**3.2 Case 2: 40 year-old male with a brainstem ependymoma**

A 40 year-old male presented with cervical myelopathy (bilateral sensory loss in the hands, broad based gait, neck pain, and clonus). Imaging revealed a heterogeneously enhancing, intrinsic, intra-axial lesion at the craniocervical junction, with cystic and solid components (**Figure 2A** and **B**, yellow arrows). The index surgery was performed conventionally with intraoperative neuromonitoring (IOM) of somatosensory and motor evoked potentials (SSEPs and MEPs, respectively)

#### **Figure 2.**

*Intra-axial cervico-medullary recurrent ependymoma. Pre-op MRI A) sagittal T2WI and B) sagittal T1WI post-contrast scan showing cystic partly enhancing lesion. Post-op MRI C) sagittal and D) axial T1WI post-contrast scans showing generous resection. Post-contrast E) sagittal, F) coronal, G) axial T1WI and H) sagittal, and I) axial T2WI showing tumor recurrence in the previous surgical bed. Pre-op fMRI showing J) sagittal, K) coronal, and L) axial views of the recurrent tumor completely displacing the motor fibers. Post-op MRI M) sagittal, N) axial T2WI and O) sagittal, P) axial T1WI post-contrast scans of the repeat resection cavity. Yellow arrows indicate location of the tumor.*

#### *Pre-Surgical and Surgical Planning in Neurosurgical Oncology - A Case-Based Approach… DOI: http://dx.doi.org/10.5772/intechopen.99155*

via a posterior midline dorsal raphé approach with a myelotomy just inferior to the obex. Further resection was halted when the patient demonstrated prolonged drops in blood pressure and periods of asystole with ongoing dissection. Intra-operative frozen section pathology revealed a low-grade ependymoma. Post-operative imaging demonstrated a generous decompression (**Figure 2C** and **D**, yellow arrows). The patient had complete recovery of his myelopathy and he deferred adjuvant treatment, choosing to have follow-up surveillance with sequential imaging.

After 3 years of surveillance, the patient re-presented with recurrent symptoms and a recurrent tumor in the same location though significantly larger (**Figure 2E**–**I**). DTI images were acquired, clearly depicting that the pyramidal tract was displayed anterior and lateral to the lesion (**Figure 2J**–**L**, yellow arrows), allowing for a surgical window from posterior for resection. Resection for recurrent disease was again performed with IOM of SSEP, MEPs, monitoring of cranial nerves 5, 7, 9, and 12, as well as direct nerve stimulation. A suitable plane was established allowing for a gross total resection of what now was diagnosed as a tanycytic ependymoma. Only minimal amplitude drops in SSEPs were encountered during the surgery. Due to the manipulation of the recurrent surgical bed and delicate nature of the surgery, the patient was kept intubated following the surgery on high-dose steroids to prevent peri-operative edema of the surrounding brain stem tissues. He was successfully extubated on post-operative day 3 with no neurological deficits. Post-operative imaging showed no residual disease and a slim rim of cervical medullary parenchyma that carried all functional tracts with a large access window posteriorly positioned exactly between the posterior funiculus (**Figure 2M**–**P**, yellow arrows).

### **3.3 Case 3: 68 year-old female with a left subfrontal glioma**

A 68 year-old female patient presented to our emergency department with new onset speech arrest episodes interpreted as seizures and secondary manifestation as Grand Mal. She had an unremarkable past medical history and no systemic signs of infection. The patient was started on antiepileptic drugs with an MRI scan revealing multiple ring enhancing lesions in the left frontal lobe (**Figure 3A**–**C**, yellow arrows). Differential diagnosis included primary CNS malignancies (e.g. malignant glioma), secondary malignancy (e.g. metastasis or lymphoma), or abscess. fMRI scan showed localization just adjacent to Broca's area but without infiltration of the frontal operculum (**Figure 3D**–**F**). A frontotemporal image-guided craniotomy was performed with intraoperative frozen pathology indicative of malignant glioma. Post-operative imaging demonstrated a generous resection (**Figure 3G**–**I**, yellow arrows). The patient went on to receive post-operative concurrent chemo-radiation as per the Stupp protocol.

### **3.4 Case 4: 38 year-old male with a fourth ventricular ganglioglioma**

A 38 year-old male presented with episodes of headaches and nausea with no neurological deficit. MRI scan revealed a 1.5 cm ring enhancing lesion in the inferior 4th ventricle that was considered to be a neoplasm or infection (**Figure 4A**–**C**, yellow arrows). It was difficult to ascertain from the MRI scans whether the lesion was intra-axial or intraventricular. CTA showed low vascularity of the lesion (**Figure 4D**–**F**, yellow arrows). DTI showed displaced corticospinal fibers with a suitable access corridor from posterior using a planned unilateral telovelar approach (**Figure 4G**–**I**, yellow arrows). Surgery was performed with IOM, SSEP, MEP and cranial nerves 5, 7, 8, 9, and 10 monitoring. A small remnant of tumor was left laterally in situ since attempts for a complete resection caused cranial nerves 9 and 10 signal changes. Successful

#### **Figure 3.**

*Left sub-frontal glioma. Pre-op MRI A) sagittal, B) coronal, and C) axial T1WI post-contrast scans showing solid-cystic, multi-focal, enhancing lesions in the left subfrontal cortex. Pre-op fMRI scans showing D) sagittal, E) coronal, and F) axial anterior inferior frontal gyrus, Broca's area, and composite language map. Post-op MRI showing G) sagittal, H) coronal, and I) axial T1WI post-contrast scans of the frontal resection cavity.*

subtotal resection was accomplished with pathology revealing a benign WHO Grade I ganglioglioma (**Figure 4J**–**L**, yellow arrows). The patient did not suffer any surgical morbidity and is being followed with surveillance imaging. Should there be further progression of disease, SRS *vs* a second repeat resection could be contemplated.

#### **3.5 Case 5: 53 year-old female with a recurrent left temporal lobe glioma**

A 53 year-old female had a previous subtotal resection of a small left temporal lobe GBM followed by concurrent chemo-radiation as per the Stupp protocol. She presented 2 years later to our institution's multidisciplinary tumor board, neurologically intact, with a left recurrent temporal lobe lesion (**Figure 5A**–**C**, yellow arrows). The differential diagnosis was recurrent disease *vs* radiation necrosis or pseudo-progression.

*Pre-Surgical and Surgical Planning in Neurosurgical Oncology - A Case-Based Approach… DOI: http://dx.doi.org/10.5772/intechopen.99155*

#### **Figure 4.**

*Fourth ventricular ganglioglioma. Pre-op MRI A) sagittal, B) coronal, and C) axial T1WI post-contrast scans showing ring-enhancing cystic lesion originating from the floor of the 4th ventricle. Pre-op CTA D) sagittal, E) coronal, and F) axial views to assess vascularity of the lesion. Pre-op fMRI G) sagittal, H) coronal, and I) axial images showing clear anteromedial displacement of the pyramidal tracts by the lesion. Post-op MRI J) sagittal, K) coronal, and L) axial T1WI post-contrast scans assessing near total resection of the tumor. Yellow arrows depict location of the lesion.*

MR perfusion (MRP) scan confirmed a hyper-perfused area in the left middle temporal fossa corresponding to the area of enhancement on MRI (**Figure 5D**, yellow arrow). Given the location of the recurrence (anterior to the 6 cm line measured from the temporal tip) with predominantly mesial extension with no proximity to the superior temporal gyrus and sparing anatomical language areas, we decided to perform a conventional asleep temporal lobe resection without the need for awake surgery with language mapping. The patient did not have any post-operative neurological deficits with good radiographic evidence of resection of contrast-enhancing disease (**Figure 5E** and **F**, yellow arrows) and a generous anterior mesio-temporal

#### **Figure 5.**

*Left mesiotemporal recurrent glioma. Pre-op MRI A) sagittal, B) coronal, and C) axial T1WI post-contrast scans of a left intra-axial anterior temporal lobe recurrent glioma. D) MR perfusion scan showing relative increased cerebral blood velocity in the left anterior temporal lobe corresponding to the area of increased enhancement on MRI. Post-op MRI E) sagittal, F) axial T1WI post-contrast, and G) coronal, and H) axial T2WI scans of the resection cavity. Yellow arrows define tumor bed.*

resection cavity (**Figure 5G** and **H**). This case demonstrates the ability to do a safe maximal surgical resection in the absence of DTI or fMRI as long as there is strong correlation with other imaging modalities such as MRP delineating areas of suspected disease recurrence and an adequate anatomical distance between the resection margins and eloquent areas of the brain.
