title: Minimally invasive approach for small ventrally located intradural lesions of the craniovertebral junction.
abstract: OBJECTIVE
  The surgical management of lesions ventral to the neuraxis at the level of the craniovertebral junction (CVJ) and upper cervical spine is challenging. Here, the authors describe a minimally invasive dorsal approach for small ventrally located intradural lesions at the CVJ as an alternative for the more extensive classic transoral approach or variants of suboccipital approaches.
  
  
  METHODS
  Between 2012 and 2014, 6 symptomatic patients with a small lesion of the ventral aspect at the CVJ level were treated using a minimally invasive dorsal approach at the University Medical Center in Hamburg-Eppendorf, Germany. The anatomical distance between the posterior atlantooccipital membrane and the posterior atlantoaxial ligament, as determined by CT images, was assessed in the treated patients and in 100 untreated persons.
  
  
  RESULTS
  The authors treated 6 patients (mean age 54.7 years) who had a clinical presentation of mild neurological symptoms that disappeared after resection. Minimally invasive surgical dorsal access was achieved by using tubular systems and using the natural space between the occiput (C-0) and C-1, and in 1 case between C-1 and C-2, without having to remove bony structures. The postoperative course in each of the 6 patients was uneventful. The neuropatho-logical findings confirmed a meningotheliomatous meningioma (WHO Grade I) in 5 cases and an extramedullary cavernous hemangioma in 1 case. MRI confirmed complete resection of all the lesions. The atlantooccipital distances ranged from 3 to 17 mm (mean 8.98 mm) in the supine neutral position, and the atlantoaxial distances ranged from 5 to 17 mm (mean 10.56 mm). There were no significant differences between women and men (atlantooccipital p = 0.14; atlantoaxial p = 0.72).
  
  
  CONCLUSIONS
  The results of this study demonstrate that the minimally invasive dorsal approach using the space between C-0 and C-1 or C-1 and C-2 provides direct and sufficient exposure for the safe surgical resection of small ventrally located intradural lesions at the CVJ level while reducing the necessity for musculoskeletal preparation to a minimum.
authors.affiliation: Department of Neurosurgery, University Medical Center, Hamburg-Eppendorf, Germany.
authors.forename: Sven O
authors.initials: SO
authors.lastname: Eicker
authors.forename: Klaus Christian
authors.initials: KC
authors.lastname: Mende
authors.forename: Lasse
authors.initials: L
authors.lastname: Dührsen
authors.forename: Nils Ole
authors.initials: NO
authors.lastname: Schmidt
mesh_terms: D001268:Atlanto-Axial Joint / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods*; D012189:Retrospective Studies; D013119:Spinal Cord Injuries / Q000473:pathology* / Q000601:surgery*; D013131:Spine / Q000601:surgery
keywords: C-0 = occiput; CVJ = craniovertebral junction; cervical spine; craniocervical junction; meningioma; minimally invasive; spinal tumor