Frameless stereotactic targeting devices: technical features, targeting errors and clinical results.

BACKGROUND: Brain biopsies (BB) and depth electrode placements (DEP) are increasingly performed using frameless stereotactic targeting devices. This paper is intended to provide a comprehensive review of the technical features, targeting errors and clinical results.

METHODS: A PubMed literature search from 1995-2010 was performed.

RESULTS: (A) Modified stereotactic arcs, (B) arm-based devices with and without aiming facilities, and (C) skull affixed devices were found. Guidance technologies were navigation systems (all groups), prospective stereotaxy and custom designed platforms (group C). Mean total errors ranged between 4.4 and 5.4 mm for BB and 2.0 and 3.2 mm for DEP. Diagnostic yield of BB was 89-100%. The clinical success rate for DEP was 96-100%.

CONCLUSIONS: Frameless stereotactic targeting devices may reach targeting errors and clinical results comparable with standard frame-based stereotaxy. Advantages and disadvantages of different devices should be acknowledged to ensure optimal technical performance.