Indications and Preoperative Considerations
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Selective deep-seated intra-axial tumors can be surgically resected with the use of a tubular retractor system that creates a controlled surgical corridor with minimal brain retraction and damage to surrounding brain tissue.
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This controlled surgical corridor can be used for most intra-axial lesions, including lesions involving:
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Basal ganglia.
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Insular cortex.
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Lateral and/or third ventricle.
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Pineal region.
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Pulvinar/posterior thalamus.
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Surgical Procedure
Patient Positioning
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Preoperative MRI is obtained with fiducial markers (stereotactic navigation) and preoperative trajectory planning with special attention not to injure the corticospinal tracts and/or other eloquent tracts in the brain ( Figure 4.1 ).
Figure 4.1 Pre- and postoperative imaging. (A) Preoperative T2-weighted FLAIR image. A non-enhancing lesion is seen arising in the posterior third ventricle. This lesion was compatible with an epidermoid tumor. (B) Postoperative T2-weighted FLAIR image after a resection via the trans-sulcal approach with a tubular retractor. The lesion has been resected and the trajectory of the tubular retractor can be visualized. These images demonstrate the minimal invasive access with minimal impact to the surrounding parenchyma.© A. Quiñones-Hinojosa. - •
A Mayfield headholder is applied and registration with the navigation system is performed.
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The head is rotated so the tumor plane is perpendicular to the floor.
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The head is kept above the level of the heart.
Skin Incision
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The incision and craniotomy are planned based on the location of the lesion using preoperative MRI and/or frameless stereotactic navigation.
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Patients with anterior lesions in the basal ganglia can also be approached through an eyebrow or eyelid incision with a supraorbital craniotomy.
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Soft tissue dissection should be carefully made with good hemostatic control.
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The musculocutaneous flap can be retracted with retractors or elastic bands depending on the shape of the flap.
Craniotomy
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An entry point is selected based on tumor location and image guidance.
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One burr hole is often sufficient for small craniotomies. Extended craniotomies may require more burr holes.
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Gentle detachment of the dura mater from the bone is done with a Penfield No. 3 dissector.
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A tailored craniotomy is performed with a high-speed drill. The craniotomy must be large enough to fit the tubular retractor.
Dural Opening and Intradural Dissection
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Dural opening is done according to the need of resection and localization of the lesion. Generally a cruciate dural opening is performed. A C-shaped opening is also a feasible option.
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For subcortical tumors, a cylindrical retractor may be inserted through the planned surgical corridor to access the deep-seated pathology and to protect the healthy parenchyma and surrounding white matter during the resection.
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The initial approach can be transcortical or trans-sulcal.
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Corticectomy or sulcus splitting is planned such that any major veins and arteries will not be sacrificed. Non-eloquent gyrus can be entered so that eloquent gyri may be preserved. Cortical stimulation with cortical mapping can also be useful when eloquent cortex is involved and/or where the question arises.
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Some procedures can be performed while the patient is awake.
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Major white fiber tracts must be avoided at the depth of the trajectory.
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The corticectomy is done via a pial incision for the transcortical trajectory, while an arachnoid dissection is made for a trans-sulcal trajectory. The opening must be large enough to place the retractor tube.
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A 14-French peel-away sheath cannula can be advanced into the parenchyma with the navigation probe along the desired trajectory.
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The elliptical-shaped tubular retractor gently splits the cortex as it is advanced into white matter without further damage or transection ( Figure 4.2 ).
Figure 4.2 (A) Visual field with the tubular retractor. The white matter can be visualized. (B) Visual field after removing the tubular retractor. The cortical transection is minimal. The surrounding parenchyma has not been affected; there were no signs of ischemia or brain edema on postoperative imaging.Stay updated, free articles. Join our Telegram channel

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