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Timothy R. Miller, Clifford J. Eskey and Alexander C. Mamourian

Spinal dural arteriovenous fistula (DAVF) is an uncommon condition that can be difficult to diagnose. This often results in misdiagnosis and treatment delay. Although conventional MRI plays an important role in the initial screening for the disease, the typical MRI findings may be absent. In this article, the authors present a series of 4 cases involving patients with angiographically proven spinal DAVFs who demonstrated cord T2 prolongation on conventional MRI but without abnormal subarachnoid flow voids or enhancement. These cases suggest that spinal DAVF cannot be excluded in symptomatic patients with cord edema based on conventional MRI findings alone. Dynamic Gd-enhanced MR angiography (MRA) was successful in demonstrating abnormal spinal vasculature in all 4 cases. This limited experience provides support for the role of spinal MRA in patients with abnormal cord signal and symptoms suggestive of DAVF even when typical MRI findings of a DAVF are absent.

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Tsz Lau, Raul Olivera, Timothy Miller Jr., Katheryne Downes, Christopher Danner, Harry R. van Loveren and Siviero Agazzi

Object

Recent natural history studies of vestibular schwannomas (VSs) suggest that most of these tumors do not grow. The impact of these new data on management trends in the US is currently unknown. The aim in the present study was to evaluate current trends in the treatment of VS in the US by analyzing a national cancer database.

Methods

The Surveillance, Epidemiology, and End Results Program is a national database maintained by the National Cancer Institute representing 26% of the US population. Data from the database were downloaded using provided software. Cases were isolated based on histology codes and the site code. Data from 2004 to 2007 were included in the analysis. The number of patients undergoing resection was compared with the number treated with beam radiation and observation, based on tumor size.

Results

Three thousand six hundred fifty cases were identified in the database. Over the study period, management choices for VSs showed a significant change only for tumors with a diameter < 2 cm. In this tumor category, a decrease in resection and an increase in radiation were observed, with observation showing a modest increase but remaining low at an average of 25%.

Conclusions

Study data demonstrated a shift in the management of small VSs in the US between 2004 and 2007, with microsurgical removal giving way to radiation treatment and the overall rate for observation remaining low and stable. With recent literature suggesting that the majority of small tumors do not grow, the authors assert that VSs are being overtreated in the US.

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Alexandra M. Giantini Larsen, David J. Cote, Hasan A. Zaidi, Wenya Linda Bi, Paul J. Schmitt, J. Bryan Iorgulescu, Michael B. Miller, Timothy R. Smith, M. Beatriz Lopes, John A. Jane Jr. and Edward R. Laws Jr.

OBJECTIVE

The authors report the diagnosis, management, and outcomes of 6 cases of spindle cell oncocytoma (SCO) in an effort to guide clinical diagnosis and management of these uncommon lesions.

METHODS

This study is a retrospective review of cases involving adult patients who underwent resection of pituitary lesions at the authors’ institutions between January 2000 and October 2017. The authors identified patients with histopathological confirmation of SCO and collected clinical data, including preoperative, perioperative, and postoperative management, complications, and outcomes.

RESULTS

Six patients with SCO were identified. Clinical findings at initial presentation included visual disturbances, dizziness, and headache. All patients underwent resection. Four resections were initially performed by the transsphenoidal approach, and 2 resections were performed by craniotomy at an outside institution with subsequent transsphenoidal reoperations. Neither necrosis nor increased mitotic activity was seen in the tumor samples. All samples stained positive for S100 protein and thyroid transcription factor 1 and negative for glial fibrillary acidic protein and pituitary hormones. Five of the samples stained positive for epithelial membrane antigen. The average MIB-1 index was 8.3% (range 2–17). Postoperatively, 3 of the 6 patients received further treatment for progression of residual tumor or for recurrence, 2 have stable residual tumor, and 1 has had no recurrence after gross-total resection. Two patients developed postoperative complications of transient sixth cranial nerve palsy and diplopia. There were no other complications.

CONCLUSIONS

SCO poses both a diagnostic and therapeutic challenge. These tumors are often initially misdiagnosed as nonfunctional pituitary adenomas because of their sellar location and nonspecific symptomatology. Postoperatively, SCO must also be distinguished from other neoplasms of the posterior pituitary gland through histopathological examination. Resection of SCO can be challenging, given its highly vascular and adherent nature. Long-term follow-up is critical, as the tumor is associated with higher recurrence and progression rates compared to other benign neoplasms of the sella.

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Timothy R. Miller, Sijia Guo, Elias R. Melhem, Howard M. Eisenberg, Jiachen Zhuo, Nathaniel Kelm, Mor Dayan, Rao P. Gullapalli and Dheeraj Gandhi

OBJECTIVE

Magnetic resonance–guided focused ultrasound (MRgFUS) ablation of the globus pallidus interna (GPi) is being investigated for the treatment of advanced Parkinson’s disease symptoms. However, GPi lesioning presents unique challenges due to the off-midline location of the target. Furthermore, it remains uncertain whether intraprocedural MR thermometry data can predict final lesion characteristics.

METHODS

The authors first performed temperature simulations of GPi pallidotomy and compared the results with those of actual cases and the results of ventral intermediate nucleus (VIM) thalamotomy performed for essential tremor treatment. Next, thermometry data from 13 MRgFUS pallidotomy procedures performed at their institution were analyzed using 46°C, 48°C, 50°C, and 52°C temperature thresholds. The resulting thermal models were compared with resulting GPi lesions noted on postprocedure days 1 and 30. Finally, the treatment efficiency (energy per temperature rise) of pallidotomy was evaluated.

RESULTS

The authors’ modeled acoustic intensity maps correctly demonstrate the elongated, ellipsoid lesions noted during GPi pallidotomy. In treated patients, the 48°C temperature threshold maps most accurately predicted postprocedure day 1 lesion size, while no correlation was found for day 30 lesions. The average energy/temperature rise of pallidotomy was higher (612 J/°C) than what had been noted for VIM thalamotomy and varied with the patients’ skull density ratios (SDRs).

CONCLUSIONS

The authors’ acoustic simulations accurately depicted the characteristics of thermal lesions encountered following MRgFUS pallidotomy. MR thermometry data can predict postprocedure day 1 GPi lesion characteristics using a 48°C threshold model. Finally, the lower treatment efficiency of pallidotomy may make GPi lesioning challenging in patients with a low SDR.

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Oral Presentations

2010 AANS Annual Meeting Philadelphia, Pennsylvania May 1–5, 2010