Calcium pyrophosphate dihydrate of the ligamentum flavum in the cervical spine - A review of the literature.

Background: Calcium pyrophosphate dihydrate (CPPD) deposition, also known as pseudogout, in the cervical ligamentum flavum (CLF), is a rare disease which can cause spinal cord signaling changes leading to rapid deterioration in function. The natural history of cervical myelopathy as a result of CPPD deposition within the CLF is not well understood. Our objective is to describe the presentation, imaging findings, and treatment options of CPPD deposition or pseudogout of the cervical spine. Methods: Using PubMed, we analyzed studies published from 1978 to 2022. Key words used were "pseudogout," "CPPD deposit disease," "cervical yellow ligament," "CLF," and "cervical spine." We excluded "crowned dense syndrome" and "ossification of ligament flavum." Using a department database, we queried for patients treated for CPPD of the cervical spine. Results: Twenty clinical studies on CPPD of the cervical spine with 69 patients aged between 15 and 92 years (mean = 72) were identified. Neck pain and numbness of the hands were the most common symptoms. Diabetes mellitus and hypertension were the most common comorbidities. Males and females were affected at equal rates. C4-C5 and C5-C6 were the most affected segments. Earlier surgical treatment produced better outcomes. A laminectomy and fusion or laminoplasty were the most common procedures performed with most patients experiencing some return of neurologic function. Conclusion: Although rare, CPPD deposit disease in the CLF should be readily considered as a differential diagnosis due to the continuously aging population. CPPD's progressively worsening nature makes an early diagnosis and treatment important in improving the patient's overall quality of life.