title: Cranial neuropathy due to intradural disc herniation.
abstract: BACKGROUND
  Herniated intervertebral disc fragments rarely penetrate the thecal sac, and intracranial hypotension attributable to such penetrating fragments is even more unusual. We describe the first reported case of a cranial neuropathy due to intradural herniation of a disc fragment, in which intracranial hypotension from a resulting cerebrospinal fluid leak caused bilateral abducens palsies.
  
  
  METHODS
  A 45-year-old man presented with a positional headache after having experienced a "popping" sensation in his back while lifting a heavy object. He also reported blurred vision and was noted to have lateral gaze palsies bilaterally. Magnetic resonance imaging (MRI) of the brain revealed bilateral subdural collections, abnormal pachymeningeal enhancement, and cerebellar tonsillar herniation, suggesting intracranial hypotension. T2-weighted MRI of the spine revealed extrusion of the T12-L1 disc and suggested the presence of a disc fragment in the intradural space, displacing the caudal nerve roots. A myelogram demonstrated a filling defect extending into the subarachnoid space adjacent to the disc herniation, consistent with a free disc fragment in the intradural space. A diagnosis of intracranial hypotension due to a cerebrospinal fluid leak resulting from an intradural herniated disc was made. The diagnosis was confirmed intraoperatively.
  
  
  CONCLUSIONS
  Surgical removal of the herniated disc fragment and repair of the dural defect resulted in complete resolution of the cranial neuropathy. This rare etiology of a cranial neuropathy, arising from pathology in the thoracolumbar spine, illustrates the clinical teaching that the sixth cranial nerve is highly sensitive to deformation induced by intracranial hypotension.
authors.affiliation: Departments of *Neurological Surgery, ‡Neurology and Neuroscience, and §Otolaryngology, New York-Presbyterian Hospital, Weill Cornell Medical College, New York, New York.
authors.forename: Benjamin I
authors.initials: BI
authors.lastname: Rapoport
authors.forename: Roger
authors.initials: R
authors.lastname: Hartl
authors.forename: Theodore H
authors.initials: TH
authors.lastname: Schwartz
mesh_terms: D020434:Abducens Nerve Diseases / Q000209:etiology*; D019567:Back Injuries / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D065634:Cerebrospinal Fluid Leak / Q000175:diagnosis / Q000209:etiology*; D003389:Cranial Nerve Diseases / Q000175:diagnosis / Q000209:etiology*; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000150:complications* / Q000601:surgery; D019585:Intracranial Hypotension / Q000209:etiology*; D008159:Lumbar Vertebrae / Q000293:injuries; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D013355:Subdural Space / Q000473:pathology; D013904:Thoracic Vertebrae / Q000293:injuries; D014057:Tomography, X-Ray Computed