case_images: PMC9086508_01
case_images: Preoperative sagittal (A-C) and axial (D,E) T2-weigthed magnetic resonance images revealed a lesion of the OP and the retro-odontoid region (yellow stars) with brainstem compression and displacement (red block arrows) and also cystic component (blue block arrows and blue circle). Furthermore, the cervical vertebral bodies C3 to C6 were fused due to Saethre-Chotzen syndrome (orange block arrow). Preoperative CT and CTA of cervical spine (F-H): A sagittal (F) and an axial (G) CTA (soft tissue window) revealed a "normal" anatomy of the vertebral artery and furthermore a spinal stenosis in the level of C 1 (yelow arrows). An axial CT (bone window) showed a "horseshoe" or "crown-like" calcification, which is located posterior to the OP (H).
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case_images: F1
case_images: Magnetic resonance imaging (MRI) of the craniovertebral junction (CVJ) and cervical spine revealed a lesion of the OP and the retro-odontoid region (Figures 1A,B) with mainly solid components, as well as small cystic components (Figure 1C), and brainstem compression and displacement (differential diagnoses include metastasis, rheumatoid arthritis, and spondylodiscitis) (Figures 1C,D). Computed tomography (CT) revealed spinal stenosis and odontoid erosion with signs of instability (Figures 1F-H). MRI also revealed a fusion of the cervical vertebral bodies C3 to C6 due to Saethre-Chotzen syndrome (Figure 1A).
case_images: Different steps of surgery: (A) In first step, fusion surgery of the CVJ C0-C4 was performed with an OC plate (OCP) with occiptocervical decompression (by enlargement of the foramen magnum and laminectomy of the medial C1 arc); (B,C) After fusion and decompression the lower lateral part of the C1 arc (subperiostal, with remnant upper C1 arc) and the lateral superior part of the left side of the C2 arc. Doppler sonography (DS) was used to analyze the anatomy of vertebral artery. (D) The entry point was located directly above the superior part of the C2 root. The trajectory was located medial to the pedicle of C2, medial to the C1-C2 facet joint, and medial to the tubercle for the transverse ligament of the atlas. A biopsy of the lateral portions of the lesions was obtained by bioptic forceps (BF) under microscope guidance.
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case_images: F2
case_images: Laminectomy of the medial C1 arc and the lower lateral part of the C1 arc (subperiostal, with remnant upper C1 arc), removal of the left superior part of the left side of the C2 arc, and flavectomy were performed (Figure 2). Doppler sonography was used to analyze the anatomy of vertebral artery (Figure 2). A bioptic instrument was inserted under microscope guidance (Figure 2).
case_images: Post-operative CT-scan of cervical spine (A) and different three-dimensional reconstruction (B,C) revealed a sufficient decompression and furthermore regular placement of screws. Histopathologic findings of bioptic probe showing fibrous connective tissue (HE x 200) (D) with multifocal deposits of birefringent crystals (under polarized light x 200) (E).
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case_images: F3
case_images: A postoperative CT scan showed proper positioning of the screws and sufficient decompression of the spinal cord at the level of the CVJ (Figures 3A-C). Pathologic examination of the mass revealed fibrous connective tissue with deposition of birefringent crystals compatible with calcium pyrophosphate (CPP) due to CPPD disease (Figures 3D,E).
case_images: Preoperative (A) and follow-up (B) sagittal T2-weigthed magnetic resonance images: follow-up MRI scan revealed regression of the pannus (yellow star) and the cyst with replacement of the brainstem (blue circle).
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case_images: F4
case_images: At follow-up examination 6 months after surgery, an MRI scan of the cervical spine revealed regression of the pannus and the cyst with replacement of the brainstem (Figure 4), clinical improvement of walking, and increased strength of the left hand.