title: Polytetrafluoroethylene-induced granuloma and brainstem cyst after microvascular decompression for trigeminal neuralgia: case report.
abstract: OBJECTIVE
  Microvascular decompression is commonly performed for medically refractory trigeminal neuralgia. A piece of polytetrafluoroethylene (PTFE) is usually placed between the trigeminal nerve and the blood vessel causing the compression. The procedure is effective and relatively safe, and PTFE is presumed to be inert. Reactions to PTFE are rare.
  
  
  METHODS
  We report a patient who developed progressive neurological symptoms 5 years after microvascular decompression surgery. Imaging showed an enhancing cerebellopontine mass resembling a posterior fossa tumor with a large cyst compressing the brainstem.
  
  
  METHODS
  Craniotomy was performed to decompress the cyst. Biopsy of the enhancing mass showed granulomatous inflammation. The patient underwent a second brainstem decompression surgery with placement of a catheter in the cyst connected to an Ommaya reservoir; she has moderate to severe residual neurological deficits.
  
  
  CONCLUSIONS
  This may be the first case of a severely disabling, space-occupying cyst resulting from a reaction to intracranial PTFE. Should this exceptionally rare complication be disclosed to patients or is it an idiosyncratic reaction unlikely to occur again?
authors.affiliation: Department of Neurology, The University of Chicago Medical Center, Chicago, Illinois, USA.
authors.forename: Gabor
authors.initials: G
authors.lastname: Toth
authors.forename: Helene
authors.initials: H
authors.lastname: Rubeiz
authors.forename: R Loch
authors.initials: RL
authors.lastname: Macdonald
mesh_terms: D001933:Brain Stem; D020863:Central Nervous System Cysts / Q000175:diagnosis* / Q000209:etiology; D003560:Cysts / Q000175:diagnosis* / Q000209:etiology; D019299:Decompression, Surgical / Q000009:adverse effects*; D005260:Female; D006099:Granuloma / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D008866:Microsurgery / Q000009:adverse effects; D008875:Middle Aged; D011138:Polytetrafluoroethylene / Q000009:adverse effects*; D011183:Postoperative Complications / Q000175:diagnosis / Q000209:etiology; D014277:Trigeminal Neuralgia / Q000473:pathology / Q000601:surgery*
chemical_list: D011138:Polytetrafluoroethylene