Expert Medical Testimony As To Causation Must Be In Terms Of Medical Probability, Not Possibility

A two-year-old boy suffered from Chediak–Higashi Syndrome (CHS), a rare genetic disease characterized by neurological and bleeding disorders affecting the organs and compromising the immune system. Because of this, the child experienced seizures for which he was prescribed topiramate (brand name Topomax), an anticonvulsant medication, specifically two 25–milligram pills, three times a day (a total of 150 milligrams per day).


At a regularly scheduled doctor’s appointment, it was discovered that the child had a high fever, so he was admitted to the defendant medical center. While in the medical center, a nurse administered 200–milligram dose of topiramate. Subsequently his mother noticed the boy became lethargic and had trouble breathing. The boy was transferred to the pediatric ICU. He died approximately four hours after the nurse administered the topiramate. The autopsy report listed the cause of death as “acute splenic sequestration crisis secondary to the accelerated phase of Chediak–Higashi Syndrome.”


The mother sued the medical center for medical malpractice and wrongful death. Before the bench trial, the defendant medical center stipulated that it had breached the standard of care by giving the boy an incorrect dosage of topiramate. The sole issue at trial was whether the boy had died as a result of the dosage error or from complications related to CHS.


The plaintiff called a physician, who was both a retired psychiatrist and retired pathologist, to testify as an expert regarding the boy’s death. He had no knowledge or experience with CHS prior to this case. He did have knowledge of topiramate. He stated several times during his testimony that he could not determine whether the boy died due to the topiramate overdose because a toxicology screen for topiramate was not conducted.


The medical center filed a motion for a directed verdict arguing that the plaintiff’s “medical expert” was not qualified to testify and he failed to provide his opinions to a reasonable degree of medical probability. The trial court denied the motion for a directed verdict. A bench trial resulted in a verdict in favor of the mother. The medical center appealed arguing that the trial court erred by denying its motion for a directed verdict.


The Supreme Court of Mississippi reversed the trial court holding that while the plaintiff’s medical expert was qualified to testify, he failed to testify within a reasonable degree of medical probability whether the boy died of the topiramate or complications of CHS. The court clarified that expert medical testimony as to causation must be set forth in terms of medical probability, not probability or possibility as previously implied in Brandon HMA, Inc. v. Bradshaw, 809 So.2d 611, 617 (Miss.2001).


See: University of Mississippi Medical Center v. Lanier, 2012 WL 3031276 (Miss., July 26, 2012) (not designated for publication).