Extensive calcification of the ligamentum flavum causing cervical myelopathy in a Caucasian woman

Calcification of the ligamentum flavum (CLF) is a rare disease mainly occurring in the cervical spine (Miyasaka et al. 1983). CLF results in posterior spinal cord compression, which may cause myelopathy and successive neurological deficits. It mostly occurs in the Asian population (Ahn et al. 2014). However, several cases in Caucasian patients have been reported (Khan et al. 2005; Ugarriza et al. 2001). The exact pathophysiology is unknown, although findings from multiple case-reports describing CLF suggest that CLF could be a rare manifestation of the deposition of calcium pyrophosphate dehydrate crystals (CPPD) (Berghausen et al. 1987; Brown et al. 1991; Giulioni et al. 2007; Seki et al. 2013). Clinical manifestation usually starts with a loss of vibration, proprioception and functional gait worsened by motor weakness and paresthesia. To distinguish CLF from other causes of dorsal spinal cord compression, radiological imaging, cerebral spinal fluid (CSF) analysis and histological tissue examination are needed. In this report, we describe a case of cervical and thoracic myelopathy due to extensive CLF in a 63-year-old Caucasian woman and its treatment.

Dorsal spinal cord compression can be caused by different pathological conditions. MRI imaging is important to differentiate from neoplasm, meningioma, lymphoma and chronic calcified epidural hematoma (Boutarbouch et al. 2008; Matsui et al. 2014; Seo et al. 2014; Zhong et al. 2011). To exclude pachymeningitis, CFS analysis is needed (Senapati et al. 2014). Sagittal CT-imaging revealed oval nodular densities, partially connected with the laminae. This distinguishes CLF from OLF since OLF arises from the lamina and moves inward towards the midline (Miyasaka et al. 1983). The exact pathophysiology of CLF is yet to be discovered. Seki et al. described a large calcified mass in the ligamentum flavum level L4/5 and after resection, additional analyses showed the mass mostly consisted of calcium triphosphate and calcium phosphate with degenerative changes possibly involved in the formation of this mass (Seki et al. 2013). Other reports describing cervical CLF also mention nodular deposition of calcium pyrophosphate dehydrate crystals in the ligamentum flavum (Berghausen et al. 1987; Brown et al. 1991; Cabre et al. 2001). CPPD crystal formation can be sporadic or hereditary and may be related to metabolic diseases such as hypophosphatemia, hypothyroidism, hyperparathyroidism and hemochromatosis (Berghausen et al. 1987; Riccio et al. 2016). Calcium crystal deposition in the ligamentum flavum seems to progress with a reduction in elastic fibers, an increase in collagen fibrils and migration of hypertrophic chondrocytes (Mwaka et al. 2009). This indicates that CPPD may be a consequence of degenerative changes in the ligamentum flavum, which might explain the broad extension of the lesion in our case. Recent research shows that mechanical load may be a contributing factor to CLF. They found that mechanical load induces the differentiation of ligamentum flavum cells leading to calcium depositions (Chao et al. 2016).

The only treatment for CLF is surgical decompression of the spinal cord (Ahn et al. 2014; Delgado-Lopez et al. 2007; Inoue et al. 2013; Khan et al. 2005; Sun et al. 2014; Yuan et al. 2014). The right method of decompression, we believe, is laminectomy. A retrospective study of thoracic OLF showed that laminectomy with fusion had a better outcome than laminoplasty (Li et al. 2006). Such a large study has not been executed for CLF. One study shows good clinical outcome after endoscopic partial laminectomy (Yabuki and Kikuchi 2008). Since the diagnoses was uncertain and we considered it to be a lymphoma we decided to perform a laminectomy of only C6 first in order to decompress the spinal cord where it showed myelopathy and to obtain tissue for histology. Since clinical outcome improved, we, in consolation with our patient, decided to only further decompress the spinal cord should neurological deterioration occur in the future. Clinical symptoms were mild and stable and no further decompression was there for deemed necessary.

Although rare, CLF should be considered as a possible diagnosis of extensive dorsal spinal cord compression. It is important to recognize and treat CLF at an early stage, since timely decompression results in better neurologic outcome.