title: C2 spondylotic radiculopathy: the nerve root impingement mechanism investigated by para-sagittal CT/MRI, dynamic rotational CT, intraoperative microscopic findings, and treated by microscopic posterior foraminotomy.
abstract: C2 radiculopathy is known to cause occipito-cervical pain, but their pathology is unclear because of its rarity and unique anatomy. In this paper, we investigated the mechanism of C2 radiculopathy that underwent microscopic cervical foraminotomies (MCF).
  
  
  
  Three cases with C2 radiculopathy treated by MCF were investigated retrospectively. The mean follow-up period was 24 months. Pre-operative symptoms, imaging studies including para-sagittal CT and MRI, rotational dynamic CT, and intraoperative findings were investigated.
  
  
  
  There were 1 male and 2 females. The age of patients were ranged from 50 to 79 years. All cases had intractable occipito-cervical pain elicited by the cervical rotation. C2 nerve root block was temporally effective. There was unilateral spondylosis in symptomatic side without obvious atlatoaxial instability. Para-sagittal MRI and CT showed severe foraminal stenosis at C1-C2 due to the bony spur derived from the lateral atlanto-axial joints. In one case, dynamic rotational CT showed that the symptomatic foramen became narrower on rotational position. MCF was performed in all cases, and the C2 nerve root was impinged between the inferior edge of the C1 posterior arch and bony spur from the C1-C2 joint. After surgery, occipito-cervical pain disappeared.
  
  
  
  This study demonstrated that mechanical impingement of the C2 nerve root is one of the causes of occipito-cervical pain and it was successfully treated by microscopic resection of the inferior edge of the C1 posterior arch. Para-sagittal CT and MRI, rotational dynamic CT, and nerve root block were effective for diagnosis.
authors.affiliation: Department of Orthopedic Surgery, Hiroshima City Asa Citizens Hospital, 2-1-1 Kabe-minami, Asa-kita-ku, Hiroshima, 731-0293, Japan. ys.fujiwara@nifty.com.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Fujiwara
authors.affiliation: Department of Orthopedic Surgery, Hiroshima City Asa Citizens Hospital, 2-1-1 Kabe-minami, Asa-kita-ku, Hiroshima, 731-0293, Japan.
authors.forename: Bunichiro
authors.initials: B
authors.lastname: Izumi
authors.affiliation: Department of Orthopedic Surgery, Sada Hospital, Fukuoka, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Fujiwara
authors.affiliation: Department of Orthopaedic Surgery, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Nakanishi
authors.affiliation: Department of Orthopaedic Surgery, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Tanaka
authors.affiliation: Department of Orthopaedic Surgery, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Adachi
authors.affiliation: Department of Orthopedic Surgery, Hiroshima City Asa Citizens Hospital, 2-1-1 Kabe-minami, Asa-kita-ku, Hiroshima, 731-0293, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Manabe
mesh_terms: D000368:Aged; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D005260:Female; D059526:Foraminotomy; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008853:Microscopy; D008875:Middle Aged; D011843:Radiculopathy / Q000000981:diagnostic imaging / Q000601:surgery; D012189:Retrospective Studies; D055009:Spondylosis / Q000000981:diagnostic imaging / Q000601:surgery; D014057:Tomography, X-Ray Computed
keywords: Cervicogenic headache; Foraminotomy; Microscopic surgery; Occipital neuralgia; Radiculopathy