title: Arachnoiditis ossificans.
abstract: OBJECTIVE
  Arachnoiditis ossificans is an uncommon clinical entity in which arachnoid ossification leads to clinical symptomatology. In this case report, we describe the case of a myelopathic patient with arachnoid ossifications, an arachnoid cyst, and syringomyelia coexisting with a herniated thoracic disc at the same levels.
  
  
  METHODS
  An 81-year-old woman presented with rapidly progressive leg weakness, dysesthetic pains, and urinary incontinence.
  
  
  RESULTS
  The patient underwent thoracic laminectomy with costotransversectomy for resection of ossified arachnoid and re-establishment of cerebrospinal fluid pathways.
  
  
  CONCLUSIONS
  Altered cerebrospinal fluid dynamics secondary to the obstruction in subarachnoid flow may predispose to the formation of an arachnoid cyst, and the cyst itself may be the proximate cause of the myelopathy.
authors.affiliation: Department of Neurosurgery, Mount Sinai School of Medicine, New York, New York, USA.
authors.forename: Harshpal
authors.initials: H
authors.lastname: Singh
authors.forename: Scott A
authors.initials: SA
authors.lastname: Meyer
authors.forename: Madhu R
authors.initials: MR
authors.lastname: Jannapureddy
authors.forename: Nirit
authors.initials: N
authors.lastname: Weiss
mesh_terms: D000369:Aged, 80 and over; D001099:Arachnoid / Q000000981:diagnostic imaging / Q000473:pathology*; D016080:Arachnoid Cysts / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D001100:Arachnoiditis / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000473:pathology; D009999:Ossification, Heterotopic / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D011859:Radiography; D013117:Spinal Cord Compression / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D013118:Spinal Cord Diseases / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D013904:Thoracic Vertebrae / Q000473:pathology; D016896:Treatment Outcome