title: C1 laminectomy for retro-odontoid pseudotumor without atlantoaxial subluxation: review of seven consecutive cases.
abstract: OBJECTIVE
  A retro-odontoid pseudotumor is usually a reactive fibrocartilaginous mass associated with atlantoaxial subluxation (AAS). However, a retro-odontoid pseudotumor not associated with AAS, which undergoes spontaneous regression following C1 laminoplasty, has been reported. The purpose of this study was to report surgical outcomes of C1 laminectomy for retro-odontoid pseudotumor without AAS.
  
  
  METHODS
  The cases of seven patients (mean age 75.6 ± 7.6 years-old) with retro-odontoid pseudotumor without AAS were reviewed. The mean follow up time was 52.3 ± 25.5 months. Each patient underwent a C1 laminectomy with an additional C3-6 expansion laminoplasty in three patients. The Japanese Orthopaedic Association score (JOA score) was used for neurological assessment. Pseudotumor size and additional AAS were analyzed using MRI and radiography.
  
  
  RESULTS
  All patients exhibited neurological improvement following surgery, the JOA score improved from 7.2 ± 3.2 to 14.1 ± 2.6. The mean O-C2 and C2-7 angle decreased from -3.2 ± 2.1° to -3.9 ± 1.7°, showing a slight kyphotic change. Postoperative AAS was not observed. All pseudotumors spontaneously resolved, and recurrence and regrowth were not observed. Five patients had MRIs after gadolinium administration; four patients who showed enhancement of the pseudotumor had almost complete reduction within 1 year following surgery.
  
  
  CONCLUSIONS
  Our study, assessing the outcome of C1 laminectomy for retro-odontoid pseudotumor, found neurological improvement in all cases. Since all pseudotumors were reduced and additional AAS was not observed, C1 laminectomy for retro-odontoid pseudotumor, in the absence of AAS, is recommended as a therapeutic strategy.
authors: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuo-ku, Kobe, 650-0017, Japan. kenkakutani@gmail.com
authors: Kenichiro
authors: K
authors: Kakutani
authors: Minoru
authors: M
authors: Doita
authors: Masaho
authors: M
authors: Yoshikawa
authors: Koji
authors: K
authors: Okamoto
authors: Koichiro
authors: K
authors: Maeno
authors: Takashi
authors: T
authors: Yurube
authors: Norihide
authors: N
authors: Sha
authors: Masahiro
authors: M
authors: Kurosaka
authors: Kotaro
authors: K
authors: Nishida
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D001270:Cervical Atlas / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D007796:Laminectomy / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009809:Odontoid Process / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D011859:Radiography; D012189:Retrospective Studies; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D016896:Treatment Outcome
references: J Clin Neurosci. 2010 May;17(5):649-52
references: 20189392
references: Neurochirurgie. 2008 Feb;54(1):32-6
references: 18314145
references: Adv Perit Dial. 1992;8:116-9
references: 1361765
references: Spine (Phila Pa 1976). 1996 Jan 15;21(2):235-41
references: 8720410
references: Spine J. 2006 May-Jun;6(3):228-32
references: 16651215
references: Surg Neurol. 2001 Apr;55(4):223-7
references: 11358595
references: J Orthop Sci. 1999;4(6):399-406
references: 10664422
references: Spine (Phila Pa 1976). 2002 May 15;27(10):E266-70
references: 12004188
references: Spine (Phila Pa 1976). 2000 Apr 1;25(7):871-5
references: 10751300
references: J Orthop Sci. 2000;5(3):229-31
references: 10982662
references: Neuroradiology. 1993;35(5):367-9
references: 8327114
references: Acta Orthop Scand Suppl. 1957;23:1-150
references: 13434893
references: Eur Spine J. 2003 Oct;12(5):548-51
references: 12759811
references: Spine (Phila Pa 1976). 2009 Feb 1;34(3):E110-4
references: 19179910
references: Spine (Phila Pa 1976). 1997 Jul 15;22(14):1580-3; discussion 1584
references: 9253092
references: J Neurosurg Spine. 2006 Aug;5(2):156-60
references: 16925083
references: Arthritis Rheum. 1990 Oct;33(10):1567-73
references: 2222537
references: Radiology. 1986 Nov;161(2):391-4
references: 3763907
references: Spine (Phila Pa 1976). 1996 Jan 15;21(2):230-4
references: 8720409
references: J Neurosurg Spine. 2006 Nov;5(5):455-60
references: 17120898
references: Spine (Phila Pa 1976). 1981 Jul-Aug;6(4):354-64
references: 6792717
references: AJNR Am J Neuroradiol. 1988 May-Jun;9(3):573-7
references: 3132833
references: Spine (Phila Pa 1976). 2009 Jan 15;34(2):184-8
references: 19139669
references: Spine (Phila Pa 1976). 1996 Dec 15;21(24 Suppl):2S-9S
references: 9112320
references: J Neurol Neurosurg Psychiatry. 1991 Sep;54(9):817-21
references: 1955901
references: Rev Chir Orthop Reparatrice Appar Mot. 1994;80(2):144-9
references: 7899632
references: Surg Neurol. 2001 Nov;56(5):333-6; discussion 337
references: 11750011