Court Strikes Stroke Expert’s Speculative Diagnosis Testimony

    Court: United States District Court for the Eastern District of Tennessee
    Jurisdiction: Federal
    Case Name: Wilson v. GMAC
    Citation: 2008 U.S. Dist. LEXIS 119995

    The plaintiff in this medical malpractice case relied on a stroke expert witness to support his claim that a clinician’s negligence led to his stroke. The expert’s conclusions, however, rest on the assumption that the plaintiff was under great stress at the time of treatment. The court explains that the plaintiff’s mental state is only speculative and the jury would also need to accept this interpretation in order for the expert testimony to be helpful. Thus, the expert’s testimony was tossed as it was not deemed reliable.


    This case was filed after the plaintiff went to the ER with weakness on his right side and newly diagnosed hypertension and was diagnosed with a transient ischemic attack. He later suffered a stroke and alleged this was due to the defendant’s negligent treatment. The plaintiff retained a stroke expert witness to discuss how the defendant’s conduct led to his stroke.

    The Plaintiff’s Stroke Expert Witness

    The plaintiff retained a stroke expert witness to establish a connection between the defendant’s conduct and the plaintiff’s stroke. The expert was board-certified in internal medicine and board-eligible in pulmonary medicine. The expert opined that the plaintiff had presented potential risk factors for a cerebrovascular event: atherosclerosis (a disease in which plaque fills up inside the arteries), hypertension, and was a smoker. The expert also explained the plaintiff was under significant stress at the time of hospitalization and cited studies correlating psychosocial stress with transient hypertension.

    On receipt of the stroke expert’s written report, the defendant filed the new motion to exclude him as a witness. The defendant claimed the expert’s opinion was not helpful for the trier of fact, his opinions were unreliable, and he was not qualified to testify.


    The defendant claimed the expert didn’t have the necessary qualifications to testify about any causal link between the plaintiff’s stroke and the defendant’s actions. Here, the court disagreed, explaining the expert’s CV demonstrated more than adequate educational and professional qualifications to express an opinion on physiology and the cause of strokes.

    The defendant argued that the expert’s testimony that the plaintiff’s severe stress may have precipitated his hypertension and eventual stroke would not help the jury as per Federal Rule of Evidence 702 and Daubert. The court didn’t think Daubert applied here, rather, the court found it was significant that the expert did not add or amend this part of his opinion in his affidavit. As a result of the defendant’s renewed motion to exclude his opinion, the plaintiff’s counsel and the expert were aware that the defendant was directly attacking his testimony as speculative. Notwithstanding this awareness, the expert decided not to change it.

    The court wondered what use the jury could make of the expert’s claim that the plaintiff’s stress may have precipitated his hypertension. The jury would speculate just like the expert did because they would have no other knowledge to focus on. The court stated that the expert’s assertion that something is probable was not evidence. Thus, this opinion was no more accurate than the jury’s own interpretation as to the plaintiff’s actual mental state, citing Lindsey v. Miami Dev. Corp.


    The defendant’s motion to exclude the stroke expert witness’s testimony was granted.

    Key Takeaways for Experts

    Expert testimony, especially scientific in nature, must be backed with research and evidence. Be careful not to stray into speculation or make assumptions that cannot be supported with airtight facts.