bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel, Compact, Intraoperative Magnetic Resonance Imaging-guided System for Conventional Neurosurgical Operating Rooms
Authors: Hadani Moshe , Spiegelman Roberto , Feldman Zeev , Berkenstadt Haim , Ram Zvi
Published: July 2004

OBJECTIVE

Preliminary clinical experience with a novel, compact, intraoperative magnetic resonance imaging (MRI)-guided system that can be used in an ordinary operating room is presented.

DESCRIPTION OF INSTRUMENTATION

The system features an MRI scanner integrated with an optical and MRI tracking system. Scanning and navigation, which are operated by the surgeon, are controlled by an in-room computer workstation with a liquid crystal display screen. The scanner includes a 0.12-T permanent magnet with a 25-cm vertical gap, accommodating the patient's head. The field of view is 11 × 16 cm, encompassing the surgical area of interest. The magnet is mounted on a transportable gantry that can be positioned under the surgical table when not in use for scanning, thus rendering the surgical environment unmodified and allowing the use of standard instruments. The features of the integrated navigation system allow flap planning and intraoperative tracking based on updated images acquired during surgery.

OPERATIVE TECHNIQUE

Twenty patients with brain tumors were surgically treated using craniotomy or transsphenoidal approaches. One patient underwent conscious craniotomy with cortical mapping, and two underwent electrocorticography.

EXPERIENCE AND RESULTS

Planning was accurate. Resection control images were obtained for all patients during surgery, with precise localization of residual tumor tissue. There were no surgical complications related to the use of the system.

CONCLUSION

This intraoperative MRI system can function in a normal operating room modified only to eliminate radiofrequency interference. The operative environment is normal, and standard instruments can be used. The scanning and navigation capabilities of the system eliminate the inaccuracies that may result from brain shift. This novel type of intraoperative MRI system represents another step toward the introduction of the modality as a standard method in neurosurgery.
Reversal of Increased Intracranial Pressure with Removal of a Torcular Epidermoid: Case Report
Authors: Lam Cornelius H. , Solomon Robin K. , Clark H. Brent , Casey Sean O.
Published: July 2004

OBJECTIVE AND IMPORTANCE

Venous obstruction has been postulated as a cause of increased intracranial pressure, but it has been documented rarely. We present a case of obstruction of the torcula by a slow-growing epidermoid. The tumor caused increased intracranial pressure, which was relieved when it was excised. In addition, the torcular epidermoid is associated with a bifid straight sinus.

CLINICAL PRESENTATION

A 35-year-old man presented with a headache and a lump on the back of the head. Physical examination revealed a firm, bony lesion approximately 4 × 4 cm in size. Lumbar puncture demonstrated an intraspinal pressure of 39 cm H2O. Neuroradiological studies revealed an epidermoid that compressed and almost completely occluded the torcula.

INTERVENTION

After the tumor was resected, the intraspinal pressure decreased to 19 cm H2O and remained stable 6 months later.

CONCLUSION

Pure venous obstruction causes increased intracranial pressure. Removal of the obstruction relieves the intracranial hypertension. In addition, computed tomographic venography is a safe and easy method of documenting torcular anatomy, and it was useful in the follow-up of this patient. Computed tomographic venography can demonstrate a double straight sinus, which is a congenital variant that may be associated with the epidermoid.
Aneurysms of the Lateral Spinal Artery: Report of Two Cases
Authors: Chen Clark C. , Bellon Richard J. , Ogilvy Christopher S. , Putman Christopher M.
Published: July 2004

OBJECTIVE AND IMPORTANCE

The goal of this report was to describe aneurysms arising from the lateral spinal artery. The locations of aneurysms contributing to subarachnoid hemorrhage (SAH) have been well characterized and are primarily in the circle of Willis or at the bifurcation points of the internal carotid artery or the vertebrobasilar system. Although the spinal arteries are also in direct communication with the subarachnoid space, aneurysms of these arteries that lead to SAH are rare. To date, only aneurysms of the anterior and posterior spinal arteries have been described. In this communication, we report two patients with aneurysms of the lateral spinal artery who presented with SAH.

CLINICAL PRESENTATION

Review of our neurointerventional database from 1997 to the present revealed two patients with lateral spinal artery aneurysms. The medical records, as well as the operative and radiological findings, were reviewed for both patients. In both cases, the lateral spinal arteries were involved as collateral pathways for occlusive vertebral lesions, suggesting hemodynamic stress as a cause.

INTERVENTION

Endovascular treatment was attempted in both cases and was successful in one; open surgery, with aneurysm resection, was performed in the other case. We review the vascular anatomic features of the spinal cord as they relate to the lateral spinal artery, as well as treatment options for lateral spinal artery aneurysms.

CONCLUSION

Lateral spinal artery aneurysms are a rare cause of SAH. Both endovascular and surgical treatment options are available.
Embolization of Arteriovenous Malformations with Onyx: Clinicopathological Experience in 23 Patients
Authors: Jahan Reza , Murayama Yuichi , Gobin Y. Pierre , Duckwiler Gary R. , Vinters Harry V. , Viñuela Fernando
Published: July 2004

OBJECTIVE

To report our experience in treatment of arteriovenous malformations (AVMs) using a new liquid embolic agent, Onyx (Micro Therapeutics, Inc., Irvine, CA).

METHODS

Between January 1998 and May 1999, 23 patients (8 men and 15 women) were treated. The patients' average age was 40 years, with seizure being the most common presenting symptom (39%). The average Spetzler-Martin grade on presentation was 3. The average AVM volume before embolization was 14.5 cm3.

RESULTS

We observed an average 63% reduction in AVM volume after 129 arterial feeders were embolized. There were four adverse events. Two patients experienced ischemia because of inadvertent occlusion of an arterial feeder. One of these patients made a full recovery, but the other patient had a permanent deficit. Two other patients experienced transient neurological deficits that resolved within 1 week of embolization. Permanent morbidity was thus 4% (1 of 23 patients). There were no deaths. Twelve patients underwent subsequent radiosurgery, and 11 patients had surgery that resulted in complete resection of their AVMs. Histopathological examinations showed mild acute inflammation in specimens resected 1 day after embolization. Chronic inflammatory changes were observed in specimens resected more than 4 days after embolization. In two patients, angionecrosis of the embolized vessels was noted. No evidence of parenchymal hemorrhage was observed in these patients, and vessel wall integrity was maintained as well.

CONCLUSION

Onyx is a new nonadhesive liquid embolic agent that has been used to treat 23 patients at our institution with good results. Its nonadhesive nature and ease of use make it a promising agent in the future treatment of AVMs.
Multimodal Cranial Neuronavigation: Direct Integration of Functional Magnetic Resonance Imaging and Positron Emission Tomography Data: Technical Note
Authors: Braun Veit , Dempf Sibylle , Tomczak Reinhard , Wunderlich Arthur , Weller Rolf , Richter Hans-Peter
Published: July 2004

OBJECTIVE

This is the first report of the direct integration of functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) data into cranial neuronavigation.

METHODS

In a patient with a left precentral oligodendroglioma (World Health Organization Grade III), the Zeiss MKM system (Carl Zeiss Co., Oberkochen, Germany) was used for navigation based on thin-slice, T1-weighted, contrast-enhanced magnetic resonance imaging (MRI) scans. fMRI and methionine PET data were integrated by landmark matching, with reference to skin fiducials.

RESULTS

The inaccuracy of the image fusion between fMRI and T1-weighted MRI data was 1.7 mm, that between PET and T1-weighted MRI data was 4.3 mm, and that for the subsequent registration of the navigation was 1.2 mm. The correct fMRI localization of the precentral gyrus was intraoperatively verified by cortical somatosensory evoked potential (phase-reversal) monitoring. Although the tumor was not clearly defined in the MRI scans, [11C]methionine PET demonstrated a clear tumor border, enabling us to achieve gross total tumor removal without postoperative functional deficits.

CONCLUSION

Functional neuronavigation permits observation and preservation of relevant brain areas. Other functional areas (such as short-term memory areas) that can be detected only by fMRI might also warrant future monitoring. The simultaneous integration of fMRI and PET data adds a new dimension to cranial neuronavigation, enabling the observation of tumors in relation to functional cortical areas (in our case, the motor strip).
Transsphenoidal Surgery for Acromegaly: Endocrinological Follow-up of 98 Patients
Authors: Shimon Ilan , Cohen Zvi R. , Ram Zvi , Hadani Moshe
Published: July 2004

OBJECTIVE

Transsphenoidal surgery is the preferred treatment modality for growth hormone (GH)-secreting pituitary adenomas. In many series, the reported postoperative remission is based mainly on achievement of GH levels less than 2 ng/ml. Strict criteria for insulin-like growth factor I normalization and even lower GH levels (<1 ng/ml) are now suggested to define cure of acromegaly, but the evidence does not yet support such low GH levels in epidemiological follow-up. We analyzed our postoperative results in a large cohort of patients with acromegaly.

METHODS

Ninety-eight patients harboring GH-secreting adenomas (46 microadenomas and 52 macroadenomas) underwent transsphenoidal surgery between 1990 and 1999. Ninety-one patients were operated for the first time, and 12 patients underwent reoperations because of previous surgical failure (7 had undergone surgery elsewhere previously). Biochemical remission was defined as a repeated fasting or glucose-suppressed GH level of 2 ng/ml or less, and a normal insulin-like growth factor I level.

RESULTS

Remission was achieved in 74% of all patients after one operation, including 84% of patients with microadenomas and 64% of patients with macroadenomas. Seventy-three percent of patients with macroadenomas 11 to 20 mm in size achieved remission, as compared with a 20% remission rate for patients with adenomas larger than 20 mm. Patients with preoperative random GH levels lower than 50 ng/ml had a better outcome (85% remission), whereas GH greater than 50 ng/ml was associated with remission in 30% of the patients. Only one of the patients (8%) with postoperative active disease who underwent a second operation achieved remission. Recurrence was rare (one patient), and all failed surgical attempts could be detected during the immediate postoperative evaluation.

CONCLUSION

On the basis of strict postoperative GH and insulin-like growth factor I criteria to define remission, our series demonstrates the efficacy of transsphenoidal surgery for acromegalic patients with microadenomas and noninvasive macroadenomas. However, patients with large adenomas (>20 mm) and preoperative GH greater than 50 ng/ml have a poor prognosis and require adjunctive medical or radiation therapy to control GH hypersecretion.
Angioplasty of Intracranial Occlusion Resistant to Thrombolysis in Acute Ischemic Stroke
Authors: Ringer Andrew J. , Qureshi Adnan I. , Fessler Richard D. , Guterman Lee R. , Hopkins L. Nelson
Published: July 2004

OBJECTIVE

Thrombolysis has been demonstrated to improve revascularization and outcome in patients with acute ischemic stroke. Many centers now apply thrombolytic therapy locally via intra-arterial infusion. One therapeutic benefit is the ability to cross soft clots with a guidewire and to perform mechanical thrombolysis. In some instances, reopened arteries reocclude as a result of either thrombosis or vasospasm. We report the use of balloon angioplasty during thrombolysis for acute stroke.

METHODS

From June 1995 through June 1999, 49 patients underwent intra-arterial therapy for acute stroke. In this group, nine patients (seven men and two women) were treated with balloon angioplasty after inadequate recanalization with thrombolytic infusion. The mean age of these patients was 67.9 years. Nine matched control patients who underwent thrombolysis alone without angioplasty were chosen for comparison.

RESULTS

In the group of nine patients who had angioplasty, the mean National Institutes of Health Stroke Scale score at presentation was 21.8 ± 5.4. Four patients had residual distal occlusion after angioplasty, and one patient had a hemorrhagic conversion. Of the five patients in which recanalization was successful, none had reocclusion of the balloon-dilated vessel. The mean score at 30 days for the five survivors was 12.6 ± 14.9, for an improvement of 7.0 ± 14.2. Among the nine control patients, the mean score at presentation was 20.3 ± 5.2; the mean score at 30 days for the five survivors was 19.4 ± 7.7, for an improvement of 4.2 ± 7.8.

CONCLUSION

In our experience, balloon angioplasty is a safe, effective adjuvant therapy in patients who are resistant to intra-arterial thrombolysis. The use of balloon angioplasty may prevent reocclusion in a stenotic artery and permit distal infusion of thrombolytic agents.
Resection of a Giant Intracranial Dural Arteriovenous Fistula with the Use of Low-flow Deep Hypothermic Cardiopulmonary Bypass after Partial Embolization: Technical Case Report
Authors: Dufour Henry , Levrier Olivier , Bruder Nicolas , Messana Thierry , Grisoli François
Published: July 2004

OBJECTIVE AND IMPORTANCE

To describe the surgical resection of a giant intracerebral arteriovenous fistula with involvement of dura mater and surrounding bone. Intraoperative bleeding was controlled by hypothermic circulatory arrest.

CLINICAL PRESENTATION

This 46-year-old woman complained of persistent headache for 1 year; her diagnostic workup revealed the presence of an arteriovenous fistula in the dura mater of the left temporal region fed by the meningeal artery of the external and internal carotid arteries, with normal run-off into Labbé's and Trolard's veins. Magnetic resonance imaging depicted a Chiari I malformation that was most likely a result of insufficient cerebral venous drainage.

INTERVENTION

In preparation for surgery, staged embolization of feeders from the left meningeal artery and the left occipital artery was performed under controlled hypotension. This procedure failed to achieve a significant reduction in flow because of the immediate recruitment of internal branches of the internal carotid artery and dural branches of the right external carotid artery. Surgical treatment was undertaken without further embolization. Because of involvement of surrounding bone and the high risk of uncontrollable bleeding, the procedure was carried out with the patient under deep hypothermic cardiopulmonary bypass. Forty-five minutes of low flow (1.5 L/min) at 18°C allowed total resection of the involved dura mater and surrounding bone. Postoperative recovery was marked by left brain edema that disappeared within 10 days. Findings on follow-up angiography were normal, and the patient was discharged with no neurological deficit.

CONCLUSION

Low-flow deep hypothermic cardiopulmonary bypass can be used to control intraoperative bleeding for surgical excision of a giant intracerebral dural arteriovenous fistula.
Improved Cerebral Perfusion and Metabolism after Stenting for Basilar Artery Stenosis: Technical Case Report
Authors: Uchiyama Naoyuki , Kida Shinya , Watanabe Takuya , Yamashita Junkoh , Matsui Osamu
Published: July 2004

OBJECTIVE

Recent advances in stent technology have allowed the introduction of more flexible stents that may be tracked more easily in the intracranial vessels. We present a patient with improved cerebral blood flow and metabolism as assessed by positron emission tomography after stent-assisted angioplasty for symptomatic basilar artery stenosis.

CLINICAL PRESENTATION

A 62-year-old man, who had undergone left superficial temporal artery to middle cerebral artery bypass surgery for left internal carotid artery occlusion 10 years previously, presented with dizziness, blurred vision, and memory disturbance. Angiography revealed severe stenosis of the proximal basilar artery. Positron emission tomographic scans revealed decreased cerebral blood flow associated with increased oxygen extraction fraction in the entire brain, particularly in the posterior circulation and the left middle cerebral artery territory. Despite medical treatment, the patient experienced worsening visual disturbance and right-sided motor weakness.

INTERVENTION

Ticlopidine and aspirin were used as antiplatelet agents. In addition, we used argatroban, which is a direct thrombin inhibitor, as an anticoagulant during the procedure. Predilation with a coronary artery balloon was performed, followed by placement of a GFX 3- by 8-mm stent (Arterial Vascular Engineering, Santa Rosa, CA), with excellent angiographic results. The patient made a good neurological recovery, and the postoperative positron emission tomographic scan demonstrated increases in both cerebral blood flow and cerebral metabolic rate of oxygen with a normalization of oxygen extraction fraction.

CONCLUSION

Stent-assisted angioplasty can provide a favorable clinical course as well as improved cerebral perfusion and metabolism for a patient with basilar artery stenosis. Long-term follow-up data and additional clinical experience are required to assess the durability of this approach.
The Nature and Fate of Punctate (Type IV) Cavernous Malformations
Authors: Clatterbuck Richard E. , Elmaci Ilhan , Rigamonti Daniele
Published: July 2004

OBJECTIVE

Four types of cavernous malformations (Types I–IV) have been described on the basis of their magnetic resonance imaging (MRI) appearance. The nature of the Type IV cavernous malformation is unclear. It has been suggested that these small lesions, which are well observed only on gradient echo MRI scans, are capillary telangiectasias. We sought to understand the relationship of Type IV cavernous malformations to the other cavernous malformation subtypes.

METHODS

We examined serial MRI scans obtained between 1987 and 2000 from 68 patients with more than 228 cavernous malformations. Sixteen patients harbored Type IV cavernous malformations (total, >114 Type IV lesions). Spin echo T1-weighted, T2-weighted, proton density, and (when available) gradient echo MRI scans were reviewed. Cavernous malformations that met the Zabramski criteria for Type IV (poorly observed on T1- and T2-weighted images) were reviewed in serial scans from individual patients to characterize their radiographic behavior over time.

RESULTS

Type IV cavernous malformations were best observed on gradient echo images and have an MRI appearance distinct from capillary telangiectasias. Proton density images demonstrate more Type IV lesions than T1- and T2-weighted images, but far fewer Type IV lesions than gradient echo images. When observed on T1- and T2-weighted images, Type IV cavernous malformations are generally punctate and hypointense. These lesions rarely enhance with gadolinium. Four of the Type IV cavernous malformations observed serially evolved into Type I and Type II cavernous malformations, for an approximate rate of progression of 0.05 per patient year.

CONCLUSION

Although most Type IV cavernous malformations remain stable over time, a small subset of these lesions progress into Types I and II cavernous malformations.
Intra-arterial Third-generation Recombinant Tissue Plasminogen Activator (Reteplase) for Acute Ischemic Stroke
Authors: Qureshi Adnan I. , Ali Zulfiqar , Suri M. Fareed K. , Kim Stanley H. , Shatla Ahmed A. , Ringer Andrew J. , Lopes Demetrius K. , Guterman Lee R. , Hopkins L. Nelson
Published: July 2004

OBJECTIVE

We prospectively evaluated the safety and recanalization efficacy of intra-arterially administered reteplase, a third-generation recombinant tissue plasminogen activator, for treating ischemic stroke in patients considered poor candidates for intravenously administered alteplase therapy.

METHODS

Patients were considered poor candidates for intravenously administered therapy because of severity of neurological deficits, interval from onset of symptoms to presentation of 3 hours or more, or recent major surgery. We administered a maximum total dose of 8 U of reteplase intra-arterially in 1-U increments via superselective catheterization. Adjunctive angioplasty of the occluded artery was performed in seven patients. Angiographic evidence of perfusion and thrombus was graded by use of modified Thrombolysis in Myocardial Infarction (TIMI) criteria. Neurological examinations were performed before and 24 hours and 7 to 10 days after treatment.

RESULTS

Sixteen consecutive patients were treated (mean age, 64.1 ± 16.4 yr; seven were men). Initial National Institutes of Health Stroke Scale scores ranged from 10 to 26. Time from onset of symptoms to treatment ranged from 2 to 9 hours. Occlusion sites were the cervical internal carotid artery (n = 4), intracranial internal carotid artery (n = 4), middle cerebral artery (n = 6), and vertebrobasilar artery (n = 2). Complete or near-complete perfusion (TIMI Grade 3 or 4) was achieved in the arteries in 14 patients (88%), with partial recanalization (TIMI Grade 2) or minimal response (TIMI Grade 1) in the arteries in one patient each. Neurological improvement (defined as decrease of four or more points in National Institutes of Health Stroke Scale score) was observed in 7 (44%) of the 16 patients at 24 hours. Symptomatic intracerebral hemorrhage occurred in one patient; three other patients experienced intracerebral hemorrhages that did not result in neurological worsening. The overall mortality during hospitalization was 56%, related to massive ischemic stroke (n = 7), withdrawal of care at the family's request after the development of aspiration pneumonia and renal failure (n = 1), and a combination of intracerebral hemorrhage and massive ischemic stroke (n = 1).

CONCLUSION

In this study, intra-arterially administered reteplase in doses up to 8 U with or without angioplasty resulted in a high rate of recanalization. This strategy should be considered in treating patients considered poor candidates for intravenous thrombolysis.
C1–C2 Transarticular Screw Fixation: Technical Aspects
Authors: Haid Regis W.
Published: July 2004

OBJECTIVE

I review posterior atlantoaxial fusion with transarticular screw fixation, including indications, complications, and operative technique, emphasizing my experience.

METHODS

The indications for C1–C2 transarticular screw fixation include traumatic injuries to the atlantoaxial complex, instability resulting from inflammatory disease (rheumatoid arthritis), and congenital abnormalities (os odontoideum). All patients underwent stabilization using cannulated C1–C2 transfacetal screws by the method described by Magerl. Supplemental interspinous fusion with bicortical autologous iliac crest graft and titanium cable was used to restore the posterior tension band by use of the method described by Sonntag's group. Preoperatively, all patients underwent imaging with plain radiographs, magnetic resonance imaging, and axial computed tomography. Patients were maintained in a rigid cervical orthosis postoperatively.

RESULTS

Measures used to improve safety and efficacy include patient positioning, fluoroscopic guidance, preoperative magnetic resonance imaging, axial computed tomography, and open reduction of C1–C2 subluxation before screw passage. In this series of 75 patients, fusion was obtained in 72 patients (96%). There were no instances of vertebral artery injury, errant screw placement, instrumentation failure, dural laceration, spinal cord injury, or hypoglossal nerve injury.

CONCLUSION

C1–C2 transarticular screw fixation with a posterior tension band construct provides excellent fusion rates with few perioperative complications. Preoperative imaging and meticulous surgical technique improve outcomes.
Management of Cysts Arising after Radiosurgery to Treat Intracranial Arteriovenous Malformations
Authors: Pollock Bruce E. , Brown Robert D.
Published: July 2004

OBJECTIVE

The proper treatment for patients with cyst formation after arteriovenous malformation radiosurgery is unknown.

METHODS

The treatment of six patients who developed cysts after arteriovenous malformation radiosurgery is described. Four patients had undergone gamma knife radiosurgery (two patients developed cysts after repeat procedures), and two patients had undergone linear accelerator-based radiosurgery. The median prescription isodose volume at the time of the first radiosurgical procedure was 13.2 cm3 (range, 8.0–28.7 cm3).

RESULTS

The cysts were discovered a median of 48 months (range, 24–89 mo) after radiosurgery. Three patients were originally without symptoms, and observation with serial imaging was performed; two of those patients developed symptoms 13 and 40 months later, whereas one patient has remained without symptoms for 51 months. Initial treatments for patients with symptomatic cysts included cyst aspiration (n = 3) and placement of a cystoperitoneal shunt (CPS) (n = 2). The median cyst volume was 14 cm3 (range, 4–63 cm3). Cyst recurrence occurred within 2 months for patients who underwent aspiration alone, necessitating placement of a CPS. Shunt placement eliminated the cysts for four patients, at a median follow-up time of 16 months (range, 9–27 mo). One patient's cyst persisted despite CPS placement, and cyst excision was performed. No morbidity occurred with any of the cyst treatments.

CONCLUSION

Cyst formation after arteriovenous malformation radiosurgery may occur many years after the procedure. Although most symptomatic cysts can be effectively treated with CPSs, cyst excision may be necessary if the mass effect is not relieved with the less invasive approach.
Electrical Stimulation of the Prelemniscal Radiation in the Treatment of Parkinson's Disease: An Old Target Revised with New Techniques
Authors: Velasco Francisco , Jiménez Fiacro , Pérez Martha Luisa , Carrillo-Ruiz José D. , Velasco Ana Luisa , Ceballos Joel , Velasco Marcos
Published: July 2004

OBJECTIVE

In the treatment of tremor and rigidity in patients with Parkinson's disease (PD), the prelemniscal radiation (RAPRL), a subthalamic bundle of fibers, is an exquisite target that can be visualized easily on ventriculograms. We sought to evaluate the effect of electrical stimulation of the RAPRL on symptoms and signs of PD in a long-term trial and to determine the localization of the stimulated area by means of stereotactic magnetic resonance imaging studies.

METHODS

Ten patients with PD predominantly on one side had tetrapolar electrodes stereotactically oriented through a frontal parasagittal approach to the RAPRL contralateral to the most prominent symptoms. Preoperative and postoperative evaluations at 3, 6, 9, and 12 months after surgery were performed using conventional PD scales and quantitative evaluations of tremor amplitude and reaction time. Stereotactic high-resolution magnetic resonance imaging studies with the electrodes in place were used for anatomic localization.

RESULTS

In all patients, temporary suppression of tremor occurred when the electrodes reached the target. The most effective stimulation was obtained when the pair of contacts was placed in the RAPRL. Long-term stimulation at 130 Hz, 0.09 to 0.450 milliseconds, and 1.5 to 3.0 V produced significant improvement in tremor and rigidity and mild improvement in bradykinesia.

CONCLUSION

The RAPRL is an effective target for the alleviation of tremor and rigidity in patients with PD by either lesioning or neuromodulation; however, neuromodulation has the advantage of not inducing an increase in bradykinesia. The stimulated area seems to be independent of the subthalamic nucleus.
Deep Brain Stimulator Electrodes Used for Lesioning: Proof of Principle
Authors: Oh Michael Y. , Hodaie Mojgan , Kim Seong Ho , Alkhani Ahmed , Lang Anthony E. , Lozano Andres M.
Published: July 2004

OBJECTIVE

Patients with chronically implanted deep brain stimulator (DBS) electrodes can encounter complications requiring hardware removal. We assessed the safety and efficacy of using implanted DBS electrodes to create a therapeutic lesion before their removal.

METHODS

Revision or removal of the DBS electrodes was required in two patients who had previously undergone DBS implantation. We conducted a series of in vitro experiments to confirm that the DBS electrodes could be used to generate radiofrequency lesions and to assess the relationship between radiofrequency parameters and lesion size. With this information, and with the approval of the hospital ethical review board, implanted electrodes were used to create incremental radiofrequency lesions in the thalamus in one patient and in the subthalamic nucleus in another. The procedures were performed under local anesthesia with contiguous contacts of the DBS lead connected to the active and reference sites of the RF generator to create a bipolar lesion.

RESULTS

A 51-year-old man with essential tremor and a thalamic DBS required repeated battery changes secondary to tolerance and high voltage demands. Rather than replacing the battery, a radiofrequency thalamotomy was performed by using the existing left DBS electrode. At the 6-month follow-up examination, successful lesioning provided near complete tremor control. A second patient, a 50-year-old man with Parkinson's disease who had undergone bilateral subthalamic deep brain stimulation, developed skin erosion over the DBS hardware. A subthalamic nucleus lesion was made through the right DBS electrode. Lesion position and size were confirmed with magnetic resonance imaging.

CONCLUSION

Lesions can be made through chronically implanted DBS electrodes in a safe, graded fashion and can produce therapeutic benefit.
Surgical Exposure and Resection of the Vertical Portion of the Petrous Internal Carotid Artery: Anatomic Study
Authors: Suhardja Agustinus S. , Cusimano Michael D. , Agur Anne M.R.
Published: July 2004

OBJECTIVE

The goals were to determine which surgical approaches, i.e., the preauricular subtemporal infratemporal fossa (PSI), postauricular transtemporal (PAT), and/or subtemporal middle fossa (SMF) approaches, provide optimal exposure of the anterior, posterior, medial, and lateral aspects of the vertical segment of the petrous internal carotid artery (VPCA) and to determine the length of the VPCA that can be resected before a vein graft is necessary.

METHODS

Using 22 cadaveric specimens, we compared the length of exposure of the VPCA provided by the PSI, PAT, and SMF approaches. The segment of the VPCA that was exposed with each approach was measured in millimeters and expressed as a percentage of the total length of the VPCA. Resection of the VPCA in 1-mm increments was performed until a graft would be necessary; the total length of the resected segment was recorded in millimeters and was also expressed as a percentage of the total length of the VPCA.

RESULTS

The PSI approach provided average exposures of 14.1 mm (95% of the total exposure possible) of the anterior aspect and 14.3 mm (96%) of the lateral aspect of the VPCA; resection of less than 2.3 mm (16%) of the VPCA could be repaired with an end-to-end anastomosis. The PAT approach provided average exposures of 10.5 mm (71%) of the lateral aspect and 10.0 mm (76%) of the posterior aspect of the VPCA; resection of less than 2.8 mm of the VPCA could be repaired with an end-to-end anastomosis. The SMF approach provided average exposures of 6.1 mm (45%) of the anterior aspect and 5.4 mm (41%) of the lateral aspect of the VPCA; resection of less than 2.4 mm (24%) of the VPCA could be repaired with an end-to-end anastomosis.

CONCLUSION

Lesions on the anterior and lateral aspects of the VPCA can be fully exposed with the PSI approach or partially exposed with the less invasive SMF approach. Lesions on the posterior aspect of the artery are best exposed with the PAT approach. Lesions on the medial aspect of the VPCA cannot be exposed unless the VPCA is mobilized in the PSI approach. Resection of less than approximately 2.5 mm (20%) can be repaired with an end-to-end anastomosis, regardless of the approach used.
Focal Intracranial Infections Due to Propionibacterium acnes: Report of Three Cases
Authors: Chu Ray M. , Tummala Ramachandra P. , Hall Walter A.
Published: July 2004

OBJECTIVE AND IMPORTANCE

Except for its role in shunt infections, Propionibacterium acnes has been of little interest to neurosurgeons. The rarity and indolent nature of focal intracranial infections by P. acnes limit their recognition. Three cases of serious intracranial infection due to this organism are described.

CLINCAL PRESENTATION

Three patients with histories of immunosuppression and neurosurgical procedures developed nonspecific, delayed presentations (5 wk to 5 yr after surgery) of intracranial infections. In two patients, radiological investigations showed enhancing lesions that were later found to be brain abscesses. A subdural empyema was found in the third patient.

INTERVENTION

All three patients underwent surgical drainage of the purulent collections. P. acnes was isolated in each case, and each patient was treated with a 6-week course of intravenous penicillin. All three patients made good recoveries, and subsequent imaging showed no recurrence of the infectious collections.

CONCLUSION

P. acnes is an indolent organism that may rarely cause severe intracranial infections. This organism should be suspected when an intracranial purulent collection is discovered in a patient with a history of neurosurgical procedures. Immunosuppressed patients may be susceptible to this otherwise benign organism. Surgical drainage and treatment with intravenous penicillin should be considered standard therapy.
M2/M2 Side-to-Side Rescue Anastomosis for Accidental M2 Trunk Occlusion during Middle Cerebral Artery Aneurysm Clipping: Technical Note
Authors: Steiger Hans-Jakob , Ito Seiro , Schmid-Elsässer Robert , Uhl Eberhard
Published: July 2004

OBJECTIVE

A technically feasible and rapid technique for revascularizing the main branches of the middle cerebral artery (MCA) is described. This technique is applied mainly when clipping of an MCA aneurysm is complicated and occlusion of the origin of an MCA main branch results.

METHODS

M2/M2 side-to-side anastomosis was applied in two patients in whom unplanned M2 occlusion occurred during the course of complicated MCA aneurysm clipping. The first patient underwent an emergency procedure after temporoparietal intracerebral hemorrhage. Unilateral mydriasis precluded preoperative angiographic workup, and a complex large MCA aneurysm was found as the source of hemorrhage. Shaping of the aneurysm neck by bipolar coagulation and clipping resulted in accidental occlusion of the superior trunk, and patency could not be regained despite multiple clip corrections. The second patient had an unruptured multilobulated aneurysm 8 mm in maximum diameter. Continuity of the inferior trunk was lost during clipping because of a tear at the origin. In both instances, side-to-side anastomosis was placed approximately 15 mm from the bifurcation, where the MCA main trunks ran side by side for a length of approximately 5 mm.

RESULTS

After intracerebral hemorrhage, the first patient recovered to a level of moderate disability within 2 months. Substantial hemiparesis and expressive dysphasia remained as sequelae of the intracerebral hemorrhage. Digital subtraction angiography 2 months after the emergency procedure confirmed patency of the side-to-side anastomosis. The second patient was neurologically intact after recovery from anesthesia. Before discharge from the hospital on postoperative Day 8, digital subtraction angiography confirmed patency of the anastomosis.

CONCLUSION

The MCA main branches usually run in close proximity for a short segment at the bottleneck entrance to the insular cistern. M2/M2 side-to-side anastomosis at this site is a rapid and feasible mode of revascularization of an M2 trunk accidentally occluded during complicated MCA aneurysm clipping.
Quantitative Analysis of the Transcondylar Approach to the Foramen Magnum
Authors: Wanebo John E. , Chicoine Michael R.
Published: July 2004

OBJECTIVE

Condylar resection with suboccipital craniotomy increases foramen magnum exposure, but guidelines for when this is necessary are not defined. Cadaveric and computed tomography evaluations were completed to guide decision-making regarding the use and extent of condylar resection.

METHODS

Quantitative analysis of foramen magnum surgical exposures was performed on 32 skulls (64 sides) and 6 cadaveric dissections (12 sides). Computed tomographic (CT) scans were performed on cadaveric heads before and after condylar resections. Digitized images of dry skulls and CT images of cadaver heads were quantitatively analyzed. Predissection CT measurements of cadaveric heads guided extent of condylar resections, and resection accuracy was assessed with postdissection CT scans.

RESULTS

Skull measurements (means in parentheses) included the foramen magnum area (7.8 cm2), length (3.6 cm), width (3.1 cm), anteroposterior condylar length (2.3 cm), and axial condylar length (2.5 cm). Mean widths of potential surgical exposures for skulls were obtained for A) suboccipital craniotomy (2.3 cm), B) with 25% (2.6 cm), and C) 50% condylar resection (3.0 cm). Mean angles of exposure were as follows: A, 38.4 degrees; B, 49.1 degrees; and C, 54.3 degrees. CT scans of cadaveric heads before and after dissections yielded measurements of exposure equivalent to measurements found on the dry skulls.

CONCLUSION

On average, lateral exposure increases by 3 mm (13%) and 7 mm (30%) for 25 and 50% condylar resection, respectively, compared with suboccipital craniotomy alone. Angles of exposure increase by 10.7 degrees (28%) and 15.9 degrees (41%). Measurements of CT images can be used preoperatively to help analyze the need for condylar resection and intraoperatively to guide the extent of condylar resection.
Association between Intracranial Plasmacytoma and Multiple Myeloma: Clinicopathological Outcome Study
Authors: Schwartz Theodore H. , Rhiew Richard , Isaacson Steven R. , Orazi Attilio , Bruce Jeffrey N.
Published: July 2004

OBJECTIVE

Intracranial plasmacytomas are rare lesions that can arise from the calvarium, dura, or cranial base and exhibit a benign course unless associated with myeloma. Attention has recently been focused on the role of the cell adhesion molecules CD56 and CD31 in the pathogenesis of myeloma. No such information is available for intracranial plasmacytomas and myeloma-associated lesions.

METHODS

We investigated the relationship between CD56 and CD31 expression, intracranial location, and progression to myeloma for a series of nine intracranial plasmacytomas (three dural, one calvarial, and five cranial base lesions). These parameters were also correlated with proliferation indices, as assessed by MIB-1 immunostaining of the histological sections. A single pathologist (AO) performed immunohistochemical analyses and reviewed all slides.

RESULTS

Intracranial plasmacytomas presented more commonly in female patients (89%). The three dural lesions were CD56- and CD31-negative and exhibited MIB-1 staining of less than 10%; no patient developed myeloma or recurrence. Of the five cranial base lesions, three were CD56-positive, none was CD31-positive, and two exhibited MIB-1 labeling of more than 45%, with plasmablastic morphological features. Compared with other intracranial plasmacytomas, five of five patients with cranial base lesions developed bone marrow biopsy-proven myeloma (P < 0.05) within 8 months. The calvarial lesion was CD56- and CD31-positive, and the patient developed myeloma soon after diagnosis. Both of the two highly proliferative plasmablastic lesions recurred, one after gross total resection without radiotherapy and the other after a biopsy and 2000-cGy radiotherapy.

CONCLUSION

Among intracranial plasmacytomas, cranial base location was the strongest predictor of the development of multiple myeloma. Expression of the cell adhesion molecules CD31 and CD56 was not predictive of outcome. Extramedullary dural-based lesions were CD56-negative and were not associated with myeloma. A high proliferation index and plasmablastic morphological features were predictive of a short time to recurrence and aggressive behavior. We recommend 4050- to 5040-cGy fractionated radiotherapy for all intracranial plasma cell neoplasms and gross total resection for non-cranial base lesions.
Association of Chiari I Malformation, Mental Retardation, Speech Delay, and Epilepsy: A Specific Disorder?
Authors: Grosso Salvatore , Scattolini Roberto , Paolo Galluzzi , Di Bartolo Rosanna Maria , Morgese Guido , Balestri Paolo
Published: July 2004

OBJECTIVE

The Chiari I malformation is defined as tonsillar herniation of at least 3 to 5 mm below the foramen magnum. Although Chiari I malformation is considered to derive from a mesodermal disorder resulting in underdevelopment of the posterior fossa relative to its content, evidence for a possible heterogeneous etiology also has been reported. The aim of the present study is to elucidate the relationship between Chiari I malformation and mental retardation, speech delay, and epilepsy to consider a possible specific pathogenetic background.

METHODS

Thirty-five patients with Chiari I malformations were identified by use of magnetic resonance imaging during a period between 1993 and 1999. The study consisted of nine patients (four boys and five girls) who were affected by mental retardation, speech delay, and epilepsy. All patients underwent electroencephalography and brain and cervical spine magnetic resonance imaging.

RESULTS

All patients were mentally retarded with a mean intelligence quotient of 50. Seven patients had a positive history for speech delay, and five were epileptic. Electroencephalograms demonstrated abnormalities in seven patients. The mean tonsillar displacement was 10.1 mm. A thin corpus callosum and a wide cavum septum pellucidum were present in three patients. Neither hydromyelia nor scoliosis was observed. No correlation between the degree of the ectopia and clinical manifestation was noted.

CONCLUSION

The association of Chiari I malformation with epilepsy, speech delay, and mental retardation may not be a mere incidental finding but may be a marker for a different pathogenetic background.
Methodological and Technical Issues for Integrating Functional Magnetic Resonance Imaging Data in a Neuronavigational System
Authors: Roux Franck-Emmanuel , Ibarrola Danielle , Tremoulet Michel , Lazorthes Yves , Henry Patrice , Sol Jean-Christophe , Berry Isabelle
Published: July 2004

OBJECTIVE

The aim of this article was to analyze the technical and methodological issues resulting from the use of functional magnetic resonance image (fMRI) data in a frameless stereotactic device for brain tumor or pain surgery (chronic motor cortex stimulation).

METHODS

A total of 32 candidates, 26 for brain tumor surgery and six chronic motor cortex stimulation, were studied by fMRI scanning (61 procedures) and intraoperative cortical brain mapping under general anesthesia. The fMRI data obtained were analyzed with the Statistical Parametric Mapping 99 software, with an initial analysis threshold corresponding to P < 0.001. Subsequently, the fMRI data were registered in a frameless stereotactic neuronavigational device and correlated to brain mapping.

RESULTS

Correspondence between fMRI-activated areas and cortical mapping in primary motor areas was good in 28 patients (87%), although fMRI-activated areas were highly dependent on the choice of paradigms and analysis thresholds. Primary sensory- and secondary motor-activated areas were not correlated to cortical brain mapping. Functional mislocalization as a result of insufficient correction of the echo-planar distortion was identified in four patients (13%). Analysis thresholds (from P < 0.0001 to P < 10−12) more restrictive than the initial threshold (P < 0.001) had to be used in 25 of the 28 patients studied, so that fMRI motor data could be matched to cortical mapping spatial data. These analysis thresholds were not predictable preoperatively. Maximal tumor resection was accomplished in all patients with brain tumors. Chronic motor cortex electrode placement was successful in each patient (significant pain relief >50% on the visual analog pain scale).

CONCLUSION

In brain tumor surgery, fMRI data are helpful in surgical planning and guiding intraoperative brain mapping. The registration of fMRI data in anatomic slices or in the frameless stereotactic neuronavigational device, however, remained a potential source of functional mislocalization. Electrode placement for chronic motor cortex stimulation is a good indication to use fMRI data registered in a neuronavigational system and could replace somatosensory evoked potentials in detection of the central sulcus.
Reversible Posterior Leukoencephalopathy Occurring during Resection of a Posterior Fossa Tumor: Case Report and Review of the Literature
Authors: Moriarity John L. , Lim Michael , Storm Phillip B. , Beauchamp Norman J. , Olivi Alessandro
Published: July 2004

OBJECTIVE AND IMPORTANCE

Our goal was to present a clinically and radiographically documented case of reversible posterior leukoencephalopathy (RPL) that occurred during resection of a posterior fossa tumor. Although RPL has been previously described in multiple nonsurgical settings, we hope that this case description makes RPL more clinically and radiographically recognizable to neurosurgeons.

CLINICAL PRESENTATION

RPL is the clinical syndrome of headaches, altered mental status, seizures, and visual loss, with radiographic findings of reversible parieto-occipital changes on cerebral computed tomographic and magnetic resonance imaging scans. It has been previously reported in the settings of malignant hypertension, renal disease, eclampsia, and immunosuppression. To our knowledge, the patient presented represents the first clinically and radiographically documented case of RPL occurring during resection of a posterior fossa tumor. The patient intraoperatively exhibited wide fluctuations in blood pressure and awoke with clinical and radiographic findings consistent with RPL.

INTERVENTION

Aggressive intraoperative and postoperative management of the patient's blood pressure, supportive intensive care, rehabilitation, and close radiographic follow-up were performed.

CONCLUSION

RPL can occur as a result of intraoperative variations in blood pressure, even among young, previously healthy individuals. With the aforementioned interventions, the patient experienced significant clinical and radiographic recovery.