PREOPERATIVE DIAGNOSES:
1. Intraventricular tumor, etiology undetermined.
2. Associated ventricular cyst, probably secondary to tumor.
3. Status post diagnosis and biopsy of nasopharyngeal carcinoma involving the
sphenoid sinus, superior clivus, with metastases to right cervical lymph
nodes.
POSTOPERATIVE DIAGNOSES:
1. Intraventricular tumor, etiology undetermined (frozen section consistent
with very low-grade tumor, probably subependymoma).
2. Associated ventricular cyst, probably secondary to tumor.
3. Status post diagnosis and biopsy of nasopharyngeal carcinoma involving the
sphenoid sinus, superior clivus, with metastases to right cervical lymph
nodes.
OPERATIONS PERFORMED:
1. Left frontal bur hole.
2. Image-guided endoscopic biopsy, partial resection of intraventricular
tumor with fenestration and drainage of associated tumor cyst.
3. Use of the endoscope and guidance using MRI-assisted endoscopy.
4. External ventricular drain.
SURGEON:
Michael Edwards, M.D.
ASSISTANT:
ANESTHESIA:
Paul Jackson, M.D., Ph.D.
General endotracheal anesthesia, pediatric anesthesia.
PROCEDURE IN DETAIL: Xxxxxxxxx, with great difficulty, underwent a
stereotactic MR scan. Because of his claustrophobia, sedation was necessary.
He was then brought to the operating room, where careful general endotracheal
anesthesia was established, appropriate lines and monitors placed. An
arterial line and Foley catheter were inserted. He was given Rocephin 2 G.
Hyperventilation was begun and he was given dexamethasone 10 mg. He was
carefully positioned supine and placed in the Mayfield-Kees skeletal fixation.
After he was carefully positioned and all bony prominence and peripheral
nerves were padded, the fiducials on his forehead were correlated with the
image-guided system. We then determined the trajectory at the midpupillary
line overlying the coronal suture that would allow for a post to his tumor
into the ventricle that was smaller than normal necessitating the use of image
guidance. The location for the bur hole was made. We also plotted out an
area to make a craniotomy flap should it be necessary to convert this from an
endoscopic procedure to a transcortical procedure. After marking the skin and
removing the fiducials, we shaved hair in the left frontal area. We left a
marker at the glabella and then we draped out the skin with Steri-Drapes. The
skin was then scrubbed for 10 minutes with Betadine solution, painted with
alcohol and DuraPrep. The skin incision was re-marked. Sterile towels and
Ioban drape were applied. The skin was infiltrated with 5 cc of 0.5% local.
The image-guided system was covered with a sterile drape and a Steri-Drape
placed over the operative site. We again checked using our image-guided
system. We then opened the skin with a #15 blade and a needlepoint Bovie
scalpel and placed a self-retaining retractor. We again located our entry
point on the skull and using the Midas-Rex drill made a bur hole large enough
to receive the endoscope along with the 30K scope. The edges of bone were
bone waxed. The dura was coagulated.
The dura was opened in a cruciate fashion with an 11-blade and coagulated.
The pial surface was coagulated with the irrigating bipolar cautery, and
similarly incised with a #11 blade. The endoscope was set up, white balanced,
and irrigation attached.
Using the image-guided system and calculating the distance from the cortex to
the ventricle, we used a #7 Ellsberg cannula in a pass along the same
trajectory and entered into the ventricle. When CSF was obtained, we removed
the Ellsberg cannula. We carefully advanced the endoscopic sheath down to the
ventricular wall and anchored the sheath to the surrounding drapes with a skin
staple. The internal stylet was removed. The endoscope was slowly advanced
through the protective sheath and we immediately entered into the ventricle.
On inspection of the ventricle, we were able to determine that we were in the
left lateral ventricle. We identified the choroid plexus running posteriorly.
As we looked more anteriorly we identified the choroid plexus in the left
foramen of Monro. The left foramen of Monro was opened, and sitting above it
anterior was a cystic structure with a veil overlying a mass anterior to the
foramen of Monro in the frontal horn of the lateral ventricle. We opened the
veil of tissue and removed the slightly proteinaceous fluid. Biopsies of the
wall were obtained with an endoscopic biopsy forceps and this was reviewed by
neuropathology. There was no specific tumor diagnosis that could be made on
the cyst wall but the cyst wall was widely fenestrated.
Using image guidance and the endoscope, we then obtained multiple biopsies of
the mass, which was white, soft, and relatively nonvascular. No significant
bleeding was noted.
The specimens were reviewed with neuropathology. It was felt that there were
signs of calcification. The lesion appeared to be very low grade, uniform,
long-standing, and the preliminary diagnosis was that of a subependymoma.
There were no signs that this was a malignancy or evidence of metastases from
his nasopharyngeal carcinoma. We realized that the tumor was a portion of the
ventricle. It appeared to be lying under the ependyma and, therefore, the
diagnosis most consistent with a subependymoma. Given that diagnosis, we
decided not to perform a craniotomy at this time, given the child's overriding
nasopharyngeal carcinoma diagnosis and need for treatment, as well as for the
fact that this is a slow-growing lesion and if necessary could be addressed at
a later date, as it was not causing a specific problem at this time. The key
reason for surgery was to rule out this lesion as a metastasis or secondary
malignancy so that appropriate treatment could be planned in one sitting along
with treatment of his nasopharyngeal carcinoma and neck metastases.
We then obtained multiple biopsies of the tumor, which was submitted for
permanent pathology. Adequate tissue was obtained from multiple areas.
We copiously irrigated within the ventricle with warm Ringer's. We made sure
there was no evidence of any bleeding from our biopsy sites. Because of a
concern of the possibility of swelling and the possible closure of the foramen
of Monro, a 35 cm external ventricular drainage catheter was inserted through
the endoscopic sheath and advanced into the body of the left lateral
ventricle. The catheter sheath was removed. The external drain was rather
beneath the skin and brought out through a separate stab wound posteriorly.
We irrigated copiously with saline solution. We sealed the cortical area with
Gelfoam. A piece of Gelfoam was placed over the bur hole. We irrigated the
bone and skin with bacitracin solution. We closed the galea with inverted
interrupted 3-0 Vicryl, the skin with running 4-0 Monocryl. The external
drain was anchored to the skin with a 2-0 silk suture. It was attached to the
connector with a 2-0 silk and a blind connector to prevent any loss of CSF.
Before closing the drain, the ventricle was refilled with warm saline.
We then dressed the wound with Xeroform gauze, Telfa, and Tegaderm, including
the external drain to prevent migration of the drainage system. Throughout the
procedure the use of image guidance was helpful in identifying our location
within the tumor and within the ventricular system. The probe was used to
identify the structures within the ventricle and correlate with the MRI.
At the end of the procedure the drapes were removed, the child was taken out
of the Mayfield-Kees skeletal fixation. He was awoken, extubated, and
returned to the pediatric intensive care unit in stable condition.
The estimated blood loss was less than 10 cc. Blood transfusions none.
Xxxxxxxxx tolerated the procedure well. Needle, sponge, and Cottonoid count
was correct.
SPECIMENS TO PATHOLOGY:
Consisted of intraventricular tumor.
The inpatient attending was Dr. Michael Edwards.