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Introduction: Headholders or skull clamps serve as indispensable tools in neurosurgery, facilitating the precise positioning and stabilization of the head for surgery. The realm of neurosurgical training in cadaver labs presents a clear challenge due to the lack of suitable non-clinical headholders. Research question: We describe a 3D printed stainless-steel headholder for use in neurosurgical cadaver lab training. Material and methods: Computer-aided design software was used to design a headholder, utilizing a three-pin skull fixation. Through an iterative process involving a plastic 3D printed prototype, ultimately a robust model was manufactured using a 3D stainless-steel printer. Results: The headholder was fixed to a multi-angle adjustable vise, enabling optimal positioning to support simulation of neurosurgical approaches and dissection training by neurosurgical residents and staff in the cadaver lab. Discussion and conclusion: This custom-made headholder offers an effective solution for secure fixation of cadaver skulls during neurosurgical training, contributing to practicality and efficiency in cadaver dissection. Despite the lack of evidence-based guidelines for neurosurgical headholder use, this device provides a valuable tool for neurosurgical trainees to practice proper placement, understand associated complications, and improve their hands-on skills. The digitally available 3D model can be optimized, shared, and further improved by other neurosurgical units and trainees, fostering collaborative advancements in neurosurgical training.

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Diffuse idiopathic skeletal hyperostosis (DISH) frequently occurs in the spine, resulting in unstable fractures. Treating thoracolumbar fractures in patients with DISH is often difficult because the anterior opening of the vertebral body is exacerbated by dislocation in the prone position, making reduction difficult. In this study, we introduced a novel skull clamp-assisted positioning (SAP) technique. The patient is placed in a supine position with a skull clamp used in cervical spine surgery before surgery to prevent the progression of dislocation and to restore the patient's position. Using this method, the mean difference in local kyphosis angle improved from -2.9 (±8.4)° preoperatively to 10.9 (±7.7)° postoperatively. Furthermore, posterior displacement decreased from a preoperative mean of 5.5 (±4.3) mm to 0.3 (±0.7) mm postoperatively. Complications such as neurological sequelae, implant fracture, and surgical site infection were not observed through one year of postoperative follow-up. SAP may decrease invasiveness and complications. Longer-term studies and larger sample sizes are needed to establish long-term efficacy and benefits.

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In estimated 10-15% of neurosurgical interventions employing a conventional three-pin head fixation device (HFD) the patient's head loses position due to slippage. At present no scientifically based stability criterion exists to potentially prevent the intraoperative loss of head position or skull fractures. Here, data on the skull penetration depth both on the single and two-pin side of a three-pin HFD are presented, providing scientific evidence for a stability criterion for the invasive three-pin head fixation. Eight fresh, chemically untreated human cadaveric heads were sequentially pinned 90 times in total in a noncommercially calibrated clamp screw applying a predefined force of 270 N (approximately 60 lbf) throughout. Three head positions were pinned each in standardized manner for the following approaches: prone, middle fossa, pterional. Titanium-aluminum alloy pins were used, varying the pin-cone angle on the single-pin side from 36° to 55° and on the two-pin side from 25° to 36°. The bone-penetration depths were directly measured by a dial gauge on neurocranium. The penetration depths on the single-pin side ranged from 0.00 mm (i.e., no penetration) to 6.17 mm. The penetration depths on the two-pin side ranged from 0.00 mm (no penetration) to 4.48 mm. We measured a significantly higher penetration depth for the anterior pin in comparison to the posterior pin on the two-pin side in prone position. One pin configuration (50°/25°) resulted in a quasi-homogenous pin depth distribution between the single- and the two-pin side. Emanating from the physical principle that pin depths behave proportionate to pin pressure distribution, a quasi-homogenous pin penetration depth may result in higher resilience against external shear forces or torque, thus reducing potential complications such as slippage and depressed skull fractures. The authors propose that the pin configuration of 50°/25° may be superior to the currently used uniform pin-cone angle distribution in common clinical practice (36°/36°). However, future research may identify additional influencing factors to improve head fixation stability.

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Traditionally, surgical head immobilization for neurobiological research with large animals is achieved using stereotaxic frames. Despite their widespread use, these frames are bulky, expensive, and inflexible, ultimately limiting surgical access and preventing research groups from practicing surgical approaches used to treat humans. Here, we designed a mobile, low-cost, three-pin skull clamp for performing a variety of neurosurgical procedures on non-human primates. Modeled after skull clamps used to operate on humans, our system was designed with added adjustability to secure heads with small or irregular geometries for innovative surgical approaches. The system has six degrees of freedom with skull pins attached to setscrews for independent, fine-tuned depth adjustment. Unlike other conventional skull clamps which require additional mounting fixtures, our system has an integrated tray with mounting bracket for easy use on most operating room tables. Our system has successfully secured primate heads in the supine and lateral position, allowing surgeons to match surgical approaches currently practiced when operating on humans. The system also expands the opportunity for researchers to utilize imaged-guided robotic surgery techniques. Overall, we hope that our system can serve as an adaptable, affordable, and robust surgery platform for any laboratory performing neurobiological research with large animal models.

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BACKGROUND: Rigid fixation using a three-point skull clamp is a common practice during cranial surgery. Despite its frequency of use, rigid fixation is not without risk of complications including hemodynamic changes, skull fractures and venous thromboembolism. Given this, alternative head fixation should be considered when clinically appropriate. OBJECTIVE: We sought to demonstrate a safe and effective "pinless" head fixation system during endoscopic microvascular decompression (E-MVD). METHODS: Patients undergoing E-MVD were placed in the lateral position with a doughnut pillow under the head, providing support and reducing lateral neck flexion. The vertex of the cranium was angled 10 degrees downward and tape placed circumferentially in an X-shaped fashion around the head, avoiding direct pressure on the ears or eyes. The ipsilateral shoulder was pulled caudally away from the operative field and taped in place to ensure a maximal working corridor. RESULTS: Fifty-two patients underwent the E-MVD procedure with pinless head fixation without any clinical complications. Indications included trigeminal neuralgia type 1 (63.5%), trigeminal neuralgia type 2 (5.8%), hemifacial spasm (19.2%), geniculate neuralgia (7.7%) and glossopharyngeal neuralgia (3.8%). There were no intraoperative or post operative complications and operative time for patients with three-point skull clamp fixation were similar compared to pinless head fixation. CONCLUSIONS: Pinless head fixation is a suitable alternative for certain patients undergoing E-MVD and provides a way to minimize complications that can occur secondary to rigid fixation. If pinless fixation is used, diligent and continued communication with the anesthetist is necessary to ensure there is no intraoperative patient movement.

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BACKGROUND: The Mayfield skull clamp is the most commonly used 3-pin head immobilization device. It is routinely used in cranial neurosurgical procedures and selected cervical procedures. Despite its role in some serious complications, guidelines and nuances on the correct application of the Mayfield clamp are lacking. The goal of this article was to present an overview of the complications associated with the Mayfield skull clamp. We also present a conceptual framework of the correct use-in our opinion-of the Mayfield clamp in several standard approaches to avoid the most common complications. METHODS: PubMed was searched for original articles published between 1980 and 2020 with the search terms "Mayfield skull clamp" and "Mayfield head clamp." Eligibility criteria were availability of English abstract and complications clearly attributed to the Mayfield skull clamp. Both authors assessed all search results for eligibility. Additional articles were found with cross-references. RESULTS: The most common complications associated with Mayfield clamp application were due to vascular injury inflicted by the pins or skull fractures. Complications related to use of the Mayfield clamp were rare but often serious and avoidable. A conceptual framework was presented on how to avoid these complications. CONCLUSIONS: Attention to detail, anatomy, and the primum non nocere principle are imperative in every step of the neurosurgical pathway, including placement of the Mayfield skull clamp. Thoughtful application, taking into consideration several nuances, is recommended to avoid inadvertent patient harm.

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BACKGROUND: Mayfield skull clamps are widely used and indispensable in current neurosurgery. Complications such as skull fractures or intracranial hematoma from using a Mayfield skull clamp have largely been reported in the pediatric population, are likely related to the relative thinness of the skull, such as in patients with hydrocephalus, and are extremely rare in adults. Here, we report a case of skull fracture and epidural hematoma caused by a Mayfield skull clamp used for posterior decompression surgery in an adult patient with chronic hemodialysis. CASE PRESENTATION: A 67-year-old Asian male patient with a history of dialysis-dependent chronic renal failure over 36 years suffered from severe cervical myelopathy. Neurological examination and radiographic images revealed cervical spondylotic myelopathy due to dialysis-related spondyloarthropathy. Laminoplasty was planned on patient consent. A Mayfield skull clamp was applied with the patient supine. Torque was applied to the screws with gentle care, but there was no resistance and it was not easy to reach the standard 60 lb (267 N) to 80 lb (356 N). Because a skull fracture was suspected, we canceled the surgery. Emergency head computed tomography showed depressed skull fractures underlying the single-pin sites with an associated epidural hematoma. The fractures and epidural hematoma were treated conservatively, and spontaneous resolution of the hematoma was confirmed. Cervical laminoplasty was performed successfully using a mask-type head holder on the subsequent day. CONCLUSIONS: As a precaution for fractures and epidural hematoma in neurosurgical patients with bone fragility or a thin skull, use of a mask-type fixing device or halo ring is recommended.

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BACKGROUND: At this juncture, there is no consensus in the literature for the use and the safety of pin-type head holders in cranial procedures. METHODS: The present analysis of the bone response to the fixation of the instrument provides data to understand its impact on the entire skull as well as associated complications. An experimental study was conducted on fresh-frozen human specimens to analyze the puncture hole due to the fixation of each single pin of the pin-type head holder. Cone-beam CT images were acquired to measure the diameter of the puncture hole caused by the instrument according to several parameters: the pin angle, the clamping force, and different neurosurgical approaches most clinically used. RESULTS: The deepest hole, 2.67 ± 0.27 mm, was recorded for a 35° angle and a clamping force of 270 N at the middle fossa approach. The shallowest hole was 0.62 ± 0.22 mm for the 43° angle with a pinning force of 180 N in the pterional approach. The pterional approach had a significantly different effect on the depth of the puncture hole compared with the middle fossa craniotomy for 270 N pinning at 35° angle. The puncture hole measured with the 43° angle and 180 N force in prone position is significantly different from the other approaches with the same force. CONCLUSIONS: These results could lead to recommendations about the use of the head holder depending on the patient's history and cranial thickness to reduce complications associated with the pin-type head holder during clinical applications.

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BACKGROUND: Immobilization of the head and skull by head immobilization devices (HIDs) is a common practice in neurosurgery. A variety of complications and morbidities are associated with pinning the skull during application of HIDs. OBJECTIVE: Our aim is to describe a new technique that avoids repeated puncturing of the head and skull during application of HIDs and hence avoiding the potential complications resulting from multiple re-adjustments. METHODS: We used a pre-adjusted digital millimetric caliber (DMC) as a phantom for the two rocker pins of the HID to mimic and simulate the process of skull pinning. Localization and preparation of the accurate skull pinning sites are safely guided by the pinning phantom. RESULTS: The technique was applied in different neurosurgical approaches. The pinning phantom was utilized to accurately locate the suitable pinning sites. Contrary to the common practice, there was no need for repeated head and skull puncturing. Minimal manipulations of the head and neck are exerted in this approach as compared with the usual techniques. The head of the patient is allowed to be kept safe on the operating table until the final one-time confident skull pinning by the sterilized skull clamp pins. CONCLUSION: The process of scalp and skull pinning of HIDs is technically demanding. The DMC utilized as a pinning phantom is a useful technique which provides safe and confident application of the skull rocker pins of HIDs allowing the neurosurgeon to avoid multiple puncturing of scalp and skull and minimizing manipulations of the head and cervical spine.

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Intracranial aneurysm surgery is commonly performed using pinned head holders, which pose a higher risk for the pediatric population. Several authors recommend avoiding the use of this device when it is not strictly necessary, and this is currently possible considering advances in anesthesiology and monitoring. As the literature on microsurgery without skull clamp use is scant, we report the case of a 15-year-old boy presenting with a subarachnoid hemorrhage after rupture of a middle cerebral artery aneurysm. Surgical treatment was performed with the head resting on a gel cushion horseshoe; aneurysm clipping was achieved without wakefulness or awareness and the patient had a good recovery.

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Conventionally, surgery and procedural-based radiology are performed on different premises. With advances in imaging technology, the operating room is rapidly being transformed into an intraoperative imaging suite. Diagnostic imaging in conjunction with surgery has great utility and by all accounts has great future potential. During the last decade, cone beam computed tomography (CT) scanners have been introduced and have made intraoperative imaging more feasible because these scanners can be made less bulky. The current usefulness of intraoperative magnetic resonance imaging (MRI) or CT for neurosurgery, however, is impaired by the lack of completely radiolucent skull clamps, causing image artifacts. Metal artifacts are particularly problematic, given that they lead to a considerably higher image quality degradation factor for cone beam CT scanners than for conventional CT scanners. Here, we describe our experience with near-radiolucent skull clamps and their associated problems and discuss future improvements to facilitate high-quality image guidance in the field of neurosurgery.

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Several types of headholders are routinely used in neurosurgical practice to secure the head in a precise position, providing better security during surgical dissection as well as an absence of eye compression during prone positions. Nevertheless, potentially lethal complications might occur. We performed a review of the literature via PubMed and Google Scholar using the terms "Mayfield skull clamp", "Sugita headholders", "headholder complications" and "skull clamp complications". Twenty-six complications directly related to the use of headholders were identified through 19 papers published from 1981 to 2014: mainly skull fractures with or without a dural laceration (50%), epidural hematomas (23.8%), skull fractures with or without a dural laceration (50%), and air embolism (9.5%). The authors propose recommendations for the safe use of headholders.

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