Chronic Subdural Hematoma Associated with an Arachnoid Cyst in Elderly, an Intraoperative Finding after Re-Bleeding: Case Report

Intracranial arachnoid cysts (AC) are believed to be congenital and chronic subdural hematomas tend to occur in elderly patients with a history of mild head injury. The association between these two entities sporadically occur in relatively young patients but rare in elderly patients. We report a 65-year-old man who presented with headache and dizziness of 2 months’ duration with a history of head injury. Brain computed tomography (CT) a CSDH in right side and a hygroma in left side. After first operation with burr holes in both sides, the patient underwent an early recurrence of acute subdural hematoma in the right side. The evacuation of this hematoma by a craniotomy allowed seeing an AC that we resected partially with complete recovery of the patient. The association CSDH/AC is rare and possible in elderly patients and there is no consensus on treatment.

Positioning and design by computed tomography imaging in neuroendoscopic surgery of patients with chronic subdural hematoma

BACKGROUND Neuroendoscopy is a very useful technique to Chronic Subdural Hematoma(CSH).But how to achieve the goal of treatment more minimally invasive?AIM To develop a simple,fast and accurate preoperative planning method in our way for endoscopic surgery of patients with CSH.METHODS From June 2018 to May 2020,forty-two patients with CSH,admitted to our hospital,were performed endoscopic minimally invasive surgery;computed tomography(CT)imaging was employed to locate the intracerebral hematoma and select the appropriate endoscopic approach before the endoscopic surgery.The clinical data and treatment efficacy were analyzed.RESULTS According to the learning of CT scanning images,the surgeon can accurately design the best minimally invasive neuroendoscopic surgical approach and realize the precise positioning and design of the drilling site of the skull and the size of the bone window,so as to provide the most effective operation space with the smallest bone window.In this group,the average operation time was only about 1 h,and the clearance rate of hematoma was about 95%.CONCLUSION Patients with CSH can achieve good therapeutic effect by using our way to positioning and design to assist the operation of CSH according to CT scan and image,and our way is very useful and necessary.

Risk Factors of Reoperation and Outcome of Patients Operated for Chronic Subdural Hematoma in a Teaching Hospital in Rabat

Background: chronic subdural hematoma is a common pathology, especially in the elderly. Although it has a good prognosis, it poses the problem of recurrence after surgical evacuation. Objective: To analyze the risk factors of reoperation in patients surgically treated for chronic subdural hematoma (cSDH) and evaluate the outcome of patients who benefited from a reoperation. Materials and Methods: A retrospective review was conducted in a single University Hospital Center in Rabat (Morocco) on 49 patients operated on from January 2020 to June 2021 for cSDH. Possible risk factors described in the literature were analyzed and the outcome of post-operative course was evaluated. Statistical significance was defined by p-value Results: 49 patients underwent surgical evacuation of cSDH. The sex ratio of male/female was 3.08. The mean age was 70.6 years. Concerning the medical history, 8.2% were diabetics, 10.2% had heart disease, 18.4% had hypertension, 16.3% associated of comorbidities, 2% had pulmonary embolism, and 2% had neoplasm. 18.4% were on anticoagulation therapy, no patients were on new oral anticoagulants. The clinical findings upon admission were motor deficit at 57.1%, signs of intracranial hypertension at 20.4%, altered consciousness at 16.9% and impaired behavior at 6.1%. 28.6% of patients had a past history of head trauma. The pre-operative CT scan showed unilateral cSDH at 81.6%, midline shifts at 77.6%, and false membranes at 34.7%. Blood appeared chronic at 40.8%, subacute at 24.5%, and mixed densities at 34.7%. The post-operative course was uneventful in 73.5%. According to Ibanez grading 8 patients had mild complications (grade I) and 5 moderate complications (grade II) after the first surgery. We recorded 10.2% of patients who needed a second surgery because of the deterioration of neurologic status or motor deficit associated with an abnormal CT scan. According to the GOS, 85.7% of patients had a good recovery while 10.2% died. None of the factors assessed was found to be a risk factor for reoperation. Conclusion: No risk factors of reoperation after an initial burr hole evacuation for cSDH were found. However medical history and male sex was common condition among reoperated patients with their CT scan showing a chronic aspect of blood, midline shift and false membranes. Most patients who underwent revision surgery died on the postoperative course.

Efficacy evaluation of neuroendoscopy vs burr hole drainage in the treatment of chronic subdural hematoma:An observational study

BACKGROUND Chronic subdural hematoma(CSDH)is a common disease in neurosurgery.The traditional treatment methods include burr hole drainage,bone flap craniectomy and other surgical methods,and there are certain complications such as recurrence,pneumocephalus,infection and so on.With the promotion of neuroendoscopic technology,its treatment effect and advantages need to be further evaluated.AIM To study the clinical effect of endoscopic small-bone approach in CSDH.METHODS A total of 122 patients with CSDH admitted to our hospital from August 2018 to August 2021 were randomly divided into two groups using the digital table method:the neuroendoscopy group(n=61 cases)and the burr hole drainage group(n=61 cases).The clinical treatment effect of the two groups of patients with CSDH was compared.RESULTS At the early postoperative stage(1 d and 3 d),the proportion of 1/2 re-expansion of brain tissue in the hematoma cavity and the proportion of complete reexpansion was higher in the neuroendoscopy group than in the burr hole drainage group,and the difference between the two groups was statistically significant(P<0.05).The recurrence rate of hematoma in the neuroendoscopy group was lower than that in the burr hole drainage group,and the difference between the two groups was statistically significant(P<0.05).No intracranial hematoma,low cranial pressure,tension pneumocephalus or other complications occurred in the neuroendoscopy group.CONCLUSION The neuroendoscopic approach for the treatment of CSDH can clear the hematoma under direct vision and separate the mucosal lace-up.The surgical effect is apparent with few complications and definite curative effect,which is worthy of clinical promotion and application.

Efficacy of Single Burr Hole in Management of Chronic Subdural Hematoma

Background: Surgery of chronic subdural hematoma (CSDH) is a common practice of neurosurgeons. CSDH is considered a pathology of the elderly and usually many co-morbidities are present. CSDH carries high risk of mortality if not treated or not treated well. So, the minimal, safe and adequate surgical intervention is the bases to choose specific surgical maneuver. Aim of the Study: The efficacy of a single burr in evacuation and treatment of chronic subdural hematoma. Methods: This study was held in Assiut university hospitals, neurosurgical department. It is a prospective randomized controlled study. 113 patients were enrolled in this study in the period between March 2018 and June 2019. We included all cases of chronic subdural hematoma (CSDH) and subacute subdural hematoma that were evacuated with single burr hole. Hematomas either, unilateral or bilateral were included. Septated hematomas were excluded. Patients’ clinical characteristics as age, sex, clinical presentation, co-morbidities and patients outcome were recorded. Postoperative status as regards improvement of the neurological status, complications and recurrence of hematoma were recorded. Results: We had 113 patients operated via properly situated single burr hole in our study. 113 patients were included in this study, 79 males (69.9%) and 34 females (30.1%). Age of the patients ranges between 27 years old and 90 years old. Postoperative follow up was evaluated according to Glasgow outcome score (GOS). We had 98 patients with good recovery, 4 patients with moderate disability, 6 patients with severe disability and 5 patients died. Complications were in form of 3 patients with residual hematoma, 2 patients with tension pneumocephalus, 7 patients developed postoperative seizure, 5 cases developed cortical/parenchymal hematoma and 9 cases developed hematoma recurrence. Conclusion: Single, properly situated burr hole with previously described characters is an effective treatment option in cases of CSDH. It helps adequate, effective and safe removal of the pathology with limited maneuver.

Traumatic Subdural Effusion Evolving into Chronic Subdural Hematoma

Background: Chronic subdural hematoma (CSDH) is a common complication in head injuries. The objective of this study is to establish the evolution of traumatic subdural effusion (TSDE) into CSDH using clinical signs and symptoms as well as radiology. Our aim is to effectively manage such cases without postoperative recurrence (PR). Methodology: The study was a retrospective cohort carried out in the No. 1 People’s Hospital of Jingzhou from August 2007 to November 2013. The hospital is affiliated to the Yangtze University. All the patients included in this study were involved in road traffic accidents and sustained various degree of head injury. Serial CT scans were done to establish the development TSDE and the evolution of the TSDE into CSDH and treatment options. Results: In all 159 patients developed TSDE and out of these 34 which constitute 21.38% had their TSDE evolving into CSDH. Most of the patients were elderly. Twelve patients were treated conservatively while the remaining patients were treated surgically by drilling and drainage of hematoma. All the patients survived with marked improvement in their sign and symptoms with no recurrence. Conclusion: TSDE is one of the etiological factors for the development of CSDH in the elderly although in most cases the etiology of CSDH is usual multifactory. It must be stated clearly that, the evolution of TSDE into CSDH is initially a hidden process and presents with nonspecific signs and symptoms which can easily be missed. CT scan is usually the initial radiology of choice in making diagnosis of TSDE but MRI could be used to make early diagnosis of the transgression of TSDE into CSDH, and hence early surgical intervention before the formation of a neomembrane could reduce PR rate.

Twist Drill Evacuation of Chronic Subdural Hematoma in Comorbid Patients

Chronic Subdural Hematoma (CSDH) is one of the most common types of intracranial hemorrhage, and the prognosis is good if treated properly. The standard treatment for CSDH is surgical evacuation. Various surgical procedures are used such as burr holes evacuation, twist-drill craniostomy, and craniotomy. Our aim is to evaluate the feasibility and safety of twist dill as a first-choice treatment in evacuation of CSDH in comorbid patients. Methods: This study is a prospective analysis of CSDH evacuation using two twist drill craniostomy holes and irrigation conducted on 21 patients with different comorbidities in Assuit University Hospital between May 2017 and May 2018. Results: The overall postoperative clinical improvement was 95.2%. The operative time was less than 10 minutes in 71.4% of the patients. 4 patients showed residual collection in the post-operative CT (19%). Pneumocephaly was detected in 2 patients (9.5%). Postoperative seizures occurred in 2 patients (9.5%), and subarachnoid hemorrhage was detected in one patient (4.7%). Conclusion: This approach is a new modification of twist drill craniostomy which can decrease the postoperative residual and recurrence rates and also still a minimally invasive and lifesaving technique in patients with different comorbidities.

Chronic Subdural Hematoma: Pitfalls to Avoid for Better Outcome

Introduction: Chronic subdural hematoma is one of the commonest intracranial haemorrhages that affect elderly. Headache and focal neurological deficits are among the commonest presentations. It carries excellent prognosis especially when evacuated probably on right timing. Recurrence rate ranging from 8% - 37% in literatures, we will highlight tricks during peri-operative period to have better outcome and decrease recurrence. Patients and methods: We operated 45 cases of chronic subdural hematoma in Cairo university emergencyhospital, during the period from November 2016 to December 2017;CT brain was done for all cases;clinical data were reported;burr hole evacuation was the standard technique. Suction drain with mild suction pressure was applied and hospital stay was 3 - 4 days after surgery. Patients were followed up to three months. Results: Forty-five patients were operated with 27 cases (60%) having their ages between 5th and 7th decades. Among Twenty-nine males and 16 females, eleven patients (25%) were confused;headache was observed in 12 patients, weakness in 31 cases (69%), dysphasia in two cases and two patients were on renal dialysis. Hypertension was associated as a comorbidity in 18 patients, diabetes mellitus in 11 patients, and smoking in 11 patients. Forty-two patients were discharged home within 3 - 4 days;two cases developed small-sized intra-cerebral hematoma, one case of wound infection, and excellent outcome for all cases on three months follow up visit. Conclusions: Chronic subdural hematoma is one of the commonest intra-cranial haemorrhages in elderly with excellent outcome if managed meticulously in right timing. Good control of co-morbidities, insuring slow clearing of hematoma fluid and staged closure technique are factors linked with better outcome. But larger studies are needed.

Effect of Postoperative Administration of Saireito for Bilateral Chronic Subdural Hematomas

The aim of this retrospective study was to investigate the efficacy of saireito for bilateral chronic subdural hematomas (B-CSDH). Between April 2006 and March 2010, a total of 18 patients undergoing unilateral burr hole drainage for B-CSDH took part in a controlled clinical study. Postoperative status of the nonsurgical side was subsequently evaluated, with (n = 10) and without (n = 8) saireito administration. Two in the saireito-treated group patients and four in the control group patients ultimately required contralateral surgical intervention. The remainder, including eight saireito-treated hematomas, resolved without further surgery, generally within eight weeks of the surgical side procedure. However, two of the four resolving control lesions took longer to regress. The hydragogue and anti-inflammatory/steroid-evoking properties ascribed to saireito may facilitate hematoma resolution. After unilateral surgery for B-CSDH, saireito administration may prevent symptomatic deterioration of a contralateral low-density CSDH, preempting subsequent surgery.

Resolution of Chronic Subdural Hematoma after Treatment with Tumor Necrosis Factor Alpha Inhibitor

Background and Importance: Chronic subdural hematomas (cSDH) are a common problem for which solutions remain imperfect. Surgery is effective, but not without risk. Recent data have suggested a role for inflammation in the genesis of cSDH and several reports have documented some benefit to steroid treatment. In this report, a possible role for tumor necrosis factor alpha blockade in the resolution of a multiply recurrent cSDH is described. Clinical Presentation: An 86-year-old man with rheumatoid arthritis treated with infliximab presented with a large, symptomatic, multiloculated cSDH. Infliximab was withheld and craniotomy for evacuation was uncomplicated, but recurrent symptoms were noted and a recurrence was operated upon again several weeks later. Follow up CT showed a second recurrence. The patient requested to go back on his infliximab due to painful arthralgias. After a single dose of 10 mg/kg, follow up CT showed that the cSDH resolved and did not recur. Conclusion: Anti-TNF-alpha treatment with infliximab may have played a role in the resolution of this patient’s cSDH. Further investigation of this possible effect seems warranted.

Bilateral Chronic Subdural Hematoma after Endoscopic Third Ventriculostomy in a Child: A Case Report and Review of the Literature

Hydrocephalus had been managed by ventriculoperitoneal shunt (VPS) or endoscopic third ventriculostomy (ETV) since several years. But these two different technics had some complications that must be managed promptly to avoid eventual fatal evolution. Chronic subdural hematomas after ETV is among these complications and is a very rarely situation observed in our department. This rare event associated with malaria in a child is considered to have a high mortality. Here we report a rare case of bilateral chronic subdural hematoma occurring in a 4-month-old boy after ETV and we discuss the likely pathogenesis and the difficulties of management.

Minimal Access Surgical Evacuation of Unilateral Chronic Subdural Hematoma

Chronic subdural hematoma (CSDH) is one of the most common neurosurgical conditions occurring mostly in elderly and ideally treated with surgical drainage. Many surgical techniques of different degrees of invasiveness have been proposed for its treatment with controversy about the best surgical procedure. The study aims to evaluate the efficacy of the minimal access technique of single burr-hole craniostomy and massive irrigation for treatment of unilateral CSDH. The study is a prospective descriptive study involved all patients with symptomatic radiologically proven unilateral CSDH admitted and treated surgically in department of Neurosurgery, Al-Hussein University hospital, Al-Azhar University, Cairo, Egypt, over 3 years, from January 2013 to January 2016. In the results we found that total 64 patients of CSDH, treated surgically by this procedure. Men formed 72% and women 28%. Age range was 51 to 82 years;the mean age was 65 years. Clinical presentation was impaired consciousness in 7%, headache (59%), right hemiparesis in 56% and left hemiparesis in 37%. CT was done for 91% and MRI 27% patients. The hematoma was left in 61% and right in 39%. Surgical evacuation utilizing this procedure was done in all patients. Complete recovery was obtained in 82% of patients and partial recovery in 11% of patients. Follow up for 4 months was done. Recurrence was detected in 6% of patients. We concluded that unilateral CSDH can be treated effectively by single nondependent burr-hole craniostomy and massive irrigation with excellent outcome.

Endoscopic Assisted Microscopic Fenestration of Inner Membrane in Cases of Chronic Subdural Hematoma

Introduction: Chronic subdural hematoma (CSDH) is one of the most common types of intracranial hemorrhages and carries a significant morbidity;there is no clear optimal treatment. Recurrence, pneumocephaly and seizures are common complications. We will evaluate outcome after inner membrane fenestration in comparison to burr-hole evacuation only in cases of CSDH. Patients and Methods: Our work was conducted on 20 patients with CSDH from February 2017 to July 2017. Endoscopic-assisted microscopic fenestration technique was used to do inner membrane fenestration in ten patients and the other 10 patients operated upon by traditional burr-hole evacuation. Regular follow up was done up to one month. Results: Clinical outcome was nearly the same in the two groups. Recurrence rate was only noted in the non-fenestration group (20%). Midline shift was better in the membrane fenestration group after one month and we experienced no intraoperative surgical complications related to the fenestration technique. Postoperative complications, such as Pneumocephalus and seizures, were seen in both study groups. Conclusion: Endoscopic assisted microscopic technique decreases surgical risks to do inner membrane fenestration although there is no major difference between doing fenestration or not in clinical outcome, but it may decrease recurrence, but larger studies are needed.

A Clinical Analysis to Detect Risk Factors of Chronic Subdural Hematoma Recurrence

Introduction: The etiology of recurrence of chronic subdural hematoma (CSDH) after surgical evacuation has not been completely understood until now, but several risk factors for recurrence have been reported. Meanwhile, the definitive risk factors have not been defined until now. Aim of Study: Analyze the potential risk factors, and emphasize preoperative, operative and post-operative ones for CSDH recurrence. Patients and Methods: This study is a prospective randomized clinical trial study including 82 patients with symptomatizing CSDH who underwent burr holes procedure and irrigation with closed system drainage for CSDH at Neurosurgical Department—Assuit University Hospital from July 2016 to July 2018. The possible factor studied for recurrence included age, hypertension, diabetes mellitus, liver diseases, Hemoglobin (Hb) level, prothrombin concentration and time (PC and PT), hematoma thickness and internal architecture, number of burr holes and position of drain, duration of drainage, amount of drainage and presence of postoperative residual hematoma on follow up CT brain. Multiple logistic regression analysis is used to assess the predictors of recurrence. Results: This study included 70 males and 12 females. The mean age was 58.9 years (range 34 - 93 years). 6 patients presented with recurrent CSDH. Age above 60 years, Hypertension, Diabetes mellitus (DM), prolong PT, separated and trabecular internal architecture of hematoma, and the thickness of hematoma more than 20 mm in pre-operative CT and postoperative residual hematoma were statistically significant factors for recurrence of CSDH. Conclusion: This information might be helpful in detecting patients with possible high incidence of recurrence and directing for close follow ups and acts that may reduce the incidence of recurrence.

Hematoma within the Outer Membrane of the Arachnoid Cyst Located in the Middle Fossa: A Mechanism of Development of Chronic Subdural Hematoma Associated with Arachnoid Cysts

It is well known that chronic subdural hematoma (CSDH) occasionally arises in patients harboring an arachnoid cyst (AC) located in the middle fossa. Although the pathogenesis of CSDH associated with ACs remains unknown, several possible mechanisms have been proposed. In many reported cases, the patients with ACs in the middle fossa would be symptomatic according to development of CSDH. A 9-year-old girl presenting with a headache, nausea, and diplopia was referred to our department. Magnetic resonance imaging showed an AC in the left-side middle fossa and ipsilateral CSDH with a remarkable mass effect. Irrigation of the CSDH, partial removal of the outer membrane of the AC and CSDH, and endoscopic cystocisternostomy were performed to relieve her symptoms. Postoperative clinical course was excellent. Histopathological examination of the outer membrane of the CSDH demonstrated an arachnoid cell layer and hemorrhage from the granulation inside the membrane, and collagen fibers outside the membrane. These findings strongly suggested that the membrane and the content of the CSDH were derived from the outer membrane of the AC, and the CSF including the hemorrhage within the membrane, respectively. Laceration and hemorrhage from granulation tissue within the outer membrane of the AC are considered as one of the developmental mechanisms of the CSDH associated with AC in the middle fossa.

Ossified Subdural Chronic Hematoma: Two Cases Report and Literature Review

Ossified subdural chronic hematoma (OSCH) is a rare disease that accounts 0.3% to 2% of subdural chronic hematoma which is common. The surgical management depends on his clinical expression. The aim of this study is to highlight the surgical procedure because the management of this type of lesion has no consensus. The authors reported two cases of OSCH which were successfully excised with good outcomes. Taking care during the procedure of dissection from parenchyma is the key for this surgery.

Estimation of Chronic Subdural Hematoma Size Using CT Imaging;a Comparison of In-Plane Thickness to 3D Volumetry

Backgrounds: Pre- and postoperative chronic subdural hematoma (CSDH) sizes have been used in clinical trials to predict the risk of postoperative recurrence. Commonly, dimensions of the pre- and postoperative lesions have been assessed by computerized tomography (CT) scans using maximum thickness as a linear measurement. Our goal was to characterize this common method for quantification of pre- and postoperative lesion sizes and to assess its estimation validity compared to estimation by hematoma volumetry. Methods: We prospectively investigated pre- and 1st postoperative day CT scans of 107 adult surgical patients with uni- or bilateral CSDH. Pre- and postoperative thickness of CSDH was determined and then compared to pre- and postoperative lesion volume measured with 3D hematoma volumetry. Results: Pearson correlation coefficients between mean pre- and postoperative lesion thickness and mean pre- and postoperative lesion volume in the unilateral subgroup were 0.491 and 0.498, respectively;in the bilateral subgroup 0.505 and 0.579, respectively;and in the whole series 0.653 and 0.472, respectively. Conclusions: Pre- and postoperative thickness of CSDH does not offer reasonable approximations of the pre- and postoperative lesion size when compared with results from 3D volumetry in the unilateral subgroup, bilateral subgroup or overall.

Enigmatic rapid organization of subdural hematoma in a patient with epilepsy:A case report

BACKGROUND Determining a subdural hematoma(SDH)to be chronic by definition takes 3 wk,whereas organized chronic SDH(OCSDH)is an unusual condition that is believed to form over a much longer period of time,which generally demands large craniotomy.Therefore,it is a lengthy process from the initial head trauma,if any,to the formation of an OCSDH.Acute SDH(ASDH)with organization-like,membranaceous appearances has never been reported.CASE SUMMARY A 56-year-old woman presented to our hospital with a seizure,and computed tomography(CT)on admission was negative for signs of intracranial hemorrhage.She had clear consciousness and unimpaired motor functions on arrival and remained stable for the following week,during which she underwent necessary examinations.On the morning of day 10 of hospitalization,she accidentally hit her head hard against the wall in the bathroom and promptly lapsed into complete coma within 2 h.Therefore,we performed emergency CT and identified a left supratentorial SDH that was an absolute indication for surgery.However,the intraoperative findings were surprising,with no liquefaction observed.Instead,a solid hematoma covered with a thick membrane was noted that strongly resembled an organized hematoma.Evacuation was successful,but the family stopped treatment the next day due to financial problems,and the patient soon died.CONCLUSION Neurosurgeons should address SDHs,especially ASDHs,with discretion and individualization due to their highly diversified features.

Epidural blood patch for spontaneous intracranial hypotension with subdural hematoma: A case report and review of literature

BACKGROUND Cerebrospinal fluid(CSF)leakage at C1/2 in spontaneous intracranial hypotension(SIH)is rare.Subdural hematoma(SDH),a serious complication of SIH,may lead to neurological deficits.This report presents a case of SDH after spontaneous C1/2 CSF leakage,which was treated with a targeted epidural blood patch(EBP).CASE SUMMARY A 60-year-old man with no history of trauma was admitted to our hospital with orthostatic headache,nausea,and vomiting.Brain computed tomography imaging revealed bilateral,subacute to chronic SDH.Brain magnetic resonance imaging(MRI)findings were SDH with dural enhancement in the bilateral cerebral convexity and posterior fossa and mild sagging,suggesting SIH.Although the patient underwent burr hole trephination,the patient’s orthostatic headache was aggravated.MR myelography led to a suspicion of CSF leakage at C1/2.Therefore,we performed a targeted cervical EBP using an epidural catheter under fluoroscopic guidance.At 5 d after EBP,a follow-up MR myelography revealed a decrease in the interval size of the CSF collected.Although his symptoms improved,the patient still complained of headaches;therefore,we repeated the targeted cervical EBP 6 d after the initial EBP.Subsequently,his headache had almost disappeared on the 8th day after the repeated EBP.CONCLUSION Targeted EBP is an effective treatment for SDH in patients with SIH due to CSF leakage at C1/2.

Multiple Density Subdural Hematomas

The chronic subdural hematoma is a well known entity in old age and the treatment is very challenging. Treatment protocol depends upon the radiological finding. The loculation and multilayering indicates the bleeding at multiple times and respectively found in 13.2% and 13.6%, which was more common in patients more than 75 years. Burr hole evacuation was the treatment of choice except in recurrent cases where craniotomy was performed.