Search Results (3)

Background: A pseudotumor adjacent to the odontoid has been reported to be a non-neoplastic mass that is mainly associated with atlantoaxial instability. Methods: Case report. Results: A 72-year-old woman presented to our clinic with a chief complaint of bilateral fine motor dysfunction and gait disturbance. She had rheumatoid arthritis as a comorbidity. Physical examination revealed bilateral hand fine motor dysfunction and signs of myelopathy, including hyperreflexia of the deep tendon reflexes in the lower extremities. Magnetic resonance imaging (MRI) showed a retro-odontoid pseudotumor. Surgery was proposed to the patient, but she did not wish to undergo surgery at this time. At a follow-up visit approximately one year after the initial visit, she complained of the progression of the bilateral hand fine motor dysfunction and gait disturbance. MRI demonstrated a pseudotumor in the space anterior to the odontoid process, indicating that the localization of the pseudotumor around the odontoid process changed from the posterior space to the anterior space in its natural course. Conclusions: The speculated sequential mechanism of the change in the location of the pseudotumor from the posterior space to anterior space to the odontoid process in the natural course is as follows: As the rheumatoid arthritis progressed, the C1-2 joint was immobilized in the dislocated position, and as a result, the retro-odontoid pseudotumor disappeared due to immobilization of the C1-2 joint. Following the disappearance of the retro-odontoid pseudotumor, the odontoid process shifted backward owing to rupture of the transverse annular ligament. Consequently, a new space appeared in front of the odontoid process. Subsequently, damage to the apical and alar ligaments resulted in pseudotumor formation in the new space. Considering our case, the formation of an antero-odontoid pseudotumor occurs only in limited cases, with extreme progression of the pathology. Most cases of retro-odontoid pseudotumors are treated by surgery before such a progression; therefore, we consider that such a case has not yet been reported in the literature. Full article

Study design: Technical note. Objectives: To present a novel C-arm-free technique guided by navigation to insert and place a C1 lateral mass screw. Background and Objectives: Atlantoaxial subluxation (AAS) is a relatively common sequelae in patients with rheumatoid arthritis (RA) and upper cervical trauma. If they present with severe symptoms, surgical intervention such as posterior fusion is indicated. The established treatment for AAS is fixation with a C1 lateral mass screw and C2 pedicle screw (modified Goel technique) to achieve bony fusion. However, this technique requires fluoroscopy for C1 screw insertion. To avoid exposing the operating team to radiation, we present here a novel C-arm-free C1 lateral mass screw insertion technique for AAS. Materials and Methods: A 67-year-old man was referred to our hospital with neck pain, quadriparesis, and clumsiness and numbness of both upper and lower limbs. He had undergone C3–6 posterior fusion previously in another hospital. In physical examination, he had severe muscle weakness of bilateral upper limbs and hypoesthesia of all four limbs. He had hyper-reflexia of bilateral lower limbs and pollakiuria. His Japanese orthopedic score was 8 points out of 17. Preoperative radiograms showed AAS with an atlantodental interval (ADI) of 7 mm. MRI indicated retro-odontoid pseudotumor and severe spinal cord compression at the C1–2 level. The patient underwent posterior atlantoaxial fixation under navigation guidance. To prevent epidural bleeding during the insertion and placement of a C1 lateral mass screw, we have here defined a novel screw insertion technique. Results: The surgical time was clocked as 127 min and blood loss was 100 mL. There were no complications per-operatively or in the postoperative period. The patient showed almost full recovery (JOA 16/17) at two months follow-up and a solid bony fusion was noticed in the radiograms at one year follow-up. Conclusions: This novel surgical procedure and C1 lateral mas screw placement technique is a practical and safe method in recent advances of AAS treatment. Procedurally, the technique helps prevent epidural bleeding from the screw entry point and also allows for proper C1 screw insertion under navigation guidance without exposing surgeons and staff to the risk of fluoroscopic radiation. Full article

Backgroundand Objectives: To date, imaging characterization of non-rheumatic retro-odontoid pseudotumors (NRROPs) has been lacking; therefore, NRROPs have been confused with atlantoaxial joint involvement of rheumatoid arthritis (RA). It is important to differentiate these two disease because the treatment strategies may differ. The purpose of this study is to characterize imaging findings of NRROPs and compare them with those of RA. Material and Methods: From January 2015 to December 2019, 27 patients (14 women and 13 men) with NRROPs and 19 patients (15 women and 4 men) with RA were enrolled in this study. We evaluated various imaging findings, including atlantoaxial instability (AAI), and measured the maximum diameter of preodontoid and retro-odontoid spaces with magnetic resonance imaging (MRI) and computed tomography (CT). Results: Statistical significance was considered for p < 0.05. AAI was detected in eight patients with NRROPs and in all patients with RA (p < 0.0001). Seventeen patients with NRROPs and six patients with RA showed spinal cord compression (p = 0.047). Compressive myelopathy was observed in 14 patients with NRROPs and in 4 patients with RA (p = 0.048). Subaxial degeneration was observed in 25 patients with NRROPs and in 9 patients with RA (p = 0.001). Moreover, C2-3 disc abnormalities were observed in 11 patients with NRROPs and in 2 patients with RA (p = 0.02). Axial and longitudinal diameter of retro-odontoid soft tissue and preodontoid and retro-odontoid spaces showed significant differences between NRROP and RA patients (p < 0.0001). Furthermore, CT AAI measurements were differed significantly between NRROP and RA patients (p < 0.05). Conclusions: NRROPs showed prominent retro-odontoid soft tissue thickening, causing compressive myelopathy and a high frequency of subaxial and C2-3 degeneration without AAI. Full article