Modified Skin Incision and Location of Burr-Hole Surgery via a Retrosigmoid Approach: An Anatomical Study

Objective This study aims to reduce the tissue damage during craniotomy with retrosigmoid approach. A modified sickle-shaped skin incision was developed, and a new burr-hole positioning method was proposed. Methods Five adult cadaveric heads (10 sides) were used in this study. The sickle-shaped skin incision was performed during craniotomy. The nerves, blood vessels, and muscles were observed and measured under a microscope. Additionally, 62 dry adult skull specimens (left sided, n = 35; right sided, n = 27) were used to measure the distance between the most commonly used locating point (asterion [Ast] point) and the posteroinferior point of the transverse sigmoid sinus junction (PSTS) (Ast-PSTS), as well as the distance between the new locating O point and the PSTS (O-PSTS). Then, the reliability of the new locating O point was validated on the same five adult cadaveric heads (10 sides) used for the sickle-shaped skin incision. Results The sickle-shaped skin incision reduced the damage to the occipital nerves, blood vessels, and muscles during the surgery via a retrosigmoid approach. The dispersion and variability of O-PSTS were smaller than those of Ast-PSTS. Conclusion The sickle-shaped skin incision of the retrosigmoid approach can reduce the tissue damage and can completely expose the structures in the cerebellopontine angle. The modified O point is a more reliable locating point for a burr-hole surgery than the Ast point.

Multiple and quantitative measurements using computed tomography images reveal the factors associated with chronic subdural hematoma recurrence

Objective: The aim of this retrospective single–center study was to quantitatively assess chronic subdural hematomas (CSDHs), reveal the correlations between multiple and quantitative values calculated from computed tomography images, and determine the risk factors for CSDH recurrence. Methods: We enrolled 225 patients who underwent 304 burr-hole surgeries between April 2005 and October 2021 at Otemae Hospital. Patients′ medical records and quantitative values including preoperative CSDH volume (ml), thickness (mm), computed tomography values (CTV), postoperative CSDH volume (ml), and air volume (ml) were evaluated. The locations of CSDH thickness and burr holes were also assessed quantitatively using Montreal Neurological Institute coordinates. Univariate and multivariate regression analyses and receiver operating characteristic (ROC) analyses were performed. Results: Thirty–seven patients (12%) showed CSDH recurrence requiring reoperation. Preoperative CSDH volume was positively correlated with age, preoperative CSDH thickness, CTV, postoperative CSDH volume, and air volume. Univariate Cox proportional hazards regression analysis showed that age, preoperative CSDH volume, Glasgow Coma Scale score (3–14), postoperative hemiplegia, and gait disturbance were risk factors for recurrence requiring reoperation, and a higher CTV (hazard ratio 0.95, 95% confidence interval 0.91–0.99) was associated with a lower risk of recurrence requiring reoperation. Only preoperative CSDH volume was a significant risk factor for recurrence requiring reoperation in multivariate regression analyses. The postoperative air volume and locations of CSDH thickness and burr hole had no influence on recurrence requiring reoperation. ROC curve analysis revealed that the optimal preoperative CSDH volume cut-off value as a predictor was 155 ml, the thickness was approximately 36.3 mm calculated from a regression line. Conclusions: A larger and more hypodense CSDH has a high risk of recurrence requiring reoperation. Residual air volume after surgery and locations of CSDH and burr hole had no influence on recurrence requiring reoperation.

High Precision Bone Cutting by Er: YAG Lasers Might Minimize the Invasiveness of Navigated Brain Biopsies

Biopsies of brain tissue are sampled and examined to establish a diagnosis and to plan further treatment, e.g. for brain tumors. The neurosurgical procedure of sampling brain tissue for histologic examination is still a relatively invasive procedure that carries several disadvantages. The “proof of concept”-objective of this study is to answer the question if laser technology might be a potential tool to make brain biopsies less invasive, faster and safer. Laser technology might carry the opportunity to miniaturize the necessary burr hole and also to angulate the burr hole much more tangential in relation to the bone surface in order to take biopsies from brain regions that are usually only difficult and hazardous to access. We examined if it is possible to miniaturize the hole in the skull bone to such a high extent that potentially the laser-created canal itself may guide the biopsy needle with sufficient accuracy. The 2-dimensional, i.e. radial tolerance of the tip of biopsy needles inserted in these canals was measured under defined lateral loads which mimic mechanical forces applied by a surgeon. The canals through the skull bones were planned in angles of 90° (perpendicular) and 45° relative to the bone surface. We created a total of 33 holes with an Er : YAG laser in human skull bones. We could demonstrate that the achievable radial tolerance concerning the guidance of a biopsy needle by a laser created bone canal is within the range of the actual accuracy of a usual navigated device if the canal is at least 4 mm in length. Lateral mechanical loads applied to the biopsy needle had only minor impact on the measurable radial tolerance. Furthermore, in contrast to mechanical drilling systems, laser technology enables the creation of bone canals in pointed angles to the skull bone surface. The latter opens the perspective to sample biopsies in brain areas that are usually not or only hazardous to access.

Postoperative Drainage for 6, 12, or 24 Hours After Burr-Hole Evacuation of Chronic Subdural Hematoma in Symptomatic Patients (DRAIN-TIME 2): Study Protocol for a Nationwide Randomized Controlled Trial

Background: Chronic subdural hematoma (CSDH) is a common acute or subacute neurosurgical condition, typically treated by burr-hole evacuation and drainage. Recurrent CSDH occurs in 5-20 % of cases and requires reoperation in symptomatic patients, sometimes repeatedly. Postoperative subdural drainage of maximal 48 hours is effective in reducing recurrent hematomas. However, the shortest possible drainage time without increasing the recurrence rate is unknown.Methods: DRAIN-TIME 2 is a Danish multi-center, randomized controlled trial of postoperative drainage time including all four neurosurgical departments in Denmark. Both incapacitated and mentally competent patients are enrolled. Patients older than 18 years, free of other intracranial pathologies or history of previous brain surgery, are recruited at time of admission or no later than 6 hours after surgery. Each patient is randomized to either 6, 12, or 24 hours of passive subdural drainage following single burr-hole evacuation of a CSDH. Mentally competent patients are asked to complete the SF-36 questionnaire. The primary endpoint is CSDH recurrence rate at 90 days. Secondary outcome measures include SF-36 at 90 days, length of hospital stay, drain-related complications, and complications related to immobilization and mortality.Discussion: This multi-center trial will provide evidence regarding shortest possible drainage time without increasing the recurrence rate. The potential impact of this study is significant as we believe that a shorter drainage period may be associated with fewer drain-related complications, faster mobilization, fewer complications related to immobilization, and shorter hospital stays—thus reducing the overall health service burden from this condition. The expected benefits for patients’ lives and health costs will increase as the CSDH patient population grows.Trial registration: ISRCTN15186366. https://doi.org/10.1186/ISRCTN15186366. Registered in December 2020 and updated in October 2021.This protocol was developed in accordance with the SPIRIT checklist and by use of the structured study protocol template provided by BMC Trials.

National randomized clinical trial on subdural drainage time after chronic subdural hematoma evacuation

OBJECTIVE Placement of a subdural drain reduces recurrence and death after evacuation of chronic subdural hematoma (CSDH), but little is known about optimal drainage duration. In the present national trial, the authors investigated the effect of drainage duration on recurrence and death. METHODS In a randomized controlled trial involving all neurosurgical departments in Denmark, patients treated with single burr hole evacuation of CSDH were randomly assigned to 24 hours or 48 hours of postoperative passive subdural drainage. Follow-up duration was 90 days, and the primary study outcome was recurrent hematoma requiring reoperation. Secondary outcome was death. In addition, complications and length of hospital stay were recorded and analyzed. RESULTS Of the 420 included patients, 212 were assigned 24-hour drainage and 208 were assigned 48-hour drainage. The recurrence rate was 14% in the 24-hour group and 13% in the 48-hour group. Four patients died in the 24-hour group, and 8 patients died in the 48-hour group; this difference was not statistically significant. The ORs (95% CIs) for recurrence and mortality (48 hours vs 24 hours) were 0.94 (0.53–1.66) and 2.07 (0.64–7.85), respectively, in the intention-to-treat analysis. The ORs (95% CIs) for recurrence and mortality per 1-hour increase in drainage time were 1.0005 (0.9770–1.0244) and 1.0046 (0.9564–1.0554), respectively, in the as-treated sensitivity analysis that used the observed drainage times instead of the preassigned treatment groups. The rates of surgical and drain-related complications, postoperative infections, and thromboembolic events were not different between groups. The mean ± SD postoperative length of hospital stay was 7.4 ± 4.3 days for patients who received 24-hour drainage versus 8.4 ± 4.9 days for those who received 48-hour drainage (p = 0.14). The mean ± SD postoperative length of stay in the neurosurgical department was significantly shorter for the 24-hour group (2 ± 0.9 days vs 2.8 ± 1.6 days, p < 0.001). CONCLUSIONS No significant differences in the rates of recurrent hematoma or death during 90-day follow-up were identified between the two groups that randomly received either 24- or 48-hour passive subdural drainage after burr hole evacuation of CSDH.

Surgical safety criteria for burr hole surgery with urokinase in patients with acute subdural hematoma: Retrospective comparison between burr hole surgery and craniotomy

Background: Acute subdural hematoma (ASDH) is a common disease and craniotomy is the first choice for removing hematoma. However, patients for whom craniotomy or general anesthesia is contraindicated are increasing due to population aging. In our department, we perform burr hole surgery under local anesthesia with urokinase administration for such patients. We compared the patient background and outcomes between burr hole surgery and craniotomy to investigate the surgical safety criteria for burr hole surgery. Methods: We reviewed 24 patients who underwent burr hole surgery and 33 patients who underwent craniotomy between January 2010 and April 2020 retrospectively. Results: The median age of the burr hole surgery group was older (P = 0.01) and they had multiple pre-existing conditions. Compared with the craniotomy group, neurological deficits and CT findings were minor in the burr hole surgery group, whereas the maximum hematoma thickness was not significantly different. The hematoma was excreted after a total of 54,000 IU of urokinase was administered for a median of 3 days. The Glasgow Coma Scale score improved in all patients in the burr hole surgery group and there were no deaths. Age, especially over 65 y.o., (OR 1.16, 95% CI 1.04–1.30) and the absence of basal cistern disappearance (OR 0.04, 95% CI 0.004–0.39) were significant factors. Conclusion: Burr hole surgery was performed safely in all patients based on the age, especially older than 65 y.o., and the absence of basal cistern disappearance. ASDH in the elderly is increasing and less invasive burr hole surgery with urokinase is suitable for the super-aging society.

Unilateral drainage of bilateral chronic subdural hematoma

Bilateral chronic subdural hematoma (bCSDH) is a condition frequently encountered in neurosurgical practice, and it is usually the result of head trauma. Despite its frequency, no consensus currently exists regarding its optimal treatment. While the use of corticosteroids in the treatment of chronic subdural hematoma is not currently accepted by the neurosurgical community, there is enough evidence in the literature that supports its use. In bCSDH the unilateral burr hole evacuation of the larger of the subdural collections followed by a course of corticosteroids seems to be an effective and safer course of action in the management of bilateral chronic subdural hematoma.