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PubMedDate not supplied

Radio frequency electrode system for optical lesion size estimation in functional neurosurgery.

Radiofrequency (RF) lesioning in the human brain is one possible surgical therapy for severe pain as well as movement disorders. One obstacle for a safer lesioning procedure is the lack of size monitoring. The aim of this study was to investigate if changes in laser Doppler or intensity signals could be used as markers for size estimation during experimental RF lesioning. A 2 mm in diameter monopolar RF electrode was equipped with optical fibers and connected to a digital laser Doppler system. The optical RF electrode's performance was equal to a standard RF electrode with the same dimensions. An albumin solution with scatterers was used to evaluate the intensity and laser Doppler signal changes during lesioning at 70, 80, and 90 degrees C. Significant signal changes were found for these three different clot sizes, represented by the temperatures (p<0.05, n=10). The volume, width, and length of the created coagulations were correlated to the intensity signal changes (r=0.88, n=30, p<0.0001) and to the perfusion signal changes (r=0.81, n=30, p<0.0001). Both static and Doppler-shifted light can be used to follow the lesioning procedure as well as being used for lesion size estimation during experimental RF lesioning.

Brain Neoplasms↗

PubMed2004

Respiration tracking in radiosurgery.

Respiratory motion is difficult to compensate for with conventional radiotherapy systems. An accurate tracking method for following the motion of the tumor is of considerable clinical relevance. We investigate methods to compensate for respiratory motion using robotic radiosurgery. In this system the therapeutic beam is moved by a robotic arm, and follows the moving target through a combination of infrared tracking and synchronized x-ray imaging. Infrared emitters are used to record the motion of the patient's skin surface. The position of internal gold fiducials is computed repeatedly during treatment, via x-ray image processing. We correlate the motion between external and internal markers. From this correlation model we infer the placement of the internal target during time intervals where no x-ray images are taken. Fifteen patients with lung tumors have recently been treated with a fully integrated system implementing this new method. The clinical trials confirm our hypothesis that internal motion and external motion are indeed correlated. In a preliminar study we have extended our work to tracking without implanted fiducials, based on algorithms for computing deformation motions and digitally reconstructed radiographs.

Clinical Trials as Topic↗

PubMed2001

Investigation of extra-temporal epilepsy.

Medically intractable epilepsy of extra-temporal origin can represent a difficult therapeutic challenge. Our Epilepsy Service has managed these patients using standard investigative methods as well as ictal SPECT and intracranial electrode recording. In the present series of patients, image-guided surgery was used for all electrode implantation and resective surgery. Seizure localization and successful resection were achieved in 70-80% of 42 patients with follow-up of at least one year. Normal MRI and previous failed intracranial investigation were not associated with poorer outcome.

Diagnostic Imaging↗

PubMed2001

Chronic motor cortex stimulation for phantom limb pain: correlations between pain relief and functional imaging studies.

Chronic motor cortex stimulation (CMCS) has provided satisfactory control of pain in patients with central or trigeminal neuropathic pain. We used this technique in 3 patients with intractable phantom limb pain after upper limb amputation. Functional magnetic resonance imaging (fMRI) correlated to anatomical MRI permitted frameless image guidance for electrode placement. Pain control was obtained for all the patients initially and the relief was stable in 2 of the 3 patients at 2 year follow-up. CMCS can be used to relieve phantom limb pain. fMRI data are useful in assisting the neurosurgeon in electrode placement for this indication.

Adult↗

PubMed2001

New possibilities for stereotaxis. Information-guided stereotaxis.

Information-guided stereotaxis, assisted by visualization of medical information, will become the next generation of neurosurgical systems. We performed 76 open MRI surgeries at Tokyo Women's Medical University between March 3, 2000 and April 12, 2001. Of them, comparisons of pre- and post-operative MR images for malignant gliomas in 21 cases revealed an average resection rate of 90.3% (the maximum 100%, the minimum 55%). In this article we describe real time updated navigation, augmented reality navigation, three-dimensional navigation, chemical navigation, information-guided navigation system (High definition visual Computer Aided Surgery System: HivisCAS), and open MRI-guided surgery that we are developing.

Humans↗

PubMed2002

Surgery of brain metastases - pro and contra.

CONCLUSION: Surgery should be considered whenever possible. This means that the patient has to be in good clinical condition (Karnofsky performance score > 70), the extracerebral metastases should be stable, the number of cerebral lesions should not exceed more than 3 seedings, and the age of the patient should be below 70 years. Since brain metastases are usually well circumscribed, complete extirpation seems to be possible. Postoperative MRI should be demanded in order to confirm complete extirpation. Additional radiotherapy is indicated in case of subtotal resection of a single lesion and in multiple lesions. In single brain metastasis a prospective randomized trial is necessary to prove whether conventional radiotherapy is essential after surgery in the primary treatment of the tumors or can be delayed until cerebral lesions recur. Radiosurgery is an alternative to surgery in the treatment of metastasis.

Brain Neoplasms↗

PubMed2002

MRI-guided frameless stereotactic percutaneous cordotomy.

BACKGROUND: Use of intraoperative myelography as a radiologic guidance for percutaneous cervical cordotomy (PCC) has been superseded by more modern imaging. The only significant advancement in cordotomy techniques over the last 30 years has been CT-guided PCC. The goal of this study was to demonstrate the feasibility of an MRI-guided frameless technique in high cervical cordotomy. METHODS: We describe 6 patients with intractable pain treated using a frameless, MRI-guided, stereotactic, PCC technique in combination with standard physiological localization procedures. Results were compared with those from 32 patients who underwent PCC in the last 5 years using physiological localizing techniques only. RESULTS: Six patients (100%) who underwent the frameless technique had excellent pain relief postoperatively. Patients in the non-stereotactic group, on average, required a higher number of lesions (2.5 vs. 1.2, p < 0.005), and 7 (22%) of these patients had unsatisfactory pain relief following PCC (p = 0.21). Five patients in the non-stereotactic group had weakness postoperatively and 1 had changes in bladder function. Postoperative weakness occurred in 1 patient undergoing the frameless technique. At an average of 6 months of follow-up (range 5-11), excellent pain relief was achieved in 83% (5/6) of MRI frameless PCC patients and 55% (16/29) of standard PCC patients (p = 0.20). CONCLUSIONS: Intraoperative frameless stereotaxy provides surgeons with accurate information that helps to guide the operative approach and precisely tailor the trajectory and depth of the electrode, potentially increasing the safety and efficacy of the operation.

Cervical Vertebrae↗

PubMed2002

Impact of posterior GPI pallidotomy on leg tremor in Parkinson's disease.

Although stereotactic thalamotomy is the mainstay in the surgical treatment of tremor in patients with Parkinson's disease (PD), this surgery is not favored and is even a matter of potential concern in the treatment of leg tremor since it carries a significant risk of injury to the internal capsule. In this study we have carried out a quantitative assessment of leg tremor alleviation in 12 patients with PD after MRI-/microelectrode-guided stereotactic ablation of the posterior part of the globus pallidus internus (GPi). The results showed that posterior GPi pallidotomy combined with drug therapy is a satisfactorily effective therapeutic strategy to treat parkinsonian leg tremor.

Globus Pallidus↗

PubMed2002

Preliminary exploration of the clinical effect of bleomycin on craniopharyngiomas.

OBJECTIVE: To investigate the antitumor effect of bleomycin on craniopharyngiomas. METHODS: A series of cystic craniopharyngiomas were randomly divided into three groups: (A) intracystic chemotherapy with bleomycin; (B) intracystic chemo-radiotherapy with bleomycin and (32)P; (C) intracystic radiotherapy with (32)P and 0.9% saline. The agents were injected into the cysts through stereotactically inserted silicone tubes. Follow-up was done for a minimum of 6 months. Outcome was based on a comparison of the volume of cysts before treatment and at follow-up. The index and lactate dehydrogenase (LD) of the cystic fluids, blood and cerebrospinal fluids and the endocrine function of these patients were determined before and after therapy. RESULTS: 19 patients finished the whole therapeutic course: 5 from group A, 9 from group B and 5 from group C. Four tumors in group A were polycystic, and the drug was selectively injected into the largest cyst. At follow-up, the volumes of the cysts in groups A and B regressed from 92 to 0%, while the drug-free cysts enlarged. In group B, 6 cysts almost disappeared and another 3 regressed from 78 to 57%. In group C, one cyst progressed and the others shrank by different degrees, but none disappeared completely or nearly. All patients in groups A and B had fever of different degrees, which resolved spontaneously in 8-24 h. The complications in group B included hyponatremia in 1 patient, and both adephagia obesity and cerebral infarction in 2 patients (1 of whom died after 6 months). Apart from the oculomotor paralysis occurring in 1 patient, the remainder of group C had no other severe complications. Blood chemistry, liver, kidney, pituitary and endocrinal functions changed little during the course in all these 19 patients. LD and its isoenzymes from the cystic fluids, CSF and serum showed no marked change after bleomycin injection. CONCLUSION: Bleomycin injected into cysts of craniopharyngiomas causes the tumor to shrink. When (32)P is added, the therapeutic effect seems better than treatment with either (32)P or bleomycin alone. Blood chemistry, liver, kidney and endocrine functions change little irrespective of the therapy applied. However, the combination of chemotherapy and radiotherapy may severely disturb both serum electrolytes and endocrine function. LD and its isoenzymes in the cystic fluids, CSF and serum may not change after bleomycin treatment.

Adolescent↗

PubMed2002

Brachytherapy for intracranial meningioma using a permanently implanted iodine-125 seed.

PURPOSE: To investigate the response and complications of iodine-125 brachytherapy for the treatment of recurrent and newly diagnosed meningiomas. Clinical cases of 2 patients treated with this method are presented. MATERIALS AND METHODS: Thirteen patients with primary and recurrent intracranial meningioma were treated by frameless stereotactic implantation of iodine-125 seeds from January 1996 to June 1998. The total dose to decay ranged from 7,000 to 17,000 cGy, with a dose rate of 5-10 cGy/h. RESULTS: All 11 evaluable patients had a decrease or stabilization in the size of their lesions as detected by MRI during follow-up. There were no acute complications. All patients who received a total dose greater than 10,000 cGy had postoperative radiation necrosis and/or vasogenic edema while only 20% of the patients who received doses of 10,000 cGy or less had radiation changes (p = 0.002). CONCLUSIONS: MRI-guided stereotactically assisted permanent implantation of iodine-125 seeds seems to be a safe, effective and noncomplicated method for the treatment of primary and recurrent meningiomas for selected patients, when doses are limited to 10,000 cGy.

Aged↗

PubMed2002

Interventional MRI-guided frameless stereotaxy in pediatric patients.

INTRODUCTION: We prospectively reviewed our experience with intraoperative MRI (iMRI)-guided stereotactic procedures in pediatric patients. METHODS: All procedures were performed within the magnet bore of the General Electric Signa SP MRI system, which allows for either continuous real-time or periodic imaging. The internal optical tracking system was used to plan and monitor target localization and instrument trajectory. RESULTS: Fifteen patients underwent 16 frameless stereotactic procedures, consisting of 4 tumor biopsies and 12 cyst aspirations and stereotactic catheter placements (average age 6 years, range 6 weeks to 18 years). There were no hemorrhagic, neurologic or infectious complications. CONCLUSION: iMRI is an important component in expanding the horizon of minimally invasive neurosurgery for pediatric patients. Thus far, we have found this technology to be safe, reliable and extremely useful for frameless stereotactic procedures.

Adolescent↗

PubMed2002

Frameless stereotaxy without rigid pin fixation during awake craniotomies.

OBJECTIVE: The accuracy and precision of resection with awake brain mapping is augmented when combined with frameless stereotaxy. Frameless stereotactic assisted surgery, however, typically involves immobilization in Mayfield pins. Rigid fixation, however, may be problematic for individuals undergoing awake craniotomy. We describe an alternate method of frameless stereotaxy without the use of pin fixation. METHODS: The MRI fiducials are placed in proximity to the proposed incision and prepared and draped in the operative field. After craniotomy, the epidural skull clamp (standardly used to support the electrode holder during corticography) is attached. Using the Stealth Navigational System, a spinal reference arc is then clamped onto the skull clamp base. After the fiducials and arc are registered, the probe is used for frameless guidance. RESULTS: In 14 of 15 cases (93%), this technique was successful. One case failed because of close proximity of the fiducials to the incision. The accuracy of the 14 successful cases was less than 4 mm. The error within the lesion itself was always less than 2 mm. Overall, these results are comparable to those achieved using a Mayfield head holder. In all tumor cases, postoperative imaging concurred with intraoperative assessment of a total versus subtotal resection. CONCLUSIONS: By affixing the spinal arc to the skull, the complications and discomfort associated with pin fixation are avoided completely. The patient is free to move without affecting the accuracy. The spine arc, in combination with the skull clamp, provides an efficient, well-tolerated, and accurate method of frameless navigation for the awake patient undergoing craniotomy.

Awareness↗

PubMed2002

Co-registration of function and anatomy in frameless stereotaxy by contour fitting.

We investigated a co-registration algorithm using a contour-fitting procedure to integrate functional data from magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) for frameless stereotaxy. In fMRI the shape of the head was reconstructed from anatomical images, in MEG it was scanned using an electromagnetic sensor position indicator. Functional information was transferred to the 3D-MR image set used for frameless stereotaxy by fitting the digitized (MEG) and reconstructed head shape (fMRI) to the 3D-MR images. The mean residual error of the contour fit was 2.3 mm for the MEG and 1.3 mm for the fMRI registration. According to computer simulations, the achievable transformation error is 0.75 and 0.5 mm, respectively. This method enables independent recording of functional and anatomical measurements with a co-registration accuracy better than 2 mm.

Brain↗

PubMed2003

From letterbox to keyhole approach for resecting intracranial lesions.

BACKGROUND: Computer-assisted neurosurgery systems (CANS) have the ability to translate preoperative image data sets directly to the operating field and were thought to be very useful in neurosurgery. However, key questions regarding their use remain only partially addressed. METHODS: To answer the doubts of the skeptics, we set up a registry of all CANS and any non-CANS procedures in our institution. The results of 354 procedures are presented in this paper. RESULTS: CANS was used in 254 procedures, with a mean accuracy of 1.9 mm and a failure rate of 2.8%. Over time, the accuracy improved to 1.6 mm and failures were abolished. The CANS was most useful in anterior skull approaches and took less time in the operating room, and the patients were discharged earlier than those who underwent non-CANS procedures. CONCLUSION: We feel that the introduction of CANS has changed our practice for the better, with significant benefits to patients, surgeons and the hospital at large, and we recommend its usage as a standard of care.

Humans↗

PubMed2003

Functional magnetic resonance imaging in a low-field intraoperative scanner.

BACKGROUND: Functional magnetic resonance imaging (fMRI) has been used for preoperative planning and intraoperative surgical navigation. However, most experience to date has been with preoperative images acquired on high-field echoplanar MRI units. We explored the feasibility of acquiring fMRI of the motor cortex with a dedicated low-field intraoperative MRI (iMRI). METHODS: Five healthy volunteers were scanned with the 0.12-tesla PoleStar N-10 iMRI (Odin Medical Technologies, Israel). A finger-tapping motor paradigm was performed with sequential scans, acquired alternately at rest and during activity. In addition, scans were obtained during breath holding alternating with normal breathing. The same paradigms were repeated using a 3-tesla MRI (Siemens Corp., Allandale, N.J., USA). Statistical analysis was performed offline using cross-correlation and cluster techniques. Data were resampled using the 'jackknife' process. The location, number of activated voxels and degrees of statistical significance between the two scanners were compared. RESULTS: With both the 0.12- and 3-tesla imagers, motor cortex activation was seen in all subjects to a significance of p < 0.02 or greater. No clustered pixels were seen outside the sensorimotor cortex. The resampled correlation coefficients were normally distributed, with a mean of 0.56 for both the 0.12- and 3-tesla scanners (standard deviations 0.11 and 0.08, respectively). The breath holding paradigm confirmed that the expected diffuse activation was seen on 0.12- and 3-tesla scans. CONCLUSIONS: Accurate fMRI with a low-field iMRI is feasible. Such data could be acquired immediately before or even during surgery. This would increase the utility of iMRI and allow for updated intraoperative functional imaging, free of the limitations of brain shift.

Adult↗

PubMed2004

Frameless stereotactic navigation in transsphenoidal surgery: comparison with fluoroscopy.

Surgical navigation systems (frameless stereotaxy) have been used in addition to or instead of fluoroscopy during transsphenoidal surgery. This study compares the intraoperative localization by an optical tracking system (Elekta Viewscope) with fluoroscopy. Viewscope and fluoroscope sagittal images were compared by the establishment of a Cartesian coordinate system based on anatomical landmarks and by the spatial localization of surgically relevant points for 20 patients. The Viewscope was found to have a total deviation of 3.0 +/- 0.6 mm (mean +/- SD) compared to fluoroscopy (p < 0.01). Much of the error resulted from the registration process, which according to the Viewscope software had an expected error of 3.1 +/- 0.8 mm for this series of patients, and from the probe-to-system correlation (error of 1.0 +/- 0.3 mm). Although frameless stereotactic systems give the surgeon useful trajectory data with three-dimensional visualizations, they remain somewhat inaccurate. The multiplanar abilities of the Viewscope provide an additional but not mandatory advantage to the simplicity and accuracy of fluoroscopy during this type of surgery.

Adolescent↗

PubMed2005

Frameless stereotactic ventricular shunt placement for idiopathic intracranial hypertension.

INTRODUCTION: Cerebrospinal fluid (CSF) shunting effectively reverses symptoms of idiopathic intracranial hypertension (IIH). Lumboperitoneal (LP) shunts have traditionally been used in patients with IIH due to a frequently undersized ventricular system. However, the advent of image-guided stereotaxis has enabled effective ventricular catheter placement in patients with IIH. We describe the first large series of frameless stereotactic ventriculoperitoneal (VP) shunting for patients with slit ventricles and IIH. METHODS: We describe the frameless stereotactic VP shunting technique for IIH in 32 procedures. Outcomes following shunt placement, time to shunt failure, and etiology of shunt failure are reported. RESULTS: A total of 21 patients underwent 32 ventricular shunting procedures (20 VP, 10 ventriculoatrial, 2 ventriculopleural). One hundred percent of shunts were successfully placed into slit ventricles, all requiring only one pass of the catheter under stereotactic guidance to achieve the desired location and CSF flow. There were no procedure-related complications and each ventricular catheter showed rapid egress of CSF. All (100%) patients experienced significant improvement of headache immediately after shunting. Ten percent of ventricular shunts failed at 3 months after insertion, 20% failed by 6 months, 50% failed by 12 months, and 60% failed by 24 months. Shunt revision was due to distal obstruction in 67%, overdrainage in 20%, and distal catheter migration or CSF leak in 6.5%. There were no shunt revisions due to proximal catheter obstruction or shunt infection. CONCLUSIONS: In our experience treating patients with IIH, frameless stereotactic ventricular CSF shunts were extremely effective at treating IIH-associated intractable headache, and continued to provide relief in nearly half of patients 2 years after shunting without many of the shunt-related complications that are seen with LP shunts. Placing ventricular shunts using image-guided stereotaxis in patients with IIH despite the absence of ventriculomegaly is an effective, safe treatment option.

Adult↗

PubMedDate not supplied

Endoscopic, single-catheter treatment of Dandy-Walker syndrome hydrocephalus: technical case report and review of treatment options.

Optimal treatment for hydrocephalus related to Dandy-Walker syndrome (DWS) remains elusive. Patients with DWS-related hydrocephalus often require combinations of shunting systems to effectively drain both the supratentorial ventricles and posterior fossa cyst. We describe an endoscopic technique, whereby a frontally placed, single-catheter shunting system effectively drained the supratentorial and infratentorial compartments. This reduces the complexity and potential risk associated with the combined shunting systems required by so many with DWS-related hydrocephalus.

Catheterization↗