Simple methods for cerebrospinal fluid collection in fetal, neonatal, and adult rat.

BACKGROUND: Cerebrospinal fluid (CSF) collection and its analysis are common medical practices useful in the diagnosis, therapy, and prevention of central nervous system (CNS) disorders. In recent years, several types of research have improved our insight into CSF and its role in health and disease. Yet, many characteristics of this fluid remain to be fully understood. NEW METHODS: Here, we describe how to collect CSF from embryonic, postnatal, and adult stages of the rat. In adults, CSF can be collected through simple stereotaxic surgery to expose the membrane overlying the cisterna magna (CM) of an anesthetized rat and collection of CSF through micropipette puncture through the membrane. In embryos and pups, CSF is aspirated, using a fire-polished micro-capillary pipette, from the CM of animals. RESULTS: Application of these methods provides the maximum volume of pure, uncontaminated CSF (embryonic day 19: 10-15 microliter, postnatal day 5: 20-30 microliter, adults: 100-200 microliter) with a success rate of approximately 95% in every age. COMPARISON WITH EXISTING METHODS: Compared to the existing protocols, these methods obtain considerable volumes of CSF, which may accelerate the measurement of biological markers in this fluid. Also, these techniques do not require surgical skills and according to the practical points mentioned during sampling, the procedures can be performed in rapid fashion. CONCLUSION: We describe simple methods for collecting CSF in live rats. These protocols provide clean, uncontaminated CSF for experiments to understand the exact role of this fluid in the development and maintenance of the CNS health.

Stereotaxic Surgical Approach to Microinject the Caudal Brainstem and Upper Cervical Spinal Cord via the Cisterna Magna in Mice.

Stereotaxic surgery to target brain sites in mice is commonly guided by skull landmarks. Access is then obtained via burr holes drilled through the skull. This standard approach can be challenging for targets in the caudal brainstem and upper cervical cord due to specific anatomical challenges as these sites are remote from skull landmarks, leading to imprecision. Here we outline an alternative stereotaxic approach via the cisterna magna that has been used to target discrete regions of interest in the caudal brainstem and upper cervical cord. The cisterna magna extends from the occipital bone to the atlas (i.e., the second vertebral bone), is filled with cerebrospinal fluid, and is covered by dura mater. This approach provides a reproducible route of access to select central nervous system (CNS) structures that are otherwise hard to reach due to anatomical barriers. Furthermore, it allows for direct visualization of brainstem landmarks in close proximity to the target sites, increasing accuracy when delivering small injection volumes to restricted regions of interest in the caudal brainstem and upper cervical cord. Finally, this approach provides an opportunity to avoid the cerebellum, which can be important for motor and sensorimotor studies.

Suturing of the Arachnoid Membrane for Reconstruction of the Cisterna Magna: Technical Considerations.

BACKGROUND: Postoperative cerebrospinal fluid (CSF) fistula following cranial or spinal surgery is associated with increased morbidity and mortality. To prevent CSF fistulas, various techniques have been described. Here, we describe the arachnoid membrane continuous-running suture technique in cisterna magna reconstruction for preventing postoperative CSF leakage. METHODS: After craniotomy and dural opening, the incision of the arachnoid of the cisterna magna was performed using a diamond blade. To prevent the arachnoid from drying out and shrinking during surgery, it was periodically irrigated with warm saline solution. Posterior fossa surgery was performed. When closing the membranes, the arachnoid membrane was closed with the running-suture technique. After the first surgical knot was made in the cranial end of the arachnoid opening, continuous suturing with a 2-mm distance between the stitches was performed without stretching them. After every 3 stitches, the free end of the thread was pulled gently along the suturing axis, and the edges of the arachnoid were closed. After the arachnoid edges were approximated, the surgical knot was tied. Watertight closure was checked by performing the Valsalva maneuver at the end of the surgery. RESULTS: No CSF leakages were observed after surgery. CONCLUSIONS: Arachnoid membrane suturing seems to be safe and effective in preventing postoperative CSF leakage and CSF-related complications. Using continuous running suturing alone, without any sealant, might be effective in cases with untraumatized arachnoid membrane.

Subtemporal-Transtentorial Approach for Microsurgical Resection of Hemorrhagic Ambient Cistern Arteriovenous Malformation.

Arteriovenous malformations (AVMs) of the ambient cistern are an extremely rare and complex subgroup of vascular malformation, representing a clinical challenge due to the deep-seated, highly eloquent anatomic location and the debilitating, life-threatening consequences related to hemorrhagic presentation and surgical morbidity. Ultimately, a tailored treatment, based on the presenting symptoms, AVM angioarchitecture, and annual risk of hemorrhage should be discussed among a multidisciplinary team to find the best individualized strategy balancing between the pros and cons of each approach. In Video 1, we present the case of a 60-year-old man with a hemorrhaged AVM of the right ambient cistern, present the pros and cons of each possible treatment strategy, and illustrate the successful resection of this lesion through a subtemporal-transtentorial microsurgical approach.

A step-by-step guide for microsurgical collection of uncontaminated cerebrospinal fluid from rat cisterna magna.

BACKGROUND: Cerebrospinal fluid (CSF) analysis is of significant clinical importance for the diagnosis of diseases. In humans, CSF is easily accessible and can be collected using minimally invasive methods. However, obtaining uncontaminated CSF from rats is still challenging. NEW METHOD: This study described a microsurgical technique for sampling large quantities (>200 µL) of clear and non-blood-contaminated CSF from the rat cisterna magna in a comprehensible step-by-step guide and provided a graphical visualization. RESULTS: CSF was sampled in 5-10 min (n = 29 animals; average surgical time 7.6 min). In visual control, 28 samples (97 %) of clear and uncontaminated CSF were obtained. The volume of CSF collected was 124-337 µL, with an average volume of 207 µL/sample. Using the Valsalva maneuver, we could collect higher volumes (up to 400 µL) several times. COMPARISON WITH EXISTING METHOD(S): There is no need for special surgical skills to perform this method accurately. The method takes a few minutes longer than a percutaneous puncture (<1 min in pups). However, the volume of CSF obtained using the percutaneous approach in adult rats (50-70 µL) is comparatively low. CONCLUSIONS: We described a practical method of sampling CSF from rats that enables large volumes of CSF to be collected without blood contamination. No special surgical skills are required to use this method. With proper practice, the time between skin incision and CSF sampling is <10 min. Depending on the experimental design requirements, some additional time must be planned for wound closure.

An Uncommon Case of Neuroenteric Cyst Located at the Lateral Cerebellomedullary Cistern.

We present the case of a 42-year-old woman with a 5-week history of headache, progressive dysphagia, dysphonia, and hoarseness. A brain magnetic resonance imaging revealed an extra-axial cyst of the left lateral cerebellomedullary cistern. The subsequent histopathologic examination diagnosed a neuroenteric cyst. This case sheds light on the pivotal role of histologic identification of neuroenteric cyst, which could be crucial for further diagnostic investigations, especially in pediatric patients.

Adult cerebellopontine angle ependymoma presenting as an isolated cisternal mass: A case report.

INTRODUCTION: Ependymomas represent approximately 2%-8% of all primary intracranial brain tumors. The occurrence of extra-axial posterior fossa ependymomas in adults is rare. CASE AND OUTCOMES: We report a case of extra-axial cerebellopontine (CP) angle ependymoma in an adult patient, managed through gross total resection (GTR) and adjuvant radiotherapy. At her one-year postoperative visit, the patient remained clinically stable without any symptoms or focal neurological deficit and a follow up MRI showed no evidence of tumor recurrence. DISCUSSION: Only six cases of adult cerebellopontine angle ependymomas have been reported in the English literature, with the left side affected more commonly. Including this case, the mean age of the reported cases of adult extra-axial CP angle ependymoma is 44.14 years (range 22-66 years). Men accounted for five out of seven cases (71.4%). Maximal surgical resection is the mainstay of treatment in extra-axial CP angle ependymomas. Among seven reported cases, five received GTR and two had subtotal resection (STR). Patients were followed an average of 13.6 months (range 2-30 months) and only two patients with STR died during the follow-up period (6 weeks and 2 months after surgery). Six of the seven reported cases (including this one) received adjuvant radiotherapy. CONCLUSION: Although rare, extra-axial CP angle ependymomas should be considered as a differential diagnosis to other lesions of the CPA. Radical resection, whenever possible, is usually associated with a good outcome. Adjuvant radiotherapy remains an optional treatment with an unknown impact on overall and progression-free survival.

Double Direct Injection of Blood into the Cisterna Magna as a Model of Subarachnoid Hemorrhage.

Among strokes, subarachnoid hemorrhage (SAH) consecutive to the rupture of a cerebral arterial aneurysm represents 5-9% but is responsible for about 30% of the total stroke-related mortality with an important morbidity in terms of neurological outcome. A delayed cerebral vasospasm (CVS) may occur most often in association with a delayed cerebral ischemia. Different animal models of SAH are now being used including endovascular perforation and direct injection of blood into the cisterna magna or even the prechiasmatic cistern, each exhibiting distinct advantages and disadvantages. In this article, a standardized mouse model of SAH by double direct injection of determined volumes of autologous whole blood into the cisterna magna is presented. Briefly, mice were weighed and then anesthetized by isoflurane inhalation. Then, the animal was placed in a reclining position on a heated blanket maintaining a rectal temperature of 37 °C and positioned in a stereotactic frame with a cervical bend of about 30°. Once in place, the tip of an elongated glass micropipette filled with the homologous arterial blood taken from carotid artery of another mouse of the same age and gender (C57Bl/6J) was positioned at a right angle in contact with the atlanto-occipital membrane by means of a micromanipulator. Then 60 µL of blood was injected in the cisterna magna followed by a 30° downward tilt of the animal for 2 minutes. The second infusion of 30 µL of blood into the cisterna magna was performed 24 h after the first one. The individual follow-up of each animal is carried out daily (careful evaluation of weight and well-being). This procedure allows a predictable and highly reproducible distribution of blood, likely accompanied by intracranial pressure elevation that can be mimicked by an equivalent injection of an artificial cerebral spinal fluid (CSF), and represents an acute to mild-model of SAH inducing low mortality.

Pioneers in the cisterna magna puncture.

At the beginning of the 20th century, cerebrospinal fluid (CSF) collection and analysis emerged as a promising aid in the diagnosis of diseases of the central nervous system. It was obtained through the established procedure of lumbar puncture, described by Heinrich Quinke in 1891. The search for an alternative way to gather the CSF emerged in animal research, highlighting the cisterna magna as a promising source, with relative safety when performed by someone trained. Described initially and in detail by James Ayer in 1920, the procedure was widely adopted by neurologists and psychiatrists at the time, featuring its multiple advantages and clinical applications. After a period of great procedure use and exponential data collection, its complications and risks relegated the puncture of the cisterna magna as an alternative route that causes fear and fascination in modern Neurology.

Pioneers in the cisterna magna puncture / Pioneiros na punção da cisterna magna

Abstract At the beginning of the 20th century, cerebrospinal fluid (CSF) collection and analysis emerged as a promising aid in the diagnosis of diseases of the central nervous system. It was obtained through the established procedure of lumbar puncture, described by Heinrich Quinke in 1891. The search for an alternative way to gather the CSF emerged in animal research, highlighting the cisterna magna as a promising source, with relative safety when performed by someone trained. Described initially and in detail by James Ayer in 1920, the procedure was widely adopted by neurologists and psychiatrists at the time, featuring its multiple advantages and clinical applications. After a period of great procedure use and exponential data collection, its complications and risks relegated the puncture of the cisterna magna as an alternative route that causes fear and fascination in modern Neurology.

Resumo No início do século XX, a coleta e análise do líquido cefalorraquidiano (LCR) despontavam como um promissor auxílio no diagnóstico das doenças do sistema nervoso central. Sua obtenção se dava através do consagrado procedimento de punção lombar, descrito por Heinrich Quinke em 1891. A busca por uma via alternativa na obtenção do LCR ganhou destaque nas pesquisas animais, destacando-se na cisterna magna promissora fonte, com relativa segurança quando executada por alguém treinado. Descrito inicialmente e de maneira pormenorizada por James Ayer em 1920, o procedimento foi amplamente adotado por neurologistas e psiquiatras à época, com destaque para suas múltiplas vantagens e aplicações clínicas. Após um período de grande uso do procedimento e exponencial obtenção de dados, suas complicações e riscos relegaram a punção da cisterna magna como via alternativa que causa medo e fascínio na Neurologia moderna.

Tonsillectomy with modified reconstruction of the cisterna magna with and without craniectomy for the treatment of adult Chiari malformation type I with syringomyelia.

BACKGROUND: In light of the controversies regarding the surgical treatment of adult Chiari malformation type I (CM-I) with syringomyelia, a retrospective study was conducted to evaluate the safety and efficacy of tonsillectomy followed by modified reconstruction of the cisterna magna with or without craniectomy. METHODS: Between 2008 and 2017, 78 adult CM-I patients (36 males and 42 females, mean age 40.6 years old) with syringomyelia were treated with posterior fossa decompression (PFD) with tonsillectomy and modified reconstruction of the cisterna magna. Patients were divided into two study groups: group A (n = 40) underwent cranioplasty with replacement of the bone flap; group B (n = 38) underwent suboccipital craniectomy. Neurological outcomes were evaluated by traditional physician assessment (improved, unchanged, and worsened) and the Chicago Chiari Outcome Scale (CCOS). Syringomyelia outcomes were assessed radiologically. RESULTS: The procedure was successfully performed in all patients, and restoration of normal cerebrospinal fluid (CSF) flow was confirmed by intraoperative ultrasonography. The median postoperative follow-up was 20.3 months (range 18-60 months). Clinical improvement was evident in 66 (84.6%) patients, with no significant differences between the two groups (85.0% vs. 84.2%, P = 0.897). According to the CCOS, 36 patients (90.0%) in group A were labeled as "good" outcome, compared with that of 34 (86.8%) in group B (P = 0.734). Improvement of syringomyelia was also comparable between the groups, which was observed in 35 (87.5%) vs. 33 (86.8%) patients (P = 0.887). The postoperative overall (7.5% vs. 23.7%, P = 0.048) and CSF-related (2.5% vs. 18.4%, P = 0.027) complication rates were significantly lower in group A than group B. CONCLUSIONS: Tonsillectomy with modified reconstruction of the cisterna magna without craniectomy seems to be a safe and effective surgical option to treat adult CM-I patients with syringomyelia, though future well-powered prospective randomized studies are warranted to validate these findings.

ATP Measurement in Cerebrospinal Fluid Using a Microplate Reader.

Imbalance in extracellular ATP levels in brain tissue has been suggested as a triggering factor for several neurological disorders. Here, we describe the most sensitive and reliable technique for monitoring the ATP levels in mice cerebrospinal samples collected by cisterna magna puncture technique and quantified using a microplate reader.

A modified park bench position: the "Dormeuse" position.

BACKGROUND: Because of the restricted volume of the cisternal space, proper patient positioning on the operating table is of utmost importance during surgery by retrosigmoid approaches. Three positions are commonly used: supine, with the head rotated to the side contralateral to the lesion; the semi-sitting position; and the park bench position. Each position has advantages and disadvantages, and the surgeon should choose the one best suited to the individual patient and the pathology to be treated. METHODS: We describe a modified park bench position that we call the Dormeuse position. CONCLUSION: The Dormeuse position guarantees decrease in the posterior fossa pressure and allows optimal neural and vascular manipulation and control of any aspect of the cerebellopontine angle.

Effects of stylet-in versus stylet-out collection of cerebrospinal fluid from the cisterna magna on contamination of samples, sample quality, and collection time.

OBJECTIVE: To evaluate safety of stylet-in and stylet-out techniques for collection of CSF from the cisterna magna and to assess whether there were differences between techniques with regard to contamination of samples, sample quality, and efficiency of collection. ANIMALS: 10 adult purpose-bred research Beagles. PROCEDURES: A prospective crossover study was conducted. Preanesthetic physical and neurologic examinations and hematologic analyses were performed. Dogs were anesthetized, and collection of CSF samples from the cisterna magna by use of a stylet-in or stylet-out technique was performed. Two weeks later, samples were collected with the other sample collection technique. Samples of CSF were processed within 1 hour after collection. RESULTS: Cellular debris was detected in higher numbers in stylet-in samples, although this did not affect sample quality. The stylet-out technique was performed more rapidly. No adverse effects were detected for either technique. CONCLUSIONS AND CLINICAL RELEVANCE: Both techniques could be safely performed in healthy anesthetized dogs. The stylet-out technique was performed more rapidly and yielded a sample with less cellular debris. Both techniques can be used in clinical practice to yield CSF samples with good diagnostic quality.

Efficacy of cyst-cisternal shunt for refractory cyst regrowth of cystic vestibular schwannomas.

Vestibular schwannomas (VSs) are generally benign and slow-growing tumors, and microsurgical resection is the commonly recommended treatment. Some reports suggested that inserting a cystoperitoneal shunt was effective for treatment of cystic VSs; however, there was no report of a cyst-cisternal shunt which diverts cyst fluid into cistern. We report a case of cystic VS with repeated cyst regrowth within weeks after repeated surgeries. We prevented further recurrence using cyst-cisternal shunt. This technique may be a new treatment option for refractory cyst regrowth of cystic VSs.

Cerebrospinal fluid collection in laboratory mice: Literature review and modified cisternal puncture method.

BACKGROUND: The composition of cerebrospinal fluid (CSF) is an invaluable parameter in better understanding of cellular and molecular processes within the mammalian brain. However, the collection of significant volumes of clean CSF can be technically challenging in studies with laboratory mice. Over the past five decades, several approaches have been developed to maximize the quantity and quality of CSF samples, either from live or euthanized animals. Due to the small amounts collected, samples from single mice were often pooled or diluted to meet volume requirements of automated counters and multiple assays. NEW METHOD: This paper reviews previous work on CSF collection in mice, thus providing methodological background for the current post-mortem procedure. This modified cisternal puncture method involves the use of a peristaltic pump for consistent and slow intracardiac perfusion, as well as a loupe headset with a custom-made glass pipette for piercing a single hole in the atlanto-occipital membrane during repeated CSF draws. Sample cleanness is verified by comparing the colour of the glass pipette and the bottom of centrifuged PCR vial against a white background. RESULTS: With three trained experimenters, the entire procedure (including anesthesia) takes ∼11-13 min and often results in the collection of up to 40 µl of clean CSF from males of different murine strains. Properly staggered collections allow processing of relatively large cohorts of mice per day. CONCLUSIONS: This modification of previously employed methods can be used in studies that require tightly-timed collections of larger volumes of undiluted, tissue-free CSF and/or individual data records.

Cannula Implantation into the Cisterna Magna of Rodents.

Cisterna magna cannulation (CMc) is a straightforward procedure that enables direct access to the cerebrospinal fluid (CSF) without operative damage to the skull or the brain parenchyma. In anesthetized rodents, the exposure of the dura mater by blunt dissection of the neck muscles allows the insertion of a cannula into the cisterna magna (CM). The cannula, composed either by a fine beveled needle or borosilicate capillary, is attached via a polyethylene (PE) tube to a syringe. Using a syringe pump, molecules can then be injected at controlled rates directly into the CM, which is continuous with the subarachnoid space. From the subarachnoid space, we can trace CSF fluxes by convective flow into the perivascular space around penetrating arterioles, where solute exchange with the interstitial fluid (ISF) occurs. CMc can be performed for acute injections immediately following the surgery, or for chronic implantation, with later injection in anesthetized or awake, freely moving rodents. Quantitation of tracer distribution in the brain parenchyma can be performed by epifluorescence, 2-photon microscopy, and magnetic resonance imaging (MRI), depending on the physico-chemical properties of the injected molecules. Thus, CMc in conjunction with various imaging techniques offers a powerful tool for assessment of the glymphatic system and CSF dynamics and function. Furthermore, CMc can be utilized as a conduit for fast, brain-wide delivery of signaling molecules and metabolic substrates that could not otherwise cross the blood brain barrier (BBB).

Ventriculocisternal Shunt Redivivus: Third Ventricle-Cisterna Magna Intradural Shunt: A Technical Note and Case Report.

OBJECTIVE: To present a hitherto unreported modification of the classic Torkildsen procedure: passing a catheter intracranially, between the third ventricle and cisterna magna. METHODS: We applied our technique to a 56-year-old man who presented to our department for treatment of a pineal region mass. RESULTS: The patient was placed in sitting position and the mass was gross totally removed through a supracerebellar infratentorial approach. After the completion of the tumor resection, the patency of the cerebral aqueduct was checked, but the permeability was doubtful. During the same procedure, a shunt was inserted, under direct microsurgical control, into the third ventricle and passed over the cerebellar surface into the cisterna magna. The postoperative course was uneventful, and the patient was discharged from our unit with no neurological deficits and able to carry on with his day-to-day life. CONCLUSIONS: Our case illustrates that ventriculocisternal shunting can successfully be used in selected cases. The variation we describe can be a valuable surgical strategy in patients with pineal region masses, in whom a supracerebellar infratentorial route is used and in whom uncertainty exists regarding the patency of the sylvian aqueduct.

Endoscopic ventriculo-cisterno-ventricular approach in the treatment of bilateral trapped temporal horn related to fungal infection in a child: case report and review of the literature.

INTRODUCTION: Focal hydrocephalus including trapped temporal horn (TTH), isolated lateral and fourth ventricles, is caused by obstruction and/or adhesion related to various etiologies. With the advent of the neuroendoscope, endoscopic procedures have become an alternative in selected cases. CASE REPORT: A 2-year-old male from a rural town in México was referred to our institution because of multiple supra- and infra-tentorial abscesses and hydrocephalus. The patient had progressive deterioration and developed bilateral trapped temporal horn related to multi-septated hydrocephalus, so we performed an endoscopic ventricular-cistern-ventriculostomy through a single right temporal burr hole. POSTOPERATIVE COURSE: Bilateral TTH and multi-septated hydrocephalus were effectively treated with a single external ventricular drainage (EVD) catheter, from the right temporal horn to the left temporal horn through the interpeduncular cistern; after clamping the EVD for 3 days with no evidence of hydrocephalus, the EVD was removed. The size of the ventricles remained stable afterwards, and no clinical or radiological evidence of hydrocephalus was observed after 3 months of follow-up. DISCUSSION: Endoscopic ventriculocisternostomy is effective in selected cases of TTH. We know that dilatation of the temporal horn widens the window between the anterior choroidal artery and optic tract superiorly, and the posterior communicating and CN III inferiorly, making the described procedure feasible, even in the approach to the contralateral side. Even though this is a rare condition, we believe it is a safe and effective option to eliminate multiple shunts and/or to reduce the number of catheters needed to treat bilateral THH related to multi-septated hydrocephalus.

Cisterna magna arachnoid membrane suturing decreases incidence of pseudomeningocele formation and incisional CSF leakage.

OBJECTIVE: A pseudomeningocele and an incisional cerebrospinal fluid leak are considered frequent complications following neurosurgical operations. The rate of these complications especially increases following neurosurgical procedures on the posterior cranial fossae. According to some publications, the rate of pseudomeningoceles has been reported as high as 40%, whereas that of incisional cerebrospinal fluid leaks is up to 17%. For the purposes of reducing the risk of these complications after a midline suboccipital craniotomy, we propose suturing the arachnoid membrane of the cisterna magna. In this paper, we present a retrospective analysis of arachnoid membrane suturing. METHODS: Seventy patients underwent midline suboccipital craniotomy by the first author between 2012 and 2016 at Burdenko Neurosurgery Institute. In this group was included a consecutive group of patients with posterior fossae tumors where the approach was performed through the cisterna magna arachnoid membrane following midline suboccipital craniotomy and dural opening. The patients were divided into two groups. Group 1 included 38 patients to whom cisterna magna arachnoid membrane suturing was performed with monofilament nonabsorbable suture 7.0., and additionally, the suture was sealed with fibrin adhesive sealant TachoComb®. Group 2 included 32 patients without arachnoid membrane suturing. There was no other significant difference in terms of clinical signs and surgical procedures between these groups. In the postoperative period, the frequency of developing a pseudomeningocele and an incisional cerebrospinal fluid leak was assessed in these two groups. The results were evaluated on the basis of clinical, CT, and MRI data performed in the postoperative period. RESULTS: In the patients who underwent arachnoid membrane suturing (group I), pseudomeningocele formation was observed in one (2.6%) and CSF leak in one (2.6%) of the 38 patients. In group II, in which patients had no arachnoid membrane suturing, we observed pseudomeningocele formation in 11 (34.4%) patients and a CSF leak in 7 (25.0%) out of 28 patients with known follow-up. Statistical analysis of the data indicates a significantly higher risk of postoperative pseudomeningocele formation and/or an incisional cerebrospinal fluid leak in a group of patients who did not undergo arachnoid membrane suturing (p < 0.05). CONCLUSIONS: Suturing of the arachnoid membrane of the cisterna magna and its further sealing with fibrin adhesive sealant TachoComb® create an additional barrier for preventing cerebrospinal fluid collection in the extradural space. This technique significantly reduces the risk of postoperative pseudomeningocele formation and/or an incisional cerebrospinal fluid leak in patients with midline suboccipital craniotomy.