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case_images: Computed tomography (CT) scan on admission of an 86-year-old man with retro-odontoid pseudotumor. A, The slice showed C2-C7 osteophyte formation (white arrowheads). B, Sagittal slice revealed more obvious high-density area than on (A) (white arrowheads).
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case_images: When the image brightness was adjusted using the window level, it revealed a retro-odontoid mass extending from the posterior part of the axis up to the cranial base (Fig. 1).
case_images: Magnetic resonance imaging (MRI) on admission of an 86-year-old man with retro-odontoid pseudotumor. A, The mass was seen as an iso-intensity area on T1-weighted imaging (white arrow). B, T2-weighted imaging showed cord compression by the low-intensity area (black arrow) posterior to the odontoid process of the axis with high-intensity of the cervical spine at the C1-C2 level (white circle).
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case_images: T2-weighted imaging (WI). The mass was seen as an area of iso-intensity on T1-WI and of low-intensity on T2-WI (Fig. 2).
case_images: Flexion extension X-rays of the cervical spine on day 3 of hospitalization of an 86-year-old man with retro-odontoid pseudotumor. A, Flexion test revealed no cervical instability. B, Extension test revealed no cervical instability.
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case_images: The flexion extension X-rays of the cervical spine showed no atlantoaxial subluxation (Fig. 3).