Nitinol in Medical Devices: Not so Innocuous (P3-5.019)

Abstract

<h3>Objective:</h3> We report two cases of delayed leukoencephalopathy (DLE) secondary to aneurysmal intracranial stenting and a middle ear prosthesis, both made of a nickel-titanium alloy (nitinol). <h3>Background:</h3> Nitinol is widely used in medical device manufacturing due to its favorable physicochemical properties: shape memory, biocompatibility, superelasticity, and corrosion resistance. <h3>Design/Methods:</h3> Two case reports. <h3>Results:</h3> A 36-year-old woman with a history of ankylosing spondylitis presented with headache and visual distortion. She was found to have an intracranial aneurysm that was repaired with the Neuroform Atlas Stent System. Five weeks later, she acutely developed a fluctuating right sensorimotor deficit. Magnetic resonance imaging (MRI) of the brain showed small regions of T2 hyperintensity with stippled enhancement in the right frontal lobe along the superior frontal sulcus and the white matter of the left parietal and occipital lobes. Another 72-year-old woman with a history of otosclerosis, status post-surgery with eclipse piston prosthesis, presented with right trigeminal neuralgia. A brain MRI showed a right paraclinoid meningioma and three upper cervical cord lesions on sagittal slices. She received radiotherapy with improvement. Seven weeks later, she developed hypersomnolence, vomiting, diplopia, and ataxia. Brain MRI demonstrated an interval appearance of multifocal and bilateral ring-enhancing lesions in the cerebellum, pons, and the right midbrain. Both patients had extensive and unremarkable serum, CSF, vascular and spine imaging, and malignancy workup. A manufacturer review of both devices revealed that they were made of nitinol. <h3>Conclusions:</h3> Titanium and nitinol are less well-known as allergens than nickel. In ionic form, they act as haptens, bonding to native proteins and stimulating the immune system 1) immediately with mastocytes and basophils degranulation (Type I) or 2) in a delayed, type IV cellular hypersensitivity that might present in the brain and spinal cord as a demyelinating disease. We hope to increase clinician awareness of nitinol-induced DLE, which could be easily misdiagnosed. <b>Disclosure:</b> Dr. Zabad has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Bayer. Dr. Zabad has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biogen. Dr. Zabad has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Genentech. Dr. Zabad has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Celgene/BMS. Dr. Zabad has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Genzyme. Dr. Zabad has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Merck Serono. Dr. Zabad has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Teva Neurosciences. Dr. Zabad has received personal compensation in the range of $500-$4,999 for serving as a Consultant for TG Therapeutics. Dr. Zabad has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Teva. Dr. Zabad has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Novartis. Dr. Zabad has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Genentech. Dr. Zabad has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for BMS. The institution of Dr. Zabad has received research support from Adamas. The institution of Dr. Zabad has received research support from Biogen. The institution of Dr. Zabad has received research support from Novartis. The institution of Dr. Zabad has received research support from Sun Pharma. The institution of Dr. Zabad has received research support from Parexel &amp; MedDay Pharmaceuticals. Dr. Solis has nothing to disclose. Dr. Venegas has nothing to disclose. Dr. Dennis has nothing to disclose. Dr. Piccione has nothing to disclose. Dr. Westerhuis has nothing to disclose. Dr. Arcot Jayagopal has nothing to disclose.