Pushing the limits of the Leksell stereotactic frame for spinal lesions up to C3: fixation at the maxilla.

Abstract

Spinal radiosurgery is not considered in the domain of traditional Gamma Knife radiosurgery (GKRS) setup. The major obstacles in GKRS for upper cervical spine lesions remain in difficulty of frame fixation, avoiding collision and maintaining the integrity of the relative position of the lesion from image acquisition to treatment. The supraorbital margin remains the standard lowest fixation point for Leksell stereotactic frame. We describe fixation at the maxilla to target and treat upper cervical spine lesions (up to C3 vertebra) with measures to ensure cervical immobilisation and precision of the GKRS treatment. We have treated two patients at the upper cervical spine up to C3 vertebra by fixing anterior pillars of the Leksell stereotactic frame at the maxilla. To ensure cervical immobilisation and precision of treatment, the neck was immobilised with a Philadelphia collar. The relative position between the head and sternum with the couch from image acquisition to the radiation delivery was kept constant. Docking angle was kept neutral (90 degrees) throughout the treatment (from image acquisition to actual treatment). The maxilla is a potential alternative for stereotactic frame fixation. Measures to ensure cervical immobilisation with lower-down frame position permits treatment of lesions as low as C3 vertebra.