January 19, 2016
Spinal cord ependymomas harbor different degrees of adherence to the surrounding normal cord, and also may carry cystic components. Let's review the case of a 48 year old male who presented with myelopathy, and, on MRI evaluation, was diagnosed with a mass within the spinal cord. This intramedullary mass contained a cystic component, a solid component, and a small hemorrhagic component at its inferior pole. I expect this cyst to have a gliotic wall, which would be very adherent and infiltrative to the surrounding spinal cord ependyma. This gliotic margin should not be manipulated. The solid component can be readily removed, as long as it's not very adherent to the dorsal spinal cord columns. The hemorrhagic component, obviously, should be readily resectable. You can see the appearance of this lesion, which is relatively heterogeneous on enhanced coronal images. On axial images, again, you can see the cystic component and the solid component of this ependymoma. This patient underwent multilevel cervical laminectomy. A midline durotomy was completed. SSEPs and motor evoked potentials were monitored. You can see the appearance of the expanded spinal cord, stimulation may be used for localizing the exact midline. A midline myelotomy is completed and the cyst was entered. The tumor was first biopsied. It was consistent with a low grade ependymoma. Therefore, the myelotomy was lengthened and the solid portion of the tumor was identified. You can see the tumor is relatively adherent to the surrounding dorsal columns. I continued to dissect around the solid portion and was able to remove a portion of the solid component for further histopathological analysis. To find the solid portion of the tumor, I continued my myelotomy more superiorly. Here is the more solid part of the tumor. Here is the gliotic margin of the cyst. The solid portion is more dissectable, better defined. This solid portion is delivered into our resection cavity. Further removal is possible via extension of the midline myelotomy. Sharp incisions within the spinal cord is more appropriate. You can see the solid portion of the tumor is being dissected. The angle dissector minimizes the need for aggressive retraction of the spinal cord. I used some temporary peel incisions to be able to more effectively dissect this solid portion of the tumor. This is the inferior aspect of the myelotomy. You can see the gliotic wall of the cyst is very much incorporated into the spinal cord ependyma and parenchyma, and should not be aggressively manipulated. The myelotomy is just gently and slightly further expanded inferiorly to expose the inferior hemorrhagic pole of the tumor, as demonstrated at the tip of my arrow. The margins between the tumor and the spinal cord are more identifiable along the solid portion of the tumor. Obviously, these margins will disappear as one gets closer to the cystic portion of the mass. Coagulation is minimized, and pulmonary irrigation is used to keep the operative field clean. Retraction maneuvers and dissection maneuvers are adjusted based on any changes in MEPs and SSEPs, where the tumor becomes very adherent to the anterior aspect of the spinal cord. The tumor is sharply cut, and the gliotic wall, again, is left untouched. Here is the superior pole of the resection cavity. You can see the color of the cystic wall is different than the tumor. Some changes within the motor evoked potentials were noted at this time, and all the peel retraction sutures were released. After these changes subsided, further resection of the tumor was continued without the use of peel retention sutures, and you can see the gliotic wall of the cyst versus the tumor. The color and consistency is quite different. Obviously, complete removal of this tumor is not safe. Only the part that is readily dissectable without injuring the parenchyma of the spinal cord is evacuated. Further inspection reveals the small nodules of the tumor, some of which can be safely mobilized, other ones are left behind or slightly coagulated. Then this wall of the cyst is left untouched as much as possible. Here's the hemorrhagic part of the tumor. Ample amount of irrigation is used during gentle coagulation of the bleeding sources. Further inspection reveals no gross tumor, or grossly visible tumor that can be removed. Immaculate hemostasis is secured. The dura is closed in a watertight fashion using a running suture. This patient awoke from the anesthesia with some worsening in his sensory function. This function has improved significantly in the six months follow-up. Thank you.
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