Standard Pterional Craniotomy Research Articles

The Minipterional Craniotomy for Anterior Circulation Aneurysms

The pterional craniotomy is well established for microsurgical clipping of most anterior circulation aneurysms. The incision and temporalis muscle dissection impacts postoperative recovery and cosmetic outcomes. The minipterional (MPT) craniotomy offers similar microsurgical corridors, with a substantially shorter incision, less muscle dissection, and a smaller craniotomy flap. To report our experience with the MPT craniotomy in select unruptured anterior circulation aneurysms. From January 2009 to July 2013, 82 unruptured aneurysms were treated in 72 patients, with 74 MPT craniotomies. Seven patients had multiple aneurysms treated with a single MPT craniotomy. The average patient age was 56 years (range: 24-87). Aneurysms were located along the middle cerebral artery (n = 36), posterior communicating (n = 22), paraophthalmic (n = 22), choroidal (n = 1), and dorsal ICA segments (n = 1). The MPT craniotomy utilized an incision just posterior to the hairline and a single myocutaneous flap. The average aneurysm size was 5.45 mm (range: 1-14). There were no instances of compromised operative corridors requiring craniotomy extension. Three significant early postoperative complications included epidural and subdural hematomas requiring evacuation, and a middle cerebral artery infarction. Average length of hospitalization was 3.96 days (range: 2-20). Two patients required reoperation for wound infections. Average follow-up was 421 days (range: 5-1618). Minimal to no temporalis muscle wasting was noted in 96% of patients. The MPT craniotomy is a worthwhile alternative to the standard pterional craniotomy. There were no instances of suboptimal operative corridors and clip applications when the MPT craniotomy was utilized in the treatment of unruptured middle cerebral artery and supraclinoid internal carotid artery aneurysms proximal to the terminal internal carotid artery bifurcation.

Novel embalming solution for neurosurgical simulation in cadavers

Surgical simulation using postmortem human heads is one of the most valid strategies for neurosurgical research and training. The authors customized an embalming formula that provides an optimal retraction profile and lifelike physical properties while preventing microorganism growth and brain decay for neurosurgical simulations in cadavers. They studied the properties of the customized formula and compared its use with the standard postmortem processing techniques: cryopreservation and formaldehyde-based embalming. Eighteen specimens were prepared for neurosurgical simulation: 6 formaldehyde embalmed, 6 cryopreserved, and 6 custom embalmed. The customized formula is a mixture of ethanol 62.4%, glycerol 17%, phenol 10.2%, formaldehyde 2.3%, and water 8.1%. After a standard pterional craniotomy, retraction profiles and brain stiffness were studied using an intracranial pressure transducer and monitor. Preservation time-that is, time that tissue remained in optimal condition-between specimen groups was also compared through periodical reports during a 48-hour simulation. The mean (± standard deviation) retraction pressures were highest in the formaldehyde group and lowest in the cryopreserved group. The customized formula provided a mean retraction pressure almost 3 times lower than formaldehyde (36 ± 3 vs 103 ± 14 mm Hg, p < 0.01) and very similar to cryopreservation (24 ± 6 mm Hg, p < 0.01). For research purposes, preservation time in the cryopreserved group was limited to 4 hours and was unlimited for the customized and formaldehyde groups for the duration of the experiment. The customized embalming solution described herein is optimal for allowing retraction and surgical maneuverability while preventing decay. The authors were able to significantly lower the formaldehyde content as compared with that in standard formulas. The custom embalming solution has the benefits from both cryopreservation (for example, biological brain tissue properties) and formaldehyde embalming (for example, preservation time and microorganism growth prevention) and minimizes their drawbacks, that is, rapid decay in the former and stiffness in the latter. The presented embalming formula provides an important advance for neurosurgical simulations in research and teaching.

Awake craniotomy for trapping a giant fusiform aneurysm of the middle cerebral artery

Background:Giant fusiform aneurysms of the distal middle cerebral artery (MCA) are rare lesions that, because of the absence of an aneurysm neck and the presence of calcified walls and partial thrombosis, can be difficult to clip without sacrificing the parent vessel. Moreover, when the aneurysm is located in the dominant hemisphere, it is not possible to test language and cognitive functions during surgical intervention, making the closure of the parent vessel extremely dangerous.Case Description:A 46-year-old woman presented with a one-year history of frontal headache without neurological deficit. A magnetic resonance imaging and an angiography showed a giant fusiform aneurysm of the left M2 tract. Because of the location and the absence of a neck, the aneurysm was considered difficult to coil and not amenable to preoperative balloon occlusion; thus, the patient was a candidate for surgical treatment. After a preoperative psychological evaluation, patient underwent awake craniotomy with the asleep–awake–asleep technique. A standard left pterional approach was performed to expose the internal carotid artery, the MCA and the aneurysm originating from the frontal branch of the MCA. Neurological examination responses remained unchanged during temporary parent artery occlusion, and trapping was successfully performed.Conclusions:Awake craniotomy is a useful option in intracranial aneurysm surgery because it permits neurological testing before vessels are permanently clipped or sacrificed. With the asleep–awake–asleep technique, it is possible to perform a standard pterional craniotomy, which allows good exposure of the vascular structures without cerebral retraction.

Brain Injuries during Intraoperative Ventriculostomy in the Aneurysmal Subarachnoid Hemorrhage Patients

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). 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. 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. 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.

Modified abbreviated transcavernous approach to basilar artery aneurysms—Case report

Background Endovascular procedures and direct surgical clipping are the main therapeutic modalities for managing of BAAs. Furthermore, giant or wide-necked aneurysms and those that involve the PCA or perforators at its neck usually are not embolized. Case Description A 55-year-old man presented to the emergency room complaining of sudden and intense headache. Neurological examination evidenced meningismus. Computed tomography disclosed a subarachnoid hemorrhage (Fisher grade III). Arteriograms revealed BAA, whose neck was partially obscured by the PCP. A standard pterional craniotomy was performed, followed by extensive drilling of the greater sphenoid wing. The neck was partially hidden by the PCP, and no proximal control was obtained without drilling the PCP and opening the CS (modified TcA). Drilling of the PCP was begun by cutting the overlying dura and extended caudally as much as possible. Next, opening of the roof of the CS was performed by incising the dura in the oculomotor trigone medial and parallel to the oculomotor nerve and lateral to ICA; the incision progressed posteriorly toward the dorsum sellae. Further resection of the dorsum sellae and clivus was carried out. After performing these steps, proximal control was obtained, aneurysm was deflated, perforators were saved, and aneurysm was clipped. Conclusions This study has demonstrated the clinical usefulness of an abbreviated form of the TcA, which led the “modified TcA,” in approaching complex low-lying BAA. It provides additional surgical room by removing the PCP and partially opening the CS, which permits further bone removal and improves exposure.

Outcome determinants of pterional surgery for tuberculum sellae meningiomas

Current literature on tuberculum sellae meningiomas is very heterogenous due to wide variation in nomenclature, diagnostic and operative techniques. The aim of this study is specifically to analyze the results of pterional craniotomy for tuberculum sellae meningiomas. A homogenous cohort of 42 consecutively operated tuberculum sellae meningioma cases are reviewed with special emphasis on the effects of pterional microsurgery on visual outcome. This is a retrospective clinical analysis. 42 consecutive patients operated upon during the period of 15 years in a single institution using standard imaging protocols and pterional microsurgery are presented and effect of various variables on visual outcome analysed. 81% of the patients presented with visual symptoms. The mean duration of symptoms was 12 months. Tumour volumes ranged from 7.5 to 210 mm(3). A right sided pterional microsurgery was used in all patients. Complete resection rate was 81%. Vision improved in 58%, worsened in 14%. Non-visual morbidity was 7.1% and mortality was 2.4%. The follow up period of patients ranged from 3 to 192 months (median: 30 months). The mean was 37.5 months (SD = +/-36.7 months) and a recurrence rate of 2.4% was observed. A standard pterional craniotomy using microsurgical technique provides the necessary exposure enabling total removal while keeping the complications to a minimum. Upon analysis of our findings we found that patient age of more than 60, duration of visual symptoms longer than 1 year, severe visual symptomatology, predominantly vertical growth, presence of significant peri-tumoural oedema, absence of an intact arachnoid plane and subtotal removal were correlated with a dismal visual outcome.

Microsurgical Anatomic Features of the Olfactory Nerve: Relevance to Olfaction Preservation in the Pterional Approach

The pterional approach represents the standard approach for most lesions of the anterior and middle cranial fossa. It requires some degree of frontal lobe retraction, which may result in temporary or permanent damage of olfaction because of nerve avulsion or mechanical compression. The purpose of this study, based on microanatomic dissection of human cadaveric specimens, was to review the microsurgical anatomic features of the nerve and suggest operative nuances that may contribute to reducing the rate of postoperative olfactory dysfunction. Twenty olfactory nerves and tracts were examined in 10 human cadaveric heads obtained from three fresh and seven formalin-fixed adult cadavers. A standard pterional craniotomy was performed. The olfactory nerve was dissected from its arachnoidal envelopes and then mobilized for an average length of 30 mm (range, 25-35 mm). The possible retraction of the frontal lobe was 10 to 15 mm. More retraction invariably resulted in nerve disruption. The standard sylvian and basal cistern opening may be insufficient to guarantee preservation of olfactory function. Early identification and arachnoidal dissection of the nerve may reduce the rate of olfaction compromise. The opening of the subarachnoidal space should be performed in a proximal-to-distal manner to allow early visualization of the olfactory bulb and its dissection. The arachnoidal dissection should be performed with sharp instruments, avoiding any traction on the posterior portion of the olfactory tract. Any direct retractor compression should also be avoided to spare the microvasculature lying on the dorsal surface of the nerve.

Anatomic and Surgical Basis of the Sphenoid Ridge Keyhole Approach for Cerebral Aneurysms

In vascular neurosurgery, the pterional approach has been used primarily for the treatment of a wide variety of diseases (cavernous angiomas, arteriovenous malformations, etc.), and it is used to take advantage of naturally occurring planes and spaces to expose the major structures of the circle of Willis. It provides access to the major part of the anterior circulation aneurysms and those occurring in the upper and most proximal part of the posterior circulation. Conversely, there has been an increasing interest in the so-called minimally invasive procedures or keyhole approaches to treating cerebral aneurysms in specific locations. In this work, we describe a novel keyhole approach that was conceived to achieve the angle of vision and advantages of the classic pterional approach. This surgical approach is based on the anatomic location of the sphenoid ridge and its relationship with the sylvian fissure and basal cisterns. The initial incision is made over the hairline behind the external border of the eye on the side selected. A skin and muscular flap is reflected anteriorly, and a small 3 x 3-cm craniotomy is completed around the external landmarks of the sphenoid ridge. Further extradural drilling is completed down to the anterior clinoid process. The dura is opened in a semilunar manner, and the sylvian fissure is opened completely to reach the sylvian and basal cisterns. Thereafter, the aneurysm is dissected and clipped according to the standard microtechnique of the neurosurgeon. A step-by-step description of the approach is offered in this work to facilitate a clear understanding of it. We recommend this approach for treatment of aneurysms arising at the anterior part of the circle of Willis. It has the advantages of less operative time, fewer days of hospitalization, and similar morbidity and mortality compared with the standard pterional craniotomy (5.7% on our service for nongiant ruptured aneurysms).

Management of surgical clinoidal meningiomas

Clinoidal meningiomas remain a major neurosurgical challenge. Surgery-related outcome has been less than desirable in the past, and little attention has been directed toward improving visual deficits. The authors advocate a skull base technique for the removal of these difficult tumors and describe its advantages in terms of improving extent of resection and enhancing overall outcome, particularly visual function. A retrospective analysis was performed on data obtained in 26 consecutive patients with clinoidal meningiomas (including one patient with hemangiopericytoma) who underwent resection between June 1995 and January 2003. In 24 cases the skull base procedure involved extradural anterior clinoidectomy, optic canal unroofing, and optic sheath opening; in two cases a standard pterional craniotomy was performed. Fourteen of the 26 patients suffered significant preoperative visual deficits. All patients underwent thorough pre- and postoperative ophthalmological evaluations. The follow-up period ranged from 3 to 91 months (mean 42.3 months). Total resection was achieved in 20 patients (77%), and the majority (76.9%) of patients with preoperative visual impairment experienced significant improvement. With the use of the skull base technique, total resection and excellent visual outcome may be achieved with minimal morbidity in most patients with clinoidal meningiomas.

Surgical management of clinoidal meningiomas.

Surgical outcome has been less than desirable in the management of patients with clinoidal meningiomas in the past, and little attention has been directed at improving their visual function. The purpose of this article is to advocate an available cranial base technique for removing these difficult tumors and to delineate the technique's advantages that aid in achieving an improved extent of tumor resection and enhancing the patients' overall outcome, particularly their visual outcome. A retrospective analysis was performed on 15 consecutive patients with clinoidal meningiomas (including a patient with hemangiopericytoma) who underwent surgical resection at the Cleveland Clinic Foundation between June 1995 and January 2000. A cranial base technique consisting of extradural anterior clinoidectomy, coupled with optic canal unroofing and optic sheath opening, was used in 13 patients, and standard pterional craniotomy was used in 2. Eight of 15 patients had significant visual deficits preoperatively. All patients had thorough preoperative and postoperative ophthalmological evaluations. The follow-up period ranged from 6 to 60 months (mean, 37.2 mo). Total resection was achieved in 13 (86.7%) of the 15 patients in this series, and the majority of the patients with preoperative visual impairment experienced significant improvement (6 of 8 patients; 75%). In the majority of patients with clinoidal meningiomas, total resection may be achieved with minimal complications. For large tumors encasing the optic nerve and internal carotid artery, or for those tumors causing preoperative visual impairment, use of the cranial base technique delineated in this study may lead to significant improvement in the patients' visual and overall outcomes.

Transorbital keyhole approach to anterior communicating artery aneurysms.

The transorbital keyhole approach to anterior communicating artery aneurysms was developed as a minimally invasive method for safe control of the anterior communicating artery complex. This approach does not necessitate resection of the gyrus rectus. The technique is described in detail. The transorbital keyhole approach provides more ventral access than the supraorbital approaches, and the anterior communicating artery complex can be controlled by splitting the basal aspect of the interhemispheric fissure. Since late 1998, the authors have used the transorbital keyhole approach routinely. During the initial experience with 33 patients, the only observed complication specific to this approach was transient diplopia in one patient. At follow-up examinations 2 to 15 months after surgery, the cosmetic results were favorable as compared with those of standard pterional craniotomy. We have designed a small, custom-tailored approach to the anterior communicating artery complex for routine use. The small orbitocranial approach is a step toward the ideal of purely extra-axial safe control of anterior communicating artery aneurysms. The orbitocranial keyhole approach seems to be substantially better than the craniotomy, although it requires additional effort and time.

内頸動脈硬膜輪近傍巨大動脈瘤に対する手術手技の工夫

Direct clipping of giant aneurysms of the internal carotid (IC)-juxta dural ring region is considered very difficult. Several methods are currently available for the treatment of giant aneurysms. We describe our experience with the Dolenc' pterional combined epidural and subdural approach and emphasize the technique of temporary trapping of the aneurysms followed by aspiration and collapse, and subsequent clipping. Eight patients presented with 5 giant (>25mm in diameter) and 3 large (15mm to 25mm in diameter) aneurysms of the IC artery in the juxta dural ring region during a 4-year period, manifesting as subarachnoid hemorrhage (SAH) in 5 patients, mass effects (visual disturbance, oculomotor paralysis) in 2 patients, and 1 incidental finding. Preoperative collateral circulation and tolerance to ischemia were studied in 3 patients by the Allcock and balloon Matas tests.The IC artery in the neck was exposed and catheterized for temporary occlusion during collapse, dissection and clipping of the aneurysm. Standard pterional craniotomy was performed. The posterior orbital roof together with the sphenoid wing, and the dorsal wall of the optic canal and the anterior clinoid process were removed through the epidural approach. Complete opening of the dural ring, and exposure of the surgical genu and axilla of the IC artery were achieved through the subdural approach. Intraaneurysmal blood was aspirated through a catheter placed in the cervical IC artery during trapping of the aneurysm, resulting in collapse of the giant aneurysm and easy dissection of the aneurysm from the surrounding structures. Clipping was then relatively easy with the use of tandem Sugita's fenestrated angled clips. Intraoperative angiography was then performed to confirm aneurysm occlusion.Postoperative carotid angiography revealed that all 8 aneurysms were completely obliterated by the clip. Transient CSF leakage due to opening of the ethmoid sinus occurred in 1 patient. One patient died of severe delayed cerebral vasospasm. The other 7 patients returned to their preoperative occupations without neurological deficits. The Dolenc' pterional combined epidural and subdural approach is the procedure of choice for IC-juxta dural ring giant aneurysms.

内頸動脈硬膜輪近傍動脈瘤に対するcombined epi- and subdural approach (Dolenc)

Between January 1990 and August 1991, 103 patients with intracranial aneurysms were admitted to our hospital and underwent microsurgical operations. Of the 103 patients, 6 had juxta DURAL-RING aneurysms. Kobayashi and his collaborators classify Juxta DURAL-RING aneurysms into 3 types: infraclinoid type, carotid cave type and intradural type. Of the present 6 cases, 3 cases were carotid cave type and 3 intradural type.We applied Dolenc' pterional combined epi- and subdural approach to these aneurysms.Surgical procedures are as follows: (1) a standard pterional craniotomy; (2) in the epidural approach, removal of the orbital roof together with the sphenoid wing, removal of the dorsal wall of the optic canal and the anterior clinoid process. Following these procedures, the anterior loop of the internal carotid artery (IC) can be traced through the thin membrane (Dolenc' anteromedial trangle); (3) in the subdural approach, complete opening of the dural ring, and the exposure of the surgical genu and axilla of the IC. (4) Utilizing these procedures, clipping is relatively easy with the use of Sugita's curved-blad ring (fenestrated) clip.Postoperative carotid angiograms revealed that all 6 aneurysms were completely obliterated by the clips.There were 2 complications: l is transient CSF leakage due to opening of the ethomoid sinus; the other is transient oculomotor nerve paresis presumably due to packing the oxycel into the cavernous sinus. All patients returned to their preoperative occupations without any neurological deficits.From these results, we conclude that the pterional combined epi- and subdural approach is the procedure of choice for the juxta-Dural Ring aneurysms.

Combined orbito-frontal, sub- and infratemporal fossa approach to skull base neoplasms. Surgical technique and clinical application.

Neoplasms located along the antero-lateral skull base, with probable involvement of the orbit and with extension into the pterygoid and/or infratemporal fossa can usually not be sufficiently exposed using standard neurosurgical or otosurgical approaches, which is why combined approaches to these skull base targets have been developed in the recent past. In this report we describe our experience, using a combined orbito-frontal, sub- and infratemporal fossa approach which, starting with a pre-auricular incision and a standard pterional craniotomy, is extended to an extensive osteoplastic enbloc resection of the orbito-zygomatic area allowing for direct visualisation of the antero-temporo-lateral skull base from the orbital cavity to the depth of the infratemporal and pterygoid fossa. The surgical technique as well as the clinical experiences accumulated with this approach are described.