First, let us revisit Bacon’s famous quote: Every man owes it a debt to his profession to put on record whatever he has done that might be of use to others. -Francis Bacon (1561-1626) Neurosurgery Department, Helsinki, Finland Professor Juha Hernesniemi is currently recognized as a top authority on cerebrovascular disease in the international neurosurgical community and a representative leader in the microsurgical treatment of cerebrovascular disease. I have benefited from studying with Prof. Juha Hernesniemi in the Department of Neurosurgery in Helsinki, Finland. Pineal tumors are diverse and often present with severe clinical symptoms. Since the pineal region has a very important deep venous system as well as midbrain and mesencephalic structures, pineal tumor resection is an extremely complex and risky procedure in neurosurgery, and is recognized as one of the most challenging procedures in the neurosurgical community. Here, I detail Prof. Juha Hernesniemi’s experience regarding microsurgical treatment of pineal tumors (119 cases from 1980 – 2007). The first such surgical access was performed by Horsley, Brummer and Schloff with very poor results. Eight years later, Dandy used a transcallosal approach to remove three pineal tumors, but the results were still poor. in 1926, Krause used a supratentorial approach to remove three pineal tumors with no surgical deaths. In 1931, Van Wagenen proposed a transcortical-lateral ventricular approach via the right parietal and lateral ventricles to reach the pineal region. Subsequently, Suzuki completed 19 pineal tumor resections using this approach in 1965, with only 2 cases without postoperative complications. With the development of micro-neurosurgical techniques, the supratentorial (proposed by Krause and improved by Stein) and trans-cerebellar occipital longitudinal approach (proposed by Poppen and improved by Yasargil) have greatly reduced the surgical morbidity and mortality rate. In addition, advances in neuroimaging techniques, better knowledge of anatomy, and improved perioperative care and anesthesia techniques have led to significant improvements in surgical outcomes for lesions in the pineal region, with a near-zero morbidity and mortality rate. Professor Juha Hernesniemi’s group of 119 cases, 107 pineal tumors, 6 Galen’s vein malformations, 4 cavernous hemangiomas, and 2 AVMs, were treated primarily with a supratentorial cerebellar approach.Professor Juha’s understanding and implementation of surgical principles follows the philosophy of Francis Bacon and Drake: ” simple, fast and preserves normal: “The anatomical considerations of the pineal region] The deep cerebral veins and neural structures surrounding the pineal gland are extremely complex and pose a great problem in designing the surgical approach. The surgical anatomy of this area focuses on the deep veins such as the Galen vein and its branches, and Chaynes describes these vascular anatomies in great detail, which makes it easier to focus on the surgically relevant anatomy. The supratentorial approach to the pineal gland is suitable for resection of pineal lesions because the majority of these large veins are located above this approach. Pineal region] The dorsal aspect of the pineal region is the tetraspanic pool, which is conical in shape, and its top is the lower surface of the corpus callosum pressure. The upper part of the anterior wall of the pineal region is composed of the pineal gland, the bridle triangle and the medial part of the medial bridle and, laterally, the medial part of the thalamus occipitalis. The middle part of the anterior wall of the pineal gland consists of the perineal cap of the tetraspanic pool, while the pineal gland bodies are located between the paired superior colliculi. The lower part of the anterior wall of the pineal gland consists of the earth tongue located in the midline and the superior peduncle of the cerebellum on either side. The underside of the pineal region consists of the superior ventral flank of the cerebellum. The lateral surface of the pineal region is composed of: anteriorly by the peduncle of the fornix and posteriorly by the medial surface of the occipital lobe (below the pressure of the corpus callosum). The angle between the base and the apex of the pineal region: Galen’s vein enters the rectus sinus. Galen’s vein and its branches] The Galen’s vein originates a few millimeters posterior to the pineal gland, and the vein itself varies in length from a few millimeters to 1 inch. the Galen’s vein travels posteriorly and laterally, draining into the rectus sinus (which is approximately 1 cm from the apex of the pineal gland). According to Chaynes’ study, the veins that receive drainage from the Galen vein include The internal cerebral vein: originates at the posterior border of the foramen of Monro and joins the septal vein and the thalamus vein. The two internal cerebral veins travel over the roof of the three ventricles without any bridging veins connecting them. The internal cerebral vein travels inferiorly to the corpus callosum pressure and reaches the lateral pineal gland, then travels upward and joins the Galen vein. 2. The anterior central cerebellar vein and the superior earthworm vein: these veins run in the middle cerebellar fissure and above the superior cerebellar peduncle. They can either merge into Galen’s vein separately or as a trunk (i.e., superior cerebellar vein). 3. Basilar vein: It follows the optic tract medially posteriorly and inferiorly, travels laterally between the cerebellar peduncle and the hook gyrus, and finally enters the tegmental pool. Its confluence with Galen’s vein is located below the point of confluence of the internal cerebral veins. 4. Medial occipital vein: This vein originates from the inferior medial aspect of the occipital lobe, drains the medial aspect of the occipital lobe, travels anteromedially, and converges into the lateral part of Galen’s vein. Arteries associated with the inferior superior cerebellar approach and the longitudinal fissure approach through the cerebellar curtain] 2 posterior choroidal arteries: the medial branch and the lateral branch. The posterior medial choroidal artery originates from the posterior medial part of the proximal posterior cerebral artery (located in the interpeduncular pool), then travels within the circumventricular pool (parallel to the posterior cerebral artery), supplying blood to the superior-inferior colliculus and pineal gland, and then travels along the choroidal tissue of the three ventricles. The posterior medial choroidal artery folds backward at the foramen of Monro and enters the choroid plexus in the lateral ventricles, where it anastomoses with the posterior lateral choroidal artery and supplies blood to the anterior thalamic nucleus, medial geniculate body, and thalamic occipital. The posterior lateral choroidal artery originates from the posterior cerebral artery, travels within the cricoid pool, enters the choroid plexus of the lateral ventricle via the choroidal fissure, and forms an anastomosing branch with the posterior medial choroidal artery and the anterior choroidal artery. The posterior lateral choroidal artery is responsible for the blood supply to the lateral geniculate body and part of the thalamus. The tegmental or parietal artery originates from the posterior cerebral artery and joins medially with the posterior communicating artery. It travels within the circumventricular pool and is responsible for the blood supply to the superior colliculus. Branches of the superior cerebellar artery are responsible for the blood supply to the inferior colliculus. The medial occipital artery is an extended branch of the posterior cerebral artery and gives off the talar artery into the talar sulcus and the parieto-occipital artery into the parieto-occipital sulcus. The inferior inferior cerebellar approach requires the head to be flexed 30° forward (approximately 2 transverse finger widths between the mandible and the clavicle) for exposure of the inferior inferior approach. This angle allows for an almost horizontal position of the cerebellar curtain and facilitates the surgeon’s manipulation. Skin incision A median or paramedian incision is made over the external occipital ridge and extends towards the cervicococcipital region for approximately 3-5 cm. The posterior cervical musculature is stripped and pulled laterally to expose the occipital bone. Two curved automatic retractors are routinely used, and when possible, the muscles in the midline area are not stripped to avoid bleeding. Craniotomy A hole is drilled medially in the superior parietal aspect of the external occipital ridge. In young patients, only one drill is sufficient. In the elderly, 2-3 holes are required because of dural adhesions. This requires special attention to the location of the sinus sink, whose damage can lead to fatal and catastrophic results, so the key task during the craniotomy is to protect the sinus sink and the transverse sinuses on both sides. When stripping the dura mater adhering to the intraoccipital ridge, we use a special curved striker. A small bone flap is freed around the transverse sinus miller. During this procedure, air embolism due to venous hemorrhage is not uncommon, although it can be monitored by precordial Doppler or based on a decrease in end-expiratory carbon dioxide concentration (less than 3.0 mmHg). The location of venous hemorrhage can be quickly detected by compression and closure of the jugular vein. Dural opening and tumor resection The dura is usually cut in a “Y” pattern, while for paramedian craniotomy, the dural flap is drawn toward the transverse sinus (unilateral), and for both right and left cerebellar hemispheric dura, the dural flap is drawn toward the transverse sinus and sinus confluence line for fixation. The midline sinus of the cerebellar falx can sometimes be avoided, and in case it must be faced, careful suturing, bipolar electrocoagulation cautery, and the use of biologic gel are required to stop the bleeding. In fact, this bleeding is not obvious in the seated position, whereas it is not in the prone position. The superior cerebellar vein and the draining veins on the cerebellar surface can be cut by electrocoagulation in order to better expose the operative field, which does not lead to postoperative complications. It is safer to cut the draining veins as close to the cerebellum as possible rather than close to the cerebellar curtain. Of course, we want to protect these draining veins as much as possible to reduce the chance of postoperative venous infarct hemorrhage. After complete separation of the arachnoid and drainage veins between the cerebellum and the cerebellar curtain, the cerebellar tissue then naturally drops down, which creates a very good surgical view without pulling the brain tissue. If necessary, the occipital pool can be opened and cerebrospinal fluid released to further reveal the surgical field. Along the surgical pathway, the dorsal arachnoid pool of the midbrain is reached, opened to release cerebrospinal fluid and further expand the surgical space for further separation. At this point, it is critical to clearly identify the deep veins within the dark blue arachnoid pool. The central anterior cerebellar vein is exposed and, if necessary, electrocoagulated to facilitate adequate exposure of the Galen vein and the anatomy beneath it. This is the most important part of the procedure. Sometimes, the arachnoid membrane in this area is abnormally thickened due to tumor irritation, which makes dissection difficult. Usually, we start the separation from the lateral side first, and after finding the anterior central cerebellar vein, we trace it back to its source, taking care to avoid damaging the posterior choroidal artery during the separation. The separation is started from the lateral side of the tumor and intra-tumoral decompression is performed using suction and electrocoagulation until the posterior part of the three ventricles is revealed. The ultrasonic suction knife is not very helpful in pineal tumor surgery due to the small operating space, especially when dealing with the anterior aspect of the tumor, which requires extra-long instruments. In some cases, we also only partially remove the tumor because it is malignant in nature and has eroded the surrounding vital structures. The surface of the tumor is often covered with a thick layer of arachnoid membrane that obscures the tumor. After opening the arachnoid membrane with microscopic scissors and bipolar forceps, the tumor can be revealed and then a portion of the tumor is immediately excised for pathological examination. Intra-tumor resection is performed using suction and bipolar electrocoagulation with simultaneous electrocoagulation of the blood vessels within the tumor. When adequate decompression within the tumor is completed, the tumor capsule wall is fully freed from the surrounding veins using a water separation technique. The trophoblastic vessels entering the tumor can be cut off by electrocoagulation. The posterior part of the three ventricles is completely opened to release cerebrospinal fluid to create additional space to separate the remaining tumor tissue. Great care is taken when dealing with the posterior company and the underlying corners, as even the slightest hemorrhage in this area can be catastrophic. Therefore, in this area, even the smallest vessels need to be cut by electrocoagulation to avoid tearing these vessels while dragging the tumor. The final exploration is performed using endoscopy. In our experience, hemostasis was quite difficult in two cases, one in an infant with a ganglioneuroma and the other in a female patient with a hemangioepithelial cell tumor. In conclusion, careful hemostasis is paramount, as even the smallest clot within the trigeminal ventricles may lead to acute hydrocephalus. Transoccipital longitudinal approach] This surgical approach is mainly used to manage vascular malformations and meningiomas in the pineal region. Initially, a “U” shaped flap was used, which was first used by Yasargil. Nowadays, we use a straight paramedian incision, about 7-8 cm long, with 2 automatic retractors to open the incision, one above and one below. Usually we choose a right-sided approach. The craniotomy is performed by drilling one hole in the midline and then using a milling knife to free 3-4 cm of bone flap after carefully separating the subdural bone flap. In the elderly, 2 holes are often required. Dissection of the dura The dura is dissected under the microscope. If the sagittal sinus is scratched, repair with atraumatic sutures is required. The occipital lobe is gently retracted with bipolar electrocoagulation to reveal the area below the corpus callosum pressure. There is usually no bleeding during this procedure because the occipital lobe has few bridging veins. After the occipital lobe is protected by a cotton pad, the retractor is placed. The posterior corpus callosum and dorsal arachnoid pool of the midbrain are opened and cerebrospinal fluid is released to create enough space to complete the tumor resection. If necessary, the falx and cerebellar curtain can be opened using a blade or microscopic shears. The safest and easiest way to incise the cerebellar curtain is to make a 1 cm long incision in the midline, posterior to anterior, which avoids damaging the superior cerebellar vein of the pontine vein, which is often sacrificed if the approach is made from below the curtain. The length of the cerebellar curtain incision should be sufficient to allow direct visualization of these pontine veins; too small an incision increases the difficulty of hemostasis. Great care should be taken to avoid injury to the larger vein connecting the large Galen vein. Here, care needs to be taken to protect the Rosenthal vein, which is often confused with the dark blue dorsal midbrain arachnoid pool. In addition, the internal occipital vein and the posterior periportal vein will be encountered, and injury to these veins often leads to lateral isotropic hemianopia and venous infarction. Venous hemostasis methods: electrocoagulation and fibrin glue (fibrin glue is a very effective method for managing venous bleeding.)