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Ventriculoperitoneal shunt (VPS) placement is an important therapeutic technique. Placement of the abdominal portion of VPS can be difficult in the setting of previous abdominal surgery, prior failure of VPS, or obesity. Even under ideal circumstances, standard mini-laparotomy does not allow precision in VPS positioning. We describe a single-port technique for VPS placement. While the neurosurgeon places a right frontal ventricular catheter and valve, an infraumbilical trocar is placed utilizing the open Hasson technique. A 12-mm operating laparoscope with an 8-mm channel is used to inspect the abdomen and identify the VPS entry site. Adhesions interfering with shunt placement can be lysed through the working channel of the laparoscope. Under laparoscopic visualization, an 18-gauge needle is introduced through a 5-mm incision in the right upper quadrant and the VPS tubing is tunneled to that site. A J-tipped guidewire is introduced, and the needle is exchanged for a dilator and peel-away sheath. The VPS is delivered through the sheath, which is sectioned and removed. An atraumatic grasper, placed through the laparoscope, directs the VPS to the desired intraabdominal location. Function of the VPS is assessed visually while compressing the valve. Suture closure of the trocar site and VPS entry site completes the procedure. We used this method successfully in a series of five patients with excellent outcome. A 14-month follow-up has revealed no failures or postoperative complications. This method is less invasive than mini-laparotomy, allows for precision placement of the abdominal portion of VPS, and confirms appropriate function.

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OBJECTIVE: As more information evolves regarding the natural history of cavernous malformations (CMs), the risks of operative intervention must be balanced against nonoperative management. In an attempt to better delineate the surgical risks for operable CMs, we undertook a retrospective analysis of 94 patients with 97 CMs surgically excised at the Massachusetts General Hospital. METHODS: Data regarding surgical complications and outcome measures, including neurological status and seizure outcome, were analyzed. RESULTS: The incidence of transient neurological morbidity was 20.6%, but only 4 of the 97 operations (4.1%) resulted in persistent disabling neurological complications and 2 (2.1 %) in nondisabling deficits. There was no operative mortality. Brain stem lesions (n=14) were associated with the highest incidence of neurological complications, both transient and persistent (odds ratio, 4.8; 95% confidence interval, 1.5-15.7). The overall neurological outcome was excellent or good in 89.7% of all lesions: 96.8% of lobar CMs (n=63), 64.2% of brain stem CMs (n=14), 87.5% of cerebellar CMs (n=8), 100% of cranial nerve CMs (n=4), and 75% of spinal cord CMs (n=8). Patients with brain stem and spinal cord CMs were in poorer preoperative neurological condition than were patients with CMs in other locations and therefore had a significantly reduced level of function after surgery (P < 0.01). There was improvement in 35.7% of the patients with brain stem lesions and 62.5% of the patients with spinal cord lesions after surgery. In the 38 patients presenting with seizures, 97% were seizure-free after surgery. CONCLUSION: The risks of operative management of CMs varies based on location. When evaluating patients with operable CMs for surgery, the incidence of complications as well as final neurological outcome should be carefully weighed against the existing knowledge of the natural history of lesions managed expectantly.

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We report management and outcome data on 118 patients that presented to our emergency room over a 4 year interval (1990-1994) in poor neurological condition after subarachnoid hemorrhage. All patients were treated following a strict protocol. After initial evaluation, patients underwent a head computerized tomography (CT) scan to try to understand the mechanism of coma. If CT did not show destruction of vital brain areas, a ventriculostomy was inserted and ICP measured. If ICP was less than 20 mm Hg, or if standard treatment of increased ICP was able to lower the ICP to a value less than 20 mmHg, patients were evaluated with cerebral angiogram to determine the location of the ruptured aneurysm. The lesion was then treated by craniotomy for aneurysm clipping or endovascular obliteration. Postoperative monitoring for vasospasm with clinical exam and transcranial doppler studies was performed routinely. If vasospasm developed, this was managed aggressively with hypertensive, hypervolemic and hemodilutional therapy and, at times, endovascular treatment with angioplasty or papaverine. Outcome was measured at 1 year or more after treatment. Among patients who met criteria for aneurysm treatment, 47% had excellent or good neurologic outcome. There was a 30% mortality rate in these patients. In patients with high ICP, poor brainstem function or destruction of vital brain areas on CT, comfort measures only were offered and almost all died. It is concluded that an approach of early aneurysm obliteration and aggressive medical and endovascular management of vasospasm is warranted in patients in poor neurological conditions after subarachnoid hemorrhage.

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OBJECTIVE: To evaluate the use of an anterior, transfacial transclival approach to midline posterior circulation aneurysms in five patients. SURGICAL APPROACH: A skin incision is made on the right side of the nose with subsequent bony and cartilaginous disarticulation of the nasal complex. The nose remains attached along the left side and is reflected laterally. Removal of the nasal septum and bilateral ethmoidectomy, medial maxillectomy (usually bilateral), and opening of the sphenoid yield a large triangular exposure of the anterior clivus. After removal of the clivus with a drill, the vertebral and basilar arteries are exposed through a midline dural opening. RESULTS: The approach provided excellent exposure of basilar artery trunk aneurysms with room available for temporary clip placement in three patients. In a fourth patient, a midline posterior inferior cerebellar artery aneurysm was clipped using this technique. A basilar trunk dissection was treated by proximal basilar occlusion through this exposure in a fifth patient. Although three patients developed transient cerebrospinal fluid leaks with symptoms of meningitis, no permanent neurological morbidity resulted from the use of the approach. CONCLUSION: The transfacial transclival approach to midline aneurysms of the basilar trunk and its branches provided excellent exposure for surgical treatment in five patients. No patient had postoperative palatal dysfunction and cosmetic results were excellent. Cerebrospinal fluid leak and meningitis continue to be the major drawbacks to the use of this approach, although the availability of modern broad-spectrum antibiotics lessens the chance of permanent neurological sequelae.

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Over the last 30 years, perfluorocarbons (PFCs) have been extensively investigated as oxygen carriers. Early studies indicated that these compounds could be used as blood substitutes or protective agents against ischemia. Adverse characteristics such as instability, short intravascular half-life, and uncertainties concerning possible toxicity precluded wide clinical application. However, advances in PFC technology have led to the development of improved second-generation oxygen carriers that incorporate well-tolerated emulsifiers (egg-yolk phospholipids). The authors review recent developments in this field and consider the potential role of PFCs in future neurosurgical practice. Diagnostic applications could include their use to assess cerebral blood flow, local oxygen tension, and brain metabolism or to achieve enhanced imaging and precise staging of inflammatory, neoplastic, or vascular disease processes by means of computerized tomography, ultrasonography, and magnetic resonance studies. Therapeutic applications could include cerebral protection, an adjunctive role in radiotherapy of malignant brain tumors, protection against air embolism, the preservation of organs for transplantation, and ventilatory support in head-injured patients with compromised lung function. In addition, PFCs have been used successfully as a tool in ophthalmic microsurgery and potentially they could fulfill a similar role in microneurosurgery.

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Temporary vessel occlusion is an effective technique used by microvascular surgeons to facilitate dissection and permanent clipping of cerebral aneurysms; however, several questions remain regarding the overall safety of this technique. To identify technical and patient-specific risk factors for perioperative stroke, the authors examined a series of patients in whom induced hypertension and mild hypothermia and intravenous mannitol administration were used as protection during temporary vessel occlusion for aneurysm clipping. The study comprises a nonconcurrent prospective analysis of 132 consecutive aneurysm clippings performed with the aid of temporary vascular occlusion and a specific antiischemic anesthetic protocol at the Massachusetts General Hospital from 1991 to 1993. Factors studied included duration of the temporary clip application, number of occlusive episodes, patient age and neurological status, presence of preoperative subarachnoid hemorrhage (SAH), and intraoperative aneurysm rupture ("forced" temporary clipping), as well as whether proximal vessel occlusion or complete aneurysm trapping was used. In a univariate analysis, patient age, intraoperative aneurysm rupture, temporary clipping lasting more than 20 minutes, clipping between the 4th and 10th day after SAH, and multiple clipping episodes were all significantly associated with stroke outcome. Multivariate logistic regression revealed that intraoperative aneurysm rupture (relative risk 5.6, p = 0.02) and a duration of temporary clip application that lasted more than 20 minutes (relative risk 9.4, p = 0.04) were independently associated with stroke outcome. Overall, 5.2% of the patients had postoperative clinical strokes. Based on their findings the authors conclude that temporary clipping is a safe adjunct to aneurysm surgery, particularly when the duration of clipping is short.

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Autosomal dominant polycystic kidney disease (ADPKD) is associated with increased prevalence of cerebral aneurysms and increased risk of subarachnoid hemorrhage. A decision analysis by Levey et al. in 1983 demonstrated that patients with ADPKD would not significantly benefit from routine arteriographic screening for cerebral aneurysms. We reexamined this conclusion in light of new clinical data and the introduction of magnetic resonance imaging (MRI) as a screening method. We compared an MRI screening strategy with a nonscreening strategy. The screening strategy specified MRI screening and then neurosurgical management of detected aneurysms. The nonscreening strategy specified cerebrovascular care only in the event of subarachnoid hemorrhage. The decision tree incorporated estimates derived from the clinical literature for the prevalence of asymptomatic aneurysms in patients with ADPKD (15%), the annual incidence of aneurysmal rupture (1.6%), the morbidity and mortality rates associated with subarachnoid hemorrhage (70 and 56%, respectively), the risk of transfemoral arteriography (0.2%), the sensitivity and specificity of MRI, the morbidity and mortality rates associated with surgical treatment of an unruptured aneurysm (4.1 and 1.0%, respectively), and the life expectancy of patients with ADPKD. The model predicted that the screening strategy would provide 1.0 additional year of life without neurological disability to a 20-year-old patient with ADPKD. A sensitivity analysis showed that the model was most sensitive to estimates of the prevalence of aneurysms in ADPKD, the annual incidence of rupture, and the morbidity and mortality rates associated with rupture. A financial analysis showed that a screening strategy is likely to cost less than a nonscreening strategy. The model predicts that an MRI screening strategy would increase the life expectancy of young patients with ADPKD and reduce the financial impact on society of ADPKD.

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The location of the carotid artery bifurcation and the distance atherosclerotic disease extends distally in the internal carotid artery (ICA) are two factors that contribute to the technical difficulty of carotid endarterectomy. When the bifurcation is high (above C-3) or the disease extends distally, standard approaches may not provide adequate exposure for dissection of plaque or for arteriotomy repair. A simple method of mandibular subluxation is described for added exposure of the distal carotid artery. The criteria for use of this method include: a carotid bifurcation at or above C-2; disease extending to within 2 cm of the skull base; and a small-caliber distal ICA lumen with the expectation of a patch graft extending close to the skull base. In dentulous patients, the mandible is subluxed by attaching an intradental wire from the ipsilateral mandibular bicuspid to an intradental wire around the contralateral maxillary bicuspid. In edentulous patients, a wire is placed around the ipsilateral mandible and secured to a wire placed through the anterior nasal spine. The entire preoperative subluxation requires 10 to 15 minutes under anesthesia and an additional 1 to 2 minutes postoperatively to remove the wires. A single skin suture and an absorbable intraoral suture were placed in some edentulous patients. This technique has been evaluated over a 15-month reference period during which 115 carotid endarterectomies were performed. The criteria stated above were met in seven cases (six patients, 6%) and jaw subluxation was performed preoperatively. An additional 1 to 2 cm of distal exposure was obtained by using this technique and endarterectomy proceeded without complication. A slight "shift" of the standard anatomical landmarks occurred due to the movement of the mandible, which was easily recognized. There were no significant postoperative complaints related to the subluxation; specifically, no temporomandibular joint pain, no other postoperative pain, and no tooth damage were encountered. It is concluded that this relatively simple approach to mandibular subluxation provided significant added exposure to the distal ICA without notably increasing operative time. In addition, there was no morbidity and little additional care was needed when compared with other more radical approaches to high carotid artery exposure.

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The source of bleeding remains obscure in most cases of subarachnoid hemorrhage (SAH) with a negative angiogram. From January 1, 1989, to July 1, 1993, 40 patients were admitted to the Massachusetts General Hospital with angiogram-negative SAH; 9 of these patients underwent surgical exploration. In seven of these explorations, an arterial source of the hemorrhage was discovered. These arterial sources included three anterior communicating artery complex lesions, two middle cerebral artery lesions, one internal carotid artery aneurysm arising at the origin of the posterior communicating artery, and one vertebral/posterior inferior cerebellar artery aneurysm. Three of these seven lesions had small aneurysmal sacs, but the other four were microaneurysms too small to accept a surgical clip. No source of hemorrhage could be found during surgery on one patient with a perimesencephalic pattern of blood. Two of the four patients with a microaneurysmal source of hemorrhage had two episodes of SAH. We propose that microaneurysms are the source of a significant percentage of nonperimesencephalic angiogram-negative SAH and suggest that these lesions may represent a forme fruste of saccular aneurysms. These findings lead us to propose a protocol for the management of angiogram-negative SAH based on the distribution of blood as seen on the patient's first computed tomogram.

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BACKGROUND: Middle cerebral artery (MCA) aneurysms are typically approached surgically using one of three basic techniques. The sylvian fissure can be opened in one of two ways; either from medial to lateral or from lateral to medial. Alternatively, an incision in the superior temporal gyrus with subpial resection can be used to expose the MCA branches and aneurysm neck. METHODS: We reviewed 65 middle cerebral aneurysms in 62 patients operated on over a 5-year interval where a choice of operative approach was made based on preoperative evaluation of available radiological studies. RESULTS: The superior temporal gyrus was used when intraparenchymal hematoma was present in the temporal lobe or when the length of the middle cerebral artery trunk was long (average length 2.44 +/- 0.41 SE cm). This approach was used in 20 operations on 22 aneurysms. The sylvian fissure approach was used in cases where the middle cerebral artery main trunk was short (1.32 +/- 0.41 SE cm) or the direction of the aneurysm was favorable. This approach was used in 38 operations. In 4 operations (5 aneurysms) we combined the two approaches to remove clot, obtain adequate exposure, and secure control of the proximal MCA. CONCLUSIONS: In most cases of MCA aneurysms the decision as to which surgical approach to use is made preoperatively depending on the presence of intraparenchymal clot, size of aneurysm, direction of aneurysm, and length of the proximal middle cerebral artery.

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The authors describe a case of carotid-cavernous fistula that was not treatable by the standard interventional neuroradiological techniques of transarterial or transvenous occlusion of the fistula because access was blocked by prior trapping procedures. Access to the venous side of the fistula was gained by means of a transethmoidal transsphenoidal exposure, making it possible to embolize the lesion with coils. The details of this approach are described.

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An endovascular non-detachable balloon technique was used to treat 14 patients with cerebral aneurysms. Eight patients presented with subarachnoid hemorrhage, and six others presented with headache or mass effect. Six aneurysms were located in the anterior circulation and eight in the posterior circulation. Seven aneurysms were giant, three were large, and four were small. All target aneurysms or vessels were occluded successfully. Parent vessel was successfully spared in seven cases. There were no procedural complications related to the non-detachable nature of the balloon used. Follow-up angiography detected refilling of aneurysms in three of 11 patients, two with small ruptured aneurysms that bled again following partial deflation or balloon movement. The other aneurysms tested remained occluded, as demonstrated on follow-up angiograms, for up to 15 months. Outcomes were good to excellent in 10 patients, poor in one, and three died. Non-detachable balloons might be preferred for treatment of certain types of cerebral aneurysms including those where intraaneurysmal maneuvers might be considered dangerous, for example, with recent bleeding or intraluminal fresh clots; where precise placement of the balloon is required, for example, in the vicinity of perforators or collaterals emerging near the neck; and where detachment could be dangerous or difficult in broad neck and fusiform aneurysms or in tortuous parent vessels.

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A lecithin-emulsified "Pluronic F-68"-free perfluorochemical compound, named F-1,3-DMA, was tested as a new agent in the prevention of central nervous tissue ischemia. A permanent ischemia leading to cerebral infarction was induced after microsurgical exposure and occlusion of the internal carotid, anterior, and middle cerebral arteries in the rabbit. Following arterial occlusion, F-1,3-DMA was administered intravenously, in a solution rendered isotonic to plasma, over a 30 minute period. The F-1,3-DMA was well tolerated. Hemodynamic, cardiovascular and metabolic parameters were not affected by the infusion of F-1,3-DMA. Although PO2 remained virtually unchanged, animals treated with F-1,3-DMA (n = 9), had smaller infarct volume by 61 percent as compared to the control (n = 8) group (P < 0.04, Student's t-test). Histopathology did not reveal any F-1,3-DMA related damage in the non-infarcted brain. These results suggest that F-1,3-DMA has nervous tissue ischemia protective properties possibly because of microflow effects although O2 transport to "local" tissue may be enhanced as well. We believe that further research is necessary in order to make clinical trials of F-1,3-DMA possible.

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Dural arteriovenous malformations (AVMs) are rare vascular abnormalities that most frequently involve the cavernous, transverse or sigmoid sinus. Anterior cranial fossa dural AVMs are uncommon. We report the clinical, radiological and surgical features of an incidentally discovered anterior fossa dural AVM. The literature regarding the anatomy and clinical presentation of this lesion is reviewed.

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BACKGROUND AND PURPOSE: Perfluorocarbons (PFCs) are considered promising cerebral protection agents because they could combine the beneficial effects of decreased blood viscosity with enhanced oxygen-carrying capacity and oxygen tissue delivery, but trials of PFCs as hemodilutants have been very limited. We evaluated fluoromethyloadamantane (FMA), a new perfluorocarbon compound, as an isovolemic hemodilutant and compared it with low-molecular-weight dextran 40 (D40) and a control group. METHODS: Through a transorbital craniectomy, the internal carotid, anterior, and middle cerebral arteries were coagulated to create a cerebral infarction in anesthetized, mechanically ventilated rabbits. No other experimental procedure was performed in control animals. In the two other groups, hemodilution was commenced 30 minutes after the arterial occlusion with either D40 or FMA. Hemodynamic parameters and brain and systemic temperature were monitored throughout the experiments. All animals were killed 6 hours after the arterial occlusion. RESULTS: Hemodynamic and metabolic parameters and blood oxygen content were not affected by the infusion of either FMA or D40. Brain and systemic temperature remained constant. The ratio of infarct volume to the hemispheric volume was 19.6 +/- 3.7% in the FMA group (n = 17), 19.9 +/- 4.6% in the D40 group (n = 16), and 40.3 +/- 5.7% in the control group (n = 17). The difference in infarct volume of both FMA and D40 animals compared with controls was statistically significant (P < .01) when tested with Student's t test. There was no significant difference between FMA and D40 groups. CONCLUSIONS: These results suggest that FMA has cerebral protective properties and should be purified, optimized, and further tested experimentally to develop a stable, efficient, and safe oxygen carrier, potentially suitable for clinical trials.

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A patient with trigeminal neuralgia caused by a tortuous and ectatic vertebrobasilar artery is presented. He was treated with microvascular decompression using a fine silicone sling sutured to the dura over the petrous pyramid. The technical details are described.

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True intracranial arteriovenous fistulas are rare. The authors report a case of a direct fistula between the intracranial portion of the vertebral artery and the lateral medullary venous system. The patient initially presented with a subarachnoid hemorrhage. An open surgical approach with clip obliteration of the lesion was used. The anatomy of this lesion and its surgical management are described.

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Radiological and clinical analysis was performed in 5 patients with posterior fossa dural arteriovenous fistulas (DAVFs) with isolated sinus segment due to sinus thrombosis, and their patho physiological, diagnostic, and therapeutic concerns were discussed. Patients ranged in age from 36 to 73 years old with a mean of 57 years and included 2 males and 3 females. Two patients presented with ataxia, one with ataxia and bruit, one with atypical facial pain, and one with parietal dysfunction. One patient had a history of hemorrhagic event. DAVFs were located at transverse-sigmoid sinus (3 cases), superior petrosal sinus (1 case), and straight sinus (1 case). They were fed by many branches of external carotid artery including middle meningeal artery, ascending pharyngeal artery, posterior auricular artery, occipital artery, meningeal branches of vertebral artery and posterior cerebral artery, and meningohypophyseal trunk of internal carotid artery. Shunt flow drained into contralateral transverse-sigmoid or supratentorial sinuses via the isolated venous segment through markedly dilated cortical and/or deep venous systems, which caused altered normal venous drainage pattern and venous hypertension. Transarterial embolization in multiple stages (mean 3.4) using n-butyl cyanoacrylate (NBCA) could alleviate symptoms in all cases. DAVFs were almost totally obliterated in 3 patients. Further embolization in one case, and surgical excision in one case were planed because of some residual dilated cortical venous drainage. Posterior fossa DAVFs with isolated sinus segment accompany markedly dilated cortical and/or deep venous systems. They could cause cerebellar, brainstem, or cranial nerve dysfunctions, and sometimes present distant supratentorial symptoms or hydrocephalus due to abnormal venous drainage and venous hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

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