Cosgrove Gr

Experience with Microelectrode Guided Subthalamic Nucleus Deep Brain Stimulation

OBJECTIVE: Subthalamic deep brain stimulation (DBS) has rapidly become the standard surgical therapy for medically refractory Parkinson disease. However, in spite of its wide acceptance, there is considerable variability in the technical approach. This study details our technique and experience in performing microelectrode recording (MER) guided subthalamic nucleus (STN) DBS in the treatment of Parkinson disease. METHODS: Forty patients underwent surgery for the implantation of 70 STN DBS electrodes. Stereotactic localization was performed using a combination of magnetic resonance and computed tomographic imaging. We used an array of three microelectrodes, separated by 2 mm, for physiological localization of the STN. The final location was selected based on MER and macrostimulation through the DBS electrode. RESULTS: The trajectory selected for the DBS electrode had an average pass through the STN of 5.6 ± 0.4 mm on the left and 5.7 ± 0.4 mm on the right. The predicted location was used in 42% of the cases but was modified by MER in the remaining 58%. Patients were typically discharged on the second postoperative day. Eighty-five percent of patients were sent home, 13% required short-term rehabilitation, and one patient required long-term nursing services. Seven complications occurred over 4 years. Four patients suffered small hemorrhages, one patient experienced a lead migration, one developed an infection of the pulse generator, and one patient suffered from a superficial cranial infection. CONCLUSION: Simultaneous bilateral MER-guided subthalamic DBS is a relatively safe and well-tolerated procedure. MER plays an important role in optimal localization of the DBS electrodes.

Functional MRI Localization of Language in a 9-Year-Old Child

BACKGROUND Localizing critical brain functions such as language in children is difficult and generally requires invasive techniques. Recently sensory, motor and language functions in adults have been mapped to specific brain locations using functional imaging techniques. Of these techniques, functional MRI (fMRI) is the least invasive and has the highest spatial and temporal resolution. Its use in adults is well documented but application to children has not been as well described. In the present study lateralization and localization of language was evaluated with fMRI prior to epilepsy surgery in a nine-year-old male with complex partial seizures, attentional difficulty and decreased verbal proficiency. METHODS Two language paradigms well studied in adults (read, verb generation) and two additional language paradigms (antonym generation, latter fluency) were studied using whole brain fMRI after stimulus items and timing were adjusted to achieve the desired performance level during imaging. The patient was also conditioned to the magnet environment prior to imaging. RESULTS Word reading and letter fluency tasks produced lateralized and localized activation similar to that seen in adults. The patient had no language deficits following an anterior 2/3 dominant temporal lobe resection. CONCLUSIONS With modifications of protocols such as those detailed in this report, this non-invasive method for localizing language function is feasible for the presurgical evaluation of children as well being applicable for a variety of developmental language issues.

Interstitial irradiation of brain tumors, using a miniature radiosurgery device: initial experience.

OBJECTIVE This report describes the clinical evaluation of a novel stereotactic radiosurgical device for interstitial irradiation of malignant brain tumors. METHODS Fourteen patients with cerebral lesions less than 3.5 cm in greatest diameter were treated with a single fraction of stereotactic interstitial irradiation (average, 12.5 Gy). Clinical evaluation, Karnofsky Performance Scale ratings, and neuroimaging studies were obtained at 6-week intervals postoperatively to assess treatment response. Reduction or stabilization of tumor size on follow-up imaging was accepted as local control, whereas tumor enlargement indicated local failure. INSTRUMENTATION This battery-powered miniature x-ray generator device produces low-energy x-ray photons that are attenuated rapidly within tissue. A dose decline rate proportional to 1/r3 yields extremely sharp dose fall-off curves with minimal exposure to surrounding tissue. Dose rates of 200 cGy per minute are possible, allowing for the administration of 12.5 Gy to a lesion 3 cm in diameter in less than 1 hour. RESULTS Local control (stabilization or reduction in lesion size) was obtained in 10 of the 13 patients with tumors with follow-up of 1.5 to 36 months (mean, 12 mo). Of three patients with radiographic progression, recurrence was symptomatic in only one. All patients tolerated the procedure well, and most patients were discharged home the day after treatment. No new neurological deficits were noted after biopsy and irradiation. CONCLUSIONS Preliminary experience with this novel radiosurgical device has demonstrated its feasibility and safety. Clinical efficacy of this technique is now under investigation in an international multicenter study.

Outcomes following staged bilateral pallidotomy in advanced Parkinson's disease.

The authors assessed clinical outcome for up to one year after staged bilateral pallidotomy in 14 patients with advanced PD. One year after surgery, dyskinesias were virtually abolished and there were significant reductions in “off” time (67%) and activities of daily living “off” scores (24%), as well as nonsignificant reduction in “off” motor score (39%); “on” scores were unchanged. One patient developed a visual field deficit; two had transient confusion. Staged bilateral pallidotomy improves motor function in selected patients with advanced PD.

Functional magnetic resonance imaging for cortical mapping in pediatric neurosurgery.

Currently there is considerable interest in applying functional imaging modalities to the problem of cortical localization. We present the case of a 15-year-old boy with a seizure disorder related to a tumor in the dominant supplementary motor area. This case illustrates the usefulness of functional magnetic resonance imaging as a new imaging tool for localization of cortical function in younger patients. The functional magnetic resonance imaging provided an anatomically accurate topographic map of operative site and subcortical structures along with relevant functional cortex. This information was useful for both presurgical planning and intraoperative localization. Validation of the technique in this instance was confirmed with intraoperative cortical motor mapping and the postoperative result.

A Magnetic Resonance Imaging Study of Regional Cortical Volumes Following Stereotactic Anterior Cingulotomy

The purpose of this study was to test the hypothesis that orbitofrontal cortical volume would be reduced following anterior cingulotomy for obsessive-compulsive disorder (OCD). Whole brain cortical parcellation was performed on magnetic resonance imaging (MRI) data from nine patients, before and 9 (+/-6) months following anterior cingulotomy. No significant volumetric reductions were found in the orbitofrontal cortex. Exploratory findings of reduced volume in ventral temporo-fusiform and posterior cingulate regions were consistent with chance differences, in the face of multiple comparisons. Therefore, though the circumscribed lesions of anterior cingulotomy have recently been associated with corresponding volumetric reductions in the caudate nucleus, no comparable volumetric reductions are evident in cortical territories. Taken together, these results are most consistent with a model of cingulo-striatal perturbation as a putative mechanism for the efficacy of this procedure. While limitations in sensitivity may have also contributed to these negative findings, the methods employed have previously proven sufficient to detect cortical volumetric abnormalities in OCD. The current results may reflect a relatively diffuse pattern of cortico-cortical connections involving the neurons at the site of cingulotomy lesions. Future functional neuroimaging studies are warranted to assess possible cortical or subcortical metabolic changes associated with anterior cingulotomy, as well as predictors of treatment response.

Beneficial effect of subsequent lesion procedures after nonresponse to initial cingulotomy for severe, treatment-refractory obsessive-compulsive disorder.

BACKGROUND Anterior cingulotomy (AC) can be an effective therapy for patients with severe obsessive-compulsive disorder who are refractory to traditional medical therapy. For patients who do not respond to AC, the benefit of additional lesion procedures vs continued medical management remains unknown. OBJECTIVE To determine whether a second lesion procedure is beneficial after unsuccessful initial AC. METHODS In this retrospective cohort study, we reviewed the records of 31 patients who were nonresponders to initial AC. Full response was defined as at least a 35% decrease and partial response as a 25% to 34% decrease in Yale-Brown Obsessive-Compulsive Scale scores. Yale-Brown Obsessive-Compulsive Scale change was compared between patients who underwent additional surgery and those treated nonsurgically. In addition, for patients who underwent additional surgery, we compared the benefit of subcaudate tractotomy with repeat AC (extension of the initial lesion) as the second procedure. RESULTS Nineteen patients underwent a second surgery and 12 patients continued nonsurgical therapy. Fifty-three percent of patients who received additional surgery were full responders and 21% were partial responders at the most recent follow-up compared with 17% full responders and 25% partial responders among those who continued conventional therapy (P = .02). Of the patients who underwent an additional surgery, there were 64% full and 9% partial responders in the subcaudate tractotomy group compared with 38% full and 38% partial responders in the repeat AC group (P = .04). CONCLUSION Second lesion surgery can be a safe and effective therapy for patients who do not respond to initial AC. Subcaudate tractotomy may confer a higher response rate than repeat cingulotomy.

Multiple peripheral aneurysms of the posterior inferior cerebellar artery associated with a cerebellar arteriovenous malformation: case report

The authors describe a rare case of multiple peripheral aneurysms of the posterior inferior cerebellar artery found in association with a midline cerebellar arteriovenous malformation. Successful trapping of the aneurysms and excision of the arteriovenous malformation was accomplished with an excellent clinical result. The literature concerning aneurysms of the posterior inferior cerebellar artery, cerebellar arteriovenous malformations, and combined intracranial vascular abnormalities is discussed.