✓ The Pelorus stereotactic system guided by magnetic resonance imaging was used to implant intracerebral depth electrodes for monitoring seizure activity. This stereotactic system is frameless and does not require the use of a computer. It is based on the concept of a ball-and-socket type stereotactic arc director and uses the center-of-arc principle to establish a trajectory for electrode placement. The system not only allows the use of the orthogonal approach, but also provides ample working space and flexibility to choose different entry points and trajectory angles.
Hwa-Shain Yeh, Jamal M. Taha and William D. Tobler
Rajaraman Viswanathan, Narayana K. Swamy, William D. Tobler, Alson L. Greiner, Jeffrey T. Keller and Stewart B. Dunsker
Object. Familiarity with the microsurgical anatomy of the far-lateral compartment is essential for operating in patients with far-lateral discs. In this report the authors address the microsurgical anatomy studied in 24 extraforaminal lumbar disc spaces in three cadavers.
Methods. Cadaveric dissections confirmed the authors' operative experience in which they found an arterial arcade to be associated with the nerve trunk. The main trunk of the lumbar artery was located lateral to the exiting nerve root in the region of intervertebral foramen. The trunk of the lumbar spinal nerve descending from the level above was 7 mm (± 3 mm [standard deviation]) lateral to the lumbar artery.
Conclusions. Clarification of the microsurgical anatomy of the far-lateral compartment confirmed the authors' clinical impression that the optimum approach to far-lateral discs is via the inferomedial quadrant of the extraforaminal compartment. In this quadrant, exposure of the main nerve root can be facilitated by dividing the posterior primary ramus and a newly described arterial arcade that envelops the nerve trunk. Once this arcade is divided, the nerve can be retracted with relative ease and safety, and the disc can be removed more easily.