Did shaking or a fall cause baby’s fatal injuries?

WOODLAND — Two brain-injury experts figuratively duked it out in a Yolo County courtroom last week, offering dueling theories as to what could have caused a 3-month-old boy’s fatal injuries in the autumn of 2012.

The prosecution’s expert, UC Davis Medical Center neuropathologist Dr. Bennet Omalu, said there’s no doubt in his mind that Samuel Stone died of a severe traumatic brain injury triggered by “adult-induced nonaccidental trauma” — formerly known in the medical field as shaken-baby syndrome.

“This is a child who has had more than one episode of traumatic brain injury,” said Omalu, who took the stand in Yolo Superior Court on Tuesday in the trial of Quentin Paul Stone, a 40-year-old Woodland resident accused of inflicting his infant son’s fatal wounds. Stone has denied the allegations.

But Dr. John Plunkett, a critic of the shaken-baby theory who testified several days later for the defense, said it’s just as possible that Samuel’s injuries stemmed from a fall from a 3-foot-high bed onto a hardwood floor, as described by the boy’s parents who said the tumble occurred in their home on Sept. 5, 2012.

“If you land on your head, even on a carpeted floor, the injury could be devastating,” Plunkett told the nine-man, three-woman jury on Friday. He went on to say that Samuel “had no evidence of shaking or impact (injuries),” either upon his admission to the hospital on Oct. 3, 2012, or when he died six days later.

Last week’s witness lineup in the Stone case has been referred to among court observers as a “battle of the experts,” whose conflicting testimony is expected to factor heavily into the jurors’ deliberations when they get the case later this week.

Under questioning last week by Supervising Deputy District Attorney Steve Mount, Omalu said he formulated his opinion as a result of examining baby Samuel’s brain, eyes, spinal cord and dura mater — the thick membrane that surrounds the brain — as well as reviewing medical and autopsy reports.

Among his findings: that Samuel’s brain was “markedly swollen,” with evidence of contusions and areas of bleeding both old and new — including bleeding between the brain’s two hemispheres indicative of a blood-vessel tear.

An examination of Samuel’s eyes “showed evidence of a constellation of findings that would be consistent with traumatic brain injury,” including hemmorhaging that extended from the optic nerves to the retinas, which were detached from the walls of the eyes, Omalu testified.

The UCD doctor also noted that the baby had sustained rib fractures near his spinal column which, given the young bones’ still-flexible nature, is “indicative a violent compressive injury of the child’s trunk.” The fractures were believed to be two to three weeks old, he said.

Omalu attributed the brain injuries to what he called “angular rotational acceleration-deceleration” — in other words, sudden movement of the head that causes the brain to hit the skull’s interior. He said he further ruled out that the injuries were caused by either oxygen or glucose deprivation.

Asked whether a 3-foot fall would be likely to cause the injuries Samuel suffered, Omalu answered no, citing the lack of a laceration, abrasion or any other external injury to the infant’s head. He also noted that such a fall would result in bleeding to just one area of the brain — such as the point of impact — and not the widespread hematoma shown in Samuel’s brain scans.

“It’s not medically feasible,” he said of the alleged fall, which defense lawyers contend caused Samuel’s fatal injuries that went unrecognized by family doctors during several follow-up examinations.

Plunkett, the defense witness, largely contradicted Omalu’s testimony when he took the stand several days later, saying not only could Samuel’s injuries have been caused by a short-distance fall, but may even have been set in motion during his birth.

Testifying as an expert in biomechanics as well as forensic pathology, Plunkett said studies have shown that the force generated by even the most violent shaking movement is far below the threshold required to cause significant brain injuries.

“It is extremely unlikely to be able to cause brain damage in an infant by shaking it,” Plunkett said. Instead, “I would expect to see major structural neck damage — a broken neck,” which was not among Samuel’s injuries.

In the case of a fall, however, the body sustains what Plunkett referred to as “impact loading” — the collision of two solid objects — and “you will see the head rotate as a result of the impact,” he said. That impact, he added, “is going to be a minimum of 10 times the force of a shake.”

As for the infant’s detached retinas, Plunkett said the condition frequently occurs post-mortem, noting that a forensic ophthalmologist’s report about the case made no mention of retinal detachment in baby Samuel. An insufficient amount of vitamin D in the boy’s bloodstream, as detected in hospital lab tests, may have accounted for the rib fractures, he added.

Plunkett, who reviewed reports, autopsy photographs and microscope slides of tissue samples in the case, said he concluded that Samuel died of an expanding chronic subdural hematoma — a large area of bleeding to his brain that in turn caused increased intracranial pressure and triggered the seizures that ultimately landed the baby in the hospital.

Accompanying symptoms, Plunkett said, can include vomiting and irritability, both of which were reported to the Stones’ family doctors following the alleged fall but were attributed to acid reflux.

“This may have ultimately been due to natural causes” if the bleeding was present at birth, Plunkett said. If caused by a fall, “then I would call it an accident. But I have no evidence that he had a nonaccidental injury caused by anyone.”

Testimony in the case resumes Monday in Judge Paul Richardson’s courtroom.