Neurosurgeon Case Studies
- Navigated Resection of a Brainstem Cavernous Malformation
- A Total Resection of an Intraventricular Mass Using Surgical Navigation
- Right Sided, Deep Temporal Lesion With Discrete Perifocal Edema
Navigated Resection of a Brainstem Cavernous Malformation
Patient Profile
Thirty-four-year-old female with a longstanding history of mild, right-sided hemiparesis and left visual disturbance was evaluated by the Barrow Neurological Institute, complaining of a sudden, severe headache accompanied by nausea and vomiting. MR imaging revealed a left pontine and cerebral peduncle cavernous malformation, measuring approximately 3.5 x 2.5 x 1.0 cm in size with evidence of old and new hemorrhage. Following information regarding the risks of surgery, the patient made the decision to proceed with surgical resection of the lesion, utilizing an orbitozygomatic craniotomy.
Operation
Prior to surgery, the patient had fiducial markers carefully placed on her head, then underwent gadolinium enhanced MR imaging, using the StealthStation® protocol. After anesthesia and fixation of the head holder, the StealthStation® TREON® Treatment Guidance System was registered to the patient using a standard paired-point PointMerge® image correlation. Surgery commenced once image correlation was tested and verified. After the craniotomy and osteotomy were performed and the dura retracted, Robert Spetzler, MD, and his team carefully worked their way down to the cavernous malformation. Here again, Dr. Spetzler utilized the StealthStation® system, incorporating an integrated Zeiss OPMI® Neuro/NC4 microscope with MultiVision™ image injection system as a navigational probe. After identifying the exact entry point on the brainstem utilizing the image-guided system, a series of microdissectors were used to gently dissect the cavernous malformation from the surrounding brainstem. Because of the cavernous malformation’s large size, Dr. Spetzler again used the StealthStation® system to assist in dissecting the lesion along its margins, respecting a plane between the cavernous malformation and the adjacent neural tissue.
Conclusion
The patient tolerated the procedure without apparent complication and was taken to the recovery room with stable vital signs. Postoperative CT imaging the day after surgery revealed excellent resection. Following a brief recovery period at the hospital, the patient was discharged to home with no new deficits and is slowly recovering from her previous disability.
Comments
“The introduction of image guidance such as the StealthStation® system integrated to the Zeiss OPMI® Neuro/NC4 microscope has made it possible, for the first time, to remove deep and difficult lesions such as cavernous malformations from such previously inoperable regions as the brainstem. We have removed well over 100 brainstem cavernous malformations that were invisible when the brainstem had been exposed and their localization and subsequent resection was completely dependent on the information provided by the StealthStation® system. There is no question that image guidance has expanded our operative capabilities and led to fewer complications. I depend on it on a daily basis.” - Robert Spetzler, MD, Neurosurgeon, Barrow Neurological Institute, Phoenix, AZ
A Total Resection of an Intraventricular Mass Using Surgical Navigation
Patient Profile
38-year-old female presented with a history of headaches and a normal neurological examination with no prior neurosurgical procedures. Her initial MRI revealed an intraventricular mass and she was medically managed until her six-month follow-up MRI revealed an enlargement of the 2cm enhancing intraventricular mass. After the risks and benefits of surgery were explained to the patient, she decided to proceed with a surgical resection of the mass.
Operation
The patient underwent a gadolinium MRI with fiducials placed pre-operatively. In the prone position, patient’s head was fixed with a Mayfield® head holder, a StealthStation® cranial reference arc attached, registered and verified. Initially the StealthStation® TREON® Treatment Guidance System was used to outline a hair-sparing cranial incision. James Chandler, MD, resected the deep-seated intraventricular lesion, with a minimally invasive approach, using a parieto-occipital craniotomy and guidance with the StealthStation® system. Dr. Chandler was able to minimize the bone and cortical exposure. He again used the StealthStation® system to safely access the ventricular system, which housed the mass, while traversing the least amount of cortical surface. The entire mass lesion was removed utilizing a gentle microdissection technique under the guidance of the Leica® OHS-1 microscope with laser as pointer.
Conclusions
The patient recovered from surgery with no neurological deficits. A 24-hour post-operative enhancing MRI confirmed a gross total resection of the lesion, and no other abnormal findings. The patient was released neurologically intact from the hospital after a three-day post-operative recovery period.
Comments
“The advantage of utilizing a surgical navigation system is for the surgeon to assure the patient the absolute safest surgery possible while ensuring a confidence of a total resection of the lesion. I’m impressed with the StealthStation® image guidance system and what it has allowed me to accomplish in the operating room.” - James Chandler, MD Neurosurgeon Northwestern Memorial Hospital Chicago, Illinois
Right Sided, Deep Temporal Lesion With Discrete Perifocal Edema
Patient Profile
An otherwise healthy, 13 year old boy presented with two seizures and normal neurological and visual field examinations. Diagnostic MRI showed a right sided, deep temporal lesion with discrete perifocal edema and irregular contrast enhancement.
Procedure
The patient was positioned supine, his upper trunk and shoulders hanging slightly over the table and his head turned to the left (Figure 1). Preoperative non-enhanced PoleStar® scans nicely showed the tumor, and its relationship critical structures (Figure 2). During initial approach exact delineation of the tumor was difficult because its color and consistency were almost identical to surrounding healthy tissue. The integrated PoleStar® navigation system proved very useful during this stage (Figure 3). The tumor was carefully dissected and resected as much as possible en bloc. It turned out to be a ganglioma grade II.
Because of the vicinity of eloquent structures such as the basal ganglia (anteromedial) and optic radiation (posteromedial), safety margins in this neurologically intact boy were quite small. For this reason we were happy to have real-time navigation and resection control available.
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Figure 1: Patient positioned supine, shoulders slightly over the table,head turned to the left, head coil positioned over the vertex. The magnet has been lowered from scanning position, enabling the use of standard instrumentation, microscope, and ultrasonic aspirator.
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Figure 2: Pre-craniotomy non-enhanced iMR images in axial plane nicely show the tumor, its relationship to the trigone, and an isolated temporal horn.
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Figure 3: Reconstructed iMR images with navigational crosshairs on the postero-lateral margin of the tumor confirming visual identification in the surgical field.
Conclusions
Comparing post-resection PoleStar® images without and with gadolinium (Figure 4) confirmed that the tumor has been resected completely. Indeed the young patient has made an uneventful recovery without any visual field deficit.
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Figure 4: Pre-op and Post-op axial images with and without gadolinium demonstrate complete tumor resection. The deeper cavity represents the decompressed trigone which is enlarged as the skull is still open.
Interestingly, the resection cavity was much better delineated on iMR images, with open skull and clear irrigation fluid inside, than on high-field strength MR images taken within 24 hours postoperatively (Figure 5). This has consistently been our experience in other cases as well. With more experience we expect these iMR images (though coming from a 0.15 Tesla system) will obviate early postoperative high-field strength MR imaging, certainly in selected cases such as this one.
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Figure 5: Diagnostic MR images are compared to post-op iMR images. Note that resection cavity, trigone and temporal horn were much better seen on iMR images.
NOTE: Each experience described here is specific to a particular patient. Results vary and every response is not the same. Patients should always talk with their doctors to see if they may benefit from this therapy and for a full review of indications and side effects.
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