Pineal Region Astrocytoma: Midline Supracerebellar Approach
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Most pineal region masses are removed via the midline suboccipital supracerebellar craniotomy. However, I have really enjoyed the use of a paramedian lateral cerebellar or lateral supracerebellar craniotomy for resection of these tumors, as the more inferior slope of the lateral cerebellum allows a more unobstructed or unhindered operative trajectory toward the midline. Let's go ahead and review this traditional midline supracerebellar approach for a section of pineal region masses. This is a 16 year-old female who presented with sudden onset headaches. MRI evaluation revealed a partially hemorrhagic mass within the area of the anterior vermis and pineal region. Patient underwent the procedure in the sitting position to allow cerebellar sagging, therefore increasing the operative corridor within the supracerebellar area. You can see the placement of this skull clamp. A midline incision was utilized. You can see the dissection along the midline avascular planes to avoid injury to the muscles, decreasing the risk of postoperative neck pain. Two burr holes were placed just inferior to the edges of the transverse sinus and a small craniotomy was elevated. Again the foramen magnum was not unroofed as this procedure is primarily within the supracerebellar corridor. Here's the exposure of the torcular and transverse sinuses on roofing of these dural venous sinuses is important so that these venous sinuses can be mobilized superiorly using retention sutures. Here's the interdural part of the operation. You can see the sitting position allows sagging of the cerebellum and a wide operative trajectory toward the midline. One or two bridging veins may have to be sacrificed. Next the arachnoid bends over the anterior vermis are exposed. This mass is essentially an anterior vermis mass, therefore manipulation of the pineal gland or the area related to the pineal gland is not necessary. Here you can see the arachnoid bands over the pineal region. Here's the part of the tumor involving anterior vermis. Mass is somewhat hemorrhagic, small court economy's completed the tumor is interred and debarked and biopsied. This tumor turned out to be a pile of cystic astrocytoma. Resection was extended all the way to the level of the colliculi. An important operative blind spot is just around the cerebellum close to the superior aspect of the fourth ventricle. I generally use dynamic retraction and angle the microscope from the superior to inferior direction, to be able to inspect this operative blind spot and assure complete removal of the mass. Alternatively, a lateral superior cerebellar approach provides a more inferior trajectory toward the more caudal part of the mass. Here's the opening toward the fourth ventricle, that means the tumor has been adequately evacuated. No residual tumors apparent. And the post-operative MRI revealed growth store resection of the mass without any complicating features. Thank you.
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