temporal branch in 57.5% of the hemispheres. B: The M 1 segment gave rise to temporal and frontal branch arteries in 35% of the hemispheres. C: The M 1 segment gave rise to a frontal branch in 2.5% of the hemispheres. D: The M 1 segment gave rise to no major cortical branches (only LLAs and uncal arteries) in 5% of the hemispheres. The LLAs are denoted by dotted lines. A 1 = precommunicating segment of the ACA. Lateral Lenticulostriate Arteries In all hemispheres the M 1 segment gave rise to the LLAs, located mainly on the inferomedial aspect of the M 1 segment
Uğur Türe, M. Gazi Yaşargil, Ossama Al-Mefty and Dianne C. H. Yaşargil
JNSPG 75th Anniversary Invited Review Article
Shawn L. Hervey-Jumper and Mitchel S. Berger
Surgery, University of California, San Francisco. Published with permission. The insular cortex has a rich vascular supply, extending from the internal cerebral and middle cerebral arteries ( Fig. 2 ). The middle cerebral artery bifurcates at the limen insula, forming between 1 and 6 insular M 2 branches, which overlie the insular surface. Insular arteries supply the insular cortex, extreme capsule, claustrum, and external capsule. The lateral lenticulostriate arteries supply the internal capsule, putamen, and globus pallidus. 45 , 46 Microscopically, there is
Juan C. Fernández-Miranda, Albert L. Rhoton Jr., Yukinari Kakizawa, Chanyoung Choi and Juan Álvarez-Linera
The goal in this study was to examine the microsurgical and tractographic anatomy of the claustrum and its projection fibers, and to analyze the functional and surgical implications of the findings.
Fifteen formalin-fixed human brain hemispheres were dissected using the Klingler fiber dissection technique, with the aid of an operating microscope at × 6–40 magnification. Magnetic resonance imaging studies of 5 normal brains were analyzed using diffusion tensor (DT) imaging–based tractography software.
Both the claustrum and external capsule have 2 parts: dorsal and ventral. The dorsal part of the external capsule is mainly composed of the claustrocortical fibers that converge into the gray matter of the dorsal claustrum. Results of the tractography studies coincided with the fiber dissection findings and showed that the claustrocortical fibers connect the claustrum with the superior frontal, precentral, postcentral, and posterior parietal cortices, and are topographically organized. The ventral part of the external capsule is formed by the uncinate and inferior occipitofrontal fascicles, which traverse the ventral part of the claustrum, connecting the orbitofrontal and prefrontal cortex with the amygdaloid, temporal, and occipital cortices. The relationship between the insular surface and the underlying fiber tracts, and between the medial lower surface of the claustrum and the lateral lenticulostriate arteries is described.
The combination of the fiber dissection technique and DT imaging–based tractography supports the presence of the claustrocortical system as an integrative network in humans and offers the potential to aid in understanding the diffusion of gliomas in the insula and other areas of the brain.
Necmettin Tanriover, Albert L. Rhoton Jr., Masatou Kawashima, Arthur J. Ulm and Alexandre Yasuda
Object. The purpose of this study was to define the topographic anatomy, arterial supply, and venous drainage of the insula and sylvian fissure.
Methods. The neural, arterial, and venous anatomy of the insula and sylvian fissure were examined in 43 cerebral hemispheres.
Conclusions. The majority of gyri and sulci of the frontoparietal and temporal opercula had a constant relationship to the insular gyri and sulci and provided landmarks for approaching different parts of the insula. The most lateral lenticulostriate artery, an important landmark in insular surgery, arose 14.6 mm from the apex of the insula and penetrated the anterior perforated substance 15.3 mm medial to the limen insulae. The superior trunk of the middle cerebral artery (MCA) and its branches supplied the anterior, middle, and posterior short gyri; the anterior limiting sulcus; the short sulci; and the insular apex. The inferior trunk supplied the posterior long gyrus, inferior limiting sulcus, and limen area in most hemispheres. Both of these trunks frequently contributed to the supply of the central insular sulcus and the anterior long gyrus. The areas of insular supply of the superior and inferior trunks did not overlap. The most constant insular area of supply by the cortical MCA branches was from the prefrontal and precentral arteries that supplied the anterior and middle short gyri, respectively. The largest insular perforating arteries usually arose from the central and angular arteries and most commonly entered the posterior half of the central insular sulcus and posterior long gyrus. Insular veins drained predominantly to the deep middle cerebral vein, although frequent connections to the superficial venous system were found. Of all the insular veins, the precentral insular vein was the one that most commonly connected to the superficial sylvian vein.
Frederick F. Lang, Nancy E. Olansen, Franco DeMonte, Ziya L. Gokaslan, Eric C. Holland, Christopher Kalhorn and Raymond Sawaya
Object. Surgical resection of tumors located in the insular region is challenging for neurosurgeons, and few have published their surgical results. The authors report their experience with intrinsic tumors of the insula, with an emphasis on an objective determination of the extent of resection and neurological complications and on an analysis of the anatomical characteristics that can lead to suboptimal outcomes.
Methods. Twenty-two patients who underwent surgical resection of intrinsic insular tumors were retrospectively identified. Eight tumors (36%) were purely insular, eight (36%) extended into the temporal pole, and six (27%) extended into the frontal operculum. A transsylvian surgical approach, combined with a frontal opercular resection or temporal lobectomy when necessary, was used in all cases. Five of 13 patients with tumors located in the dominant hemisphere underwent craniotomies while awake. The extent of tumor resection was determined using volumetric analyses. In 10 patients, more than 90% of the tumor was resected; in six patients, 75 to 90% was resected; and in six patients, less than 75% was resected. No patient died within 30 days after surgery. During the immediate postoperative period, the neurological conditions of 14 patients (64%) either improved or were unchanged, and in eight patients (36%) they worsened. Deficits included either motor or speech dysfunction. At the 3-month follow-up examination, only two patients (9%) displayed permanent deficits. Speech and motor dysfunction appeared to result most often from excessive opercular retraction and manipulation of the middle cerebral artery (MCA), interruption of the lateral lenticulostriate arteries (LLAs), interruption of the long perforating vessels of the second segment of the MCA (M2), or violation of the corona radiata at the superior aspect of the tumor. Specific methods used to avoid complications included widely splitting the sylvian fissure and identifying the bases of the periinsular sulci to define the superior and inferior resection planes, identifying early the most lateral LLA to define the medial resection plane, dissecting the MCA before tumor resection, removing the tumor subpially with preservation of all large perforating arteries arising from posterior M2 branches, and performing craniotomy with brain stimulation while the patient was awake.
Conclusions. A good understanding of the surgical anatomy and an awareness of potential pitfalls can help reduce neurological complications and maximize surgical resection of insular tumors.
territory. If the patient does not tolerate MCA occlusion, and no anterior cerebral artery collaterals can be demonstrated, a superficial temporal to MCA bypass procedure can be performed prior to embolization. While occluding the MCA with a calibrated-leak balloon, two precautions are recommended. The first is the continuous use of heparinized perfusion, and the second is a slow, low-pressure injection to prevent rupture of the vessel. 1 Fig. 2. Coaxial superselective angiogram of a lateral lenticulostriate artery, frontal (left) and lateral (right
Saran S. Rosner, Albert L. Rhoton Jr., Michio Ono and Margaret Barry
45 90 1–10 2.2 2–19 6.2 0.1–0.7 0.33 middle cerebral artery (total lenticulostriate arteries) 50 100 1–21 10.4 3–49 26.2 0.1–2.2 medial lenticulostriate arteries 25 50 1–5 2.1 1–9 4.0 0.1–0.6 0.23 intermediate lenticulostriate arteries 47 94 1–10 3.3 7–37 14.4 0.1–1.7 0.73 lateral lenticulostriate arteries 50 100 1–9 4.8 2–21 8.3 0.1–2.2 0.31 anterior cerebral artery A 1 segment 48 96 1–11 6.4 4–49 21.9 0.1–0.6 0
Mandy Binning, Bradley Duhon and William T. Couldwell
of a left lateral lenticulostriate artery origin ( Fig. 1A–D ). The parent artery was shown to be patent, and this aneurysmal thrombus was thought to be the source of the patient's embolic stroke. F ig . 1. A: Initial noncontrast head CT scan demonstrating subtle hyperdensity along the left MCA (arrow) . B: Diffusion MR image demonstrating an infarct in the left basal ganglia. C: Axial T2-weighted MR image showing an approximately 1-cm aneurysm dilatation (arrow) along the left M1 segment. D: Preoperative angiogram showing 4-mm residual filling of
Long Chen, Ivanna Yau, Gabrielle deVeber, Peter Dirks, Derek Armstrong and Timo Krings
of the lateral lenticulostriate arteries. A time-of-flight (TOF) MR angiography (MRA) study demonstrated a right-sided dumbbell-shaped middle cerebral artery (MCA) aneurysm just proximal to the MCA bifurcation, with preaneurysmal MCA narrowing. The vessel wall surrounding the aneurysm demonstrated a crescent-shaped T1 hyperintense rim indicating intramural hematoma. The patient underwent cerebral angiography on the same day, which revealed focal preaneurysmal narrowing and an irregularly shaped aneurysm proximal to the normal MCA bifurcation, with delayed filling
Jaechan Park and Dakeun Lee
right, arrow ). Lateral lenticulostriate arteries seemed to arise from the M 1 segment just distal to the lesion. The lesion was misinterpreted as a ruptured dissecting aneurysm on the basis of the radiological findings. F ig . 1. Preoperative images. Left: CT scan showing a thin yet diffuse SAH in the basal cisterns. Right: Left ICA angiogram demonstrating a small bulge (arrow) on the superior wall of the horizontal segment of the MCA. Operation Sylvian fissure dissection via a pterional craniotomy revealed the M 1 segment of the MCA. In the