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Alvin Y. Chan, Diem Kieu T. Tran, Amandip S. Gill, Frank P. K. Hsu, and Sumeet Vadera

Laser interstitial thermal therapy (LITT) is a minimally invasive procedure used to treat a variety of intracranial lesions. Utilization of robotic assistance with stereotactic procedures has gained attention due to potential for advantages over conventional techniques. The authors report the first case in which robot-assisted MRI-guided LITT was used to treat radiation necrosis in the posterior fossa, specifically within the cerebellar peduncle. The use of a stereotactic robot allowed the surgeon to perform LITT using a trajectory that would be extremely difficult with conventional arc-based techniques.

A 60-year-old man presented with facial weakness and brainstem symptoms consistent with radiation necrosis. He had a history of anaplastic astrocytoma that was treated with CyberKnife radiosurgery 1 year prior to presentation, and he did well for 11 months until his symptoms recurred. The location and form of the lesion precluded excision but made the patient a suitable candidate for LITT. The location and configuration of the lesion required a trajectory for LITT that was too low for arc-based stereotactic navigation, and thus the ROSA robot (Medtech) was used. Using preoperative MRI acquisitions, the lesion in the posterior fossa was targeted. Bone fiducials were used to improve accuracy in registration, and the authors obtained an intraoperative CT image that was then fused with the MR image by the ROSA robot. They placed the laser applicator and then ablated the lesion under real-time MR thermometry. There were no complications, and the patient tolerated the procedure well. Postoperative 2-month MRI showed complete resolution of the lesion, and the patient had some improvement in symptoms.

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Nguyen Hoang, Diem Kieu Tran, Ryan Herde, Genevieve C. Couldwell, Anne G. Osborn, and William T. Couldwell

OBJECT

Oculomotor cistern extension of pituitary adenomas is an overlooked feature within the literature. In this study, 7 cases of pituitary macroadenoma with oculomotor cistern extension and tracking are highlighted, and the implications of surgical and medical management are discussed.

METHODS

The records of patients diagnosed with pituitary macroadenomas who underwent resection and in whom preoperative pituitary protocol MRI scans were available for review were retrospectively reviewed. The patient and tumor characteristics were reviewed along with the operative outcomes and complications.

RESULTS

Seven patients (4.1%) with oculomotor cistern extension and tracking were identified in a cohort of 170 patients with pituitary macroadenoma. The most common presenting symptoms were visual deficit (6 patients; 86%), apoplexy (3 patients; 43%), and oculomotor nerve palsy (3 patients; 43%). Lone oculomotor nerve palsy was seen in 2 patients without apoplexy and 1 patient with an apoplectic event. Gross-total resection was achieved via a microscopic endonasal transsphenoidal approach with or without endoscopic aid to the sella in 14%, near-total resection in 29%, and subtotal resection in 57% of patients in the data set.

CONCLUSIONS

Pituitary adenoma extension along the oculomotor cistern is uncommon; however, preoperatively recognizing such extension should play an important role in the surgeon’s operative considerations and postoperative clinical management because this extension can limit gross-total resection using the transsphenoidal approach alone.

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Ryan F. Herde, Nguyen Hoang, Diem Kieu Tran, Genevieve Couldwell, William T. Couldwell, and Anne G. Osborn

OBJECT

Peritumoral cysts are benign nonneoplastic cysts that are found adjacent to extraaxial brain tumors such as meningiomas, schwannomas, craniopharyngiomas, and esthesioneuroblastomas. Peritumoral cysts associated with pituitary macroadenomas have not been previously described in the literature. The authors report 6 cases of giant macroadenoma-associated peritumoral cysts and delineate their imaging spectrum.

METHODS

The authors retrospectively reviewed the records of 179 patients diagnosed with pituitary macroadenomas who underwent tumor resection at their institution and had preoperative MRI scans available for review. The patients were evaluated for the presence of associated peritumoral cysts. Clinical presentation, histopathology, follow-up time, tumor and peritumoral cyst dimensions were recorded. Signal intensity on T1-weighted, T2-weighted, diffusion-weighted, and FLAIR sequences, as well as pre- and postcontrast appearance, were determined.

RESULTS

Six patients (3.4%) with associated peritumoral cysts were identified in our cohort of 179 patients with pituitary macroadenoma. Twelve patients in the cohort had giant macroadenomas (≥ 4.0 cm), and 50% of these tumors had associated peritumoral cysts with significant extrasellar extension of the macroadenoma. Only tumors with craniocaudal, transverse, and anteroposterior diameters of 3.6 × 3.4 × 4.2 cm to 7.0 × 7.4 × 6.8 cm (mean 5.3 × 5.1 × 5.6 cm), respectively, had associated peritumoral cysts. The growth pattern in all tumors was suprasellar, with predominant anterior and lateral extension.

Cysts showed T1-weighted, T2-weighted, and FLAIR hyperintensity in 67%, 67%, and 60% of patients, respectively. There was no contrast enhancement of the cyst wall or fluid contents in any patient. Postoperatively, cysts had completely resolved (4 of 5) or significantly decreased in size (1 of 5). One patient was lost to follow-up.

CONCLUSIONS

Macroadenoma-associated peritumoral cysts are rare, benign, and likely nonneoplastic fluid collections that do not represent neoplasm. These cysts display a predictable pattern of hyperintensity on T1-weighted, T2-weighted, and FLAIR sequences and do not enhance. They most likely represent proteinaceous CSF in a sulcus or cistern that becomes trapped (encysted) by anterolateral extension of unusually large macroadenomas. Peritumoral cysts may facilitate resection of the associated macroadenoma by providing a cleavage plane.

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Diem Kieu Tran, Andrew V. Poliakov, Seth D. Friedman, Hannah E. Goldstein, Hillary A. Shurtleff, Katherine Bowen, Kristina E. Patrick, Molly Warner, Edward J. Novotny Jr., Jeffrey G. Ojemann, and Jason S. Hauptman

OBJECTIVE

Assessing memory is often critical in surgical evaluation, although difficult to assess in young children and in patients with variable task abilities. While obtaining interpretable data from task-based functional MRI (fMRI) measures is common in compliant and awake patients, it is not known whether functional connectivity MRI (fcMRI) data show equivalent results. If this were the case, it would have substantial clinical and research generalizability. To evaluate this possibility, the authors evaluated the concordance between fMRI and fcMRI data collected in a presurgical epilepsy cohort.

METHODS

Task-based fMRI data for autobiographical memory tasks and resting-state fcMRI data were collected in patients with epilepsy evaluated at Seattle Children’s Hospital between 2010 and 2017. To assess memory-related activation and laterality, signal change in task-based measures was computed as a percentage of the average blood oxygen level–dependent signal over the defined regions of interest. An fcMRI data analysis was performed using 1000 Functional Connectomes Project scripts based on Analysis of Functional NeuroImages and FSL (Functional Magnetic Resonance Imaging of the Brain Software Library) software packages. Lateralization indices (LIs) were estimated for activation and connectivity measures. The concordance between these two measures was evaluated using correlation and regression analysis.

RESULTS

In this epilepsy cohort studied, the authors observed concordance between fMRI activation and fcMRI connectivity, with an LI regression coefficient of 0.470 (R2 = 0.221, p = 0.00076).

CONCLUSIONS

Previously published studies have demonstrated fMRI and fcMRI overlap between measures of vision, attention, and language. In the authors’ clinical sample, task-based measures of memory and analogous resting-state mapping were similarly linked in pattern and strength. These results support the use of fcMRI methods as a proxy for task-based memory performance in presurgical patients, perhaps including those who are more limited in their behavioral compliance. Future investigations to extend these results will be helpful to explore how the magnitudes of effect are associated with neuropsychological performance and postsurgical behavioral changes.