Calcium pyrophosphate dihydrate crystal deposition (CPPD) in the retro-odontoid tissue with compression of cervicomedullary junction: Analysis of 46 cases (1984-2020) with literature review.

OBJECTIVE

Peri-odontoid calcium pyrophosphate dihydrate deposition (CPPD) results in extradural masses that compress the cervicomedullary junction (CMJ). The authors analyzed their experience in the MRI era to understand causation, radiographic pathology, treatment options, and outcome.

METHODS

Retrospective analysis of University of Iowa Hospitals & Clinics records of retro-odontoid masses consistent with diagnosis of CPPD was made. 46 patients were identified; 21 have been described and 25 now added. Patients underwent cervical motion radiographs, CT, MRI. Postoperative MRI was made in all 25 patients.

RESULTS

Mean age was 75.8 years, mean symptom duration 3.6 years. Headache presented in 84 %, myelopathy 92 %, lower cranial nerve dysfunction 36 %, urinary incontinence 36 % and misdiagnosis 52 %. Subaxial pathology (cervical fusion, DISH, lateral mass fusion) with CVJ instability was seen in 92 %. MRI revealed rim enhancement in all and 11 associated cysts. CT calcification in the mass was 96 %, odontoid fractures in 4. Primary ventral transoral resection made in patients with severe neurological deficits. Primary dorsal fixation patients had co-morbidities but showed improvement. Comparison of preoperative and postoperative status and JOA scores reflect the improvements.

CONCLUSIONS

Pathology proven diagnosis of CPPD was made in 36/46 patients of the entire series. Preoperative diagnosis can be based on retro-odontoid location, absence of MRI enhancement, CT calcifications in the mass and subaxial cervical fixation. Transoral resection of the mass should be reserved for severe CMJ compression. Dorsal C1 decompression and fusion has recently been shown to be satisfactory in others. All patients should be considered as being unstable and must be fused.