Intracranial Procedures Research Articles

Intraoperative Magnetic Resonance Imaging Guidance for Intracranial Neurosurgical Procedures

A 0.5 Tesla open configuration magnetic resonance imaging (MRI) system (SignaSP [GE Medical Systems; Milwaukee, WI]) is sited in an operating room environment at Brigham and Women's Hospital for MRI-guided surgical and interventional procedures. The vertical gap provides patient access to two surgeons or interventionalists, whereas open flexible transmit-receive coils allow exposure of the surgical field. A major application of this system at Brigham and Women's Hospital is intraoperative MRI guidance for intracranial biopsies and open craniotomies. During the past 2œ years, more than 200 intracranial procedures have been performed using intraoperative MRI guidance. For intracranial biopsies, MRI guidance provides several advantages, including high sensitivity for lesion localization; interactive navigation, eliminating the need for a stereotactic frame; multiplanar image confirmation of biopsy site location; and early detection of complications. Based on our experience with open craniotomies, we think that image guidance significantly improves the ability of the neurosurgeon to resect abnormal tissue selectively while preserving adjacent eloquent areas. Furthermore, our experience indicates that intraoperative imaging offers advantages over conventional stereotactic image guidance, including the ability to compensate for shifts in brain position during surgery, and allows for early identification of complications. Intraoperative MRI-guided neurosurgery is a multidisciplinary effort involving the neurosurgeon, neuroradiologist, technologist, nursing staff, and engineers. In our experience, there is little doubt that MRI guidance improves the technical aspects of the neurosurgical procedures; however, the impact of this technology on clinical outcomes and cost effectiveness await further study.

Surgical approach and histoanatomical aspects of the oculomotor nerve in rats.

The surgical approach and some histoanatomical characteristics of the intracavernous portion of the oculomotor nerve are described. Moreover, some perioperative precautions for intracranial surgical procedures in the rat are reported and the suitability of the rat as a model for studying intracranial nerve regeneration is discussed. With the data provided, this model of oculomotor nerve approach can be used to study various aspects of intracranial nerve regeneration.

In Vitro Release Kinetics of Gentamycin from a Sodium Hyaluronate Gel Delivery System Suitable for the Treatment of Peripheral Vestibular Disease

For certain patients who experience intense vertigo arising from unilateral vestibular lesions, the primary therapy is a vestibular nerve section, an intracranial surgical procedure. One alternative to this treatment is therapeutic ablation of vestibular function on the unaffected side using an ototoxic agent. We prepared a biodegradable sustained-release gel delivery system using sodium hyaluronate that can be administered into the middle ear using only a local anesthetic. The gel contains gentamycin sulfate, the ototoxic agent of choice for treatment of unilateral vestibulopathy, and it exhibits diffusion-controlled release of the drug over a period of hours. The released gentamycin could then diffuse into the inner ear through the round membrane. This represents an important advance over previous formulations, which used only gentamycin sulfate solutions, in that it should allow more careful control of the dose, it should reduce loss of the drug from the middle ear site, and it should maintain intimate contact with the round membrane. By carefully controlling the dose, it should be possible to inhibit vestibular function while minimizing hearing loss. Herein we describe the in vitro release kinetics of gentamycin sulfate from sodium hyaluronate gels and find that the system obeys Fickian behavior.

Controlled Continuous Spinal Drainage Using a Flow-Regulated Pump

Controlled Continuous Spinal Drainage Using a Flow-Regulated Pump

Intraoperative MR imaging of intracranial neurosurgical procedures at 1.5T: Is it feasible and/or beneficial?

Intraoperative MR imaging of intracranial neurosurgical procedures at 1.5T: Is it feasible and/or beneficial?

A malleable endoscopic suction instrument: technical note.

Flexible endoscopes are being employed for a variety of neurosurgical procedures. These instruments have drawbacks, especially in their ability to evacuate clotted blood. We have attempted to rethink the design of these instruments and have developed a malleable endoscopic suction instrument. This has proved to be helpful in a variety of intracranial and intraspinal procedures.

Early extubation following intracranial procedures: pro

Early extubation following intracranial procedures: pro

Advances in Endoscopic Neurosurgery

This article describes the authors' experience using neuroendoscopes to perform a variety of intracranial procedures with minimal invasiveness to neural tissue. The article also presents the history of neuroendoscopy and provides information about current practice. Surgical technique and intraoperative and postoperative nursing considerations are reviewed.

Operating room requirements for neurosurgical procedures

An operating room (OR) setup must be standardized to ensure safe and efficient operating conditions for neurosurgical procedures. This article reviews the basic OR setup at the Barrow Neurological Institute for neurosurgical procedures, the requirements for surgical equipment and supplies, and equipment storage and maintenance. Anesthesia equipment and the special requirements for pediatric, intracranial, spinal, and stereotactic procedures are also discussed.

Temporalis muscle fixation in pterional craniotomy. Technical note

Temporal muscle asymmetry following a pterional craniotomy can be a bothersome cosmetic and functional problem. A number of incisions in the temporalis muscle have been proposed for optimal exposure in intracranial procedures, preservation of the temporal muscle anatomy and protection of the frontal branch of the facial nerve. The interfascial temporal flap technique described by Yasargil and colleagues provides excellent exposure along the sphenoid ridge. On closing the temporalis muscle is sutured posteriorly but not superiorly to the superior temporal line. This commonly results in an inferior retraction of the muscle, creating a mass along the zygoma and an unsightly depression where the muscle was separated from the skull. Several techniques have been described to reattach the temporalis muscle at the end of the procedure. We describe a method that provides the advantage of a free bone flap, yet allowing an anatomical re-approximation of the temporalis muscle to its bone attachment. That is achieved by means of several «V» holes performed at 5 mm above the superior temporal lineo This technique provides a reliable preservation of temporal muscle bulk and function with little additional operating time and no compromise in the operative exposure. No foreign materials are used so that no increased costs are entailed. La asimetría del músculo temporal tras craniotomías pterionales puede llegar a constituir un problema estético y funcional. Se han propuesto un buen número de incisiones del músculo temporal con los objetivos de obtener un abordaje óptimo a la patología intracraneal, preservación de la anatomía del músculo temporal y la protección de las ramas temporo-faciales del nervio facial. El abordaje interfascial descrito por Yasargil y colaboradores proporciona una exposición excelente a lo largo del borde esfenoidal. Al cerrar el músculo temporal se sutura posteriormente pero no superiormente a nivel de la línea temporal superior. Esto con frecuencia induce la retracción de este músculo inferiormente, creando con ello una masa a lo largo dele arco zigomático y una depresión antiestética inmediatamente por encima. Se han descrito varias técnicas para re-insertar el músculo temporal al final del procedimiento quirúrgico. En el presente artículo se describe un método que proporciona las ventajas del colgajo óseo libre, mientras que permite la reaproximación del músculo temporal a su lugar de inserción ósea previa. Esto se consigue por medio de varios agujeros en «V» practicados a 5 mm por encima de la línea temporal superior. Esta técnica permite la conservación del volumen y función del músculo temporal, requiriendo poco tiempo y no comprometiendo el abordaje quirúrgico. No se han empleado cuerpos extraños, por lo que no hay incremento de los costos.

Infections in craniofacial surgery: a combined report of 567 procedures from two centers.

This retrospective review of infectious complications was undertaken at two craniofacial centers (Dallas and Philadelphia). Fourteen infections were identified over a 6.5-year period in 567 intracranial procedures primarily for craniosynostosis. There were no infections in infants under 13 months of age and no cases of meningitis. The overall infection rate was 2.5 percent, and 85 percent of infections occurred in secondary reoperative cases. Tracheostomies were not identified as a risk factor for infection. No difference was found in infection rates between patients with shaved and unshaved scalps. Candida and Pseudomonas were the two most common organisms identified, and 28 percent of our infections involved yeast. The average time to diagnose infection was 11.5 days (excluding three patients who averaged 5 months). Thirteen of the fourteen infections were treated surgically with placement of a subgaleal irrigation/drainage system. Initial bony debridement was kept to a minimum. Based on our findings, recommendations are made to further lower infection rates, particularly those caused by opportunistic organisms.

Management of 1000 vestibular schwannomas (acoustic neuromas): the facial nerve--preservation and restitution of function.

Although the rate of reported facial nerve preservation after surgery for vestibular schwannomas continuously increases, facial nerve paresis or paralysis is a frequent postsurgical sequelae of major concern. The major goal of this study was to define criteria for the right indication, timing, and type of therapy for patients with palsies despite anatomic nerve continuity and those with loss of anatomic continuity. One thousand vestibular schwannomas were surgically treated at the Department of Neurosurgery at Nordstadt Hospital from 1978 to 1993. Of 979 cases of complete removal and 21 cases of deliberately partial removal, the facial nerve was anatomically preserved in 929 cases (93%). The rate of preservation is increasing, as is evidenced in the most recent cases, and preservation is supported by special electrophysiological monitoring. The facial nerve was anatomically severed in 60 cases (6%). It was anatomically lost in previous operations that were performed elsewhere in 11 cases (1%). In case of nerve discontinuity (42 cases), immediate nerve reconstruction by one of three available intracranial procedures (within the cerebellopontine angle, intracranial-intratemporal, intracranial-extracranial) was performed in the same surgical setting. In case of loss of the proximal facial nerve stump at the brain stem, early reanimation by combination with the hypoglossal nerve was achieved in most patients within weeks after tumor surgery. In a few patients with anatomic nerve continuity but absence of reinnervation for 10 to 12 months, a hypoglossal-facial combination was applied. All the patients with partial or with complete palsies were treated in a special follow-up program of regular controls and of modulation of physiotherapeutic treatment every 3 to 6 months. In intracranial nerve reconstruction at the cerebellopontine angle, 61 to 70% of patients regained complete eye closure and an overall result equivalent to House-Brackmann Grade 3. Hypoglossal-facial reanimation led to Grade 3 in 79%. The duration between the onset of paralysis and the reconstructive procedure is decisive for the quality of the outcome. These data are discussed in view of other treatment options and certain parameters influencing outcome. This management contains three major principles as follows: 1) preservation of facial nerve continuity in function by the aid of intraoperative monitoring, 2) early nerve reconstruction in case of lost continuity, and 3) scheduled follow-up program for all patients with incomplete or complete palsies.

Effects of normo- and hypocapnic nitrous-oxide-inhalation on cerebral blood flow velocity in patients with brain tumors.

Nitrous oxide (N2O) use during anesthesia for intracranial procedures has been a subject of controversy in the past. To date, the isolated influence of N2O on mean cerebral blood flow velocity in the middle cerebral artery (VMCA) has not been investigated during hypocapnia in patients with brain tumors. We compared VMCA during normocapnic (ETCO2: 40 mm Hg) and hypnocapnic (ETCO2: 25 mm Hg) inhalation of air and 50% nitrous oxide in oxygen N2O/O2 in eight patients with unilateral brain tumors on both the tumor side and the healthy side. Six patients completed the study. Mean VMCA increased during normocapnic inhalation of N2O/O2 (tumor side: 86 +/- 16 cm sec-1; healthy side: 74 +/- 17 cm sec-1) when compared with air (tumor side: 72 +/- 18 cm sec-1; healthy side: 62 +/- 14 cm sec-1, p < 0.01), whereas during hyperventilation VMCA decreased on both sides (p < 0.001). Mean VMCA values were quite similar during hypocapnic inhalation of 50% N2O/O2 (tumor side: 50 +/- 12 cm sec-1; healthy side: 45 +/- 13 cm sec-1) and air (tumor side: 51 +/- 14 cm sec-1; healthy side: 45 +/- 12 cm sec-1). The data of our study suggest that in patients with cerebral tumors the N2O-induced increase in mean VMCA can be completely reversed by hyperventilation.

Low-dose aspirin and intracranial surgery. A survey of the opinions of consultant neuroanaesthetists in the UK.

Increasing numbers of patients presenting for surgery are receiving concurrent medication with low-dose aspirin. We surveyed the opinions and working practices of consultant members of the Neuroanaesthesia Society regarding patients who present for elective intracranial surgery whilst taking this form of medication. Identical questionnaires were sent to 140 members of the society and proffered four main questions: (1) the adherence to any policy of stopping aspirin preoperatively, (2) the preferred method of treatment for excessive bleeding in this context, (3) personal knowledge of haemorrhagic complications in this group of patients, (4) the neurosurgical unit concerned. There were 121 responses (86.4%) of which 116 (82.9%) were valid. Of the respondents, 78 (67.2%) were unaware of a written departmental policy for the discontinuation of pre-operative aspirin treatment and had no personal policy. Thirty-two respondents (27.6%) had a personal policy but were unaware of a written departmental policy; only six respondents (5.2%) stated that a written departmental policy was in place. The mean time suggested for discontinuation of aspirin pre-operatively was 11.3 days (range: 1-42 days). Fifty-one respondents (44.0%) considered that patients taking low-dose aspirin were at increased risk of excessive perioperative haemorrhage and 15 (12.9%) anaesthetists reported having personal experience of such problems. Fifty-seven respondents (49.1%) would use a platelet infusion, alone or in association with other blood products or prohaemostatic agents, if haemorrhagic complications developed. The majority of neuroanaesthetists felt that aspirin was a risk factor for haemorrhagic complications associated with intracranial procedures, but most adopt no policy regarding its preoperative discontinuation.

Subtotal petrosectomy in the treatment of cerebrospinal fluid fistulae of the lateral skull base

Cerebrospinal fluid (CSF) fistulae almost invariably lead to meningitis, even in the absence of other clinically obvious sequelae of the fistula such as a CSF fluid leak. The only effective means of reducing the risk of meningitis is surgical closure of the fistula. If surgery is to be recommended to patients with CSF fistulae even if they are currently asymptomatic, the morbidity of the procedure must be a principal determinant of the chosen technique. Recovery after the extracranial approach to a CSF fistula is much more rapid than after an intracranial procedure. The extracranial route is also free of the long-term risk of epilepsy which accompanies a craniotomy. The principal disadvantage of the lateral extracranial approach, failure of treatment, has been largely eliminated following studies into the obliteration of simple bony cavities using free adipose grafts. This paper describes our use of the extracranial approach to closure of CSF fistulae of the lateral skull base.

Economic impact of replacing CT with MR imaging for refractory epilepsy

Purpose: To evaluate the economic costs of using computed tomography (CT) vs. magnetic resonance (MR) imaging in the preoperative evaluation of refractory epilepsy patients. Methods: Preoperative CT and MR imaging findings from 117 patients who underwent surgery for medically refractory epilepsy during a 3.5-year period were reviewed. Cost savings were based on the paradigm that intracranial electroencephalogram monitoring (costing about $50,000) would have been necessary for preoperative localization of the epileptogenic zone in those patients without positive imaging findings. Savings attributed to replacing CT with MR were based on patients with positive MR and normal CT. A similar paradigm was used to calculate savings for replacing MR with CT. National savings were based solely on patients with neoplasms or vascular lesions because paradigms for other lesions vary considerable depending on institutional philosophy. Results: Replacing CT with MR imaging would have eliminated preoperative intracranial electrode procedures in 29 of 117 patients, with potential savings of $1,450,000 at our institution. In the 37 patients with neoplastic or vascular substrates, MR would have eliminated 10 invasive electrode procedures with estimated savings of $0.5 million institutionally and $3 to $4 million per year nationally. There were no cases to support replacing MR with CT. Conclusion: Replacing CT with MR decreases health costs associated with preoperative evaluation of intractable epilepsy requiring surgical amelioration.

Interactive image-guided surgery of the spine-use of the ISG/Elekta Viewing Wand to aid intraoperative localization of a sacral osteoblastoma

The intraoperative localization of small osteoid osteomas and osteoblastomas of the spine is often difficult. The authors report a patient with a small sacral osteoblastoma in whom the experimental use of an Interactive Image-Guidance Stereotactic system, to aid localization, is described. The Elekta Viewing Wand is a spatial localization device primarily designed for intracranial procedures. We evaluated its potential role in the localization and minimally invasive excision of a sacral osteoblastoma in this patient. A basic assessment of the limitations encountered in extracranial use of this system is presented and possible solutions to minimize these problems are discussed.

Management of symptomatic carotid stenoses with coincidental intracranial aneurysms.

There are at present strong indications for surgery in patients suffering from symptomatic extracranial carotid stenoses of > 70%. Surgery of coincidental aneurysms is a still debated problem, but there is general agreement that it is indicated in selected cases according to the patient's life-expectancy and size and site of the aneurysm. The coexistence of these two lesions raises a decision-making problem. We reviewed 389 endarterectomies and found 12 intracranial berry aneurysms in 10 (2.6%) patients. All the 10 patients were harbouring a symptomatic carotid stenosis of > 70%. Since the correction of a stenosis increases blood flow to an aneurysm, our approach was to first operate on the intracranial lesion and then the stenosis in 7 patients harbouring aneurysms > 5 mm. Two patients affected by small aneurysms < 5 mm of an A2 azygos and left internal carotid artery underwent left endarterectomy only. The last patient was submitted first to percutaneous angioplasty of a left stenosis, then to open surgery of a contralateral middle cerebral aneurysm and finally to intravascular occlusion of a small aneurysm of the left internal carotid bifurcation by menas of a coil; this policy was adopted in order to restore normal haemodynamic conditions before the intracranial procedure. There was no mortality or permanent morbidity following surgery for aneurysm or endarterectomy. Transient morbidity occurred in 2 cases after clipping of aneurysms of the anterior communicating and middle cerebral arteries. Our results suggest that surgery of coincidental aneurysms may give good results even when there is a severe symptomatic stenosis in the neck. Moreover, the presence of a small intracranial aneurysm does not seem to be an additional risk factor for endarterectomy. When the lesions are on different sides, it may be better to treat the stenosis first if it decreases the ipsilateral cerebral blood flow.

Selective Intra-Arterial Thrombolysis for Embolic Complications of Cerebral Endovascular Therapy

Cerebral thrombo-embolic complications seldom occur during intracranial endovascular therapeutic procedures. Yet, despite a systemic preventive regimen of pre-operative intravenous acetylsalicylic acid and effective systemic heparinisation, we encountered seven complications of this type over a period of five years, a 3.7 per thousand incidence (7/1858). Local intra-arterial thrombolysis performed immediately after the thrombo-embolic complication resulted in complete recanalization in five cases and partial recanalization in two. CT scans performed 24 hours after thrombolysis were normal in six of the seven patients. Only one female patient with partial recanalization showed a limited cortical infarct in the parietal distribution of the middle cerebral artery territory. In all seven cases recanalization of the occluded vessel resulted in a return to the baseline initial neurological status. This short series demonstrates the usefulness of emergent thrombolysis dealing with the thrombo-embolic complications of angiography or endovascular therapy. These results are in agreement with these experimental data showing that early recanalization can prevent macroscopically visible infarcts.

History of spinal cord stereotaxy.

Stereotactic and functional neurosurgery has experienced a remarkable degree of development during the last 50 years, from the plaster of Paris frame of Spiegel and Wycis to the technology of frameless stereotaxis. Although predominantly used for intracranial procedures, stereotaxy has its roots in experimental studies of the spinal cord. The field of spinal cord stereotaxy has not received the same amount of attention as supratentorial surgery, but there have been significant contributions to the field that have helped to further our understanding of spinal cord anatomy and physiology. Now that frameless stereotaxis has reached clinical practice, there may be further developments in the field of spinal surgery: this technique may prove useful for spinal fusion operations and, possibly, intramedullary operations as well.