Rare case of tentorial cavernous malformation mimicking a meningioma: illustrative case.

BACKGROUND: Cavernous malformations of the dura, especially of the tentorium, are exceedingly rare. In the available literature, only 10 cases have been described to date. OBSERVATIONS: The authors present the case of a 46-year-old male patient with a 1-cm infratentorial lesion suspicious for meningioma that was found on routine magnetic resonance imaging (MRI) performed for vertigo. The lesion was followed for 1.5 years with no change in signal and size. Nevertheless, the patient was concerned about the lesion and requested removal. The removal was successful and without any neurological sequelae. However, histological evaluation demonstrated a cavernous malformation. Postoperative computed tomography and MRI showed complete removal. Preoperative MRI characteristics, intraoperative images, and a video, as well as histological evaluation, are shown. The case is discussed with respect to the literature. LESSONS: Cavernous malformations of the tentorium are extremely rare and mimic meningiomas; thus, they need to be taken into account. DOTATOC positron emission tomography may help to differentiate in these cases. Considering the cases reported in the literature, in cases of large tumors, preoperative angiography and possibly embolization may be helpful. https://thejns.org/doi/10.3171/CASE24168.

[Microanatomical Investigation of the Subtemporal Transtentorial Approach]. / é¢žä¸‹ç»å°è„‘å¹•å ¥è·¯çš„æ˜¾å¾®è§£å‰–å­¦ç ”ç©¶.

Objective: To study the microanatomic structure of the subtemporal transtentorial approach to the lateral side of the brainstem, and to provide anatomical information that will assist clinicians to perform surgeries on the lateral, circumferential, and petroclival regions of the brainstem. Methods: Anatomical investigations were conducted on 8 cadaveric head specimens (16 sides) using the infratemporal transtentorial approach. The heads were tilted to one side, with the zygomatic arch at its highest point. Then, a horseshoe incision was made above the auricle. The incision extended from the midpoint of the zygomatic arch to one third of the mesolateral length of the transverse sinus, with the flap turned towards the temporal part. After removing the bone, the arachnoid and the soft meninges were carefully stripped under the microscope. The exposure range of the surgical approach was observed and the positional relationships of relevant nerves and blood vessels in the approach were clarified. Important structures were photographed and the relevant parameters were measured. Results: The upper edge of the zygomatic arch root could be used to accurately locate the base of the middle cranial fossa. The average distances of the star point to the apex of mastoid, the star point to the superior ridge of external auditory canal, the anterior angle of parietomastoid suture to the superior ridge of external auditory canal, and the anterior angle of parietomastoid suture to the star point of the 10 adult skull specimens were 47.23 mm, 45.27 mm, 26.16 mm, and 23.08 mm, respectively. The subtemporal approach could fully expose the area from as high as the posterior clinoid process to as low as the petrous ridge and the arcuate protuberance after cutting through the cerebellar tentorium. The approach makes it possible to handle lesions on the ventral or lateral sides of the middle clivus, the cistern ambiens, the midbrain, midbrain, and pons. In addition, the approach can significantly expand the exposure area of the upper part of the tentorium cerebelli through cheekbone excision and expand the exposure range of the lower part of the tentorium cerebelli through rock bone grinding technology. The total length of the trochlear nerve, distance of the trochlear nerve to the tentorial edge of cerebellum, length of its shape in the tentorial mezzanine, and its lower part of entering into the tentorium cerebelli to the petrosal ridge were (16.95±4.74) mm, (1.27±0.73) mm, (5.72±1.37) mm, and (4.51±0.39) mm, respectively. The cerebellar tentorium could be safely opened through the posterior clinoid process or arcuate protrusion for localization. The oculomotor nerve could serve as an anatomical landmark to locate the posterior cerebral artery and superior cerebellar artery. Conclusion: Through microanatomic investigation, the exposure range and intraoperative difficulties of the infratemporal transtentorial approach can be clarified, which facilitates clinicians to accurately and safely plan surgical methods and reduce surgical complications.

[Clinical anatomy of the Bernasconi-Cassinari artery]. / Klinicheskaya anatomiya arterii Bernaskoni­Kassinari.

The article provides a comprehensive overview of the Bernasconi-Cassinari's artery (marginal tentorial branch of internal carotid artery, r. marginalis tentorii a. carotis internae). It includes information on the history of its discovery, anatomical features, and topography. The interrelation between the anatomical features of this artery and the presence of neurological pathology in patients is discussed, along with neurosurgical treatment methodologies.

Preserving the cerebellar hemispheric tentorial bridging veins through a novel tentorial cut technique for supracerebellar approaches.

OBJECTIVE: The objective of this study was to describe the distribution pattern of cerebellar hemispheric tentorial bridging (CHTB) veins on the tentorial surface in a case series of perimedian or paramedian supracerebellar approaches and to describe a novel technique to preserve these veins. METHODS: A series of 141 patients with various pathological processes in different locations was operated on via perimedian or paramedian supracerebellar approaches by the senior author from July 2006 through October 2022 and was retrospectively evaluated. During surgery, the number and locations of all CHTB veins were recorded to establish a distribution map on the tentorial surface, divided into nine zones. Patients were classified into four groups according to the surgical technique used to manage CHTB veins: 1) group 1 consisted of CHTB veins preserved without intervention during surgery or no CHTB veins found in the surgical route; 2) group 2 included CHTB veins coagulated during surgery; 3) group 3 included CHTB veins preserved with arachnoid and/or tentorial dissection from the cerebellar or tentorial surface, respectively; and 4) group 4 comprised CHTB veins preserved using a novel tentorial cut technique. RESULTS: Overall, 141 patients were included in the study. Of these 141 patients, 38 were in group 1 (27%), 32 in group 2 (22.7%), 47 in group 3 (33.3%), and 24 in group 4 (17%). The total number of CHTB veins encountered was 207 during surgeries on one side. According to the distribution zones of the tentorium, zone 5 had the highest density of CHTB veins, while zone 7 had the lowest. Of the patients in group 4, 6 underwent the perimedian supracerebellar approach and 18 had the paramedian supracerebellar approach. There were 39 CHTB veins on the surface of the 24 cerebellar hemispheres in group 4. The tentorial cut technique was performed for 27 of 39 CHTB veins. Twelve veins were not addressed because they did not present any obstacles during approaches. During surgery, no complications were observed due to the tentorial cut technique. CONCLUSIONS: Because there is no way to determine whether a CHTB vein can be sacrificed without complications, it is important to protect these veins in supracerebellar approaches. This new tentorial cut technique in perimedian or paramedian supracerebellar approaches makes it possible to preserve CHTB veins encountered during supracerebellar surgeries.

Ring-shaped Dandy's superior petrosal vein.

BACKGROUND: Dandy's superior petrosal vein (SPV) anatomy is highly relevant for neurosurgeons. The SPV drains into the superior petrosal sinus (SPS), closely related to the trigeminal and internal auditory pores. METHOD: The archived enhanced MRI files of a male patient were studied. RESULTS: An infratentorial ring-shaped (RS) SPV was found on the petrosal surface of the right cerebellar hemisphere. It was inserted in the SPS above the internal auditory pore, postero-lateral to the trigeminal pore. The anterior arm of that venous ring received a delicate supratrigeminal plexus of veins from the pontine surface and continued as a single venous trunk on the cerebellar surface. CONCLUSION: Such previously unreported RS-SPV is of utmost importance to be identified before subtemporal transtentorial and retrosigmoid approaches for different neurosurgical reasons.

Simulation of the occipital transtentorial approach incorporating visualization of the cerebellar tentorium using three-dimensional computed tomography angiography and gadolinium-enhanced T1-weighted magnetic resonance imaging: technical note.

The occipital transtentorial approach (OTA) is one of the useful approaches to the lesions of the pineal region, dorsal brainstem, and supracerebellar region. However, a wide operative field is sometimes difficult to obtain due to the tentorial sinus and bridging veins. This study evaluated the usefulness of preoperative simulation of OTA, specifically including the cerebellar tentorium in 9 patients. All patients underwent computed tomography angiography and venography and gadolinium-enhanced three-dimensional T1-weighted magnetic resonance images (Gd-3D-T1WI). The images were fused, and the cerebellar tentorium, vessels, and tumor were manually extracted from Gd-3D-T1WI to obtain the simulation images. Visualization of the cerebellar tentorium could discriminate between bridging veins from the occipital lobe and cerebellum, and recognize the site of bridging to the tentorial sinus and variants which may interfere with the tentorial incision. Simulation of the tentorial incision was also possible based on the relationships between the tumor, tentorial sinus, bridging vein, and cerebellar tentorium. The simulation suggested that safe tentorial incision was difficult in two sides because of the crossed tentorial sinus draining the left basal vein and draining veins from the glioblastoma. The OTA was performed in eight cases, and no difficulty was experienced in the tentorial incision in all cases. The simulation findings of the bridging vein and tentorial sinus were consistent with the intraoperative findings. Preoperative simulation including the cerebellar tentorium is useful for determining the optimum and safe side and required extent of the tentorial incision necessary for tumor resection with the OTA.

Gunshot Wound to the Posterior Fossa With a Transcerebellar Retromesencepahlic Bullet Path, Transient Mutism, and Unexpected Functional Recovery: The Pivotal, Energy-Absorbing Function of the Petrous Bone and Tentorial Leaflet.

Given the abundance of vital neurovascular structures, gunshot wounds (GSWs) to the posterior fossa are generally fatal. We present a unique such case where a bullet entered the petrous bone, traversed the cerebellar hemisphere and overlying tentorial leaflet, and reached the dorsal aspect of the midbrain, resulting in transient cerebellar mutism with an unexpectedly favorable functional recovery. A 17-year-old boy sustained a GSW to the left mastoid region with no exit wound and presented with agitation and confusion, ultimately leading to a coma. Head CT revealed a bullet trajectory through the left petrous bone, left cerebellar hemisphere, and left tentorial leaflet, with a retained bullet fragment in the quadrigeminal cistern, overlying the dorsal aspect of the midbrain. Computed tomography venography (CTV) demonstrated thrombosis of the left transverse and sigmoid sinuses and the internal jugular vein. The patient's hospital course was marked by the development of obstructive hydrocephalus, secondary to delayed cerebellar edema with fourth ventricular effacement and aqueductal compression, possibly worsened by concomitant left sigmoid sinus thrombosis. Following the emergency placement of an external ventricular drain and two weeks of mechanical ventilation, the patient's level of consciousness improved significantly, with excellent brainstem and cranial nerve function, ultimately leading to successful extubation. Although the patient exhibited cerebellar mutism secondary to his injury, his cognitive abilities and speech improved significantly during rehabilitation. At his three-month outpatient follow-up, he was ambulatory, independent in his daily living activities, and able to verbally communicate using full sentences. Though exceptional, survival and functional recovery may occur after a GSW to the posterior fossa. A basic understanding of ballistics and the importance of biomechanically resilient anatomic barriers, such as the petrous bone and tentorial leaflet, can help predict a good outcome. Lesional cerebellar mutism tends to have a favorable prognosis, especially in young patients with central nervous system plasticity.

A retrospective study of 78 adult tentorial middle line region dural arteriovenous fistulae.

OBJECTIVE: Dural arteriovenous fistulae (DAVF) in the tentorial middle line region are uncommon with specific features and more cognitive disorders than any other region. The purpose of this study is to present clinical characteristics and our experience with endovascular treatment in this specific region. METHODS: During a 20-year period, 94.9% of patients (74/78) underwent endovascular treatment (36 in galenic, 48.6%) (12 in straight sinus, 16.2%) (26 in torcular, 35.1%). There were 63 males and 15 females with mean age of 50 (50 ± 12) years in total of 78 patients. The clinical presentation, angiographic features, treatment strategy, and clinical outcomes were recorded. RESULTS: Transarterial embolization (TAE) was performed in 89.2% of the 74 patients (66/74), transvenous embolization alone in one patient and mixed approach in seven. Complete obliteration of the fistulas was obtained in 87.5% of the patients (64/74). 71 patients (mean, 56 months) had phone, outpatient, or admission follow-up. The digital subtraction angiography (DSA) follow-up period (25/78, 32.1%) was 13.8 (6-21) months. Two of them (2/25, 8%) had fistula recurrences after complete embolization and were embolized again. The phone follow-up period (70/78, 89.7%) was 76.6 (40-92.3) months. Pre-embolization and post-embolization mRS ≥ 2 were in 44 patients (44/78) and 15 (15/71) patients, respectively. DAVF with internal cerebral vein drainage (OR 6.514, 95% Cl 1.201-35.317) and intracranial hemorrhage (OR 17.034, 95% Cl 1.122-258.612) during TAE were the risk factors for predicting poor outcomes (followed up mRS ≥ 2). CONCLUSIONS: TAE is the first-line treatment for tentorial middle line region DAVF. When pial feeders' obliteration is difficult to achieve, it should not be forced due to the poor outcomes after intracranial hemorrhage. The cognitive disorders caused by this region were not reversible as reported. It is imperative to enhance the care provided to these patients with cognitive disorders.

Case of incidental thoracic spinal dumbbell hemorrhagic arachnoid cyst and tentorial metastasis from breast carcinoma.

Background: Spinal arachnoid cysts (SACs) in adults are typically acquired dural defects following trauma, inflammation, or infection. Brain metastases from breast cancer account for 5-12% of all CNS metastases and are mostly leptomeningeal. Here, the authors reported a 50-year-old female treated for a tentorial metastasis from breast carcinoma that underwent chemotherapy and radiotherapy. Three months later, she presented with a thoracic spinal extradural dumbbell hemorrhagic arachnoid cyst. Case Description: A 50-year-old female underwent a left retrosigmoid suboccipital craniectomy for microsurgical removal of a tentorial metastasis attributed to poorly differentiated breast carcinoma (i.e., comedonic pattern). The patient subsequently underwent both chemotherapy and radiotherapy for accompanying bony metastases. Three months later, she experienced the onset of severe posterior thoracic pain. When the thoracic magnetic resonance imaging revealed a hyperintense "dumbbell" extradural T10-T11 lesion, she underwent a T10-T11 laminectomy for marsupialization and excision of the hemorrhagic lesion. The histological examination revealed blood and arachnoid tissue within a benign SAC, without accompanying tumor. Her postoperative course was uneventful, and she was discharged on postoperative day 3. Conclusion: A 50-year-old female underwent a left retrosigmoid suboccipital craniectomy for removal of a tentorial metastasis from breast carcinoma, followed by radiation/chemotherapy. Three months later, she hemorrhaged into an MR-documented T10-T11 dumbell extradural SAC that was successfully treated with laminectomy, marsupialization, and excision.

Evaluation of the frequency of tentorial hypoplasia and accompanying gyral herniation using MRI.

Purpose The cerebellar tentorium, the second-largest dural reflection in the brain, separates supratentorial and infratentorial structures. This study aimed to determine the frequency of tentorial hypoplasia (TH) and gyral herniation and their relationship with clinical findings. Methods The standard brain MRIs were examined retrospectively. The presence of TH and laterality were investigated. If hypoplasia was accompanied by a gyrus extending inferior to the line where the tentorium should be located, this was recorded as tentorial hypoplasia-herniated gyrus (TH-HG), while the cases with hypoplasia alone were noted as isolated TH. It was also determined which gyrus or gyri were herniated. The clinical findings of the patients were obtained, and the correlation between HG was explored. Results Standard brain MRIs of the 2051 patients were evaluated. Two hundred ten patients were excluded from the study due to different intracranial disorders, and 1841 patients, 739 (40.1%) males, and 1102 (59.9%) females, were included. Isolated TH or TH-HG was present in 56 patients, resulting in a prevalence of 3.04%. Of the patients with TH or TH-HG, 15 were men, and 41 were women. TH and TH-HG were significantly more common in women (p=0.038). TH-HG was unilateral in 22 (39.2%) patients and bilateral in 21 (37.5%). Left TH was found in 11 (19.6%) patients, left TH-HG in 29 (51.7%), right TH in eight (14.2%), and left TH-HG in 35 (62.5%). Conclusion Hypoplasia of the tentorium is a rare and unknown anomaly that can be easily diagnosed using MRI, and different gyral herniations may accompany TH.

Tentorial ectopic schwannoma: A case report and literature review.

Schwannomas arising within the central nervous system unrelated to a major cranial nerve rarely originate from the dura, particularly the tentorium. Hereby, the reported case is a 39-year-old female with blurred vision in her right eye for 1 month who was diagnosed with tentorial ectopic schwannoma. The tumor was almost totally resected through a posterior median incision approach without any neurological deficits. The clinical presentations and radiographic findings of such cases are discussed in the article.

Newborn with severe supratentorial subdural hematoma due to laceration of the tentorium cerebelli.

PURPOSE: A rare case of a newborn girl born by a normal vaginal delivery who developed a severe supratentorial subdural hematoma due to a laceration in the tentorium cerebelli is presented. METHODS AND RESULTS: The girl, born by normal vaginal delivery at 39 weeks and 4 days of gestation, showed an intermittent decrease in oxygen saturation and bulging of the anterior fontanelle. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a subdural hematoma centered in the left occipital region with a midline shift. Hematoma evacuation with craniotomy was performed, and the source of bleeding was a laceration of the tentorium cerebelli. CONCLUSION: Severe supratentorial subdural hematomas can occur due to laceration of the tentorium cerebelli even in a normal vaginal delivery.

Gamma Knife radiosurgery for meningiomas of the confluence of the falx and tentorium.

PURPOSE: Meningiomas arising from the confluence of the falx and tentorium (CFT) are a rare and challenging subset of meningiomas. Gamma Knife radiosurgery (GKRS) is well-established as a safe and effective management strategy for intracranial meningiomas, but its role in treating CFT meningiomas is not well-described. This paper reports the largest series focused exclusively on the outcomes of GKRS for CFT meningiomas. METHODS: We retrospectively identified 20 CFT meningiomas out of 2031 meningioma patients who underwent GKRS at our institution between 1987 and 2021. Tumor control, overall survival (OS), and complications were recorded and analyzed. The median tumor margin dose was 13 Gy at the 50% isodose line. The median tumor volume treated was 4.4 cc (IQR 3.5-7.7). The median patient age was 58 years (range 33-83), the median MRI surveillance duration was 59 months (IQR 34-92), and the median overall follow-up duration was 92 months (IQR 42-201). RESULTS: The local tumor control rate (PFS) at 5 and 10-years were 100% (N=10) and 83% (N=4), respectively. Eight patients had stable tumor volumes and 11 patients had regression. One patient with a twice-operated tumor had delayed progression at 7.5 years and was retreated with GKRS. No patient had adverse radiation effects during the period of MRI surveillance. The 5 and 10-year OS were 100% (N=13) and 100% (N=7), respectively. CONCLUSIONS: GKRS is a valuable therapeutic strategy for patients with newly diagnosed CFT meningiomas or progressive residual tumors after surgical resection.

Tentorium cerebelli formation during human embryonic and early fetal development.

The morphologies of the fetal tentorium cerebelli (TC) and brain influence each other during development. This study aimed to analyze and more comprehensively understand the three-dimensional morphogenesis of the TC and fetal brain. We examined magnetic resonance imaging from 64 embryonic and fetal specimens (crown-rump length range, 9.2-225 mm). During the embryonic period, the lateral folds of the TC elongated to traverse the middle part of the midbrain. The TC and falx cerebri appeared separated, and no invaginations at the parieto-occipital region were observed. In the early fetal period, the cerebrum covered approximately half of the midbrain. The separation of the dural limiting layer at the parieto-occipital region widened from the posterior cerebrum to the cranial cerebellum. The lateral folds of the TC were spread between its tip, continuous with the falx cerebri, and its base plane, located between the midbrain and rostral hindbrain. Differences in the TC components' growth directions gradually diminished as the cerebrum covered the midbrain. We observed rotation of the TC at its median section according to its growth, which ceased in the middle fetal period. The brainstem and cerebellum extended inferiorly via differential growth, with the cerebrum covering them superiorly. The morphology of the TC curved to conform to the cerebellar and cerebral surfaces. Our present study suggests that factors affecting TC morphology differ between the early and middle fetal periods. Present data provided a more comprehensive view of TC formation according to developmental stage.

The prevalence of isolated tentorial hypoplasia on magnetic resonance imaging.

Purpose: The tent shape of the tentorium cerebelli helps preserve brain anatomy by providing cerebellum protection against pressure caused by the brain's gravity effect. In the absence of this support structure of the tentorium, herniation occurs in the brain. Isolated tentorial hypoplasia (TH) is extremely rare. In this study, we aimed to calculate the prevalence of this entity, which is reported to be rare in the literature. Material and methods: Magnetic resonance imaging (MRI) images of 5163 patients who applied to the training and research hospital for various reasons between 1 September 2020, and 31 August 2021, who underwent brain MRI, were reviewed retrospectively. Results: The prevalence of TH among patients screened during a period of one year was calculated as 2.22%. Of these, 76.59% were female (n = 72) and 23.41% were male (n = 22). The rates of presentation of complaints among TH patients were 60.63% headache, 17.02% vertigo, 4.25% seizures, 3.19% tremor, 3.19% syncope, 7.44% forgetfulness, and 2.12% visual impairment. Five patients (11.76%) were admitted for metastasis investigation due to their primary malignancy; they did not have any complaints. Localization of TH: 18.08% (n = 17) were observed on the right side, 28.72% (n = 27) on the left side, and 53.19% (n = 50) on the bilateral tentorium leaf. Conclusions: Being aware of TH during brain MRI evaluation will help prevent possible misdiagnoses. We hope that this study with a large number of patients will increase awareness about TH, because there are no studies other than cadaver studies and a few case reports.

Investigation of role of falx and tentorium on brain simulant strain under impact loading.

Mild Traumatic brain injury (mTBI) is a major health concern. The role of the falx and tentorium (i.e., membranes) in exacerbating mTBI has been conjectured due to the involvement of clinically confirmed midbrain regions. Recent brain biomechanics investigations, mainly using computational head models, also support such a hypothesis. However, data in this regard is limited. Towards this end, using a surrogate head model, we investigate the role of membranes on brain biomechanics. Two different materials-thermoplastic polyurethane with various elastic moduli values (20, 150, 205 MPa) and polylactic acid (elastic modulus 1500 MPa) were used to examine the effect of membrane stiffness on brain simulant strain. The head surrogate was mounted on the Hybrid-III neck and subjected to coronal and sagittal plane rotations using a linear impactor system. Corresponding 6-DOF head kinematics and 2D brain simulant strains in midcoronal and midsagittal planes were measured. Our results elucidate the paradigm of strain evolution in the brain simulant in the presence of membranes. The cortical strains are decreased, whereas strains in the subcortical regions are either equivalent or increased in the presence of membranes. The elastic modulus of the membranes governs the amount of strain reduction or increase. We found that the falx displacement and constraints on stress wave propagation are dominant mechanisms dictating the mechanics of the interaction of membranes with the brain simulant. Overall, these results provide novel experimental insights into the role of membranes on brain deformations, which will motivate futuristic investigations in numerous subdomains of brain injury biomechanics.

A New Classification of the Anatomical Variations of Labbé's Inferior Anastomotic Vein.

(1) Background: The inferior anastomotic vein of Labbé (LV) courses on the temporal lobe, from the sylvian fissure towards the tentorium cerebelli and finishes at the transverse sinus (TS). The importance of the LV topography is related to skull base neurosurgical approaches. Based on the hypothesis of the existence of as yet unidentified anatomical possibilities of the LV, we aimed through this research to document the superficial venous topographic patterns at the lateral and inferior surfaces of the temporal lobe. (2) Methods: A retrospective cohort of 50 computed tomography angiograms (CTAs) of 32 males and 18 females was documented. (3) Results: Absent (type 0) LVs were found in 6% of cases. Anterior (temporal, squamosal-petrosal-mastoid, type 1) LVs were found in 12% of cases. LVs with a posterior, temporoparietal course (type 2) were found to be bilateral in 46% of cases and unilateral in 36% of cases. Type 3 LVs (posterior, parietooccipital) were found to be bilateral in 8% and unilateral in 32% of cases. In 24% of cases, duplicate LVs were found that were either complete or incomplete. A quadruplicate LV was found in a male case. On 78 sides, the LV drained either into a tentorial sinus or into the TS. (4) Conclusions: The anatomy of the vein of Labbé is variable in terms of its course, the number of veins and the modality of drainage; thus, it should determine personalized neurosurgical and interventional approaches. A new classification of the anatomical variations of Labbé's vein, as detected on the CTAs, is proposed here (types 0-3).

How I do it: decompressive hemicraniectomy supplemented with resection of the temporal pole and tentoriotomy for malignant ischemic infarction in the territory supplied by the middle cerebral artery.

Malignant ischemic infarction in the territory supplied by the middle cerebral artery is an extremely severe form of ischemic stroke associated with development of massive uncontrollable postischemic edema of the affected cerebral hemisphere; the end result of which is development of transtentorial herniation and death. METHOD: The surgical technique of performance of decompressive hemicraniectomy involves removal of an extensive bone flap in the fronto-temporo-parieto-occipital zone with resection of the temporal squama and of the greater wing of the sphenoid bone to visualize the level of entrance of the middle meningeal artery to the cranial cavity, which, in its turn, allows resection of the upright margin of the middle cranial fossa. Decompressive hemicraniectomy is supplemented with resection of the temporal pole and tentoriotomy. CONCLUSION: Performance of decompressive hemicraniectomy in combination with resection of the resection of the temporal pole and tentoriotomy is an effective surgical method of treatment of malignant ischemic stroke in the territory supplied by the middle cerebral artery, capable of reducing the lethality rate during the postoperative period.

Hypoplasia of the Tentorium Cerebelli: Case Report and Review of the Literature.

The second largest intracranial specialization of the dura mater, the tentorium cerebelli, is a transverse fold that partially separates the cerebellum and cerebral hemispheres. During routine dissection of the posterior cranial fossa, a left-sided hypoplastic region of the tentorium cerebelli was observed. This fenestration was seen at the posterior portion of the tentorium as a posteromedial strip of tissue rising vertically to interface with the falx cerebri. Although isolated cases of tentorial hypoplasia have been reported in, for example, cases of Chiari II malformation, we believe isolated fenestration of this membrane is very rare, especially in the absence of the Chiari II malformation. The current case adds to the sparse literature on isolated tentorial defects and might be of interest to neurosurgeons or clinicians who review intracranial imaging.

The importance of asynclitism in birth trauma and intrapartum sonography.

Asynclitism is malposition and malpresentation of the head in the pelvis. It is shown that asynclitism during the configuration (molding) of the head leads to an uneven distribution of the tension forces of the tentorium cerebelli (TC) and to its one-sided ruptures, mainly in the left half. It is indicated that with asynclitism larger more than 15 mm (moderate degree of asynclitism), the risk of birth trauma to the skull and brain increases. It was shown that not only severe degree of asynclitism, but also a moderate degree are pathological due to possible complications. The data on the sonographic diagnosis of asynclitism are presented. The negative effects of vacuum extraction (VE), the forceps application are considered. The mechanism of subaponeurotic hemorrhages is described. The importance of timely asynclitism diagnosis in labor to prevent its complication is shown. The cesarean section is practiced as extreme solution to the problem. The widespread use of sonography for the asynclitism diagnosis will prevent the birth trauma and reduce the incidence of mobility and mortality of the children and mother.