case_images: PMC5362863_01
case_images: Sagittal (a) T2-weighted, (b) T1-weighted and (c) T1-weighted post-contrast magnetic resonance imaging scans of the cervical spine obtained at first presentation. A circular intramedullary T2-weighted hyperintense lesion showing peripheral contrast enhancement (arrow) is seen dorsal to the dens, with a more diffuse intramedullary T2-weighted hyperintense non-enhancing lesion (arrowhead) seen in the dorsal cord from C2 to C3
case_images: 10.1177_2055116915589839-fig1.jpg
case_images: PMC5362863_01_10.1177_2055116915589839-fig1.jpg
case_images: fig1-2055116915589839
case_images: Magnetic resonance imaging (MRI) of the cervical spine was performed using a 1.5-Tesla MRI unit (Siemens Magnetom Essenza; Siemens), which revealed a well-defined rounded intramedullary lesion (0.5 cm in diameter) at the level of the atlantoaxial joint (Figure 1).
case_images: Sagittal (a) T2-weighted, (b) T1-weighted and (c) T1-weighted post-contrast magnetic resonance imaging scans of the cervical spine obtained 4 weeks after first presentation. The intramedullary lesion seen dorsal to the dens shows a significant reduction in size (arrow), and the more caudal diffuse T2-weighted hyperintense lesion has resolved
case_images: 10.1177_2055116915589839-fig2.jpg
case_images: PMC5362863_01_10.1177_2055116915589839-fig2.jpg
case_images: fig2-2055116915589839
case_images: Repeat MRI of the cervical spine revealed marked improvement of the intramedullary changes (Figure 2).
case_images: Sagittal (a) T2-weighted and transverse (b) T2-weighted at the level of mid-C2 magnetic resonance imaging scans of the cervical spine obtained 4 months after initial presentation following recurrence of clinical signs. The intramedullary lesion seen dorsal to the dens is still present (arrow), with a diffuse T2-weighted hyperintense midline intramedullary lesion seen in the dorsal cord at the level of C2 (arrowhead), suspected to represent early syrinx formation
case_images: 10.1177_2055116915589839-fig3.jpg
case_images: PMC5362863_01_10.1177_2055116915589839-fig3.jpg
case_images: fig3-2055116915589839
case_images: Repeat MRI of the cervical spine revealed a similar intramedullary lesion just dorsal to the dens, and this time a syrinx was visible caudally (Figure 3).
case_images: Lateral (a) neutral and (b) flexed radiographs of the atlantoaxial region of the cervical spine obtained 4 months after initial presentation following recurrence of clinical signs, showing a slight widening of the space between the laminae of C1 and C2 on the flexed view (arrowhead)
case_images: 10.1177_2055116915589839-fig4.jpg
case_images: PMC5362863_01_10.1177_2055116915589839-fig4.jpg
case_images: fig4-2055116915589839
case_images: Cervical radiographs showed only on the fully flexed lateral views a mildly increased distance visible between C1 and C2 spinous processes, supporting the diagnosis of atlantoaxial instability (Figure 4).