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Ronald F. Young, Francisco Li, Sandra Vermeulen and Robert Meier

Object

The goal of this report was to describe the safety and effectiveness of nucleus ventralis intermedius (VIM) thalamotomy performed with the Leksell Gamma Knife (GK) for the treatment of essential tremor (ET).

Methods

One hundred seventy-two patients underwent a total of 214 VIM thalamotomy procedures with the Leksell GK between February 1994 and March 2007 for treatment of disabling ET. Eleven patients were lost to follow-up less than 1 year after the procedures, so that in this report the authors describe the results in 161 patients who underwent a total of 203 thalamotomies (119 unilateral and 42 bilateral).

Results

There were statistically significant decreases (p < 0.0001) in tremor scores for both writing and drawing. The mean postoperative follow-up duration for all patients was 44 ± 33 months. Fifty-four patients have been followed for more than 60 months posttreatment. There were 14 patients who suffered neurological side effects that were temporary (6) or permanent (8), which accounted for 6.9% of the 203 treatments. All complications were related to lesions that grew larger than expected.

Conclusions

A VIM thalamotomy with the Leksell GK offers a safe and effective alternative for surgical treatment of ET. It is particularly applicable to patients who are not ideal candidates for deep brain stimulation but can be offered to all patients who are considering surgical intervention for ET.

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Jed Voss, Timothy B. Meier, Robert Freidel, Bornali Kundu, Veena A. Nair, Ryan Holdsworth, John S. Kuo and Vivek Prabhakaran

Object

Functional MRI (fMRI) is commonly used by neurosurgeons preoperatively to identify brain regions associated with essential behaviors, such as language and motor abilities. In this study the authors investigated the relationship between patient morbidity and mortality and the distance from the tumor border area to functional activations in secondary motor and language cortices.

Methods

Patients with primary or metastatic brain tumors who underwent preoperative fMRI motor and language mapping were selected from a large database of patients with tumors. The lesion-to-activation distance (LAD) was measured in each patient relative to the supplementary motor area (SMA) for motor tasks and the presupplementary motor area (pSMA) for language tasks. The association between LAD and the incidence of deficits was investigated using the Fisher exact tests of significance. The impact of other variables, including age, handedness, sex, and tumor grade, was also investigated. In a subset of patients, logistic regression was performed to identify the likelihood of deficits based on the LAD to primary and secondary regions. Finally, Mantel-Cox log-rank tests were performed to determine whether survival time was significantly related to the LAD to secondary motor and language areas.

Results

A significant association was observed between the LAD to the SMA and the incidence of motor deficits, with the percentage of patients with deficits dropping for those in the LAD > 2 cm group. The relationship between the LAD to the pSMA and the incidence of language deficits was not significant. Logistic regression demonstrated that the LAD to primary sensorimotor cortex does affect the incidence of motor deficits, but that the LAD to SMA does not. Finally, the authors observed no relationship between the LAD to secondary regions and patient mortality rates.

Conclusions

These results demonstrate that the LAD to SMA structures does affect morbidity, although not to the extent of LAD to primary structures. In addition, motor deficits are significantly associated with LAD to secondary structures, but language deficits are not. This should be considered by neurosurgeons for patient consultation and preoperative planning.

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Oral Presentations

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