Name:
Occipital interhemispheric transtentorial approach to a pineoblastoma in a 4-year-old child
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Occipital interhemispheric transtentorial approach to a pineoblastoma in a 4-year-old child
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T00H10M07S
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Upload Date:
2021-06-07T00:00:00.0000000
Transcript:
Language: EN.
Segment:0 .
[MUSIC PLAYING]
SPEAKER 1: In this video, we describe the occipital interhemispheric transtentorial approach to pineoblastoma in a four-year-old child. The patient is a four-year-old baby girl with a history of headache and morning vomiting in the last month and drowsiness in the week before admission. Neurological exam at admission reveals speech delay and the left sixth cranial nerve palsy. CT scan and craniospinal MRI show the triventricular hydrocephalus induced by a pineal mass without evident CSF seeding.
SPEAKER 1: These are the images of MRI at presentation, showing the midline pineal mass inducing obstructive triventricular hydrocephalus. It was decided to treat the hydrocephalus by endoscopic ventriculostomy and biopsy the tumor with the single burr hole technique, allowing both procedures through the same approach. After identification of the ideal trajectory for ETV, joining the tuber cinereum and the central motor foramen and the identification of the ideal trajectory for tumor biopsy, joining the tumor surface in the central motor foramen, we identify an entry point in the middle of the two trajectories, allowing both procedures through a single burr hole.
SPEAKER 1: Endoscopic view shows the good visualization on both the floor of the third ventricle and of the tumor mass. The small white spots of the ependyma, although suspicious for seeding, were not biopsied because considered too small. After standard third ventriculostomy, the endoscopy is directed procedurally, and the tumor is approached from behind the mass intermedia.
SPEAKER 1: Biopsy of the tumor mass can induce a small bleeding that can be managed by delicate balloon inflation. At the end of the procedure, only minor contusions or mass intermedia fornix are visible without clinical consequences. This is the immediate postoperative CT scan showing clean ventriculoscopy track with safety EVD that was removed 48 hours later. MRI performed three months after a biopsy showed on T2 DWI and the ADC sequences absence or white matter damage in the right frontal lobe following the single burr hole procedure to prove safety and feasibility of the technique in presence of anatomical conditions and with a good preoperative planning.
SPEAKER 1: Histology revealed a pineoblastoma. CSF cytology was negative, and neoadjuvant chemotherapy with vincristine and carboplatin was administered that allowed significant reduction of the tumor volume. Neoadjuvant chemo is especially important in pineoblastomas that are highly hemorrhagic lesions in reducing vascularity at radical surgery. Surgical removal of the residual tumor was decided, and two options of surgical approaches were considered, the supracerebellar infratentorial approach and the occipital interhemispheric transtentorial approach.
SPEAKER 1: The SCIT approach can be uncomfortable in prone position, carries a risk of air embolism in sitting position. It is a fully infratentorial procedure with a deep narrow field can be difficult in case of steep tentorium. Sacrifice of bridging veins is necessary, and it is considered better for midline lesions. For the OITA approach, a preoperative lumbar drainage is preferable.
SPEAKER 1: It is performed in prone proposition. It's a mainly supratentorial procedure, offering the wide field after tentorium opening. It can be used independently on tentorium angle. Venous sacrifice is not always necessary and offers a better lateral exposure. To select the approach, a sagittal midline cut is chosen. The lowest point of the vein of Galen is identified. Then, the highest point of the torcular Herophili is identified.
SPEAKER 1: The line joining these two points, the Herophilus Galen line, identifies the highest possible line of sight of a microscope when performing an occipital interhemispheric transtentorial OITA approach. In this case, 100% of the tumor volume is located below this line and is therefore perfectly controlled through an OITA approach. This 3D reconstruction shows that the microscope view along the Herophilus Galen line of sight offers perfect control of the upper part of the tumor, and adequate modification of the microscope working angle allows good control of the whole tumor volume.
SPEAKER 1: Torcular was very asymmetric due to predominant right transverse sinus, so the tumor was approached through the left side. Position is prone with head in three-piece head frame turned to 15 degrees to the right. This 3D model shows the orientation of the surgical corridor from surgeon's point of view. The key structures of the torcular and the sagittal sinus and the extension on the bone flap, including the lambda, and crossing the midline for the best possible control of the sagittal sinus.
SPEAKER 1: We prefer sigmoid incision, allowing easier midline dissection in the cervical region and larger occipitoparietal craniotomy. These are the bone exposure and the extent of the craniotomy flap with control of the torcular and sagittal sinus. After opening of the lumbar drainage, interhemispheric dissection allows identification of the tentorium and quadrigeminal cistern.
SPEAKER 1: Tentorium is extensively coagulated with the bipolar, and then it is largely opened using the contact Thulium laser. The arachnoid of the quadrigeminal cistern is exposed and opened using a Rhoton dissector or a sharp dissector. Larger opening of the arachnoid allows easy identification of the tumor tissue, and after completion of this step, the dissection of the deep vein complex can start.
SPEAKER 1: After chemotherapy, the arachnoid can be very thick. So sharp dissection is necessary, at least to open the outer layer of arachnoid that covers both the tumor and the deep vein complex to avoid the risk of traction or tearing of vessels. The initial dissection allows the unveiling of the vein of Galen and of the homolateral basal vein of Rosenthal. And the red, dark mass of the tumor is well visible among them.
SPEAKER 1: After initial dissection and identification of the veins, tumor dissection can start, allowing identification of the superior vermian vein. The outer layer of the tumor is coagulated and opened sharply, and biopsy followed by internal debulking can be carried out with the ultrasonic surgical aspirator, until visualization of the cavity of the third ventricle. Then, we start to dissect the lateral extensions of the tumor, starting from the left pole that can be delicately removed by gentle fragmentation and aspiration with the ultrasonic device.
SPEAKER 1: At this point, we improve our dissection of the deep vein complex. After chemotherapy, deep veins are embedded in a thick layer of arachnoid tissue that can nevertheless be opened, allowing sharp dissection and identification of the vein of Galen, internal cerebral veins, basal vein of Rosenthal, and superior vermian vein. Here, we are dissecting the left internal cerebral vein from the superior vermian vein.
SPEAKER 1: As you can see, the arachnoid layer is very thick. But sharp dissection allows identification of the dissection plane between the thick arachnoid layer and the wall of the veins, allowing dissection and identification of all the anatomical structure, avoiding excessive traction on the wall of the veins. After complete anatomical identification of the two Rosenthals, two internal cerebral veins, vein of Galen and superior vermian vein, safer dissection of the upper pole of the tumor can be performed after sacrifice of the superior vermian vein.
SPEAKER 1: that is the only vein of the complex that can be sacrificed with impunity, if necessary. After this step, it is possible to have clear and larger access to the contralateral side, where the right component of the tumor can be finally dissected and removed. Here, the last adhesions or the last remnant of the tumor are disconnected, and the tumor is removed. And this is the cavity of the third ventricle. The last remnants of the lower pole are easily identified on the tectal plate, carefully dissected and removed at very high magnification.
SPEAKER 1: The operative field is limited by the splenium intracranial part, the left internal cerebral vein, the contralateral basal vein of Rosenthal in the upper part of the operative field, and the homolateral basal vein of Rosenthal in the lower part. Vein of Galen is evident in the cranial part of the field at the attachment with the tentorium falx junction. This is an overview of the surgical field at the end of surgery at lower magnification, showing the falx in the tentorium with the straight sinus running at the attachment.
SPEAKER 1: Occipital lobe surface is clean, without contusions after patties removal. This is the postoperative MRI is axial cuts and sagittal cuts showing complete removal of the tumor. T2 DWI and ADC sequences showed absence of cortical or white matter damage in the left occipital lobe due to retraction and absence of vascular problems related with the sacrifice of the superior vermian vein.
SPEAKER 1: The patient presented to transient upward gaze palsy, Parinaud's syndrome, without focal deficit. This is the patient dancing at her sixth day postoperatively. Asymptomatic left subdural hygroma was precautionary treated by subdural peritoneal shunt before referring to high-dose chemotherapy with the rescue peripheral blood stem cells transplantation. Craniospinal irradiation was administered with 54 Gray boost on tumor bed.
SPEAKER 1: In conclusion, pineoblastomas are exceedingly rare entities. Initial endoscopic single burr hole technique is key for treatment of hydrocephalus and tissue sample. Neoadjuvant chemotherapy allows tumor shrinkage. The Herophilus Galen line of sight is helpful in choosing surgical approach. Interhemispheric transtentorial approach allows complete removal of residual tumor without neurological deficits.