Split laminotomy and complementary spacer insertion for opening and enlargement of the thoracic spinal canal at infiltrative intramedullary tumor removal.

Objective: The author main objective was to improve the previously developed technique of split laminotomy and moderate enlargement of the spinal canal with preservation of the majority of posterior structures, and to avoid the complications of the classic autologous bone grafting procedure.

Methods: A multilevel spinous process splitting and distracting laminotomy technique with complementary spacer insertion between the laminar parts was developed. We used Poly-Ether-Ether-Ketone (PEEK) cages. This improved method was used in five patients to remove malignant intramedullary tumors at the thoracic level.

Results: Adequate surgery of the tumors located intramedullary, and permanent decompression of the spinal canal was achieved in all patients using our new modified procedure. The results have been postoperatively confirmed with MRI and CT. The affected spine was the thoracic in all cases. The numbers of split laminae were three to five. Histological results were as follows: four intramedullary astrocytomas, one ependymoma. The ependymoma was completely, while the astrocytomas were only subtotally removed. In all cases heterologous grafts were inserted between the sides of the distracted laminas, to achieve the enlargement of the spinal canal. The mean duration of the whole surgical procedure was 118 minutes (range 91 to 145 minutes). The average follow-up was 11.2 months, with the range from five to 16 months. Upon postoperative neurological follow-up, no complications were revealed related to the newly developed procedure. The postoperative followup CT scans demonstrated bony healing, with a cage between the osteotomized faces. No compression or dislocation of the spacer was seen. Instability was not detected in any of the patients by flexion or extension lateral radiographs.

Conclusion: This modification of the split laminotomy and heterologous grafting method fulfills the requirements of other laminotomy techniques. The split laminotomy is suitable for removing intramedullary tumors, and the posterior stabilizing structures of the spine, as the vertebral laminae and the longitudinal musculature are completely prevented. Due to use of allograft the complications of the classic hip bone grafting procedures are avoided. The spacers, inserted between the osteotomized faces, provided permanent decompression of the spinal canal, and bony healing--throughout the spacer--of the splitted vertebral laminae, without iliac graft complications.