Stereotactic and functional neurosurgery
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Stereotact Funct Neurosurg · Jan 1997
Positron emission tomography during motor cortex stimulation for pain control.
We studied regional changes in cerebral flood flow (rCBF) in 9 patients undergoing motor cortex stimulation (MCS) for pain control. Significant increase in rCBF was observed in the lateral thalamus ipsilateral to MCS probably reflecting corticothalamic connections from motor/premotor areas. Subsignificant increases were observed in the anterior cingulate, left insula and upper brainstem. ⋯ Our results support a model of MCS action whereby activation of thalamic nuclei directly connected with motor and premotor cortices would entail a cascade of synaptic events in other pain-related structures, including the anterior cingulate and the periaqueductal gray. MCS could influence the affective-emotional component of chronic pain by way of cingulate activation, and lead to descending inhibition of pain impulses by activation of the brainstem. Such effects may be obtained only if thalamic activation reaches a 'threshold' level, below which the analgesic cascade would not be successfully triggered.
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Stereotact Funct Neurosurg · Jan 1997
Modulation of spinal pain mechanisms by spinal cord stimulation and the potential role of adjuvant pharmacotherapy.
Experimental studies indicate that the effects of spinal cord stimulation (SCS) on 'hypersymptoms' in neuropathic pain conditions may at least partly be mediated via GABAergic and adenosine-dependent mechanisms. Concomitant intrathecal administration of receptor-active drugs modulating the function of the GABA and adenosine systems may both depress and enhance the effects of SCS. The first few patients with simultaneous intrathecal administration of the GABAB agonist baclofen and/or adenosine together with SCS, when the stimulation alone proved insufficient, are reported.
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Stereotact Funct Neurosurg · Jan 1997
The present and future role of intraoperative MRI in neurosurgical procedures.
We have worked in conjunction with scientists from the General Electric Corporation over 6 years to develop an open-bore MR imaging system (0.5 T) enabling optimal vertical access of surgeon and assistant to the patient, and real-time imaging during major neurosurgical procedures. ⋯ MRT is especially useful in guiding biopsies and resections near cysts, ventricles and critical vascular structures where preoperative images with framed/frameless techniques would be inadequate to show anatomic changes during the procedure. Real-time images of a biopsy needle within the abnormal area are very useful in cases of subtle pathologic change. More complete resection of infiltrative tumor is readily accomplished. SPL image fusion of SPECT and neurofunctional data (e.g. from magnetic stimulation preoperatively) into the imaging space enables the surgeon to better visualize tumor invasion or neural function in real-time imaging during resection. Imaging of thermal gradients for cryoprobe or laser ablation, and combination with endoscopy and robotics will offer additional benefit in the performance of difficult neurosurgical procedures.
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Stereotact Funct Neurosurg · Jan 1997
Volumegraph (overlaid three-dimensional image-guided navigation). Clinical application of augmented reality in neurosurgery.
We have developed an overlaid three-dimensional image (Volumegraph)-guided navigation system that allows navigation during operative procedures. The three-dimensional image is superimposed on the patient's head and body via a semi-transparent mirror. The Volumegraph can display three-dimensional images in the air by a light beam which is based on CT/MRI. ⋯ This preliminary study of overlaid three-dimensional-image-guided navigation demonstrated its clinical usefulness. The application of augmented reality in the surgical field makes it possible to do a neurosurgical intervention easily and accurately.
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Stereotact Funct Neurosurg · Jan 1997
Angiographic follow-up in 37 patients after radiosurgery for cerebral arteriovenous malformations as part of a multimodality treatment approach.
Modified Linac radiosurgery was utilized at our institution between 1990 and 1995 in 54 patients with cerebral arteriovenous malformations (AVMs) as part of a multimodality therapeutic approach. Most patients also underwent surgery and embolization of the AVMs prior to radiosurgery. The goal of the adjunctive radiosurgical treatment was the complete angiographic obliteration of the deep residual AVM after subtotal embolization and resection. ⋯ These data support the use of radiosurgery for treatment of cerebral AVMs as part of a multimodality approach if the surgical risk of any residual AVM after embolization and microsurgical resection is deemed excessive. The adjunctive use of radiosurgery in this series resulted in the safe complete obliteration of many very difficult grade 4 and 5 AVMs. These data do not support the use of radiosurgery as the primary treatment of surgically resectable AVMs since there is a risk of interval hemorrhage and the obliteration rate is far inferior to that of microsurgical resection.