Stereotactic procedures usually require burr hole trephination. To date, there is no Conformité Européenne-certified drilling system that can be integrated into a stereotactic apparatus, thus enabling stereotactically guided trephinations (SGTs). Therefore, free-hand burr hole trephination is the standard of care, often requiring time-consuming burr hole widening.

We developed a novel drill, which can be picked up through a standard cordless drill and a novel guide sleeve (Instrument guide inner diameter: 10 mm for Riechert–Mundinger [RM] rail holder for microprobe insertion), which can be easily integrated into a stereotactic RM-system. This device enables stereotactic guidance of the drill. Over a period of 8 months, we recorded the trephination in all patients who underwent stereotactic-guided biopsy or catheter insertion in our department. In the first 4 months, a freehand trephination (FHT) using a standard trepan was performed; in the second half of the period, the novel SGT was performed. An unpaired t-test and chi-square test were used to compare SGT with FHT in terms of time for trephination, time from trephination to dura incision, and whether additional surgical measurements (osteoclastic enlargement, hemostasis) were necessary.

Overall, 84 trephinations (SGT: n = 27, FHT = 57) for stereotactic biopsies were included. The mean time for completing the burr hole showed no difference between the groups (SGT: 64 s, FHT: 55 s, p = 0.485). The mean time until dura incision was significantly (p = 0.018) reduced when using SGT (FHT: 304 ± 170 s vs. SGT: 136 ± 89 s). Additional osteoclastic expansion was frequently necessary in the FHT group (81% [n = 46] vs. 3.7% [n = 1], p < 0.001). Similar results were observed for hemostasis, which was significantly less necessary in the SGT group (71% [n = 41] vs. 40% [n = 11], p = 0.006). We did not observe any difference between board-certified neurosurgeons and trainees for all these parameters.

SGT significantly shortens the time until dura opening compared to FHT. Additionally, time-consuming hemostasis and osteoclastic entlargements are no longer necessary when using SGT. Furthermore, SGT seems to be successfully applied regardless of the surgeon's level of training.

Received: 15 January 2025

Accepted: 05 September 2025

Article published online:
18 November 2025

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