iii. Overview of Dr. Blitshteyn's Diagnosis and Opinion on Causation
Dr. Blitshteyn opined, that A.M. suffered from autoimmune limbic encephalitis ("ALE") as a result of receiving the second of a three-shot series of the HPV vaccine. Pet. Ex. 25 at 4. She made that diagnosis based on (1) A.M.'s multiple EEGs, (2) her November 2007 MRI of the brain showing increased signal in the left temporal lobe, (3) the intractable epilepsy A.M. developed in the context of a febrile illness, (4) the December 2008 biopsy demonstrating neuronal disorganization and gliosis without inflammatory, neoplastic or cortical dysplasia, and (4) A.M.'s subsequent behavioral disorder.
According to Dr. Blitshteyn, ALE often presents with a prodromal viral-like illness and an acute amnestic syndrome10 with seizures evolving over less than one week. Pet. Ex. 25 at 4. Patients with ALE usually have persistent cognitive impairment and seizures. Id. Dr. Blitshteyn cited literature which reported on a series of patients who experienced a prodromal illness before an amnesic syndrome in association with seizures that developed acutely. See Pet. Ex. 24A.11 All of whom, had persistent cognitive impairment and seizures with normal cerebrospinal fluid ("CSF") counts and highly localized signal change on MRI in the hippocampus, thought to be due to seizure induced edema or gliosis. Id. at 392-93. These signs and symptoms, in the view of the authors, provided circumstantial evidence for an autoimmune process. Id. Dr. Blitshteyn noted the similarity of the presentations to A.M., in which there was a flu like prodrome with rapidly developing seizures, normal CSF, increased signal intensity in the left temporal lobe on the third MRI, gliosis, and persistent cognitive deficits and seizures. Tr. at 30-31.
In this case, Dr. Blitshteyn opined that the temporal association between the onset of encephalitis and the administration of the second HPV vaccine "likely caused an overwhelming autoimmune response [in A.M.], resulting in the development of [ALE]." Pet. Ex. 25 at 5. Based on scientific literature on the occurrence of Acute Disseminated Encephalomyelitis ("ADEM")12 in persons receiving an HPV vaccine, Dr. Blitshteyn noted that A.M. developed her condition in approximately the same timeframe—five weeks after the second "booster shot" of HPV—as the reported development of ADEM in other persons who have received an HPV vaccine. Id. Dr. Blitshteyn opined that since a booster shot is expected to generate a stronger immune-mediated response than the first injection, "it is not surprising" that A.M. developed encephalitis after receipt of the second HPV vaccine. Id.; Tr. at 26-28. According to Dr. Blitshteyn, this theory is further supported by the fact that A.M. developed a febrile illness and seizures after receipt of the third HPV vaccine on February 21, 2008. Tr. at 95-96.