Minimally Invasive Surgery for Osteoid Osteoma of the Cervical Spine Using Microendoscopic Discectomy System
The patient was an 18-year-old man who complained of right neck pain. Pain from the right neck to the back had been present for one year prior to his initial visit to our hospital. He had consulted another doctor approximately eleven months previously. No abnormalities were seen through plain radiography, and symptoms were alleviated by administration of a non-steroidal anti-inflammatory drug (NSAID). When the NSAID was discontinued six months later, symptoms recurred. Based on CT and magnetic resonance imaging (MRI), an osteoid osteoma in the superior articular process of C7 was suspected and the patient was referred to our hospital for surgery. There was tenderness at the paraspinal muscles of the right neck. Flexion and extension of the cervical spine exacerbated the right neck pain. No neurological abnormalities were noted, nor were there any abnormal blood test findings. Alignment also appeared normal on a plain cervical radiograph, and there were no obvious abnormalities. Upon closer inspection, however, indistinct lucency of the bone was observed in the right C6/7 facet joint (). On the plain CT scan, a nidus was seen in the right superior articular process of C7 (). On the contrast MRI, there were signal changes in the right superior articular process of C7, and a conspicuous contrast effect was seen in the surrounding tissue (). Osteoid osteoma of the right superior articular process of C7 was diagnosed based on these findings.\nMicroendoscopic surgery using a tubular retractor (METRx System Medtronic Sofamor Danek, Co., Ltd., Minneapolis, MN, USA) was selected because of its low invasiveness. A 2-cm incision was made 2 cm to the right of the midline, and an 18-mm in diameter tubular retractor was placed. After coagulation of the soft tissue, the right C6/7 facet joint was exposed. After excision of the C6 inferior articular process, the C7 superior articular process was removed using a chisel and rongeurs. Right C6/7 total facetectomy was performed. The right C7 nerve root could be confirmed when the C7 superior articular process was completely excised to the lateral side (). The operative time was 1 hour 29 minutes, and estimated blood loss was 5 mL. Pathologically, an osteoid formation covered with osteoblasts was seen. The pathological diagnosis was thus osteoid osteoma ().\nOn postoperative plain radiographs, the right C6/7 facet joint was completely resected (). No changes in alignment were detected. Postoperative CT confirmed complete resection of the tumor (). Postoperative MRI also showed that the tumor had been completely resected (). At 28 months after surgery, there had been no recurrence of symptoms. There was mild spondylolisthesis on C6/7. However, spinal instability such as increase of spondylolisthesis and/or posterior widening were not seen in the flexion-extension radiographs.