New York District Court Finds Neuroscience Expert Testimony Unreliable In Mirena IUD Litigation 

ByExpert Institute

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Published on February 13, 2019

Neurosurgery Expert

Court – United States District Court for the Southern District of New York
Jurisdiction
– Federal
Case Name
In re Mirena IUS Levonorgestrel-Related Prods. Liab. Litig.
Citation
– 2018 U.S. Dist. LEXIS 182420

The present multi-district litigation involved products liability claims regarding a contraceptive product, namely, the Mirena IUD (intrauterine device), developed, manufactured, and distributed by defendants Bayer HealthCare Pharmaceuticals, Inc., Bayer Pharma AG, and Bayer Oy (known together as Bayer). The Mirena IUD functions by releasing a synthetic steroid hormone known as levonorgestrel (LNG). The plaintiffs claimed that the hormonal component in Mirena caused them to suffer from idiopathic intracranial hypertension (IIH), also known as pseudotumor cerebri (PTC). IIH is an uncommon disease marked by increased cerebrospinal fluid (CSF) pressure in the skull. If untreated, IIH can cause headaches and vision problems, including, in extreme cases, blindness.

In what seemed to be preparations for a battle of experts, the plaintiffs and the defendants both retained and disclosed multiple experts and filed Daubert motions to exclude the testimony of opposing experts. For the purposes of this article, we will only focus on the testimony of the plaintiff’s neurosurgery expert witness, Dr. Conrad E. Johanson, and the challenges that the defendants made to it.

Dr. Johanson, a neuroscientist and a professor of clinical neuroscience and neurosurgery who has worked at Brown University Medical School for the last 30 years, broadly opined that IIH is caused by the “hypersecretion of CSF” and cited an article which, the court noted, did not support this proposition expressly. The court also noted that while the issue of whether IIH is caused by the hypersecretion of CSF remained unresolved, the bulk of scholarship appeared to adopt the alternative hypothesis that the root cause of excess CSF in IIH patients was impaired absorption of CSF. The court also noted that in this deposition, Dr. Johanson agreed that hampered CSF outflow was the more generally accepted hypothesis.

Following this opinion, Dr. Johanson provided a mechanism consisting of a series of theorized steps and opined that the LNG in Mirena causes the hypersecretion of CSF, and thus, IIH.

The court noted that in his deposition, Dr. Johanson admitted that he had never communicated this theory outside of this litigation and that, before being hired by the plaintiffs, he had never even considered whether LNG could cause IIH. He also admitted that he had neither tested the effects of LNG on choroid plexus ion transporters nor was aware of anyone who had done so.

Not only had he not published the theories he articulated in his expert report anywhere, it was found that he admitted his theory was no more than a “plausible working model”.

The court relied on the Second Circuit’s opinion in Amorgianos v. Amtrak, 303 F.3d at 267 in which it was held that “it was critical” the analysis of an expert “be reliable at every step”, and that a step-by-step analysis of the theories proffered by the expert be conducted. However, the court found that it was based on an unsound methodologically at nearly each step.

The testimony of the plaintiffs’ neurosurgery/neuroscience expert witness was excluded.

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