Intraoperative ventricular puncture

Management and safety of intraoperative ventriculostomy during early surgery for ruptured intracranial aneurysms

BACKGROUND

Brain edema and/or acute hydrocephalus are common features that limit working space during early surgery of aneurysmal subarachnoid hemorrhage (aSAH). Intraoperative ventriculostomy offers an immediate brain relaxation. However, management and complications related to the routine use of intraoperative external ventricular drainage (iEVD) are not well investigated.

METHODS

We retrospectively reviewed all patients who were treated with pterional craniotomy and clipping for ruptured anterior circulation aneurysms in our center between 2012 and 2019. We included in this study all patients submitted to iEVD using the Paine's point on the side of craniotomy. Indication for positioning of an iEVD was given in all cases whenever initial cisternal dissection was hampered by the lack of cerebrospinal fluid (CSF) circulation due to SAH and/or hydrocephalus.

RESULTS

In the study period, 162 patients with aSAH underwent surgical clipping. In 103 patients, an iEVD was used. The overall rate of iEVD-related complications was 6.7%, including 3 cases of catheter misplacement, one case of catheter obstruction, one case of related hemorrhage, and 2 cases of infection. The rate of shunt-dependent hydrocephalus was 16.5% (17/103 patients).

CONCLUSION

In our experience, iEVD is a safe technique that facilitates dissection during early surgery for intracranial ruptured aneurysms, without requiring an additional burr hole procedure.

Ventricular Catheter Insertion on the Occipital and Parietooccipital Bone: A Nonmetric Complementary Technique

Background and Study Aim Hydrocephalus is a common disease of the pediatric population, with cerebrospinal fluid diversion as the management of choice. All current insertion techniques require craniometrics calculation that may not be applicable for pediatric patients, due to significant variation in head circumference. We describe a complementary method of inserting ventricular catheters, devoid of craniometrics.

Materials and Methods The insertion site is based on two imaginary lines on the sagittal plane (superior and inferior limits) and four imaginary lines on the axial plane of a computed tomography/magnetic resonance imaging. The insertion point is chosen based on the shortest location from the outer table of the bone to the ventricle. The length of catheter insertion is calculated based on the distance between the calvarial outer table and the foramen of Monro.

Results Two case examples of ventricular catheter insertions, in pediatric patients with noncommunicating hydrocephalus, are described. External ventricular drain and ventriculoperitoneal shunt were inserted using this technique, with no required craniometrics measurements.

Conclusion This complementary method of inserting ventricular catheters can be easily tailored and implemented by junior neurosurgical residents to senior neurosurgeons as it precludes the measurement of the catheter insertion points.

Analysis of a Novel Entry Point for Freehand Ventriculostomy Using Computerized Tomography Scans

Background

External ventricular drain (EVD) placement is one of the most common procedures in neurosurgery. Neurosurgeons generally prefer to access the ventricles via Kocher’s point since it is the most common point of entry to this area; however, this point is used to describe different anatomic landmarks and is not well-defined.

Objective

The present study aims to describe and provide an anatomical assessment of a novel ventriculostomy access point developed by the authors using computerized tomography (CT) scans performed on 100 patients.

Materials and methods

Data were collected from 100 randomly selected patients with normal ventricular anatomy found on their 1.0 mm-slice CT scans performed at the Burdenko Neurosurgical Center from March 2019 to June 2021. The CT inclusion criteria were: CT slices < or = to 1 mm and absence of brain herniation. Patients with brain mass lesions, severe brain edema, and pneumocephalus were excluded. Age, gender, and ventricular size were not exclusion criteria.

Results

The mean patient age was 43.58 years (range 4-73), with 50 men and 50 women. The mean Evan’s index was 25.7 % (SD=4.38 %, range 10.2-41.0 %). No differences were found between the angles of EVD placement on either side (89.50±1.22 degrees on the right and 89.60±1.14 degrees on the left). Hence, nearly all EVD cases had been placed perpendicularly to the skull surface at a pinpoint location.

Conclusion

The proposed point of successful ventriculostomy placement in this study was 3 cm from the bregma along the coronal suture. The angle of EVD placement was approximately 90 degrees in almost all patients and was independent of the patient’s age and the side of the head that was entered. Little correlation was found between the value of the entry angle and Evan’s index. The point is simply identifiable, and its entry is easily accessible in practice.

Predictors of ventriculostomy-associated infections: A retrospective study of 243 patients

OBJECTIVE

Risk factors of ventriculostomy-associated infection (VAI) reported in the literature are variable due to heterogeneity of external ventricular drainage (EVD) procedures and management. This study aimed to assess the rate of VAI and its risk factors.

METHODS

The authors retrospectively reviewed the medical records of patients older than 18 years who received EVD catheterizations between January 2015 and December 2020.

RESULTS

Among 243 patients with 355 catheters, twenty-three VAIs were identified, yielding VIA rates of 9.5% per patient and 6.5% per catheter. VAI was associated with a longer total EVD duration (29.2 days vs. 15.8 days, P < 0.001), a longer procedural time (72 minutes vs. 40 minutes, P < 0.001), intraoperative ventriculostomy (39.1% vs. 9.1%, P < 0.001), craniotomy (87.0% vs. 60.9%, P = 0.014), and other systemic infections (30.4% vs. 8.2%, P = 0.004). On multivariate analysis, a longer total EVD duration (OR = 1.086, P < 0.001), intraoperative ventriculostomy (OR = 6.119, P = 0.001), and other systemic infections (OR = 4.620, P = 0.015) were associated with VAI. There was no statistical difference between the VAI rates of patients with and without prophylactic EVD exchanges at mean 12.6 days (7.1% vs. 2.2%, P = 0.401).

CONCLUSIONS

Intraoperative ventriculostomy was independently associated with VAI. Prophylactic EVD exchange at 12.6 days did not lower VAI rate.

Neurosurgery at UT Southwestern Medical Center: 1956-2020

The history of neurosurgery at UT Southwestern Medical Center in Dallas, Texas, is reviewed. Kemp Clark, MD, started the academic neurosurgical practice at Parkland Hospital in 1956. Clark developed a robust training program that required the resident to operate early. In 1972, the Dallas Veterans Affairs Hospital was added to the training program. Duke Samson, MD, became chair in 1988. He emphasized technical excellence and honest reporting of surgical outcomes. In 1989, Zale Lipshy University Hospital opened and became a center for neurosurgical care, and Hunt Batjer, MD, became chair in 2012. The program expanded significantly. Along with principles established by his predecessors, Batjer emphasized the need for all neurosurgeons to engage the community and to be active in policy leadership through local and national organizations. During his tenure, the pediatric neurosurgery group at Children's Medical Center Dallas was integrated with the department, and a multidisciplinary spine service was developed. In 2014, the Peter O'Donnell Jr. Brain Institute was established, and the William P. Clements Jr. University Hospital opened. For 64 years, UT Southwestern Medical Center has been fertile ground for academic neurosurgery, with a strong emphasis on excellence in patient care.

White Matter Governed Superior Frontal Sulcus Surgical Paradigm: A Radioanatomic Microsurgical Study-Part II

BACKGROUND

Kocher's point (KP) and its variations have provided standard access to the frontal horn (FH) for over a century. Anatomic understanding of white matter tracts (WMTs) has evolved, now positioning us to better inform the optimal FH trajectory.

OBJECTIVE

To (1) undertake a literature review analyzing entry points (EPs) to the FH; (2) introduce a purpose-built WMT-founded superior frontal sulcus parafascicular (SFSP)-EP also referred to as the Kassam-Monroy entry point (KM-EP); and (3) compare KM-EP with KP and variants with respect to WMTs.

METHODS

(1) Literature review (PubMed database, 1892-2018): (a) stratification based on the corridor: i. ventricular catheter; ii. through-channel endoscopic; or iii. portal; (b) substratification based on intent: i. preoperatively planned or ii. intraoperative (postdural opening) for urgent ventricular drainage. (2) Anatomic comparisons of KM-EP, KP, and variants via (a) cadaveric dissections and (b) magnetic resonance-diffusion tensor imaging computational 3D modeling.

RESULTS

A total of 31 studies met inclusion criteria: (a) 9 utilized KP coordinate (1 cm anterior to the coronal suture (y-axis) and 3 cm lateral of the midline (x-axis) approximated by the midpupillary line) and 22 EPs represented variations. All 31 traversed critical subcortical WMTs, specifically the frontal aslant tract, superior longitudinal fasciculus II, and inferior fronto-occipital fasciculus, whereas KM-EP (x = 2.3, y = 3.5) spares these WMTs.

CONCLUSION

KP (x = 3, y = 1) conceived over a century ago, prior to awareness of WMTs, as well as its variants, anatomically place critical WMTs at risk. The KM-EP (x = 2.3, y = 3.5) is purpose built and founded on WMTs, representing anatomically safe access to the FH. Correlative clinical safety, which will be directly proportional to the size of the corridor, is yet to be established in prospective studies.

Contralateral Ventriculostomy for Intraoperative Brain Relaxation in Supratentorial Brain Tumors

Background

CSF drainage from the ventricular system is a popular and effective technique for intraoperative brain relaxation as it reduces ICP, enlarges extra-axial operative corridors, and slackens the brain increasing its tolerance for surgical manipulation. However, sometimes when the ventricular chambers distant from the site of pathology are tapped, there is a risk of neurological worsening due to paradoxical herniation of the brain, exemplified by the phenomenon of upward transtentorial herniation observed in posterior fossa tumors, consequent to a supratentorial ventriculostomy. Expectation of an analogous phenomenon precludes contralateral ventricular drainage in supratentorial brain tumors producing midline shift, subfalcine herniation, and resultant distension of the opposite lateral ventricles.

Objective

Demonstrating the safety and efficacy of intraoperative contralateral ventricular drainage in the presence of sub-falcine herniation.

Methods

Clinical and imaging information were retrospectively collected for four cases in which this technique was adopted.

Results

The first case was a large clinoidal meningioma with a midline shift and contralateral ventriculomegaly. EVD from the dilated ventricle provided optimum brain conditions for safe resection of the tumor through an orbitopterional approach. The second case required a contralateral EVD to reduce ICP intraoperatively, for a recurrent anaplastic ependymoma with severe mass effect. It reduced the venous hypertension related to raised ICP minimizing the blood loss. Contralateral EVD was utilized to enlarge the working corridor for interhemispheric approach in two cases.

Conclusion

Contralateral ventricular drainage is a safe, effective, and convenient operative step for reducing brain turgor in the presence of sub-falcine herniation produced by large supratentorial tumors.

Intraoperative Temporal Horn Ventriculostomy for Brain Relaxation During Aneurysm Surgeries in Pterional Approaches

BACKGROUND

Achieving optimal brain relaxation is paramount in aneurysm surgery. Despite proper positioning and the use of newer anesthetic drugs and the administration of decongestants, it is often not possible to achieve satisfactory relaxation, which can lead to neurological deficits owing to excessive brain retraction. The present study aimed to provide detailed surgical notes regarding the novel technique of temporal horn tapping for intraoperative ventriculostomy.

METHODS

The hospital records of anterior circulation aneurysm surgery performed during the previous 5 years were retrieved. Only those cases in which we had used temporal horn tapping were included. Ventriculostomy was performed only in those cases in which the brain was tense despite the administration of decongestants. A small corticectomy was performed over the middle temporal gyrus and deepened to access the temporal horn.

RESULTS

This technique was used in 84 surgical cases. The mean patient age was 52.8 years. The male/female ratio was 1:1.4. Anterior communicating artery aneurysms were the most common. Adequate brain relaxation was satisfactorily achieved in all cases. Two patients had developed a small temporal hematoma attributable to the temporal corticectomy, both managed conservatively.

CONCLUSIONS

We believe that this new trajectory through the middle temporal gyrus to access the temporal horn is very safe because of the lack of proximity to any blood vessel or critical structures. We recommend the use of this technique during pterional approaches for acute aneurysmal surgery in the tight, bulging brain to achieve relaxation and avoid secondary complications such as retraction contusions and resultant cerebral edema.

Surgical Approaches to Basilar Apex Aneurysms: An Illustrative Review

Surgical management of basilar apex aneurysms remains one of the most challenging areas in neurovascular surgery. Technical demands of treating these aneurysms have inspired several generations of neurosurgeons to push the limitations of technical achievement. Advances in neuroanesthesia, cerebral protection paradigms, and critical care management have enhanced surgical outcomes of these lesions. Several approaches have been described to reach these lesions from anterolateral or lateral corridors. Each surgical approach has its own advantages and limitations and should be chosen for each patient according to the aneurysm's position, projection, parent arteries, and perforators. In this review, we will discuss pros and cons of the common approaches to these aneurysms with description of the important steps of each surgical procedure.

Craniometrics and Ventricular Access: A Review of Kocher's, Kaufman's, Paine's, Menovksy's, Tubbs’, Keen's, Frazier's, Dandy's, and Sanchez's Points

Intraventricular access is frequently required during neurosurgery, and when neuronavigation is unavailable, the neurosurgeon must rely upon craniometrics to achieve successful ventricular cannulation. In this historical review, we summarize the most well-described ventricular access points: Kocher's, Kaufman's, Paine's, Menovksy's, Tubbs’, Keen's, Frazier's, Dandy's, and Sanchez's. Additionally, we provide multiview, 3-dimensional illustrations that provide the reader with a novel understanding of the craniometrics associated with each point.

Pterional or Subfrontal Access for Proximal Vascular Control in Anterior Interhemispheric Approach for Ruptured Pericallosal Artery Aneurysms at Risk of Premature Rupture

OBJECTIVE

Cases of a ruptured pericallosal artery aneurysm with a high risk of intraoperative premature rupture and technical difficulties for proximal vascular control require a technique for the early and safe establishment of proximal vascular control.

METHODS

A combined pterional or subfrontal approach exposes the bilateral A1 segments or the origin of the ipsilateral A2 segment of the anterior cerebral artery (ACA) for proximal vascular control. Proximal control far from the ruptured aneurysm facilitates tentative clipping of the rupture point of the aneurysm without a catastrophic premature rupture. The proximal control is then switched to the pericallosal artery just proximal to the aneurysm and its intermittent clipping facilitates complete aneurysm dissection and neck clipping.

RESULTS

Three such cases are reported: a ruptured pericallosal artery aneurysm with a contained leak of the contrast from the proximal side of the aneurysm, a low-lying ruptured pericallosal artery aneurysm with irregularities on its proximal wall, and a multilobulated ruptured pericallosal artery aneurysm with the parasagittal bridging veins hindering surgical access to the proximal parent artery. In each case, the proposed combined pterional-interhemispheric or subfrontal-interhemispheric approach was successfully performed to establish proximal vascular control far from the ruptured aneurysm and facilitated aneurysm clipping via the interhemispheric approach.

CONCLUSION

When using an anterior interhemispheric approach for a ruptured pericallosal artery aneurysm with a high risk of premature rupture, a pterional or subfrontal approach can be combined to establish early proximal vascular control at the bilateral A1 segments or the origin of the A2 segment.

Modified Supraorbital Keyhole Approach to Anterior Circulation Aneurysms

Objective

To select a surgical approach for aneurysm clipping by comparing 2 approaches.

Materials and Methods

204 patients diagnosed with subarachnoid hemorrhage treated by the same neurosurgeon at a single institution from November 2011 to October 2013, 109 underwent surgical clipping. Among these, 40 patients with Hunt and Hess or Fisher grades 2 or lower were selected. Patients were assigned to Group 1 (supraorbital keyhole approach) or Group 2 (modified supraorbital approach). The prognosis according to the difference between the two surgical approaches was retrospectively compared.

Results

Supraorbital keyhole approach (Group 1) was performed in 20 aneurysms (50%) and modified supraorbital approach (Group 2) was used in 20 aneurysms. Baseline characteristics of patients did not differ significantly between two groups. Total operative time (p = 0.226), early ambulation time (p = 0.755), length of hospital stay (p = 0.784), Glasgow Coma Scale at discharge (p = 0.325), and Glasgow Outcome Scale scores (p = 0.427) did not show statistically significant differences. The amount of intraoperative hemorrhage was significantly lower in the supraorbital keyhole approach (p < 0.05).

Conclusion

The present series demonstrates the safety and feasibility of the two minimal invasive surgical techniques for clipping the intracranial aneurysms. The modified supraorbital keyhole approach was associated with more hemorrhage than the previous supraorbital keyhole approach, but did not exhibit differences in clinical results, and provided a better surgical view and convenience for surgeons in patients with Hunt and Hess or Fisher grades 2 or lower.

Brain stem herniation secondary to cerebrospinal fluid drainage in ruptured aneurysm surgery: a case report

BACKGROUND

A lumbar drainage catheter is frequently placed intra-operatively to decrease fluid pressure on the brain in aneurysmal subarachnoid cases. In rare cases, this catheter placement can lead to intracranial hypotension, resulting in brain stem herniation termed "brain sag" and it can lead to neurological injury and may prove to be fatal. We present our patient with brain sag secondary to intraoperative lumbar drainage.

CASE DESCRIPTION

A 56-year-old woman was admitted with a sudden onset of severe headache. A computed tomography (CT) scan revealed diffuse subarachnoid hemorrhage with ruptured anterior communicating artery aneurysm. After general anesthesia, a lumbar drainage catheter was placed intra-operatively to reduce pressure on the brain and 50 cc of CSF was removed during a 5-h period. Three to five days after operation, her neurologic symptoms became worse with an altered mental state and pupillary asymmetry. CT and magnetic resonance imaging (MRI) showed slit lateral ventricles, effacement of the cisterns and an elongated brain stem. After placing the patient in the Trendelenburg position, the patient rapidly recovered to her baseline neurologic state.

DISCUSSION

Typical complications of subarachnoid hemorrhage such as vasospasm or hydrocephalus also manifest as neurological deterioration, but their treatments differ greatly from those for brain sag. Thusly, it is important to distinguish between causes. Treatments such as lumbar or extra-ventricular drainage, induced hypertension or administration of mannitol must be stopped once brain sag is suspected. Also, care should be taken for typical imaging features of brain sag on CT or MRI scan. For brain sag, placing the patient in the Trendelenburg position can improve neurological status in a rapid fashion.

CONCLUSIONS

Brain sag is a rare but serious condition and can be fatal if not rapidly diagnosed and treated. We therefore recommend including brain sag in the differential diagnosis, along with vasospasm, hydrocephalus or cerebral edema as part of possible complications following subarachnoid hemorrhage treatment. We hope our clinical and imaging data from this case study contribute to the correct diagnosis of brain sag, as its early detection is important.

The ventricular system of the brain: a comprehensive review of its history, anatomy, histology, embryology, and surgical considerations

INTRODUCTION

The cerebral ventricles have been recognized since ancient medical history. Their true function started to be realized more than a thousand years later. Their anatomy and function are extremely important in the neurosurgical panorama.

METHODS

The literature was searched for articles and textbooks of different topics related to the history, anatomy, physiology, histology, embryology and surgical considerations of the brain ventricles.

CONCLUSION

Herein, we summarize the literature about the cerebral ventricular system.

Bilateral middle cerebral artery aneurysms: a comparative study of unilateral and bilateral approaches

The best surgical method for the treatment of patients with bilateral middle cerebral artery (bMCA) aneurysms has not been fully determined yet. The main purpose of this study is to compare the surgical results of unilateral and bilateral approaches to bMCA aneurysms including mean operation time, mean hospital stay, and mean cost, in the experience of the same neurosurgical team. Between January 2001 and June 2010, 22 patients with bMCA aneurysms were surgically treated in our institution. In 12 cases (54.5 %), ipsilateral and contralateral MCA aneurysms were successfully clipped via unilateral approach. In the remaining 10 cases, bilateral approach was necessary because of some technical difficulties. Although the surgical results were almost the same, mean operation time and mean hospital stay were, respectively, 46 and 37 % shorter and mean cost per person was 23 % lower for the patients in the unilateral group. In addition, the severity of brain edema, total length of the contralateral (A1+M1) segment, and the configuration of contralateral aneurysm were found to be the determinant parameters affecting the feasibility of the unilateral approach. To our knowledge, this is the first study in the literature that compares the clinical outcomes of unilateral and bilateral approaches to bMCA aneurysms. The results of surgery for both approaches are almost the same. However, the unilateral approach has certain advantages compared to the bilateral approach. Therefore, the unilateral approach may be a good alternative in surgical management of patients with bMCA aneurysms in selected cases and the abovementioned parameters can help the neurosurgeon in patient selection.

Brain Injuries during Intraoperative Ventriculostomy in the Aneurysmal Subarachnoid Hemorrhage Patients

OBJECTIVE

Intraoperative ventriculostomy is widely adopted to make the slack brain. However, there are few reports about hemorrhagic or parenchymal injuries after ventriculostomy. We tried to analyze and investigate the incidence of these complications in a consecutive series of patients with aneurysmal subarachnoid hemorrhage (SAH).

METHODS

From September 2006 to June 2007, 43 patients underwent surgical clipping for aneurysmal SAH at our hospital. Among 43 patients, we investigated hemorrhagic or parenchymal injuries after intraoperative ventriculostomy using postoperative computed tomographic scan in 26 patients. After standard pterional craniotomy, ventriculostomy catheter was inserted perpendicular to the cortical surface along the bisectional imaginary line from Paine's point.

RESULTS

Hemorrhagic injuries were detected in 12 of 26 patients (46.2%). Mean systolic blood pressure during anesthesia was with in statistically significant parameter related to hemorrhage (p = 0.006). On the other hand, parenchymal injuries were detected in 11 of 26 patients (42.3%). Female and the amount of infused mannitol during anesthesia showed statistically significant parameters related to parenchymal injury (p = 0.005, 0.04, respectively). However, there were no ventriculostomy-related severe complications.

CONCLUSION

In our series, hemorrhagic or parenchymal injuries after intraoperative ventriculostomy occurred more commonly than previously reported series in aneurysmal SAH patients. Although the clinical outcomes of complications are generally favorable, neurosurgeon must keep in mind the frequent occurrence of brain injury after intraoperative ventriculostomy in the acute stage of aneurysmal SAH.

THIRD VENTRICULOSTOMY THROUGH THE FENESTRATED LAMINA TERMINALIS DURING MICRONEUROSURGICAL CLIPPING OF INTRACRANIAL ANEURYSMS

OBJECTIVE

Fenestration of the lamina terminalis (LT) is an alternative means of cerebrospinal fluid (CSF) drainage during acute or emergency surgery of ruptured intracranial aneurysms in patients with high-grade subarachnoid hemorrhage. External ventricular drainage allows drainage of CSF and also measurement of intracranial pressure after the surgery. Catheterization of the third ventricle via the fenestrated LT after clipping the aneurysm is an alternative to conventional ventriculostomies. This method has been used by the senior author (JAH) since 2001. The authors describe their experience with this technique, which can be used safely in selected cases of high-grade subarachnoid hemorrhage.

METHODS

Seventy-eight patients with aneurysmal subarachnoid hemorrhage underwent third ventriculostomy via the LT between March 2001 and December 2005. Clinical and radiological data of these consecutive patients were retrospectively reviewed.

RESULTS

There were no procedure-related complications. Eight patients (10%) later required a conventional ventriculostomy, 7 because of catheter occlusion and 1 because of catheter displacement. In 7 patients (9%), a positive CSF culture was found.

CONCLUSION

Ventriculostomy via the fenestrated LT performed during aneurysm surgery is a practical way for later CSF removal and intracranial pressure monitoring. The catheter can be applied via the same craniotomy without the need for an additional intervention. No procedure-related complications were observed in the present series. This technique can be suggested as a safe alternative to a classical ventriculostomy.

Early surgery for ruptured cerebral aneurysms: technical note

We describe a collection of techniques to be considered in the early clipping of ruptured cerebral aneurysms located in the anterior circulation when dealing with the swollen red and scaring brain many times found after craniotomy.

Novel entry point for intraoperative ventricular puncture during the transsylvian approach

OBJECTIVE

In dealing with cases of oedematous brain, relaxation during the transsylvian approach to supratentorial aneurysms has been accomplished by ventricular drainage by using the anatomic point defined by Dr. Paine. However, we have experienced patient complications when using this point. We propose a novel anatomic point to reduce catheter-related complications and facilitate adequate ventricular puncture during ruptured aneurysm operations.

METHODS

Ten patients underwent aneurysmal neck clipping for ruptured aneurysm by means of the transsylvian approach. The use of a novel anatomic point for intraoperative drainage was examined using a neuronavigation system.

RESULTS

Using the novel point of entry for ventricular cannulation proved to be reliable for puncture and reduced chance of malpositioning.

CONCLUSION

Secure intraoperative ventricular cannulation is reliably achieved by pointing the catheter approximately 2 cm beyond a line extending from the anterior limb of the triangle described by Paine. This technique reduces injury to the deep brain and enhances preciseness and safety of ventricular cannulation.

Intraoperative ventricular puncture during supraorbital craniotomy via an eyebrow incision

✓ The authors determined the landmarks and coordinates for intraoperative ventricular puncture directly from the supraorbital craniotomy opening via an eyebrow incision.

Fifty magnetic resonance (MR) imaging studies were obtained from patients with no pathological cerebral characteristics or ventricular distortion. The cerebral entry point of the ventriculostomy was located directly under the key bur hole (just behind the zygomatic process of the frontal bone) at the base of the frontal lobe because it represents a stable, reliable point that can be used as the bur hole during supraorbital craniotomy via an eyebrow incision. From this point, the coordinates for lateral ventricular puncture were determined using MR imaging studies and neuronavigational software.

The cerebral entry point of the ventriculostomy was situated directly under the key bur hole at the base of the frontal lobe. The catheter was directed at a 45° angle to the midline and a 20° angle up from an imaginary line parallel to the orbitomeatal line. The catheter will usually be inserted into the ventricle at a point 5 cm deep to the cortex and may be inserted as deep as 6.5 cm. Using this technique, the frontal horn of the lateral ventricle can be easily tapped. The landmark required for this technique is readily available in all patients.

Fenestration of the Lamina Terminalis as a Valuable Adjunct in Aneurysm Surgery

OBJECTIVE:

Hydrocephalus, vasospasm, and frontobasal injury are common complications after aneurysmal subarachnoid hemorrhage (SAH) from anterior communicating artery aneurysms. Previous studies have suggested that fenestration of the lamina terminalis (FLT) during surgery may be associated with reduced rates of shunt-dependent hydrocephalus and vasospasm. We report 106 patients affected by anterior communicating artery aneurysms and Fisher Grade 3 aneurysmal SAH and the affect of FLT on shunt-dependent hydrocephalus, vasospasm, and frontobasal injury.

METHODS:

During a 3-year period, 53 patients underwent FLT and 53 did not. We prospectively evaluated admission and discharge clinical grades, hydrocephalus at admission, occurrence of clinical vasospasm, need for interventional vasospasm therapy, frontobasal hypodensity incidence, and permanent ventriculoperitoneal shunting requirement. Follow-up ranged from 3 to 35 months (mean, 17.9 mo).

RESULTS:

Shunting incidence after aneurysmal SAH with hydrocephalus was 4.25% in patients who underwent FLT and 13.9% in patients who did not (P&lt; 0.001). Clinical cerebral vasospasm occurred in 29.6% of patients who underwent FLT and in 54.7% of patients who did not (P&lt; 0.001). Frontobasal hypodensity was identified postoperatively in 0% of patients who underwent FLT and in 5% of patients who did not. Good outcome was reported in 69.81% of patients who underwent FLT and in 33.96% of patients who did not (P&lt; 0.001). Poor outcome was associated with higher Hunt and Hess grades, need for ventricular drainage, elevated intracranial pressure, and multiple interventional vasospasm therapies. No complications were linked to FLT.

CONCLUSION:

FLT was associated with statistically significant decreases in shunting rates, incidence of vasospasm, and better outcomes. We recommend its routine use in patients with Fisher Grade 3 anterior communicating artery aneurysmal SAH.

Extended Lateral Transsylvian Approach for Basilar Bifurcation Aneurysms

THE SURGICAL MANAGEMENT of aneurysms of the basilar apex is one of the most challenging areas in neurosurgery. Successful treatment of this subgroup of aneurysms is dependent on the mastery of technical nuances that have been pioneered and advanced over the past 4 decades. Although both the traditional transsylvian and subtemporal approaches have distinct advantages, each is associated with significant limitations. In this article, the senior author shares his insights into a hybrid approach: the extended lateral transsylvian approach. This approach combines the assets of the two traditional approaches while eliminating their liabilities.

Surgery for posterior communicating artery aneurysms

The most common site of internal carotid artery (ICA) aneurysms is at the posterior communicating artery (PComA) junction. Although ICA aneurysm surgery carries substantial risk, the ultimate outcome of patients with PComA aneurysms is better than those with aneurysms in other locations. The rate of successful surgical outcome increases when precise knowledge of the anatomy and understanding of the hazards associated with aneurysms in this region are combined with a well organized plan for the surgical approach. This article will describe details of the preoperative considerations, operative techniques, and surgical results for aneurysms arising at the ICA-PComA junction based on the 25-year personal experience of the senior author, comprising a total of 424 surgical cases.

Third ventriculostomy through the lamina terminalis for intracranial pressure monitoring after aneurysm surgery: technical note

OBJECTIVE

A new ventriculostomy technique through the lamina terminalis is described. This technique is applied mainly during aneurysm surgery at the acute stage.

METHOD

Thirteen patients were operated on intracranial aneurysms and, during the procedure, had the lamina terminalis fenestrated. A ventricular catheter was inserted into the third ventricule, left in place and connected to an external drainage system for further intracranial pressure (ICP) monitoring and/or cerebrospinal fluid (CSF) drainage.

RESULTS

ICP readings and CSF drainage were obtained in all cases. No complication was recorded.

CONCLUSION

Third ventriculostomy through the lamina terminalis is a simple and easy technique that can be used as an alternative to conventional ventriculostomy. This procedure can be indicated in cases where the ventricule is not reached by means of another technique, and when the decision to perform ventriculostomy is made at the end of aneurysm surgery.

Management and outcomes in a low-volume cerebral aneurysm practice

OBJECTIVE

To review management strategies, outcomes, and complications in cerebral aneurysm surgery in a low-volume aneurysm practice.

METHODS

Seventy-nine craniotomies to treat aneurysms were performed between June 1996 and November 1999. Patient management strategy is outlined, complications are assessed, and outcomes are described.

RESULTS

Twenty-six patients underwent surgery to treat unruptured aneurysms. Forty-two patients presented with Hunt and Hess Grade 1 to 3 subarachnoid hemorrhage. Eleven patients presented with Grade 4 or 5 subarachnoid hemorrhage. Twenty-four patients (92.3%) with unruptured aneurysms experienced favorable outcomes. Of the patients with unruptured anterior circulation aneurysms, 96% achieved favorable recoveries. Thirty-eight patients (90.5%) with Grade 1 to 3 subarachnoid hemorrhage experienced favorable outcomes; four of these patients were moderately disabled. Among patients with Grade 1 to 3 subarachnoid hemorrhage, the mortality rate was 7.1%. Of patients with Grade 4 or 5 subarachnoid hemorrhage, five (45.5%) experienced favorable outcomes, but four of these patients were moderately disabled; two patients (18.2%) were severely disabled, and four patients (36.4%) died.

CONCLUSION

Acceptable clinical outcomes can be achieved in lower-volume aneurysm practices. A multidisciplinary subspecialty approach with aggressive perioperative care, especially in the prevention and treatment of cerebral vasospasm, is important in obtaining these results. Close interaction with medical consultants and other subspecialists is necessary.

The safety of intraoperative lumbar subarachnoid drainage for acutely ruptured intracranial aneurysm: technical note

Recently, some concern has arisen regarding the safety of intraoperative spinal drainage for brain relaxation in aneurysm surgery, due to anecdotal association with both aneurysmal rebleeding and increases in symptomatic vasospasm. To address these concerns, we reviewed our experience with frequent spinal drainage and early surgery in 432 consecutive cases of surgically treated aneurysmal subarachnoid hemorrhage. Unless contraindicated by mass effect or associated pathology, all grade I-III patients referred within 14 days were treated with spinal drainage at surgery. In this cohort (n = 314), there were no cases of meningitis or nerve root injury. Only one case of intraoperative rebleeding could be associated with spinal drain placement (0.3%). In grade IV-V patients, 47% required preoperative ventriculostomy, and 11% were ineligible for spinal drainage due to mass effect. There were, however, no complications related to spinal drainage in the remaining 23 patients. Permanently-shunted hydrocephalus (8%) and symptomatic vasospasm (19%) were infrequent overall. When analyzed by grade, spinal drains were generally associated with equal or reduced incidence of these developments when compared to patients without spinal drainage. We conclude that brain relaxation can be safely and effectively obtained using intraoperative spinal drains during early aneurysm surgery.

A case of acute vertigo with incidental aneurysms

It is essential to decrease the risk to the patient to an absolute minimum when prophylactic procedures are offered against a relatively unpredictable (for the individual patient) natural history risk. Very careful preoperative planning and intraoperative execution are mandatory to maximize the chances of the patient for a successful outcome.

Combined transsylvian-subtemporal exposure of cerebral aneurysms involving the basilar apex

The surgical repair of cerebral aneurysms involving the apex of the basilar artery continues to undergo refinement and evolution. The inherent difficulty in accessing the basilar apex as well as the complexities of the microanatomy render this area a notoriously hazardous and technically challenging region in which to perform microsurgical clipping of cerebral aneurysms. Several operative approaches have been described and are constantly undergoing a state of evolution in the hopes of optimizing the exposure of the distal basilar artery and minimizing the inherent risks of surgery. The consistent decline in operative morbidity has paralleled improved understanding of the microvascular anatomy, both in this region and along the various corridors of approach. No single operative approach is universally superior, considering the wide variability of individual patient anatomy and vascular configurations. Each approach has strengths, weaknesses, and potential complications that must be considered in the though process of planning an operative attack on a basilar apex aneurysm. Intimate familiarity with the microvasculature and the microsurgical anatomy of the region is an imperative prerequisite for the application of any surgical approach to this region. This paper outlines a detailed review of the microsurgical anatomy that is pertinent to microsurgery of aneurysms in this region, and describes an approach referred to as the combined transsylvian-subtemporal approach. We have found this operative approach particularly useful in aneurysm surgery of the basilar apex but do not mean to imply that this single approach is suitable for all surgeons or all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

A review of brain retraction and recommendations for minimizing intraoperative brain injury

Brain retraction is required for adequate exposure during many intracranial procedures. The incidence of contusion or infarction from overzealous brain retraction is probably 10% in cranial base procedures and 5% in intracranial aneurysm procedures. The literature on brain retraction injury is reviewed, with particular attention to the use of intermittent retraction. Intraoperative monitoring techniques--brain electrical activity, cerebral blood flow, and brain retraction pressure--are evaluated. Various intraoperative interventions--anesthetic agents, positioning, cerebrospinal fluid drainage, operative approaches involving bone resection or osteotomy, hyperventilation, induced hypotension, induced hypertension, mannitol, and nimodipine--are assessed with regard to their effects on brain retraction. Because brain retraction injury, like other forms of focal cerebral ischemia, is multifactorial in its origins, a multifaceted approach probably will be most advantageous in minimizing retraction injury. Recommendations for operative management of cases involving significant brain retraction are made. These recommendations optimize the following goals: anesthesia and metabolic depression, improvement in cerebral blood flow and calcium channel blockade, intraoperative monitoring, and operative exposure and retraction efficacy. Through a combination of judicious retraction, appropriate anesthetic and pharmacological management, and aggressive intraoperative monitoring, brain retraction should become a much less common source of morbidity in the future.