Resection Of Gyrus Rectus Research Articles

Microsurgical management in Anterior Communicating Artery Aneurysms: an anatomical investigation

Purpose: The purpose of this study is to compare the pterional approach and the anterior interhemispheric approach for enabling a better surgical maneuverability. We describe the ideal the anatomic limitations of this surgery for anterior communicating artery aneurysms. Methods: 4 formalin-fixed and silicone injected human heads were used for each approach. Möller 20-1000 microscope was used for dissection and all the photographs were obtained at a similar angle to the surgical microscope, with Canon EOS Rebel T5 Digital SLR Digital Camera with a EF 100mm f/2.8L Macro IS USM Lens and a Canon MR-14EX II Macro Ring Lite Flash. Our dissection includes anterior interhemispheric and pterional approach with gyrus rectus resection and posterolateral orbitotomy. Results: Pterional approach was performed followed by the gyrus rectus resection and posterolateral orbitotomy. This area can be exposed by the 1x1 cm resection of the gyrus rectus. Subpial resection from posterior part of gyrus rectus is required. Posterolateral orbitotomy was performed and the orbital roof was removed up to the superior orbital fissure. The anterior interhemispheric approach allows better visualization of the anterior and inferior surface of anterior communicating artery, A1-A2 junction and the optic nerve. Conclusions: We believe the pterional approach combined with gyrus rectus resection and posterolateral orbitotomy, if needed, is more suitable for anterior, posterior and inferior type, with anterior interhemispheric approach being the safer for superior and high positioned anterior communicating artery aneurysms.

Partial Gyrus Rectus Resection as a Technique to Improve the Exposure to the Anterior Communicating Artery Complex through the Junctional Triangle: A Quantitative Study.

Objective The junctional triangle, formed by the distal A1 anterior cerebral artery (ACA) segment, the proximal A2 ACA segment, and the medial surface of gyrus rectus (GR), is a corridor of access to superiorly and posteriorly projecting anterior communicating artery (AComA) aneurysms that is widened by GR retraction or resection. Exposure of the AComA complex through the junctional triangle after GR resection has not been previously quantitatively evaluated. Design GR resection extent and increase in artery exposure through the junctional triangle were assessed in this study. Setting This study was conducted in the laboratory with a pterional approach, exposing the AComA complex. Participants Ten sides of five cadaveric heads were considered. Main Outcome Measures Exposure extent of ipsilateral and contralateral A1, A2, and AComA and accessibility of branches coming off the AComA complex were measured before and after GR resection. The GR was resected until sufficient bilateral A2 and contralateral A1 exposures were achieved. GR resection span was measured. Results The mean (standard deviation) resected span of GR was 7 ± 3.9 mm. After GR resection, the exposed span of the ipsilateral A2 increased from 2 ± 0.7 mm to 4 ± 1.1 mm ( p = 0.001); contralateral A2 exposure increased from 3 ± 1.5 mm to 4 ± 1.1 mm ( p = 0.03). Contralateral recurrent artery of Heubner (RAH) and orbitofrontal artery were accessible in five and eight specimens, respectively, before GR resection and in all 10 after resection. Conclusion GR resection improves exposure of bilateral A2 segments through the junctional triangle. Exposure improvement is greater for the ipsilateral A2 than contralateral A2. The junctional triangle concept is enhanced by partial GR resection during surgery for superior and posterior AComA aneurysms.

Relationship between Gyrus Rectus Resection and Cognitive Impairment after Surgery for Ruptured Anterior Communicating Artery Aneurysms.

ObjectiveThe gyrus rectus (GR) is known as a non-functional gyrus; hence, its resection is agreed to be a safe procedure frequently practiced to achieve a better surgical view during specific surgeries. This study aimed at comparing the cognitive outcomes following GR resection in patients who underwent surgery for ruptured anterior communicating artery (ACoA) aneurysms.Materials and MethodsFrom 2012 to 2015, 39 patients underwent surgical clipping for ruptured ACoA aneurysms. Mini-mental state examinations (MMSE) were performed in 2 different periods. The statistical relationship between GR resection and MMSE results was evaluated, and further analysis of MMSE subgroup was performed.ResultsTwenty-five out of the 39 patients (64.19%) underwent GR resection. Mean initial and final MMSE scores in the GR resection group were 16.3 ± 9.8 and 20.8 ± 7.3, respectively. In the non-resection group, the mean initial and final MMSE scores were 17.1 ± 8.6 and 21.9 ± 4.5, respectively. Neither group's scores showed a significant change. Subgroup analysis of initial MMSE showed a significant difference in memory recall and language (p = 0.02) but not in the final MMSE scores.ConclusionThere was no significant relationship between the GR resection and cognitive outcomes in terms of total MMSE scores after surgery for ruptured ACoA aneurysm. However, subgroup analysis revealed a temporary negative effect of GR resection in the categories of language and memory recall. This study suggests that GR resection should be executed superficially, owing to its close anatomical relationship with the limbic system.

Cadaveric study of the endoscopic endonasal transtubercular approach to the anterior communicating artery complex

The endoscopic transnasal approach to the anterior communicating artery (ACoA) complex is not widely performed. This cadaveric study investigated the surgical relevance of the anterior endoscopic approach to the treatment of ACoA aneurysms. Bi-nasal endoscopic transtubercular surgery was carried out on fresh adult cadavers. Primary outcomes measures incorporated dimensions of the endonasal corridor (operative field depth, lateral limits, size of the transplanum craniotomy and dural opening); vascular exposure (proximal and distal anterior cerebral arteries [ACA], ACoA, clinoidal internal carotid artery [ICA] segment); and operative manoeuvrability defined by clip placements (ipsilateral and contralateral). Eight cadaver heads were used (mean age 84±7years, range 76–94years, 75% female). Mean operative depth was 97±4mm. The lateral corridors were limited proximally by the alar rim openings (31±2mm), and distally by the optic nerves (22±6mm). The endonasal craniotomy dimensions were 21±5mm anteroposteriorly, and 22±4mm laterally. Vascular exposure was achieved in 100% of subjects for the ACoA segment and the ACA segments proximal to the ACoA (A1). The ACA segments distal to the ACoA (A2) were accessible only in 40% of subjects. Endonasal clip placement across the ACoA segment, clinoidal ICA, A1 and A2 were 100%, 90%, 90%, and 30%, respectively. The ventral endoscopic endonasal approach to the ACoA complex provides excellent vascular visualisation without brain retraction or gyrus rectus resection. However, the limitation in access to the A2 for temporary clip placement may prove to be a significant limitation of this approach.

Unilateral subfrontal approach to anterior communicating artery aneurysms: A review of 28 patients

Dear Editor, The authors present the named “unilateral subfrontal approach” for anterior communicating aneurysms, analyzed in a small clinical series. The authors present this approach mainly as an alternative to the pterional approach. This approach was previous described as the “superciliar keyhole approach” or the “lateral supraorbital approach” for the treatment not only of vascular disease but also for tumors.[2] The authors present their approach as a “tailored” pterional approach. Nevertheless, there are some aspects that are subject of criticism as the rutinary use of external ventriculostomy or lumbar drainage; these are procedures that carry additional risks: Intraoperative rebleeding, frontal lobe lesion among others. We strongly recommend the microsurgical wide opening of the basal cisterns and the fenestration of the lamina terminalis to obtain CSF drainage and brain relaxation during the surgery, we do not see the silvian fissure opening as an additional source of complications as the authors pointed out. Additionally, these microsurgical simple procedures are implicated in the prevention of the hydrocephalus and vasospasm in the subarachnoid hemorrhage secondary to ruptured aneurysms.[1] The four advantages that the authors provided are at least uncertain. In the number 4 we can say that the pterional approach provide a corridor to see up to the contralateral middle cerebral artery bifurcation. Another important issue is that they have a 50% of resection of the gyrus rectus in unruptured and 61% in ruptured aneurysms, so the approach does not avoid this designed resection of the frontal lobe; we only use a small gyrus rectus resection in the anterior communicating artery (ACoA) aneurysms superiorly projected located between the two A2 segments, especially in the large or giant lesions, in all the other cases we split the interhemispheric cistern, which is possible using the pterional approach. The authors point out that the pterional approach leave a cosmetic defect at the level of the pterion, but in their own series the leave two burr holes in the frontal bone visible in the forehead. Salma et al.[3] recently published a cadaveric anatomical study comparing this two approaches, in their paper they analyzes the qualitative and quantitative anatomic evaluation between this two approaches, showing that this kind of approach can eventually reduce the temporalis muscle trauma, and offers and equivalent access and exposure of the anterior communicating artery complex, optic nerve, optic chiasm, and sellar areas. However, like all the anatomical cadaveric models, they do not consider the role of the cisternal and ventricular opening using these anatomical corridors as the natural pathways to reach the pathology, in this case ACoA aneurysms. We think that in patient's ruptured aneurysms with hematoma or subarachnoid hemorrhage (SAH) of high Fisher grade this approach is not a good choice, because it does not allow a wide opening of the sylvian fissure for cleansing the blood clots and relaxing the brain. Hence, this approach would be useful just for treating the aneurysm, but not to deal with the SAH, without reducing neither the risk of vasospasm nor the hydrocephalus.

Sulcal and gyral anatomy of the orbitofrontal cortex in relation to the recurrent artery of Heubner: an anatomical study

The aim of this study is to investigate the sulcal and the gyral anatomy of the orbitofrontal cortex with its arterial supply. Ten gross formaline fixed adult brains (20 hemispheres) were used to show the gyral and sulcal anatomy of the inferior frontal lobe, and its arterial supply. The arteries were investigated with special attention to the relationship between the recurrent artery of Heubner (RAH) and the gyrus rectus (GR). Medial and lateral orbital sulci were connected in 4 right hemispheres, and in 7 of the left. The orbital sulci were connected with olfactory sulcus in one right hemispheres, but not in the left. In the right hemispheres, the RAH traveled across the GR in 7 hemispheres and looped over the posterior aspect of the GR in 3 hemispheres. In the left hemispheres, RAH crossed the GR in 8 and looped over the posterior aspect of the GR before entering the anterior perforating substance in 2 hemispheres. There are considerable variations among the gyri and sulci of the orbitofrontal cortex and it is difficult to describe a precise architectural pattern. The RAH demands special attention during GR resection in aneurysm surgery.

Quantitative Anatomic Study of Three Surgical Approaches to the Anterior Communicating Artery Complex

To compare the angles of approach and area of exposure to the anterior communicating artery (AComA) complex associated with pterional (PT), orbitopterional (OPT), and orbitozygomatic (OZ) craniotomies before and after gyrus rectus resection. PT, OPT, and OZ craniotomies were performed on both sides of four heads, and the angles of approach and area of exposure to the AComA complex were measured before and after resection of the gyrus rectus. The vertical angle of approach increased significantly among the PT and OPT (P = 0.001), PT and OZ (P = 0.001), and OPT and OZ approaches (P = 0.005). The horizontal angle of approach was significantly larger between the PT to OPT (P = 0.001) and PT to OZ (P = 0.001) approaches but not between the OPT and OZ approaches (P = 0.757). After gyrus rectus resection, the vertical and horizontal angles of approach increased significantly for the PT approach but not for the OPT and OZ approaches. The area of exposure to the AComA complex increased progressively from the PT to OPT to OZ approach but did not reach statistical significance (P = 0.124). Resection of the gyrus rectus resulted in significant relative gains in the area of exposure for the PT (P = 0.01) and OPT (P = 0.04) approaches but not for the OZ approach (P = 0.88). The vertical and horizontal angles of approach to the AComA complex are significantly larger for the OPT and OZ approaches compared with the PT approach. Use of the OZ approach may decrease the need for frontal lobe retraction and resection of the gyrus rectus.

Ｇｙｒｕｓ ｒｅｃｔｕｓの一部吸引にて記憶障害を生じた未破裂前交通動脈りゅうの１手術例

We have operated on 21 patients with an unruptured anterior communicating aneurysm by the pterional approach. Partial resection of the gyrus rectus was performed in 10 patients (44%). Of these patients, 1 patient had postoperative memory disturbances. We present this patient and discuss the responsibility of the gyrus rectus for memory deficit. A 61-year-old right-handed woman underwent MRI for the evaluation of chronic headache and was found to have an anterior communicating aneurysm. The aneurysm was 8 mm in size and arose from the junction of the anterior communicating artery and the left A2 segment. The fundus of the aneurysm was buried in the right gyrus rectus. A right pterional approach with partial resection of the gyrus rectus was employed. The aneurysm was successfully clipped and the postoperative course was uneventful. Postoperative CT showed only postoperative changes and postoperative MRI demonstrated only a small discrete right gyrus rectus lesion. However, the patient complained of memory disturbances on the third postoperative day. Neuropsychological tests performed 1 month after surgery revealed typical anterograde amnesia. Our case suggests that the gyrus rectus resection may be responsible for postoperative memory deficits. We propose a possible mechanism of our patient's amnesia: the gyrus rectus resection may result in disconnection of the pathway between the basal forebrain and the hippocampal region or the cortex, depriving these areas of cholinergic innervation.

高位前交通動脈りゅうに対する安全なクリッピング手術 穿通枝およびＨｅｕｂｎｅｒ’ｓ ａｒｔｅｒｙの温存法

We studied how to minimize the brain retraction and preserve the hypothalamic (hA) and Heubner's artery (HA) in clipping surgeries for high-positioned Acom aneurysms with the pterional (PT), orbitocranial (OC), and interhemispheric (IH) approaches using cadavers and in clinical cases. With the PT approach, excessive retraction of the frontal lobe was required to access Acom aneurysms located higher than 10 mm from the anterior clinoid process. Untethering of the frontal lobe (wide split of the sylvian and IH fissure, opening of the basal cisterns and division of the thick arachnoid fibers from the optic nerves and chiasma, etc.) and a gyrus rectus (GR) resection minimized brain retraction and exposed the Acom complex up to 13 mm high. Subpial GR resection was required to avoid injury of Heubner's artery (HA).Long and excessive retraction of the frontal lobe including the A1 and HA should be avoided to prevent subsequent brain infarction. The OC approach offered much wider and better exposure of Acom aneurysms up to 15 mm high. Sacrifice of the olfactory nerve, if possible, offered access to Acom aneurysms higher than 15 mm even with the PT and OC approaches. The IH approach, preferable for high-located and superiorly-posteriorly projecting Acom aneurysms, could not always offer visual access to the hA running behind the aneurysmal dome. In one such case, the hA could be prepared by placing a small rubber sheat between the aneurysmal dome and the hA.In safe clipping surgeries for high-located aneurysms, the best surgical approach should be selected according to the aneurysmal height and fundus projection, and great care should be taken during surgery to minimize brain retraction and to prepare the hA, HA, and A1 perforators.

Transorbital Keyhole Approach to Anterior Communicating Artery Aneurysms

In Reply: We appreciate the comments of Drs. Grand, Landi, and Daré, who report that they have used a supraorbital minicraniotomy alone or in combination with orbitotomy for a variety of intracranial lesions. In a recent article, Shanno et al. (1) reported that they used a transorbital roof craniotomy in 72 patients, primarily for tumor resection. Obviously, this type of approach is increasingly used for various indications. However, we want to emphasize that, in our opinion, incorporating the orbital roof is a crucial point, particularly in surgery for anterior communicating artery (AcomA) aneurysms. In contrast to the pure supraorbital craniotomy, removal of the orbital roof allows a very low basal approach with minimal brain retraction and entirely extracerebral dissection of the AComA complex, in the majority of cases. The extent or need for a gyrus rectus resection should be reduced as far as possible, especially in view of the minimal invasiveness of endovascular procedures and possible cognitive deficits. We agree with Grand et al. that it is always difficult to prove the benefit of a new procedure and to establish its advantages over the old, more standard procedure. We certainly do not recommend this approach when a neurosurgeon deals with his first AComA aneurysm. However, once the neurosurgeon is familiar with the surgical anatomy of the AComA complex and its variants, the transorbital approach provides approximately the same wide exposure and instrumentation space with less brain retraction or resection than the standard pterional approach. In this respect, the term “keyhole” might be misleading. With growing experience, the time required for this approach at our institution is even less than for the standard pterional approach, with drilling off the sphenoid ridge and flattening of the roof of the orbit. The long-term cosmetic results seem superior. We prefer an incision line behind the hairline, as for the pterional approach, instead of an eyebrow incision because an incision line remains even with the most meticulous closure technique. To date, we have operated on more than 60 AComA aneurysms using this approach exclusively (2). We have not observed any cerebrospinal fluid leakage, which has been said to be more common with the use of the transorbital than the pterional approach (1). This result might be related to the use of a hairline incision instead of an eyebrow incision. The hairline incision facilitates harvesting a piece of temporal muscle or fascia for dural repair or fashioning a pericranial flap when the frontal sinus is opened. Encouraged by recent reports, we are looking forward to extending the use of the transorbital approach to other indications. Robert Schmid-Elsaesser Hans-Jakob Steiger

375 Dissociation between object and object-in-place memory: Study on patients with partial resection of gyrus rectus

There is a growing body of evidence that the ventromedial prefrontal cortex (VMPFC) is implicated in the new learning of visual items. Little is known, however, as to the involvement of that portion of the prefrontal cortex in the learning of temporal and spatial relationship of those items. The aim of the present study, therefore, was to investigate the role of the VMPFC in memory for temporal and spatial order. Patients who had undergone surgery of the anterior communicating artery aneurysm, and normal control subjects (C), participated in the study. The patients were subdivided into three groups: with resection of the left (LGR+) or right (RGR+) gyrus rectus, and without such a resection (GR−). Subjects were presented with two memory tests: a temporal order (TO) test and a spatial order (SO) test. In the TO test, the LGR+ and RGR+ groups performed worse than the C group, while the GR− group did not differ significantly from the C group. In the SO test, the LGR+ and RGR+ groups did not differ significantly from the C and GR− groups. However, the trend appears to be the same for both tests, although only the TO test provides statistically significant group differences. Our results thus suggest that the VMPFC is involved in memory for contextual information. Together with previous findings, the data suggest that the learning of the relationship between items as well as the learning of those items are mediated by overlapping areas of the VMPFC.