Surgery for dural ossification in association with cervical ossification of the posterior longitudinal ligament via an anterior approach

Abstract

Direct removal of an ossified mass via an anterior approach carries good decompression, to one- or two-level ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. Ossification occasionally involves not only the posterior longitudinal ligament (PLL) but also the underlying dura mater. Defect of the dura mater by resection of the dural ossification (DO) can cause cerebrospinal fluid leakage or neural injury. The technique of resection of OPLL with floating of DO provides satisfactory decompression and avoids dural defect or neural injury in OPLL associated with DO. Four patients developed cervical myelopathy. Radiological examination revealed cord compression due to OPLL associated with DO. All patients underwent anterior procedures. After the necessary discectomies and corpectomies, OPLL was resected using a high-speed drill with a 4-mm steel burr and then with a 4-mm diamond burr. When the OPLL became paper-thin, it was separated from the dura mater using a microdissector and a Kerrison rongeur. There was a thin layer of the nonossified degenerated PLL between the residual OPLL and DO. Meticulous dissection of the residual OPLL over the DO was performed without removing the DO at this layer. Fixation was performed with a titanium cylindrical cage. This technical note describes the successful decompression of the spinal cord by removing OPLL only, and avoidance of dural defect or neural injury in cases of OPLL associated with DO.