Multidisciplinary treatment of posterior circulation ischemia.

Compromise of blood flow to the brain leads to cerebral ischemia, which if left untreated may even result in cerebral infarction. This has been the main cause of major morbidity and mortality over the years in the US and around the world. Cerebral ischemia to the posterior fossa is more critical and difficult to treat. This is primarily due to complex anatomy and physiology of the posterior fossa cerebal circulation. There has been multiple modalities tested over the years to treat posterior fossa ischemia which have definitely contributed in the outcome in patients with this complex problem. Improving the blood flow in the areas of brain at risk in properly selected patients could prevent impending cerebral ischemia and infarction. Today, there are mainly three types of treatment offered to patients with posterior cerebral ischemia. These are (a) medical, (b) endovascular and (c) surgical. The recent advances in technology, the diagnosis and mode of therapy, has definitely improved the outcomes of cerebral ischemia. We discuss the multidisciplinary treatment of posterior circulation ischemia. Various pre-operative and operative techniques involved in treating patients with posterior cerebral ischemia are discussed.

Bilateral paramedian thalamic infarct in the presence of an unpaired thalamic perforating artery.

Bilateral paramedian thalamic infarction is rare. The suggested mechanism is occlusion of a central unpaired thalamic perforating artery--an anatomic variant. In the few existing reports of this condition, the diagnosis was based on computed tomography (CT) or magnetic resonance imaging (MRI) findings alone. Other causes of thalamic lesions were not ruled out, and there was no angiographic demonstration of the presumed variant artery. We present a case of a 48-year-old man with a bilateral thalamic infarction seen on CT and MRI. Initial neurological examination revealed lethargy, severe combined motor and sensory aphasia, and a mild upward gaze limitation. The patient had no focal motor deficits. After 24 hours, the patient was more alert and his speech became more fluent, but Korsakoff-type amnesia with poor attention span became apparent. The patient improved slowly over 6 months of rehabilitation. Bilateral thalamic lesions can be caused by several conditions. Among those are thiamine deficiency, cerebral lupus, toxoplasmosis, cysticercosis, cerebral syphilitic gumma, and even tumors and fungal infections. All these were ruled out in our case. Superselective digital subtraction angiography (DSA) demonstrated a single unpaired thalamic perforator. To our knowledge, this is the first time this anatomical variant has been demonstrated in vivo in association with bilateral thalamic infarction.

Bedside external ventricular drain placement for the treatment of acute hydrocephalus.

The purpose of this retrospective study was to evaluate the results of external ventricular drain (EVD) placement for the management of hydrocephalus. We present our experience with 103 consecutive cases over one year, 56 of which had subarachnoid hemorrhage (SAH). Short tunnel ventriculostomy was performed at the bedside in the neurosurgical intensive care unit (NSICU), using sterile technique. Long-term care included meticulous site care by a dedicated NSICU nurse, daily cultures and prophylactic antibiotics. The average duration of EVD was 10.7 days (range 1-28 days). There was one case of positive cerebrospinal fluid (CSF) culture. Additional complications included one small intraparenchymal hematoma and two cases of EVD disconnection. No patient died form EVD-associated complications. No rebleed from aneurysmal SAH was seen. There was no correlation between the duration of EVD and infection. We conclude that placement of short EVD in the NSICU is safe and can be maintained for the required duration of treatment with minimum infection rate.

Contemporary management of subarachnoid hemorrhage and vasospasm: the UIC experience.

BACKGROUND: Cerebral vasospasm is a well-known and serious complication of aneurysmal subarachnoid hemorrhage. The means of monitoring and treatment of vasospasm have been widely studied. Each neurosurgical center develops a protocol based on their experience, availability of equipment and personnel, and cost, so as to keep morbidity and mortality rates as low as possible for their patients with vasospasm. METHODS: At the University of Illinois at Chicago, we have developed algorithms for the diagnosis and management of cerebral vasospasm based on the experience of the senior authors over the past 25 years. This paper describes in detail our approach to diagnosis and treatment of aneurysmal subarachnoid hemorrhage and vasospasm. Our discussion is highlighted with data from a retrospective analysis of 324 aneurysm patients. RESULTS: Over 3 years, 324 aneurysms were treated; 185 (57%) were clipped, 139 (43%) were coiled. The rate of vasospasm for the 324 patients was 27%. The rate of hydrocephalus was 32% for those patients who underwent clipping, and 29% for those coiled. The immediate outcomes for those who underwent clipping was excellent in 35%, good in 38%, poor in 15.5%, vegetative in 3%, and death in 8% of the patients. For those who underwent coiling the immediate outcome was excellent in 64%, good in 14.5%, vegetative in 2.5%, and death in 14.5% of the patients. These statistics include all Hunt and Hess grades. For those patients who underwent clipping, 51% were intact at 6 months follow-up, 15% had a permanent deficit, 10% had a focal cranial nerve deficit, and 2% had died from complications not directly related to the procedure. For those patients who had undergone coiling, 75% were intact at 6 months follow-up, 12.5% had a permanent deficit, and 12.5% had a cranial nerve deficit, with no deaths. CONCLUSIONS: The morbidity and mortality of cerebral vasospasm is significant. A good outcome after aneurysmal subarachnoid hemorrhage is dependent upon careful patient management in the preoperative, perioperative, and postoperative periods. The timely work-up and aggressive treatment of neurological deterioration, whether or not it is because of vasospasm, is paramount.

Head registration techniques for image-guided surgery.

Localization of the pathological structures in relation to the surrounding anatomy and understanding of the surgical anatomy are probably the most important keys to successful neurosurgery. Image-guided surgery is an important tool for understanding an individual's anatomy and for precisely locating the lesion. Head registration is the most important step in image-guided surgery, required by every system in use today, although these systems show great differences. In this study, head registration techniques and user algorithms in 83 image-guided surgery cases were analyzed. Several types of fiducials including skin markers, bone fiducials, and the stereotactic frame were used for registration. Clinical applications, ease of use, and computer-calculated accuracy values for each type were compared. The average accuracy was 1.50 mm. X-spot skin markers are the fiducials most commonly used with CT scan. The stereotactic frame was the most accurate method, with an accuracy of 0.69 mm. Disc-shaped fiducials were used when MRI was the imaging modality; they provided an average accuracy of 2.62 mm. Head registration is an important part of image-guided surgery; the procedure used for registration should be based on the requirements of each individual case. Our results indicated that the stereotactic frame is the most accurate method of registration; however, skin markers provide reasonable accuracy with significant ease of use and patient comfort.

Aneurysm clips: magnetic quantification and magnetic resonance imaging safety. Technical note.

Knowledge of the magnetic properties of cerebral aneurysm clips in patients undergoing magnetic resonance (MR) imaging is imperative. The authors quantified in electromagnetic units the magnetic properties of 13 different types of aneurysm clips by using a vibrating sample magnetometer. Their results showed that the magnetic moment of these clips ranged from 0.15 EMU/g to as high as 152.7 EMU/g. Based on these results and tests of the movement of the clips during MR imaging, they conclude that aneurysm clips with a magnetic moment less than 1 EMU/g may be safely used during MR imaging. The quantification of magnetic properties into electromagnetic units by using a vibrating sample magnetometer is a reliable method applicable to any testing field gradient. This method can be used as a standard to measure and label the magnetic properties of aneurysm clips.

Effects of combined glutamate and platelet-activating factor inhibition on the outcome of focal cerebral ischaemia - an initial screening study.

Since both glutamate excitotoxicity and inflammatory responses have been implicated in ischaemic neuronal death, we questioned whether joint inhibition of both processes would be more neuroprotective than either on its own. Therefore we assessed the effects of combined inhibition of both glutamate release (with a use-dependant sodium channel blocker, 619C89) and inflammatory processes (with a platelet-activating factor (PAF) receptor antagonist, BB-823) on the degree of motor deficit and the extent of cerebral (cortical and sub-cortical grey matter) infarction produced by middle cerebral artery occlusion (MCAO) in the rat, and compared results to appropriate single agent, vehicle and positive controls. The combination of both agents produced the greatest reduction in motor deficit, but the effect was only significant (p<0.05) acutely (4 to 6 hours post-MCAO). The extent of cortical infarction at 24 hours post-MCAO was significantly reduced in all experimental groups compared to vehicle-controls (p<0.05) and the greatest reduction occurred in the combination group (55%), though it was not significantly better than either of the single agent groups. Similarly the greatest reduction in sub-cortical infarction was in the combination group, but this was also not significantly better than the single agents. The results of this novel combination of pharmacological interventions suggest that inhibition of both glutamate excitotoxicity and inflammatory responses afforded an overall enhanced, if modest, neuroprotective effect, compared to inhibition of either process alone. The possible mechanisms involved are discussed, but warrant further clarification before therapeutic strategies are developed.

Changes in cerebral oxygen saturation with change in posture: a preliminary report.

BACKGROUND: Disease of the major vessels in the neck can disrupt autoregulation and lead to changes in the cerebral blood flow and cerebral autoregulation. These changes can be reflected by means of cerebral oxygen saturation. METHODS: We measured cerebral oxygen saturation in 20 patients with atherosclerotic disease of the carotid and vertebral arteries and compared results with 10 normal subjects. Saturation was measured using a noninvasive near-infrared device, the transcranial cerebral oximeter. RESULTS: There were marked decreases in cerebral oxygen saturation in patients with carotid-vertebral artery disease when the position of the patient was changed, from supine to erect. CONCLUSION: Changes in regional cerebral oxygen saturation inpatients with carotid-vertebral artery disease may reflect disruption of cerebral autoregulation.

Magnetic characteristics of Yasargil aneurysm clips.

BACKGROUND: Metallic bioimplants are subject to great scrutiny in order to ensure that they are totally harmless to patients. Aneurysm clips are no exception to this rule. Considering the number of aneurysm clips used and their potential for injury, they should be evaluated very meticulously. Determining the magnetic characteristics of these clips is an important part of the evaluation process. In this study, a new method for evaluating magnetism is described and the importance of that information is briefly discussed. METHODS: Twenty Yasargil aneurysm clips were analyzed using a vibrating sample magnetometer under 1.5 Tesla. This device is highly sensitive, and is capable of measuring the magnetism of small objects. RESULTS: Our measurements showed magnetism of the aneurysm clips ranged from 0.0334-0.1369 electromagnetic units (emu). CONCLUSIONS: Magnetometer measurements and real life tests under magnetic resonance imaging (MRI) have shown that these clips have a very low magnetism and are safe to use in 1.5 Tesla MRI scanners. This study also proves that the vibrating sample magnetometer is a useful device for analyzing the magnetism of aneurysm clips, and their emu values can be used as another industry standard in the production line to increase the safety of these clips.

Transverse sinus dural fistula: combined surgical and endovascular approach: a case report.

BACKGROUND: The treatment of a large dural sinus fistula can be very difficult and complicated. The very extensive and complex nature of these malformations may require a combination therapy in the form of surgery and multistaged embolization. The transverse sinus fistula in our patient was fed by multiple large high-flow feeders and was draining retrograde into the superior sagittal sinus (SSS) and the cortical veins. The SSS did not fill in the late venous phase of the carotid angiogram, suggesting increased venous pressure. METHODS: A case of transverse sinus dural fistula is described that was managed by a combination of surgery and embolization. The complex nature of this malformation encouraged us to adopt a combination of multistaged embolization and surgery for the management and clinical control. The patient underwent embolization of multiple feeders from the branches of the external carotid artery. After this procedure, the patient underwent endovascular occlusion of the transverse sinus via the SSS. Throughout the endovascular treatment, the patient had concomitant intracranial pressure monitoring and SSS pressure monitoring, along with transcranial cerebral oximetry (TCCO). Despite this aggressive endovascular intervention, the fistula could not be completely closed. The patient then underwent surgical excision of the transverse sinus along with duraplasty and cranioplasty. RESULTS: The patient had a good recovery and posttreatment angiogram revealed normal antegrade flow in the SSS with no evidence of the fistula. The combined surgical and endovascular techniques are described and their use in clinical practice is discussed. CONCLUSIONS: The complexity of certain large dural sinus fistulae should not be underestimated. They may require a prolonged multistaged treatment for their total obliteration. Also, despite the large size and complexity of the disease, complete cure can be achieved.

Transcranial cerebral oximetry in endovascular treatment of carotid-cavernous fistula.

The transcranial cerebral oximeter is a reliable, low-cost, noninvasive device that provides real-time evaluation of regional brain oxygen saturation during endovascular treatment of cerebrovascular diseases. We discuss three patients with carotid-cavernous fistulae treated by endovascular balloon occlusion, each monitored continuously before, during, and after the procedure with transcranial cerebral oximetry. The cerebral oxygen saturation measured was directly related to the side of the venous drainage of the fistula, being 15-20% higher on that side. Following endovascular occlusion of the fistula, oxygen saturation gradually became equal on the two sides.

Modified solution for filling MRI coordinate indicators for the ZD stereotactic frame.

Increased use of magnetic resonance imaging and magnetic resonance angiography in stereotactic planning highlight some technical problems in imaging. Visualization of markers during imaging are vital in stereotactic planning. In magnetic resonance imaging-guided stereotaxy, specially designed plates are used that contain water-based copper sulfate solutions as a marker. Replacement of copper sulfate solution is usually required after some time due to precipitation and leaking. The refilling procedure is quite cumbersome and can cause technical problems in imaging. In this study, we describe copper sulfate solution mixed with a water-soluble gel as a simple but useful alternative to water-based copper sulfate resolution to ease the refilling procedure and to overcome the air bubbles.