’s counsel in his summation, directed her to “work up the arm . . . [not to] immediately go up to the top of the arm to the elbow area,” as the plaintiff had claimed. Throughout the presentation of evidence and the summation to the jury, the plaintiffs counsel focused on the placement of the needle and the corresponding compliance with the standard of care, to the complete exclusion of any claim that the needle could have been inserted properly and still struck the plaintiffs nerve, even noting that “[i]n order to credit the plaintiffs position, you’ll have to find that the needle was inserted in a place where a nurse is unlikely to insert it ... . You would have to find that it was placed at a location where an [intravenous needle] is not likely to be placed .... And I suggest to you that there simply is no reason to accept that.”
The plaintiffs other expert, Richard Lechtenberg, a neurologist, did not testily about whether the defendant had breached the standard of care.
The Appellate Court relied on our decision in
Kalams
v.
Giacchetto,
supra,
We note that the diagnosis by an expert based only upon medical records can, and frequently does, satisfy the requirements of
Porter.
See, e.g.,
Poulin
v.
Yasner,
Finally, nothing in our opinion today alters the fact that ex post diagnoses are often based in sufficiently reliable methodologies to obviate the need for a Porter hearing, nor does anything in our opinion today change the fact that such diagnoses are, quite frequently, properly determined to be reliable after a Porter hearing. To the contrary, our opinion with regard *265 to Strauch’s testimony concludes two things: first, that Strauch’s specific methodology was not so well established as to favor judicial notice of its reliability, thus eliminating the need for a Porter hearing; and second, that at the Porter hearing actually held in this specific case, no evidence of the reliability of Strauch’s methodology was adduced by the defendant.
