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Background: In this video abstract, we present a one burr-hole craniotomy for the posterior interhemispheric approach developed in Helsinki Neurosurgery to access posteriorly the medial surface of cerebral hemispheres, falx cerebri, and deep midline cerebrovascular structures. Therefore, preoperative imaging is essential to achieve an optimal operative corridor for a safest and more effcient approach. Case Description: The patient with a papillary tumor of the pineal region is placed in sitting position. A midline single-layer skin incision is made in front of the superior sagittal sinus. Strong retraction maintains a clean space for craniotomy. Aiming to reduce the risk of sinus transgression or cortical veins damaging in the eloquent frontal-parietal area, a burr-hole is made over the superior sagittal sinus at the anterior border of the bone flap and the bone is detached from the dura posteriorly with blunt dissectors. Thus, proximal detachment of the dura under some visual control remains safe. A long blunt flexible dissector is used during this stage in case of elderly patients with an adherent dura. Craniotomy around the superior sagittal sinus is performed to expose 2-3 cm of the dura lateral to the sagittal sinus according to the exact location of the lesion. Moreover, craniotomy extends slightly over the contralateral side to allow some retraction of the sagittal sinus. Two cuts, from both sites of the burr-hole, are joined along the posterior midline. A few drill holes are made for tack-up sutures. Finally, a hemostatic agent covers the sagittal sinus and a sinus-based dura opening is performed under the microscope. Conclusion: The described one burr-hole craniotomy may represent a more efficient manner for performing a posterior interhemispheric approach. [ABSTRACT FROM AUTHOR]

Background: In this video abstract, we present a one burr-hole craniotomy for a modified presigmoid approach developed in Helsinki Neurosurgery to access the space extended to both middle and posterior fossa. Thus, indications for this approach are lesions that extend to both middle and posterior fossa, petroclival tumors, basilar tip aneurysms located extremely low below the posterior clinoid process, trunk basilar aneurysms, and bypass procedures from the P2 segment of the posterior cerebral artery. The procedure is composed by three stages: a temporal and presigmoid craniotomy, a partial petromastoidectomy, and the dura opening with section of the superior petrosal sinus (SPS) and the tentorium. Even though some risks related to the opening of the mastoid cells or cut of the SPS may exist, benefits of this optimized craniotomy are higher compared with the complications. Case Description: The patient with a giant petroclival meningioma is placed in park bench position and spinal drainage is inserted. Skin incision starts in front of the ear curve going to 1 inch behind the mastoid line. Strong retraction with hooks keeps a clean space for the craniotomy. Hemostatic Raney clips are placed at the superior border of the skin flap. A burr-hole is made at the most cranial part of the temporal bone. After the detachment of the dura with long flexible blunt dissectors, the craniotomy is performed to expose the sigmoid sinus, the SPS and the dura of the inferior temporal lobe, and the floor of the middle fossa. Aiming to access the posterior fossa by a presigmoid route, a partial petromastoidectomy is performed preserving the semicircular canals. Few drill holes are made for tack-up sutures. Once we properly reach the dura of the middle and posterior fossa, dura of the temporal lobe and later, the presigmoid dura are opened joining at the level of the SPS. The SPS, which is running over the petrous bone between the posterior and the middle fossa, is coagulated, ligated, and cut. After SPS is sectioned, the tentorium is cut anterior to the drainage of vein of Labbé and posterior to the deep tentorial insertion of the fourth nerve. Finally, special care should be taken to seal the opened mastoid cells with muscle and glue, and for the hermetic dura closure using pericranium or temporal muscle aponeurosis. Conclusion: The described one burr-hole craniotomy may represent the more efficient approach for the management of the deep and hardly accessible lesions extended to both middle and posterior fossa. [ABSTRACT FROM AUTHOR]

Background: In this video-abstract, we present a one burr-hole craniotomy for the anterior interhemispheric approach developed in Helsinki Neurosurgery to access the medial surface of cerebral hemispheres, the falx cerebri, the distal segment of the anterior cerebral artery, the corpus callosum, the third ventricle, and the lateral ventricles. Therefore, preoperative imaging is essential to achieve an optimal operative corridor for safest and more effcient approach. Case Description: The patient with a no ruptured right pericallosal aneurysm is placed in semi-sitting position. A midline single-layer curved skin incision is made behind the hairline with more extension to the side of the planned bone flap. Strong retraction with hooks keeps a clean space for craniotomy. Hemostatic Raney clips are placed at the posterior border of the wound. A burr-hole is made over the superior sagittal sinus at the posterior border of the bone flap. The bone is detached from the dura anteriorly with blunt dissectors. Thus, we avoid harming the superior cerebral veins distributed at the posterior frontal area. After the detachment of the dura, a craniotomy around the superior sagittal sinus is performed to expose 2-3 cm of the dura lateral to the sagittal sinus. Moreover, the craniotomy extends slightly over the contralateral side to allow some retraction of the sagittal sinus. Two cuts, from both sites of the burr-hole, are joined along the anterior midline by thinning the bone with craniotome blade without the footplate. A few drill holes are made for tack-up sutures. The bone is cracked along the thinned midline. Finally, a hemostatic agent covers the sagittal sinus and a sinus-based dura opening is performed under the microscope. Conclusion: The described one burr-hole craniotomy may represent a more efficient manner for performing an anterior interhemispheric approach. [ABSTRACT FROM AUTHOR]

Background: In this video-abstract, we present one burr-hole craniotomy for the standard suboccipital midline approach developed in Helsinki neurosurgery for the microsurgical management of forth ventricle lesions, distal posterior inferior cerebellar artery aneurysms, and tumoral and vascular lesions of the vermis, cisterna magna region, and posterior brainstem as well. Case Description: We prefer to position the patient in sitting praying position. A midline straight single-layer incision starts on the inion and extends caudally toward the level of C2. The muscles are divided with diathermia along the occipital bone. Three curved retractors, two upward and one downward, provide a wide clean space for the craniotomy. Finger palpation and blunt dissection with cottonoids balls provide identification of the foramen magnum and the spinous process of C1. A burr-hole is made 1 cm lateral and below the level of the transverse sinus. After the detachment of the dura with a curved angled dissector, two cuts from both sites of the burr-hole are made with the craniotome. In case of an adherent dura particularly present in elderly patients, a long blunt flexible dissector (yasargil dissector) is used for the detachment of the bone from the dura. A craniotomy around the midline overlying the occipital sinus and the falx cerebelli is performed to expose medial aspects of cerebellar tonsils, the medulla oblongata, and the occipital sinus. Special care should be taken to avoid damaging the vertebral artery and the epidural sinuses running at the foramen magnum. A few drill holes are made for tack-up sutures. After a craniocervical-based opening of the dura, the fourth ventricle is accessed directly by telovelar route. Conclusion: The described one burr-hole craniotomy may represent the more efficient manner for performing the suboccipital midline approach to the fourth ventricle. [ABSTRACT FROM AUTHOR]

Background: In this video-abstract, we present a one burr-hole craniotomy for the enough lateral approach (ELA) to the foramen magnum developed in Helsinki Neurosurgery, a less invasive variant of the classical far lateral approach. ELA does not require the resection of the occipital condyle nor the exposure of the extracranial/intraosseal course of the lower cranial nerves. The vertebral artery is not transposed and the sigmoid sinus is not skeletonized. ELA allow us to access lesions that are close to the level of the foramen magnum (less than 10 mm). In this regard, low-lying vertebral aneurysms, foramen magnum meningiomas, or low brainstem cavernomas and intrinsic tumors are our common indications for this approach. Case Description: The patient with a foramen magnum meningioma is placed in park bench position with slight backward rotation and elevation of the upper body to maintain the head around 20 cm above the cardiac level. The correct positioning of the head requires slight forward flexion, contralateral rotation, and contralateral tilt to open the angle with the upper shoulder. Under microscopic vision, a straight incision is made behind the mastoid process running between the zygomatic line and 4-5 cm below to the level of the mastoid process. The suboccipital muscles are split with electrocoagulation while the vertebral artery is recognized by digital palpation. Blunt dissection with cotton balls is performed at the occipitocervical junction. Strong retraction maintains a clean space for the craniotomy. A single burr-hole is placed at the posterior border of the craniotomy, and a small 3 × 4 cm craniotomy is performed over the anterior border of the intradural origin of the vertebral artery. The anterior lateral border of the craniotomy is reached under visual control using a diamond drill. In this regard, one more burr hole opposite to the first one would be a tiring and difficult procedure deep inside the lateral margin of the craniotomy. The dura is opened based on the sigmoid sinus and cerebrospinal fluid is released. Finally, under high microscopic magnification, the lesion is properly removed. Conclusion: The described procedure may represent a more efficient lateral approach to the foramen magnum. [ABSTRACT FROM AUTHOR]

Background: In this video-abstract, we present the Helsinki Neurosurgery one burr-hole craniotomy standard subtemporal approach to the floor of the middle fossa and the interpeduncular space. This procedure facilitates access to the multiple structures; the basilar artery bifurcation, the superior cerebellar artery, or the P1-P2 segments of the posterior cerebral artery, and lesions located around the posterior clinoid process/less than 10 mm above it. Even though the specific location and size of the lesion may vary, this approach accesses all mentioned structures with very minimal variation. Case Description: The patient with a basilar artery bifurcation aneurysm is placed in park bench position. A spinal drain is inserted to release 50-100 ml of cerebrospinal fluid. Next, the skin incision starts in front of the tragus above the earlobe, crossing the zygomatic line. Inferior retraction for the craniotomy is provided by hooks and hemostatic Raney clips placed at the superior border of the skin flap. The zygomatic line represents the anatomical landmark of the floor of the middle fossa. A burr-hole is made at the most cranial border of the bone flap. After the detachment of the dura with long flexible blunt dissectors, a craniotomy is performed to expose the dura of the inferior temporal lobe. A few drill holes are made for tacking-up sutures. The dural opening is then performed based on the zygomatic line. Cutting and opening of the tentorium runs posterior to the tentorial insertion of the fourth nerve. Conclusion: The described one burr-hole craniotomy offers a more efficient subtemporal approach. [ABSTRACT FROM AUTHOR]

Background: In this video-abstract, we present a one burr-hole craniotomy for the upper retrosigmoid approach developed in Helsinki Neurosurgery to access the lateral cerebellar hemisphere, the cerebellopontine angle, and lateral skull base (e.g. including the posterior petrous bone). This approach may be utilized to manage tumors of the lateral posterior fossa and to perform microvascular cranial nerve decompression of the V or VII cranial nerves. The upper portion of the vertebral-posterior cerebral artery complex, and the anterior inferior cerebellar artery may also be accessed with this technique. Even though the specific location and size of the lesion may vary, this approach accesses all mentioned structures with a very minimal variation. Case Description: The patient with an unsuspected right cerebellopontine angle metastasis from a lung cancer is placed in the park bench position. Spinal drainage is inserted to release 50-100 ml of cerebrospinal fluid. The head and upper torso are elevated so that the head is about 20 cm above the heart level. A single-layer skin incision is made about one inch behind the mastoid process; the exact cranial to caudal location of the incision varies depending on how high or low one has to be from the foramen magnum and locus of pathology. The junction of the sigmoid and the transverse sinus is usually located just caudal to the zygomatic line, between the zygoma and the external occipital protuberance, and posterior to the mastoid line that is running caudally through the tip of the mastoid process. Dissection with curved retractors creates a clean space for the craniotomy. First, a burr-hole is made at the posterior border of the bone flap. Two curved cuts are made towards the mastoid process, allowing the sigmoid sinus to be partially exposed. The bone is cracked after thinning the anterior border of the craniotomy. A few drill holes are then made for tacking-up sutures. Finally, a sinus-based dura opening is performed under the microscope. Conclusion: Here, we described a one burr-hole craniotomy that provides an excellent approach to retrosigmoid lesions. [ABSTRACT FROM AUTHOR]

Background: In this video abstract, we present a one burr-hole craniotomy for the standard supracerebellar infratentorial (SCIT) paramedian approach developed in Helsinki Neurosurgery for the microsurgical management of pineal region lesions, tentorial meningiomas, as well as arteriovenous malformations, aneurysms, and intrinsic tumors of the superior surface of the cerebellum. In this regard, the use of praying sitting position in Helsinki Neurosurgery, which is a more ergonomic variant of the classic sitting position, offers several advantages such as lower intracranial pressure, good venous outflow, gravitational retraction, and straight anatomical orientation. Case Description: The patient is placed in sitting praying position. A straight single-layer incision is made 2-3 cm lateral from the midline, starting about 1 inch cranial from the inion and extending caudally toward the foramen magnum. Curved retractors provide a wide clean space for craniotomy. A burr-hole is made above the transverse sinus, which may be identified by its anatomic relation with superior muscle insertion line on the occipital bone. After detachment of the dura with blunt dissectors, a craniotomy around the transverse sinus and continuing to the confluens sinuum is performed to expose about 3 cm of the dura below the level of the transverse sinus. In case of an adherent dura particularly present in elderly patients, a long blunt flexible dissector (Yasargil dissector) is used for the detachment of the bone from the dura. A few drill holes are made for tack-up sutures. Finally, a hemostatic agent covers the transverse sinus and a sinus-based dura opening is performed under the microscope. Conclusion: One burr-hole craniotomy for an SCIT paramedian approach may represent the more efficient procedure for approaching the pineal region, inferior surface of the tentorium, and the superior surface of the cerebellum as well. [ABSTRACT FROM AUTHOR]

Background: In this video abstract, we present a one burr-hole craniotomy for the standard lateral supraorbital approach (LSO) developed by Helsinki Neurosurgery. This is a more aesthetic variant of the classic pterional approach. Presently, the LSO approach is most commonly used at our institution. With the LSO technique, the temporal muscle is just minimally opened close to its superior insertion. Posterior and temporal extension of the craniotomy, furthermore, allows adequate access to the anterior skull base, the sellar and suprasellar regions, the middle cranial fossa, the anterior portion of the Sylvian fissure, and the distal Sylvian fissure. Even though the specific location and size of the lesion may vary, this approach accesses all mentioned structures with a very minimal variation. Case Description: The patient with an unruptured anterior communicating artery aneurysm is placed in supine position with the head elevated 30 cm from the level of the heart. The head position is determined by the specific location of the lesion. A curved frontotemporal skin incision is made behind the hairline which stops 2-3 cm above the zygoma. Anterior retraction and hemostatic Raney clips placed at the posterior border of the skin flap maintain a clean space for the craniotomy. A burr-hole is made at the level of the temporal line in the frontal bone. After the dura is detached with blunt dissection, a craniotomy is performed to reach the anterior skull base. A few drill holes are made for tack-up sutures and the dura is opened using conventional techniques. The anterior skull base, sellar/suprasellar regions, and select lesions located in the upper basilar region may be accessed through this subfrontal approach. Middle cerebral artery aneurysms and lesions located along the sylvian fissure or in the middle fossas may also be approached with this exposure, but would require further opening of the proximal sylvian fissure. Conclusion: There we described the LSO one burr-hole craniotomy technique that may represent a more efficient procedure for performing LSO. [ABSTRACT FROM AUTHOR]