Small Craniotomy Research Articles

Penetrating craniocerebral nail gun injury in a child: a case report

Penetrating craniocerebral injuries with a nail gun are extremely rare and even rarer in children. In this case, a 2-year-old boy, who was the youngest patient in the literature with an intracranial nail gun injury involving penetration of the right temporal lobe, was reported. The patient was evaluated by plain radiography and computed tomography. The nail was loosened and pulled gently out by creating a small craniotomy around the nail entrance. Although clinical characteristics and treatment methods of penetrating craniocerebral injuries were similar for reported in literature, the injury mechanism of presented case was different. Penetrating craniocerebral injuries with a nail gun are very dramatic situation, but mortality and morbidity are low. Without major vascular injury, a nail can be removed through a small incision. Penetrating injuries often occur accidentally in the pediatric age group, but the risk of child abuse should always be considered.

Organized chronic subdural hematoma treated with middle meningeal artery embolization and small craniotomy: Two case reports

The most preferred treatment for organized chronic subdural hematoma (OSDH) remains controversial. Although a large craniotomy has been reported to be necessary and effective for the treatment of an OSDH, a craniotomy is associated with postoperative hemorrhagic complications and recurrence. Although middle meningeal artery (MMA) embolization has been reported to be effective for a refractory chronic subdural hematoma (CSDH), its efficacy for an OSDH remains unclear. We report two cases of OSDH treated with MMA embolization followed by hematoma removal via a small craniotomy under local anesthesia with good progress. Case 1: A 71-year-old man underwent a single burr hole irrigation for a CSDH, which failed due to a solid hematoma. He underwent a small craniotomy under local anesthesia after an MMA embolization. During the craniotomy, a small hemorrhage from the hematoma and its outer membrane was observed. Postoperatively, the symptoms disappeared immediately, and the hematoma did not recur. Case 2: A 77-year-old man underwent a burr hole irrigation, but the hematoma was not evacuated because of an OSDH, and he remained in motor aphasia. After an MMA embolization, a craniotomy was performed under local anesthesia. Intraoperative hemorrhage was minimal, and after the craniotomy, his neurological symptoms improved without any recurrence. MMA embolization and hematoma removal with a small craniotomy could be a treatment option for an OSDH.

Comparative Study of Micro-Bone Window and Conventional Bone Window Microsurgery for Hypertensive Intracerebral Hemorrhage.

To compare and analyze the efficacy and safety of traditional craniotomy and small bone window craniotomy in the treatment of hypertensive cerebral hemorrhage (HICH). Fifty-four patients with HICH treated with traditional craniotomy and small bone window craniotomy were retrospectively analyzed. The operation time, hospitalization time, preoperative, and postoperative CT analysis, Glasgow coma scale (GCS) score and Glasgow outcome scale (GOS) scores were analyzed. There were no significant differences in gender, age, hematoma volume, GCS score and pre-operative time between the 2 groups (P > 0.05). The operation time and hospitalization time of the micro-bone window group were shorter than those of the traditional operation group (P < 0.05). The GCS and GOS scores of the small bone window group after 3 days and 6 months were higher than those of the traditional operation group (P < 0.05). However, there was no significant difference in hematoma clearance rate, re-bleeding rate and infection rate between the two groups (P > 0.05). For patients with GCS 8-12 HICH, micro-bone window not only has the same effect as traditional bone window, but also has the advantages of shorter operation time and less trauma.

A Compendium of Modern Minimally Invasive Intracerebral Hemorrhage Evacuation Techniques.

Minimally invasive intracerebral hemorrhage (ICH) evacuation has gained popularity with success in early-phase clinical trials. This procedure, however, is performed in very different ways around the world. To provide a technical description of these strategies that facilitates comparison and aids decisions in which surgery to perform, and to inform further improvements in minimally invasive ICH evacuation. Major authors of clinical trials evaluating each of the main techniques were contacted and asked to supply a case example and technical description of their respective surgeries. Five major techniques are presented including stereotactic thrombolysis, craniopuncture, endoscopic, endoscope-assisted, and endoport-mediated. Techniques differ in numerous ways including the size of the cranial access, the size of the access corridor through the brain to the hematoma, and the evacuation strategy. Regarding cranial access, a burr hole is created in stereotactic thrombolysis and craniopuncture, a small craniectomy in endoscopic, and a small craniotomy in the other 2. Access corridors through the parenchyma range from 3 mm in craniopuncture to 13.5 mm in the endoport-mediated evacuation. Regarding evacuation strategies, stereotactic thrombolysis and craniopuncture rely on passive drainage from a catheter placed during surgery that remains in place for multiple days, while the other 3 techniques rely on active evacuation with suction and bipolar cautery. Future comparative clinical trials may identify the advantageous components of each strategy and contribute to improved outcomes in this patient population.

Subdural Pneumocephalus Aspiration Reduces Recurrence of Chronic Subdural Hematoma.

Chronic subdural hematoma (cSDH) is a common neurosurgical condition, with symptoms ranging from headaches to coma. Operative evacuation is the treatment of choice. Subdural reaccumulation leading to reoperation is a vexing postoperative complication. To present a novel technique for intraoperative aspiration of pneumocephalus via a subdural drain following SDH evacuation as a method of reducing potential subdural space and promoting cerebral expansion, thereby decreasing SDH recurrence. In this retrospective study, 15 patients who underwent operative evacuation of cSDH between 2008 and 2015 were assessed. Six patients underwent a small craniotomy with intraoperative pneumocephalus aspiration. These patients were matched by age, gender, and anticoagulation status to 9 patients who underwent evacuation of SDH without pneumocephalus aspiration. Quantitative volumetric analysis was performed on the preoperative, postoperative, and 1-mo follow-up computed tomography scan to assess the subdural volume. In the immediate postoperative period, there was no difference in the percentage of residual subdural fluid between the aspiration and control groups (0.291 vs 0.251; P=1.00). There was a decrease in amount of pneumocephalus present when the aspiration technique was applied (0.182 vs 0.386; P=.041). At 1-mo follow-up, there was a decrease in the residual cSDH volume between the aspiration and the control groups (28.7 mL vs 60.8 mL; P=.011). The long-term evacuation rate was greater in the aspiration group (75.4% vs 51.6%; P=.015). Intraoperative aspiration of cSDH cavity is a safe technique that may enhance cerebral expansion and reduce likelihood of cSDH recurrence.

Ultrasonographic superb microvascular imaging for emergency surgery of intracerebral hemorrhage

Ultrasonography (US) has been used as a reliable imaging modality, providing real-time information during neurosurgical operations. One recent innovative US technique, superb microvascular imaging (SMI), visualizes small vessels and flow, which are not detected with standard US with doppler. We apply SMI to intraoperative US monitoring in emergency surgery for intracerebral hemorrhage (ICH).Eleven consecutive patients with ICH underwent endoscopic emergency surgery under US monitoring with SMI. After performing a small craniotomy, US images were obtained using SMI, a fusion technique, and a contrast agent technique, with the probe on the brain surface during surgery. Fusion images were obtained with the probe on the head before craniotomy in some patients.Animated US images with SMI could differentiate hematoma containing no vessels from brain tissue, and flow images using SMI and contrast agent techniques clarified the borderlines. Animated fusion images of intraoperative US and preoperative CT provided information on the extent of hematoma and residual hematoma during emergency surgery. We made various fusion CT images showing intracranial hematoma with US probes and decided on the skin incision line before beginning surgery, as if we were using a neuronavigation system.US with SMI, contrast agent, and fusion techniques provide information on the extent of intracranial hematoma and residual hematoma with no vessels and no flow. Monitoring by US and fusion CT images is useful for ICH surgery as a next-generation neuronavigator.

Meet in the middle: a technique for resecting nasocranial dermoids-technical note and review of the literature.

Nasal dermoids with intracranial extension are benign lesions that can have life-threatening consequences, as a nasal punctum may serve as a portal of entry for infection into the central nervous system. The surgical management of these lesions can be challenging, as the extracranial and intracranial cysts and sinus tract must be resected to prevent recurrence, and the surgery must be carried out with an acceptable esthetic result. The authors present a technique for the resection of nasocranial dermoids that eliminates the need to remove and replace the frontonasal segment. Working through a small frontal craniotomy enables the surgeon to drill out the sinus tract through the foramen cecum and inferiorly into the nose. This exposure eliminates the need to enter the frontal sinus, if it is present. The extracranial punctum and tract are resected from below in a minimally invasive fashion that permits removal of the lesion without a disfiguring scar.

Neuroendoscopic Technique for Recurrent Chronic Subdural Hematoma with Small Craniotomy.

To present a case series describing an endoscopic technique with a small craniotomy for recurrent chronic subdural hematoma (rCSDH) treatment. A total of 17 patients with rCSDH underwent neuroendoscopic hematoma removal with a small craniotomy under local or general anesthesia. The skin incision of the initial surgery on the convexity of the skull was extended, and a burr hole was created for a small craniotomy. After the removal of the outer membrane and hematoma through a small craniotomy, the hematoma was evacuated with a suction tube using the rigid endoscope. The entire hematoma cavity circumference was irrigated, while septations and trabeculae in the hematoma were cut. After hematoma evacuation, the inner membrane was incised and removed to allow brain expansion. Postoperative follow-up was performed for at least 6 months. The regrowth rate of rCSDH after the neuroendoscopy was 5.9%. One patient with recurrent chronic subdural hematoma regrowth required neuroendoscopy again, but no re-recurrence was observed for the next 6 months. All cases were successfully managed using this technique and the postoperative seizure rate was 23.5%. This neuroendoscopic technique with a small craniotomy could be useful for recurrent chronic subdural hematoma because the hematoma and septations can be visualized and evacuated along the entire circumference of the hematoma cavity, and the inner membrane can be torn to allow brain expansion.

Fifteen Cases of Endoscopic Treatment of Acute Subdural Hematoma with Small Craniotomy under Local Anesthesia: Endoscopic Hematoma Removal Reduces the Intraoperative Bleeding Amount and the Operative Time Compared with Craniotomy in Patients Aged 70 or Older.

We report cases of acute subdural hematoma (ASDH) treated by endoscopic hematoma removal with a small craniotomy under local anesthesia. From 2015 to 2019, we retrospectively analyzed 15 ASDH patients who were 70 years or older and met our criteria for endoscopic treatment: (1) comorbidities indicated risks associated with a large craniotomy under general anesthesia; (2) decompressive craniectomy was unlikely; and (3) an enlarging hematoma was absent. We also performed a case–control study using the inverse probability weighting method to compare the 15 patients to 20 ASDH patients who were 70 years or older, met criteria (2) and (3), and were treated by craniotomy between 2012 and 2019. Among the 15 ASDH patients, the median age was 86 (range, 70–101) years, and fall was the common cause. The median Glasgow Coma Scale score on admission, operative time, stay time in the operation room, and bleeding amount were 8 (6–15), 91 (48–156) min, 120 (80–205) min, and 20 (5–400) mL, respectively. The extraction rates of all the hematomas exceeded 90%. No patients required conversion to craniotomy under general anesthesia. Three patients had favorable outcomes, and five died. The comparison with craniotomy revealed that the endoscopic procedure reduced the intraoperative bleeding amount, operative time, and stay time in the operation room (p <0.001, p = 0.02, and p <0.001, respectively). In summary, endoscopic hematoma removal for selected ASDH patients aged 70 years or older did not improve functional outcomes but reduced the bleeding amount and the operative time compared with craniotomy.

Supracerebellar Infratentorial Endoscopy for Quadrigeminal Cistern Epidermoid

The standard microscopic supracerebellar infratentorial approach for the pineal region is limited by tunnel vision. Herein, we describe endoscopic supracerebellar infratentorial surgery in a patient with quadrigeminal cistern epidermoid presenting with hydrocephalus. In the sitting position, following a 6 cm longitudinal incision and small suboccipital craniotomy, the dura was cut in V shape and kept reflected. The bridging veins were coagulated and cut, taking the 0° endoscope inside. A sharp incision is given over the thickened arachnoid over the inferior paramedian area. The precentral cerebellar vein is exposed at the lower part, coagulated and divided. Gentle bimanual intracapsular removal of the epidermoid flakes is performed with intermittent saline irrigation and suction. Assisted by rotating the angled endoscope, curved coaxial instruments help remove the cerebello-mesencephalic and lateral extensions of the epidermoid. Endoscopic supracerebellar infratentorial approach provides a panoramic and angled view of the pineal region, through a narrow corridor, avoiding cerebellar retraction.

ML-14 LOW INVASIVE APPROACH FOR PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA TREATMENT INVOLVING RITUXIMAB–METHOTREXATE + PROCARBAZINE + VINCRISTINE AND TRIPLE INTRATHECAL INJECTION

INTRODUCTIONAlthough the treatment outcomes of primary central nervous system lymphoma (PCNSL) with multiple treatment regimens involving high–dose methotrexate (MTX)–based multiagent chemotherapy have improved compared with the outcomes with high–dose methotrexate therapy in recent years, its regimen has not been established. Additionally, it is controversial whether intrathecal (IT) MTX injection can be included in a regimen. Our facilities treat PCNSL with R–MPV (rituximab–methotrexate + procarbazine + vincristine) and triple IT injection (methotrexate + Ara C + prednisolone). Here we report a low invasive approach for PCNSL treatment involving R–MPV therapy and triple IT injection.CASE DESCRIPTIONA 58–year–old woman complained of prolonged headache and had undergone a medical checkup at our department. Head computed tomography revealed a mass lesion with edema near the right anterior horn of the lateral ventricle. After being hospitalized, biopsy was performed via a small craniotomy for the mass lesion near the right anterior horn of the lateral ventricle, which was suspected to be PCNSL. Multipurpose Head Frame 2 (Mizuho Co., Ltd.) was used for four points of head fixation. Vertek Biopsy Kit (Medtronic Co., Ltd.) was attached to it, and needle biopsy guided by neuronavigation was performed. Finally, biopsy samples were obtained from the lesion. Changes in the entry and target points could be easily made through the operative procedure, which was performed uneventfully. The diagnosis was B–cell–related lymphoma. Subsequently, an Ommaya reservoir was placed via lumbar puncture on postoperative day 7. Finally, the patient was successfully treated with R–MPV therapy and triple IT injection, thereby avoiding repeated lumbar puncture and reduced pain associated with IT injection.CONCLUSIONWe have reported the diagnosis of PCNSL with needle biopsy guided by neuronavigation and its treatment with R–MPV therapy and triple IT injection after lumbar Ommaya reservoir placement. This approach was associated with reduced invasion and pain in the patient.

Minimally Invasive Technique (Nummular Craniotomy) for Mesial Temporal Lobe Epilepsy: A Comparison of 2 Approaches

To describe our series of a minimally invasive technique using a small scalp incision and keyhole craniotomy for the removal of mesial temporal lobe structures through a transcortical approach in patients with medically intractable mesial temporal lobe epilepsy (MTLE). Studies that directly compare the clinical outcomes between minimally invasive and conventional techniques are scarce, and this information is lacking in the literature. The study enrolled 73 consecutive patients with refractory MTLE and unilateral hippocampal sclerosis; 30 patients were operated on with standard frontotemporal craniotomy between 2010 and 2013 and 43 patients were operated with a minimally invasive craniotomy (nummular craniotomy) between 2014 and 2016. The preoperative evaluation included clinical history, physical examination, video-electroencephalography, neuropsychologic assessment, and magnetic resonance imaging including thin-section coronal sequences. There were no deaths in either group. Postoperative complications in the standard frontotemporal craniotomy group included temporal muscle atrophy (n= 4; 13.3%), cerebrospinal fluid leakage (n= 1; 3.3%), and wound infection (n= 1; 3.3%). No complications were observed in the keyhole craniotomy group. There was no between-group difference in postoperative seizure control. The mean Engel class I seizure-free outcome was 90.4% in the standard frontotemporal craniotomy group and 90.7% in the nummular craniotomy group (P > 0.05). Lengths of hospitalization (2.81 vs. 4.37 days, P < 0.001) and operative time (85.79 vs. 142.73 minutes, P < 0.001) were lower in the keyhole than in the standard frontotemporal craniotomy group, respectively. The nummular technique was associated with faster recovery, early hospital discharge, and fewer complications than the standard technique. No differences were observed in postoperative seizure control. Keyhole craniotomy is a safe, easy, and effective treatment option for medically intractable MTLE.

Endoscopic versus open microvascular decompression for trigeminal neuralgia: a systematic review and comparative meta-analysis.

Microvascular decompression (MVD) is commonly used in the treatment of trigeminal neuralgia (TN) with positive clinical outcomes. Fully endoscopic MVD (E-MVD) has been proposed as an effective minimally invasive alternative, but a comparative review of the two approaches has not been conducted. The authors performed a meta-analysis of studies, comparing patient outcome rates and complications for the open versus the endoscopic technique. The PubMed/MEDLINE and Ovid databases were searched for studies published from database inception to 2017. The search terms used included, but were not limited to, "open microvascular decompression," "microvascular decompression for trigeminal neuralgia," and "endoscopic decompression for trigeminal neuralgia." Criteria for inclusion of studies in the meta-analysis were established as follows: adult patients, clinical studies with ≥ 10 patients (excluding case studies to obtain a higher volume of outcome rates), utilization of open MVD or E-MVD to treat TN, craniotomy and retrosigmoid incision, English-language studies, and articles that listed pain relief outcomes (complete, very good, partial, or absent), recurrence rate (number of patients), and complications (paresis, hearing loss, CSF leakage, cerebellar damage, infection, death). Relevant references from the chosen articles were also included. From a larger pool of 1039 studies, 23 articles were selected for review: 13 on traditional MVD and 10 on E-MVD. The total number of patients was 6749, of which 5783 patients (and 5802 procedures) had undergone MVD and 993 patients (and procedures) had undergone E-MVD. Analyzed data included postoperative pain relief outcome (complete or good pain relief vs partial or no pain relief), and rates of recurrence and complications including facial paralysis, weakness, or paresis; hearing loss; auditory and facial nerve damage; cerebrospinal fluid leakage; infection; cerebellar damage; and death.Good pain relief was achieved in 81% of MVD patients and 88% of E-MVD patients, with a mean recurrence rate of 14% and 9%, respectively. Average rates of reported complications were statistically lower in E-MVD than in MVD approaches, including facial paresis or weakness, hearing loss, cerebellar damage, infection, and death, whereas cerebrospinal fluid leakage was similar. The overall incidence of complications was 19% for MVD and 8% for E-MVD. The reviewed literature revealed similar clinical outcomes with respect to pain relief for MVD and E-MVD. The recurrence rate was lower in E-MVD studies, though not significantly so, and the incidence of complications, notably facial paresis and hearing loss, were statistically higher for MVD than for E-MVD. Based on these results, the use of endoscopy to perform MVD for TN appears to offer at least as good a surgical outcome as the more commonly used open MVD, with the possible added advantages of having a shorter operative time, smaller craniotomy, and lower recurrence rates. The authors advise caution in interpreting these data given the asymmetry in the sample size between the two groups and the relative novelty of the E-MVD approach.

Neuro-endoscopic management of hemorrhagic moyamoya disease in the acute stage: single institute experience

ABSTRACTBackground: Management of hemorrhagic moyamoya disease (MMD) is one of the most challenging issues in neurosurgical practice. Recently, surgical revascularization by superficial temporal artery-middle cerebral artery anastomosis was reported to significantly reduce the risk of re-bleeding in hemorrhagic-onset MMD patients in the chronic state, but the optimal treatment strategy in the acute phase of hemorrhagic MMD is undetermined. Thus, we retrospectively analyzed our surgical results for hemorrhagic MMD in the acute stage, focusing on the efficacy of neuro-endoscopic management for hematoma removal.Materials and methods: Among 26 consecutive hemorrhagic MMD patients who were managed at our institution in the acute stage, 8 patients with intracerebral hemorrhage underwent surgical evacuation of the hematoma. All patients were diagnosed with MMD before surgery by magnetic resonance angiography and/or catheter angiography.Results: The initial surgical procedure was neuro-endoscopic hematoma removal in seven patients and microsurgical hematoma removal by craniotomy in one patient. One patient treated by the neuro-endoscopic procedure required subsequent small craniotomy due to difficulty in hemostasis. Satisfactory hematoma evacuation was achieved in all eight patients, as demonstrated by post-operative computed tomography, although one patient who was deeply comatose before surgery died in the early post-operative period.Conclusion: Neuro-endoscopic hematoma removal may be the optimal management method for hemorrhagic MMD in the acute stage in terms of the maximum preservation of pre-existing collateral anastomosis without affecting the potential donor vessels used for future revascularization surgery.Abbreviations: MMD: Moyamoya disease; STA: Superficial temporal artery; MCA: Middle cerebral artery; JAM: Japan Adult Moyamoya; ICH: Intracerebral hemorrhage; IVH: Intraventricular hemorrhage; SAH: Subarachnoid hemorrhage; CT: Computed tomography; TE: Total evacuation; PE: Partial evacuation; SMR: Light mass reduction; MR: Magnetic resonance; mRS: Modified Rankin scale; GCS: Glasgow Coma Scale; ICP: Intracranial pressure.

Middle fossa approach for spontaneous cerebrospinal fluid fistula and encephaloceles.

The aim of this article is to describe the middle fossa craniotomy (MFC) approach for the repair of cerebrospinal (CSF) fistula and encephaloceles. The MFC approach has a greater than 93% success rate for managing CSF fistula and encephaloceles located along the tegmen tympani and tegmen mastoideum. Posterior fossa defects cannot be managed by an MFC approach. Multilayer repair with the combination of soft tissue and durable substances is preferred. Hydroxyapatite bone cement provides a durable repair of thinned or absent areas of bone with a low risk of infection. Concurrent management of symptomatic superior semicircular canal dehiscence may be readily performed. Small keyhole craniotomies with the utilization of the endoscope are possible as a means to minimize temporal lobe retraction. MFC repair of CSF fistula and encephaloceles is a highly effective approach for the repair of tegmen mastoideum and tegmen tympani defects.

Left Interhemispheric Craniotomy for Resection of Cavernous Malformation: 2-Dimensional Operative Video.

Thalamic cavernous malformations pose variable surgical challenges given that the location and size of the lesion often determine the approach surgical trajectory. The patient in this case has a large thalamic cavernous malformation that results in a mass effect on the third ventricle and directly abuts the lateral ventricle. A small interhemispheric craniotomy is performed to allow for an anterior interhemispheric transcallosal approach to the lesion. The lateral ventricle is accessed, and the septum is removed to enhance visualization of the surgical field. A small rim of normal parenchyma on the lateral margin of the thalamus is transgressed, and the cavernous malformation is entered. The lesion is removed in a piecemeal manner. Use of counter traction assists with the piecemeal removal. The lighted suction is critical during inspection and manipulation of the lesion within the resection cavity given the limited lighting deep within the cavity. The lesion was removed completely, and postoperative imaging confirms gross total resection. The patient gave informed consent for surgery and video recording. The institutional review board approval was deemed unnecessary. Used with permission from the Barrow Neurological Institute.

P: 18 Impaired Cerebral Oxygenation, but Preserved Cerebrovascular reactivity, in an Animal Model of Hepatic Encephalopathy

BACKGROUND: We have recently obtained evidence of energy deficiency, in the form of impaired lactate release, in the brains of cirrhotic animals with hepatic encephalopathy (HE). Previous reports of cerebral hypoperfusion in patients with HE indicated that cerebral oxygen supply could also be compromised (Dam et al., 2013). Decreased lactate and reduced oxygen supply may lead to CNS energy deficiency and have important neurological consequences, particularly in patients with advanced cirrhosis. In this study we assessed cerebral tissue oxygen tension and CO2 cerebrovascular reactivity in an animal model of HE. METHODS: HE was induced by bile duct ligation (BDL) and after 4 weeks rats were anesthetized with α-chloralose (100 mg·kg−1), instrumented for arterial blood pressure recording and artificially ventilated. 7 BDL and 6 sham-operated animals were treated daily for one week with an ammonia lowering treatment, ornithine phenylacetate (OP) in order to investigate the role of ammonia on brain oxygenation. Blood gas tensions and pH were maintained within physiological ranges in all animal groups. Cerebral tissue PO2 was monitored by fluorescence method (Oxylite™). After a small craniotomy, optical sensors were placed in the somatosensory cortex and sealed. PO2 at baseline and in response to systemic hypercapnia (10% CO2, 5 min) was recorded. RESULTS: BDL resulted in high plasma ammonia concentrations which was lowered with OP treatment. At similar levels of blood PO2 and PCO2, BDL rats had a significantly lower brain PO2 (15.3 ± 2 mm Hg; n = 10) compared to sham controls (26 ± 2 mm Hg; n = 6; P = 0.001). BDL rats treated with OP showed a significant improvement in cerebral PO2 (22 ± 1 mm Hg, n = 6, P = 1), increasing the oxygen tension to levels similar to that recorded in OP treated sham rats (27 ± 2 mm Hg, n = 7), when blood PO2 and PCO2 were constant. Systemic hypercapnia resulted in similar increases in cerebral PO2 in BDL and sham-operated animals (ΔPO2 21 ± 2 vs. 24 ± 2 mm Hg; P = 0.6). Additionally, under anaesthesia, the mean systemic arterial blood pressure was found to be significantly lower in BDL animals (60 ± 3 vs. 84 ± 8 mm Hg; P = 0.04). Cerebral oxygenation did not recover when the blood pressure was normalised via infusion of phenylephrine, but it significantly improved with infusion of acetazolamide which increases cerebral blood flow. CONCLUSIONS: In the BDL model of HE, cerebral tissue oxygen tension is compromised but cerebrovascular reactivity to CO2 appears to be preserved. The cause of the low basal PO2 remains unknown however; high ammonia concentrations and hypoperfusion could be contributing factors.

Transcranial Insertion of Atlas Facetal Screw for Atlantoaxial Fixation

We evaluated the technical feasibility and potential advantages of transcranial insertion of an atlas screw for atlantoaxial fixation. From January 2016 to August 2018, the transcranial technique for atlas screw insertion was used in 6 patients. Conventional lateral mass atlantoaxial fixation was not possible because of the presence of a complex craniovertebral junctional abnormality and difficulty in direct exposure of the facet of the atlas. In all cases, severe basilar invagination and assimilation of the atlas was present. Of the 6 patients, 3 were male and 3 were female. The age range was 12-41 years (average, 23 years). The surgical technique involved a small suboccipital craniotomy in line with the facet of the axis. Extradural elevation of the cerebellum exposed the region of the occipital condyle and fused atlas. The screw was directed medially and inferiorly into the facet of the atlas. In all 6 patients, strong and successful atlantoaxial fixation was achieved. All patients showed clinical improvement after surgery. At an average follow-up period of 21 months, successful arthrodesis of atlantoaxial joint had been achieved in all 6 patients, with no complications. Transcranial insertion of atlas screw can be used as a salvage procedure when the conventional method of screw insertion is not possible because of technical difficulties.

Minimally Invasive Endoscopic Keyhole Approach for Meningiomas

Abstract INTRODUCTION The advantages of neuroendoscopic surgery are wide viewing angle and freedom of axis of view with minimal surgical trauma. Taking advantage of the features of neuroendoscopy, the authors report the experience of minimally invasive endoscopic keyhole approach (EKA) for various meningiomas. METHODS A total of 28 cases of various type of meningiomas were treated by EKA from 2007 to 2018. A keyhole of about 2.5 cm was created according to the case, and tumor removal was performed using an endoscope and exoscope. The scope was held by a pneumatic holder controlled by the assistant to continue the procedure in a comfortable environment. RESULTS EKAs were performed for anterior skullbase lesions via eyebrow skin incision (n = 12), posterior fossa lesions including tentorial meningiomas, torcular meningiomas (n = 7), falcine lesions (n = 6), subtemporal approach (n = 2), enplaque convexity menigiomas (n = 1). All the tumors were resected as planned with minimum brain retraction and well-illuminated fine vision in deep corner. In the cases of a large tumor in the elderly, maximum internal decompression was performed, and the adhered tumor was left on the surface of the brain to avoid injury. The brain retraction was automatically limited by the small craniotomy, and excellent magnified image in deep corner was obtained by EKA. By eliminating the blind spots, radical resection is achieved. Also, in the aging society, depending on the patient with benign meningioma, it is important to consider what better treatment is, to alleviate symptoms and to coexist with the tumor. The cooperation of the assistant is important for this approach. To avoid the interference between the endoscope and the instrument, it is necessary to have a technique for moving the endoscope as needed in order to keep the fine visual field. CONCLUSION In the treatment of meningioma, the role of endoscopes is important in both the radicality obtained in a wide field of view and the less invasiveness in the aging society.

Craniotomy Size for Subdural Grid Electrode Placement in Invasive Epilepsy Diagnostics

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 cm² via which 55 ± 16 electrodes were implanted. In temporal lobe diagnostics, even smaller craniotomies were applied (21 ± 11 cm²). Craniotomies were significantly smaller than in historical controls (65 ± 23 cm², 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.