Case 6 Oligodendroglioma

Figure 6.1: MRI of the patient axial T2.

Clinical presentation

• A 36-year-old female patient, medically free, presented with a headache accompanied by blurring of vision, memory affection, and personality changes over the past two months, without any association with vomiting or loss of consciousness.
• She has a history of a single attack of fits two months ago.
• Fundus examination showed grade 1-2 papilledema. Cranial nerves were intact, speech was normal, and she had full power.
• After operation, pathology revealed oligodendroglioma.

• Q1: Can you quantify the degree of mass effect in this case?
• Mass effect in this case includes effaced sulci, compressed ventricles, midline shift, and compression of basal cisterns. We can observe compression of the cerebral peduncle by the uncus, which is the most medial part of the temporal lobe. In acute events, such as those seen with acute extradural hemorrhage, this leads to oculomotor nerve palsy, characterized by ipsilateral pupil dilatation and contralateral hemiparesis.

• Q2: What possible complications must be counseled preoperatively?
• As the lesion is located in the left dominant post-temporal and parietal Wernicke’s area, there may be an impact on language functions. Therefore, potential language impairment should be discussed with the patient preoperatively.
• Q3: What are the major tracts to be considered during surgery in the temporal lobe?

Figure 6.2. Fascicular trajectories are based on Catani and Thiebaut de Schotten (2008), Rilling et al. (2008), Saur et al. (2008), Frey et al. (2008), Makris et al. (2009), and Turken and Dronkers (2011). AF, arcuate fasciculus; CB, cingulum bundle; IFOF, inferior fronto-occipital fasciculus; ILF, inferior longitudinal fasciculus; MLF, middle longitudinal fasciculus; UF, uncinate fasciculus; VP, ventral pathway.

Q4: Based on pathology, what genetic alteration may affect the prognosis of oligodendroglioma?

• The presence of a 1p19q co-deletion affects the prognosis of oligodendroglioma positively. Patients with this genetic marker typically respond better to chemotherapy and have improved survival rates. Additionally, several surgical and radiological factors can enhance prognosis, including:

1. Younger age at presentation.

2. Frontal lobe location of the tumor.

3. Presence of calcification within the tumor.

4. Reduced degree of enhancement on imaging studies.

5. Smaller size of the lesion, less than 4 cm³.

6. More extensive surgical resection of the tumor.