Craniotomy Size for Subdural Grid Electrode Placement in Invasive Epilepsy Diagnostics

Abstract

Background: Traditionally, for subdural grid electrode placement, large craniotomies have been applied for optimal electrode placement. Nowadays, microneurosurgeons prefer patient-tailored minimally invasive approaches. Absolute figures on craniotomy size have never been reported. To elucidate the craniotomy size necessary for successful diagnostics, we reviewed our single-center experience. Methods: Within 3 years, 58 patients with focal epilepsies underwent subdural grid implantation using patient-tailored navigation-based craniotomies. Craniotomy sizes were measured retrospectively. The number of electrodes and the feasibility of the resection were evaluated. Sixteen historical patients served as controls. Results: In all 58 patients, subdural electrodes were implanted as planned through tailored craniotomies. The mean craniotomy size was 28 ± 15 cm 2 via which 55 ± 16 electrodes were implanted. In temporal lobe diagnostics, even smaller craniotomies were applied (21 ± 11 cm 2). Craniotomies were significantly smaller than in historical controls (65 ± 23 cm 2 , p < 0.05), while the mean number of electrodes was comparable. The mean operation time was shorter and complications were reduced in tailored craniotomies. Conclusion: Craniotomy size for subdural electrode implantation is controversial. Some surgeons favor large craniotomies, while others strive for minimally invasive approaches. For the first time, we measured the actual craniotomy size for subdural grid electrode implantation. All procedures were straightforward. We therefore advocate for patient-tailored minimally invasive approaches-standard in modern microneurosurgery-in epilepsy surgery as well.

Electrocorticogram (ECoG): Engineering Approaches and Clinical Challenges for Translational Medicine

“…For an in-depth understanding of neural circuit mechanisms, it is desirable to integrate ECoG arrays with systemic modalities such as microfluidic or optical components. Furthermore, commercial ECoG arrays implanted after cranial incision require a large exposure window of 28 ± 15 cm 2 on average, [81] which can cause adverse effects such as clinical infection, subdural hemorrhage, [82][83][84][85][86] cerebral edema, or aseptic meningitis. Minimally invasive surgical and systemic strategies are expected to reduce surgical side effects in patients.…”

“…Minimally invasive surgical and systemic strategies are expected to reduce surgical side effects in patients. [86,87]…”

Shape Memory Polymer-Based Insertable Electrode Array Towards Minimally Invasive Subdural Implantation

“…Traditionally, a centimetre-scale electrode array is placed on the cortex of the brain under dura mater during the craniotomy procedure, which involves a large skull opening in the range of 25-65 cm 2 . [4] Today the procedure remains traumatic for the patients [5], increasing infection risks [6] and expensive for the healthcare system [7]. The clinically approved subdural electrode arrays, fabricated from silicone sheet of millimetre thickness with metal electrodes and interconnections [8], have limited flexibility and conformability [9], and make the implantation through smaller skull opening challenging.…”

“…The problem of craniotomy size reduction has been approached by using active and passive materials in the electrode design. The electrodes fabricated from thin and flexible passive materials such as polydimethylsiloxane (PDMS), have potential to reduce the required craniotomy size from 3.2 mm to 3 mm [10], but do not provide centimetre-scale measurement area crucial for certain applications such as focal epilepsy diagnostics [4]. In contrast, integration of the stimuli-responsive active materials into the electrode structure This work is licensed under a Creative Commons Attribution 4.0 License.…”