Efficacy and safety of RD2 Ver.02, a whole blood clot therapy, coupled with a minimally invasive procedure in pilonidal sinus: a phase II study.

BACKGROUND: PNS is caused by an infection in the sacrococcygeal area triggered by hair particle accumulation in skin tunnels, resulting in infection. Surgical options range from simple excision to complex flap constructions. Primary wound healing failure and recurrence rates contribute to the burden of PNS. RD2 Ver.02, a novel autologous whole-blood clot product, demonstrated safety and efficacy in treating complex cutaneous wounds and was investigated for the management of PNS. METHODS: A Phase II open-label, pilot, single-arm prospective study was conducted from May 2021 to May 2023 (Ethics Committee approval #7952-20). Patients with PNS underwent a minimally invasive trephine procedure under local anesthesia followed by RD2 Ver.02 instillation into the cavity. Primary healing was assessed at 3, 6, and 12 months. Secondary outcomes included the collection of adverse events. RESULTS: Overall, 51 patients participated in the study. At 3 months, 42/51 healed (82.4%), 7/51 (13.7%) were granulating but not completely healed, and 2/51 (3.9%) failed to heal. At 6 and 12 months, 46/51 (90.2%) and 42/51 (82.4%) achieved complete healing, respectively. At 6 months, two PNSs recurred after initial healing and an additional four instances of PNS recurrence observed in 12 months, so a total of recurrence in six patients (11.8%). There were five adverse events (AEs) with no severe adverse events. CONCLUSION: RD2 Ver.02 is a safe and effective treatment of PNS when coupled with a minimally invasive trephine PNS procedure. Further comparative studies are needed to fully assess the role of this novel therapy for PNS.

Cranial surgery in the North Pontic region during the 3rd millennium BC.

This study examines the development of cranial surgery in the North Pontic region during the Early and Middle Bronze Age (late 4th and 3rd millennium BC according to the Eastern European chronology). 389 skulls from burials of this period were examined for evidence of surgical intervention. Twenty five such cases were identified and analysed for sex, age, temporal and spatial distribution, size and number of lesions, signs of healing, technique, motivation and complications of the surgery. The study indicates that cranial surgery was a well-developed medical practice in the North Pontic region during the period under consideration. Most of the cases are concentrated in the Dnipro steppe area, suggesting the possibility of outlining another centre of cranial surgery on the map of Europe. The predominant trepanation technique used here was scraping, although alternative methods were also practised. Treatment of traumatic injuries is considered to be one of the main reasons for cranial surgery in our sample. The percentage of individuals who underwent cranial intrusions increased significantly from 1.2% in the first half to 10.4% in the second half of the 3rd millennium BC, indicating a chronological shift in the distribution of cranial surgery. This trend is believed to be related to changes in weaponry during the Middle Bronze Age. The introduction of stone battle axes and maces as common weapons led to a significant increase in the occurrence of blunt force injuries, both depressed and penetrating. Trepanation may have been employed as an effective medical treatment for such traumas.

Burr-hole drainage with or without irrigation for chronic subdural haematoma (FINISH): a Finnish, nationwide, parallel-group, multicentre, randomised, controlled, non-inferiority trial.

BACKGROUND: Chronic subdural haematoma is a common surgically treated intracranial emergency. Burr-hole drainage surgery, to evacuate chronic subdural haematoma, involves three elements: creation of a burr hole for access, irrigation of the subdural space, and insertion of a subdural drain. Although the subdural drain has been established as beneficial, the therapeutic effect of subdural irrigation has not been addressed. METHODS: The FINISH trial was an investigator-initiated, pragmatic, multicentre, nationwide, randomised, controlled, parallel-group, non-inferiority trial in five neurosurgical units in Finland that enrolled adults aged 18 years or older with a chronic subdural haematoma requiring burr-hole drainage. Patients were randomly assigned (1:1) by computer-generated block randomisation with block sizes of four, six, or eight, stratified by site, to burr-hole drainage either with or without subdural irrigation. All patients and staff were masked to treatment assignment apart from the neurosurgeon and operating room staff. A burr hole was drilled at the site of maximum haematoma thickness in both groups, and the subdural space was either irrigated or not irrigated before inserting a subdural drain, which remained in place for 48 h. Reoperations, functional outcome, mortality, and adverse events were recorded for 6 months after surgery. The primary outcome was the reoperation rate within 6 months. The non-inferiority margin was set at 7·5%. Key secondary outcomes that were also required to conclude non-inferiority were the proportion of participants with unfavourable functional outcomes (ie, modified Rankin Scale score of 4-6, where 0 indicates no symptoms and 6 indicates death) and mortality rate at 6 months. The primary and key secondary analyses were done in both the intention-to-treat and per-protocol populations. The trial was registered with ClinicalTrials.gov (NCT04203550) and is completed. FINDINGS: From Jan 1, 2020, to Aug 17, 2022, we assessed 1644 patients for eligibility and 589 (36%) patients were randomly assigned to a treatment group and treated (294 assigned to drainage with irrigation and 295 assigned to drainage without irrigation; 165 [28%] women and 424 [72%] men). The 6-month follow-up period extended until Feb 14, 2023. In the intention-to-treat analysis, 54 (18·3%) of 295 participants required reoperation in the group assigned to receive no irrigation versus 37 (12·6%) of 294 in the group assigned to receive irrigation (difference of 6·0 percentage points, 95% CI 0·2-11·7; p=0·30; adjusted for study site). There were no significant between-group differences in the proportion of people with modified Rankin Scale score of 4-6 (37 [13·1%] of 283 in the no-irrigation group vs 36 [12·6%] of 285 in the irrigation group; p=0·89) or mortality rate (18 [6·1%] of 295 in the no-irrigation group vs 21 [7·1%] of 294 in the irrigation group; p=0·58). The findings of the primary intention-to-treat analysis were not materially altered in the per-protocol analysis. There were no significant between-group differences in the number of adverse events, and the most frequent severe adverse events were systemic infections (26 [8·8%] of 295 participants who did not receive irrigation vs 22 [7·5%] of 294 participants who received irrigation), intracranial haemorrhage (13 [4·4%] vs seven [2·4%]), and epileptic seizures (five [1·7%] vs nine [3·1%]). INTERPRETATION: We could not conclude non-inferiority of burr-hole drainage without irrigation. The reoperation rate was 6·0 percentage points higher after burr-hole drainage without subdural irrigation than with subdural irrigation. Considering that there were no differences in functional outcome or mortality between the groups, the trial favours the use of subdural irrigation. FUNDING: State Fund for University Level Health Research (Helsinki University Hospital), Finska Läkaresällskapet, Medicinska Understödsföreningen Liv och Hälsa, and Svenska Kulturfonden.

Quantitative Assessment of Brain Expansion After Evacuation of Chronic Subdural Hematoma as a Predictor of Recurrence.

BACKGROUND: A lack of brain expansion is considered a risk factor for recurrence after evacuation of a chronic subdural hematoma (CSDH). To the best of our knowledge, no studies have reported on objective measurement of brain expansion after evacuation of a CSDH. METHODS: We performed a retrospective analysis of prospectively collected data of patients undergoing 2 burr hole evacuation of a CSDH. We measured the depth of the brain surface from the frontal burr hole dural opening after hematoma evacuation using a specially devised measuring tool. Other predictors analyzed for recurrence of hematoma were age, gender, a history of hypertension, the use of anticoagulant and/or antiplatelet agents, Glasgow coma scale score at presentation, unilateral or bilateral hematoma, computed tomography appearance, and hematoma thickness. RESULTS: Among 88 patients who underwent hematoma evacuation, 3 (3.4%) underwent surgery for recurrence. The significant factors associated with recurrence were the presence of bilateral hematoma (P = 0.001), hematoma width >2.3 cm (P = 0.04), gradation type of hematoma on the computed tomography scan (P = 0.03), and the depth of the brain after hematoma evacuation (P = 0.02). The brain expanded less in those with recurrence, with a mean depth of the brain of 18 ± 6 mm versus 7.27 ± 7.8 mm in those without recurrence. CONCLUSIONS: Evacuation of a CSDH through 2 burr holes, along with copious irrigation and bed rest for 3 days, resulted in a very low recurrence rate without the use of a drain. A lack of brain expansion might be a predictor of recurrence. To the best of our knowledge, this is the first study to quantitatively measure the depth of the brain at surgery in patients undergoing surgery for CSDH.

Acute-to-chronic subdural hematoma: radiographic and clinical progression from acute subdural hematoma.

INTRODUCTION: The pathogenesis of chronic subdural hematoma (CSDH) has not been completely understood. However, different mechanisms can result in space-occupying subdural fluid collections, one pathway can be the transformation of an original trauma-induced acute subdural hematoma (ASDH) into a CSDH. MATERIALS AND METHODS: All patients with unilateral CSDH, requiring burr hole trephination between 2018 and 2023 were included. The population was distributed into an acute-to-chronic group (group A, n = 41) and into a conventional group (group B, n = 282). Clinical and radiographic parameters were analyzed. In analysis A, changes of parameters after trauma within group A are compared. In analysis B, parameters between the two groups before surgery were correlated. RESULTS: In group A, volume and midline shift increased significantly during the progression from acute-to-chronic (p < 0.001, resp.). Clinical performance (modified Rankin scale, Glasgow Coma Scale) dropped significantly (p = 0.035, p < 0.001, resp.). Median time between trauma with ASDH and surgery for CSDH was 12 days. Patients treated up to the 12th day presented with larger volume of ASDH (p = 0.012). Before burr hole trephination, patients in group A presented with disturbance of consciousness (DOC) more often (p = 0.002), however less commonly with a new motor deficit (p = 0.014). Despite similar midline shift between the groups (p = 0.8), the maximal hematoma width was greater in group B (p < 0.001). CONCLUSION: If ASDH transforms to CSDH, treatment may become mandatory early due to increase in volume and midline shift. Close monitoring of these patients is crucial since DOC and rapid deterioration is common in this type of SDH.

The enlightenment.

The period begins with the work of Richard Wiseman who was associated with royalists in the English Civil War. A little later Dionis was the first to note a relationship between a disturbance of consciousness and extravasation of blood. This notion was continued and expanded by Le Dran, Pott, and Benjamin Bell, with Pott providing a pathophysiological explanation of the phenomenon. Daniel Turner commented on how confusing Galenic teaching was on the topic of consciousness. Heister further emphasized the relationship between clinical disturbance and the extravasation of blood. Le Dran stated that symptoms following cranial trauma related to cerebral injury, an opinion supported by Pott and never subsequently challenged. Latta noted the importance of meningeal arteries in the development of hematomas. Benjamin Bell considered trepanation only appropriate for a clinical deterioration consistent with hemorrhagic extravasation. The two Irish surgeons made it clear that the presence of periosteal separation was not in fact a reliable indicator of an extravasation. The most striking change of instruments was disappearance of simple straight trepans with non-perforating tips for making small holes safely. The use of scrapers gradually declined as did that of lenticulars. There was a great debate about the value of a conical rather than a cylindrical crown. The former was said to be safer. But this opinion faded and the cylindrical crown became preferred. Another improvement in technique involved the use of constant probing to check the depth of the drilled groove.

Renaissance-Europe-16th Century continued.

This chapter is limited to the text of Della Cruce, which contains the most comprehensive account of the instruments used in cranial surgery at the time. Of particular importance is Della Cruce's attitude to what he called non-perforating straight trepans, which in general he disliked. It may be noted that his text was the last to describe this sort of instrument. In the succeeding centuries, changes to penetrating instruments were all variations on the shape of different kinds of crown trepan. Like Berengario, Della Cruce described brace and bit trepans with interchangeable bits. Various methods were employed to prevent them penetrating too deeply.

Two surgical instruments.

The only instruments for opening the cranium considered in this chapter are drills, and in some cases facilitated with a special chisel called a lenticular. There were two kinds of trepan. The modiolus was the Latin name for a crown trepan which had a circular base with teeth which sawed a hole. Then there were the non-penetrating trepans which had a bit shaped to prevent unwanted penetration. They made small openings which could be joined by chisels to remove altogether larger areas of bone than were accessible to modioli. They were the favored instrument from the ancient world up to the Renaissance. At the beginning of the Renaissance, there was a move toward greater use of crown trepans and various methods were applied to stop them sinking too far inward. These included wings in the outer wall and changing the shape of the bit from cylindrical to conic. In time preferences returned to the cylindrical shape and larger diameters. There was also two instruments called lenticulars, the illustrations of which have been confused in the literature. It is now clear that the Roman instrument was shaped to cut the cranium and minimize the need for trepanation. The Renaissance instrument had a different shape and was used to smooth rough bone edges and excise spicules penetrating the meninges. They were simply two different instruments to which the same name was applied.

Renaissance-Europe-17th Century.

The authors of the texts described in this chapter will have had access to the anatomy of Vesalius; a marked step forward. However, there was no equivalent advance in physiology. Harvey's book on the circulation of the blood was published in 1628 but it took many years for its contents to be accepted as standard teaching. The century saw the development of instruments some of which look more like instruments a modern surgeon would recognize. The two major technical advances were the acceptance of a single-handed trephine and the design of crown trepans with a conical shape and blades extending up the sides. Moreover, the crown trepan had once again become the favored instrument for gaining access to the interior of the cranium. In terms of technique there was a worrying trend that surgeons could feel when they had penetrated the inner table of the skull without the need to probe. All the way back to Hippocrates, it had been customary to use probes to assess depth while trepanning. Thus, the abandonment of this safety measure if it was real, is cause for concern. However, it is not impossible that probing was continued and simply not mentioned as it was so obviously necessary as not to require comment. The lenticular illustrated remains of the triangular shape first illustrated by Vidius. It is important to note that it was not used to incise the skull but to smooth of rough edges and spicules.

Trepanation technique.

The larger part of this chapter is concerned with the technique of drilling the cranium with a circular saw called a trepan or trephine. The terminology of the instrument is outlined. Safe use of the instrument includes probing the groove produced by its use and angling the drill so that it impinges on bone which hitherto has not been sawn through. There is then an account of how larger openings may be made by drilling multiple small holes and connecting them by means of a chisel.

Recurrence rates of pilonidal sinus disease in the pediatric population following trephine surgery.

BACKGROUND: Pilonidal sinus disease (PSD) is a common surgical disease. Multiple surgical methods exist in the literature, without clear consensus regarding which should be the first-line treatment. Minimally invasive methods such as the Gips procedure are gaining popularity in recent years. The aim of our study was to assess recurrence rates following the Gips procedure and to determine whether using the same surgical approach during re-operation is efficient and successful. METHODS: This is a single-center retrospective observational study of pediatric patients that underwent Gips procedure due to PSD between the years 2012-2022. RESULTS: 565 pediatric patients underwent an elective surgery for PSD in the study period. Recurrence rate was 8.1% (n = 46). In all the patients with recurrence, re-operation took place on average 9 months following the first surgery and using the same surgical method. Following the second surgery, only 8 patients (1%) had multiple recurrences. CONCLUSIONS: We found a relatively low recurrence rate in the pediatric population using the Gips method, and nearly 100% success rate following the second operation. Our findings set a new benchmark for pediatric recurrence following PSD operation, with clear recommendation to use the same method of surgery upon further recurrences as well.

Contralateral Nasofrontal Trephination: A Novel Corridor for a "Dual Port" Approach to the Petrous Apex.

BACKGROUND AND OBJECTIVES: Expanded endonasal approaches (EEAs) have proven safe and effective in treating select petrous apex (PA) pathologies. Angled endoscopes and instruments have expanded indications for such approaches; however, the complex neurovascular anatomy surrounding the petrous region remains a significant challenge. This study evaluates the feasibility, anatomic aspects, and limitations of a contralateral nasofrontal trephination (CNT) route as a complementary corridor improving access to the PA. METHODS: Expanded endonasal and CNT approaches to the PA were carried out bilaterally in 15 cadaveric heads with endovascular latex injections. The distance to the PA, angle between instruments through the 2 approach portals, and surgical freedom were measured and compared. RESULTS: Three-dimensional DICOM-based modeling and visualization indicate that the CNT route reduces the distance to the target located within the contralateral PA by an average of 3.33 cm (19%) and affords a significant increase in the angle between instruments (15.60°; 54%). Furthermore, the vertical vector of approach is improved by 28.97° yielding a caudal reach advantage of 2 cm. The area of surgical freedom afforded by 3 different approaches (endonasal, endonasal with an endoscope in CNT portal, and endonasal with an instrument in CNT portal) was compared at 4 points: the dural exit point of the 6th cranial nerve, jugular foramen, foramen lacerum, and petroclival fissure. The mean area of surgical freedom provided by both approaches incorporating the CNT corridor was superior to EEA alone at each of the surgical targets ( P = <.001). CONCLUSION: The addition of a CNT portal provides an additional avenue to expand on the classical EEA to the PA. This study provides insight into the anatomic nuances and potential clinical benefits of a dual-port approach to the PA.

The Lenticular.

OBJECTIVE: The lenticular was an instrument introduced by Galen to facilitate cutting the bone of the cranium. Illustrations of the instrument first appeared in the 16th century during the Renaissance. These illustrations have been widely used, but the instrument's shape seems ill-adapted to its function. Archaeological research in Rimini, Italy, unearthed a similar instrument with a shape that seems more suitable for the function of cutting cranial bone. The object of this study was to evaluate the efficacy of these two instruments for cutting the bone of the cranium. METHODS: Replicas of the two instruments were obtained. Trepanation was performed in the left parietal region of a sheep's head. In addition, the application of the instruments in the literature was analyzed. RESULTS: The Roman lenticular cut the cranium with ease. The Renaissance instrument failed to cut the bone and only separated the dura mater from the bone. The lenticular had been used to cut bone up to the 13th century. In contrast, the Renaissance instrument was not used to cut bone but to smooth roughened bony surfaces and to remove spicules of bone that were in contact with the dura. CONCLUSIONS: Analysis of illustrations in medical publications should be undertaken with the same rigor as applied to analysis of text.

Efficacy and safety of bedside percutaneous three-millimeter twist-drill trephination under local anesthesia-a retrospective study of 1000 patients.

PURPOSE: Percutaneous 3-mm twist-drill trephination (TDT) under local anesthesia as a bedside operative technique is an alternative to the conventional open surgical trephination in the operating theatre. The aim of this study was to verify the efficacy and safety of this minimal invasive procedure. METHODS: This retrospective study comprises 1000 patients who were treated with TDT under local anesthesia at bedside due to chronic subdural hematoma (cSDH), intracerebral hemorrhage (ICH), and hydrocephalus (HYD) as a result of subarachnoid hemorrhage or non-hemorrhagic causes, increased intracranial pressure (IIP) in traumatic brain injury or non-traumatic brain edema, and other pathologies (OP) requiring drainage. Medical records, clinical outcome, and results of pre- and postoperative computed tomography (CT) and/or magnetic resonance tomography (MRT) were analyzed. RESULTS: Indications for TDT were cSDH (n = 275; 27.5%), ICH (n = 291; 29.1%), HYD (n = 316; 31.6%), IIP (n = 112; 11.2%), and OP (n = 6; 0.6%). Overall, primary catheter placement was sufficient in 93.8% of trephinations. Complication rate was 14.1% and mainly related to primary catheter malposition (6.2%), infections (5.2%), and secondary hemorrhage (2.7%); the majority of which were clinically inapparent puncture channel bleedings not requiring surgical intervention. The revision rate was 13%. CONCLUSIONS: Bedside TDT under local anesthesia has proven to be an effective and safe alternative to the conventional burr-hole operative technique as usually performed under general anesthesia in the operation theatre, and may be particularly useful in emergency cases as well as in elderly and multimorbid patients.

Are there characteristic indicators for increased pressure in chronic subdural hematoma?

Chronic subdural hematoma (CSDH) is one of the most common neurosurgical disorders. However, no study has yet documented biomarkers indicating increased CSDH pressure. This study aimed to explore such indicators. A total of 50 patients underwent measurement for CSDH pressure during burr-hole irrigation. The mean hematoma pressure was 16.8 ± 7.6 cmH2O with no significant difference between new-onset and recurrent CSDHs. In 12 patients with a CSDH pressure ≥25 cmH2O, further analyses were carried out. Eight of them had bilateral CSDHs. All six patients with a CSDH pressure ≥28 cmH2O suffered headaches before surgery. Two out of three patients with a CSDH pressure ≥29 cmH2O felt nauseous. In statistical analyses, headache was positively correlated with a high CSDH pressure, whereas age and hematoma thickness were negatively correlated with it. Patients' sex, initial Glasgow coma scale score, motor weakness, midline shift on computed tomography scans, and administration of anticoagulants/antiplatelet agents, showed no significant correlation. When patients with bilateral CSDHs are not older adults and suffering headaches, an increased CSDH pressure should be assumed. For such patients, a prompt hematoma evacuation is indicated.

Chronic Subdural Hematoma Drainage under Local versus General Anesthesia: Systematic Review and Meta-Analysis.

BACKGROUND: Chronic subdural hematoma (CSDH) is one of the most frequently encountered neurosurgical conditions. Although the mainstay treatment of chronic subdural hematoma has been burr-hole drainage, no consensus yet exists on the optimal anesthetic strategy between general anesthesia (GA) and local anesthesia (LA). This systematic review compares postoperative outcomes after CSDH evacuation under LA and GA. METHODS: A search was conducted in MEDLINE (1946 to November 2023), Embase (1974 to November 2023), and PubMed (up to November 2023). We followed the PRISMA guidelines to systematically screen studies. RESULTS: Our literature search identified 629 studies, out of which 12 were included. There were 1035 patients in the LA group and 699 patients in the GA group. Our meta-analysis found that the LA group had significantly shorter operative time (mean difference, -29.28 minutes; P < 0.0001), length of admission (mean difference, -1.58 days; 95% confidence interval [CI], -2.40 to -0.76 days; P = 0.0002), and postoperative complications rate (odds ratio [OR], 0.38; 95% CI, 0.25-0.59; P < 0.0001) compared with GA. There was no significant difference between the 2 groups in revision rate (OR, 0.77; 95% CI, 0.39-1.51; P = 0.45) and mortality (OR, 1.23; 95% CI, 0.63-2.43; P = 0.55). CONCLUSIONS: In this meta-analysis, LA shows benefits in shorter operative time, shorter admission length, and fewer postoperative complications. This finding makes LA a less invasive alternative to GA, especially in elderly patients.

Template-based target point localization for occlusion of the middle meningeal artery during evacuation of space-occupying chronic subdural hematoma.

OBJECTIVE: Endovascular middle meningeal artery (MMA) occlusion may help reduce the risk of recurrence after burr hole evacuation of chronic subdural hematoma (cSDH) but carries an additional periprocedural risk and remains hampered by logistical and financial requirements. In this study, the authors aimed to describe a simple and fast technique for preoperative MMA localization to permit burr hole cSDH evacuation and MMA occlusion through the same burr hole. METHODS: The authors performed a preclinical anatomical and prospective clinical study, followed by a retrospective feasibility analysis. An anatomical cadaver study with 33 adult human skulls (66 hemispheres) was used to localize a suitable frontal target point above the pterion, where the MMA can be accessed via burr hole trephination. Based on anatomical landmark measurements, the authors designed a template for projected localization of this target point onto the skin. Next, the validity of the template was tested using image guidance in 10 consecutive patients undergoing elective pterional craniotomy, and the feasibility of the target point localization for cSDH accessibility was determined based on hematoma localization in 237 patients who were treated for a space-occupying cSDH in the authors' department between 2014 and 2018. RESULTS: In the anatomical study, the mean perpendicular distance from the zygomatic process to the target point in the frontoparietal bone was 4.1 cm (95% CI 4-4.2 cm). The mean length along the upper margin of the zygomatic process from the middle of the external auditory canal to the point of the perpendicular distance was 2.3 cm (95% CI 2.2-2.4 cm). The template designed according to these measurements yielded high agreement between the template-based target point and the proximal MMA groove inside the frontoparietal bone (right 90.9%; left 93.6%). In the clinical validation, we noted a mean distance of 4 mm (95% CI 2.1-5.9 mm) from the template-based target point to the actual MMA localization. The feasibility analysis yielded that 95% of all cSDHs in this cohort would have been accessible by the new frontal burr hole localization. CONCLUSIONS: A template-based target point approach for MMA localization may serve as a simple, fast, reliable, and cost-effective technique for surgical evacuation of space-occupying cSDHs with MMA obliteration through the same burr hole in a single setting.

Intraoperative Irrigation and Risk of Chronic Subdural Hematoma Recurrence.

BACKGROUND AND OBJECTIVES: In most neurosurgical centers, irrigation is an essential part of the surgical procedure for chronic subdural hematoma (CSDH). However, it is unknown whether the volume of irrigation fluid affects the risk of CSDH recurrence. This study aimed to investigate a potential association between the volume of irrigation fluid used during burr hole evacuation of CSDH and the risk of CSDH recurrence. METHODS: This study is a subanalysis of 2 randomized trials (Drain Time & Drain Time 2) designed to investigate the effect of drainage duration on the recurrence of CSDH. Intraoperative irrigation volume was measured, and patients were followed for 90 days for recurrent CSDH. RESULTS: A total of 525 patients with CSDH were included. There was no significant difference in the volume of irrigation fluid used between patients with recurrence (mean = 938 mL, SD = ±552) and without recurrence (mean = 852 mL, SD = ±454) ( P -value = .15). Patients with recurrent CSDH had larger primary CSDH volumes (mean = 134 cm 3 , SD = ±69) than patients without recurrence (mean = 119 cm 3 , SD = ±58) ( P = .04). Multiple logistic regression analysis revealed no association between irrigation volume and recurrence, also when stratified for hematoma size. CONCLUSION: There was no significant association between irrigation volume and recurrent CSDH within 90 days in patients undergoing burr hole surgery for CSDH.