A 47-year-old woman presented to Abbott Northwestern Hospital, Minneapolis, in June 2006 because of a visual disturbance that she described as decreased acuity and jumpiness in her right visual field, as well as some incoordination in her right hand and leg as well as increasing headaches. This prompted a brain MRI, which demonstrated a large mass in the trigone of the left lateral ventricle. The majority of the mass enhanced intensely, indicating a vascular nature for the lesion. A perilesional cyst also was present. Marked edema was present in the left temporal and parietal lobes. The initially suspected diagnosis was choroid-plexus papilloma (versus choroid-plexus carcinoma). The possibility of an intraventricular meningioma also was raised, but this was thought less likely due to the extensive edema within the adjacent brain tissues.
Due to the patient’s symptoms and the large amount of edema and mass effect secondary to the tumor, a decision was made, with the patient, to attempt a gross total resection. Because of the proximity of the lesion to the left temporal lobe and the desire to preserve language function, preoperative functional MRI (fMRI) was performed. A lateral approach through the temporal lobe was considered.
|Figure 1. (A) A functional activation map is superimposed on an anatomical axial FLAIR image of patient, revealing that patient’s Wernicke area was located in path of contemplated resection (arrow). (B) A surface-rendered view of the brain is overlaid with functional activations (arrow indicates Wernicke area). (C) Sagittal postoperative MRI compared with volume-rendered preoperative MRI shows that Wernicke area was avoided.|
A story-reading paradigm was employed and blood–oxygen-level dependent (BOLD) fMRI was performed. The functional activation map for this paradigm is shown in Figure 1A, superimposed on an anatomical axial fluid-attenuated inversion-recovery (FLAIR) image. As shown, the patient’s Wernicke area (partially responsible for language processing) was located directly in the path of the contemplated surgical resection (arrow). After consultation between the neurosurgeon and neuroradiologist, the neurosurgeon’s decision was to alter the path of resection through the brain in an attempt to avoid the area of Wernicke activation. A surface-rendered view of the brain with overlaid functional activations is shown in 1B. The arrow represents the Wernicke language-processing area.
During surgery, a highly vascular, cherry-red mass was noted in the lateral ventricle. A gross total resection was performed. Final pathology revealed a diagnosis of capillary hemangioblastoma.
Follow-up brain MRI revealed no residual contrast enhancement in the left lateral ventricle, confirming the intraoperative impression of gross total resection. Sagittal postoperative MRI (1C) compared with the volume-rendered preoperative MRI with functional overlay (1B) shows that the preoperative strategy of avoiding the Wernicke area was achieved. The resection tract was through an area of the left temporal lobe approximately 10 mm inferior to the Wernicke activation demonstrated on the preoperative fMRI.
Clinically, the patient did have some word-finding difficulty in the immediate postoperative period. After approximately 3 days, however, the patient regained full verbal abilities and had no residual language deficit thereafter. It was felt that some edema associated with the operative tract may have caused temporary dysfunction of the neuronal cells within the Wernicke area, resulting in a temporary language deficit. A permanent deficit may have been avoided, however, since no transections were performed in the region of the Wernicke area.
This case presentation shows the value of preoperative fMRI in planning surgical resection of tumors. In particular, the use of a 3T magnet for fMRI in this patient provided a better SNR and allowed greater confidence in locating the language-processing areas in this patient’s brain. Because of the greater confidence achieved with the 3T scanner, the neurosurgeon altered his surgical approach to the patient’s brain tumor and avoided causing a permanent language deficit.
Neeraj B. Chepuri, MD, is chair of the radiology department at Abbott Northwestern Hospital, and a member of the neuroradiology section at Consulting Radiologists Ltd, Minneapolis.