title: Odontoid compression of the brainstem without basilar impression-- "odontoid invagination".
abstract: We report five patients with odontoid invagination, in which the odontoid process bulges upward into the foramen magnum and compresses the brainstem without deformity of the occipital bone. Two patients had a craniovertebral abnormality associated with Chiari malformation without instability of the craniovertebral junction (stable odontoid invagination). The other three patients had dislocation of the craniovertebral junction due to iatrogenic destruction of the occipital condyle, rheumatoid arthritis or an anomaly of C2 (unstable odontoid invagination). Patients with stable odontoid invagination underwent a transoral odontoidectomy followed by occipitocervical fixation. Those with unstable odontoid invagination underwent cervical traction followed by posterior fixation in reducible cases, while in irreducible cases odontoidectomy with subsequent occipitocervical fixation was performed. Decompression of the neuraxis together with symptomatic improvement was achieved in all patients and none became unstable or developed new symptoms during follow-up ranging from 3 to 15 years.
authors.affiliation: Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Japan. kakyosh@av4.mopera.ne.jp
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Kyoshima
authors.forename: Yukinari
authors.initials: Y
authors.lastname: Kakizawa
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tokushige
authors.forename: Kotaro
authors.initials: K
authors.lastname: Akaishi
authors.forename: Miki
authors.initials: M
authors.lastname: Kanaji
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kuroyanagi
mesh_terms: D000328:Adult; D001139:Arnold-Chiari Malformation / Q000150:complications; D001269:Atlanto-Occipital Joint / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000473:pathology*; D001933:Brain Stem / Q000293:injuries* / Q000503:physiopathology; D020526:Brain Stem Infarctions / Q000209:etiology / Q000503:physiopathology / Q000601:surgery; D001270:Cervical Atlas / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000473:pathology; D002648:Child; D019299:Decompression, Surgical / Q000379:methods*; D005260:Female; D006801:Humans; D016268:Internal Fixators; D004204:Joint Dislocations / Q000150:complications / Q000473:pathology / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008526:Medulla Oblongata / Q000293:injuries / Q000503:physiopathology; D008875:Middle Aged; D009777:Occipital Bone / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000473:pathology*; D009809:Odontoid Process / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D013123:Spinal Fusion / Q000379:methods*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome