Deep Sylvian Fissure Research Articles

Basal vein of Rosenthal classification: the key to venous outflow of the deep sylvian fissure.

Mastery of sylvian fissure dissection is essential to access lesions within the deep basal cisterns. The deep sylvian vein and its tributaries play a major role during access to and beyond the carotid cistern through the sylvian fissure and determine the complexity of microdissection. Preserving the venous outflow during sylvian fissure dissection is the best reliable strategy to prevent postoperative venous strokes or venous hypertension. The authors report the role of the basal vein of Rosenthal (BVR) in the venous outflow pattern of the deep sylvian cistern. The authors analyzed 262 consecutive surgical cases involving sylvian fissure dissection from 2015 to 2017. Inclusion criteria were complete sylvian fissure dissection for the treatment of intracranial aneurysms. Exclusion criteria were giant size (aneurysm diameter > 24 mm), meningitis, subarachnoid hemorrhage within the sylvian cistern, absence of 4D CT angiography, and previous surgery. Retrospective radiological and operative video reviews were carried out to assess the association between the superficial sylvian vein and the BVR. The authors analyzed the course of the BVR and the patterns of venous drainage of the sylvian cistern. The surgical difficulty of sylvian fissure dissection was rated by the authors to study the operative significance of the venous patterns encountered. Two clinical cases are described to illustrate the proposed BVR classification. A total of 97 patients met the selection criteria. The most frequent type of BVR was immature (diameter < 0.5 mm, 68%). When the BVR was incompletely developed or absent (immature type), the deep sylvian veins drained through a middle sylvian vein in 70% of cases, requiring advanced sylvian fissure dissection techniques. However, when the BVR was completely developed (32%), the middle sylvian vein was found in a minority of cases (6%), which allowed for an unobstructed transsylvian corridor. Interrater and test-retest reliability of the surgical difficulty was greater than 0.9. Preoperative assessment of the BVR anatomy is key to predict the deep sylvian venous pattern. The authors provide objective evidence supporting the reciprocal relationship between the type of BVR and the presence of a middle sylvian vein and the deep sylvian venous outflow. An immature BVR should alert the neurosurgeon of the high likelihood of finding a complex deep venous pattern, which may drive surgical planning.

Normal Variant Vein in the Deep Sylvian Fissure (Common Vertical Trunk) Increases the Risk of Ischemic Complication after Clipping Middle Cerebral Artery Aneurysm with Short M1

Middle cerebral artery aneurysms (MCANs) associated with short M1 located in the limen insulae tend to have poor outcomes after surgical clipping due to brain contusions and ischemic complications. However, the effect of veins in the deep Sylvian fissure is unclear. The normal variant of the insular veins and deep middle cerebral vein, which runs anteriorly near the limen and drains into the sphenoparietal sinus, is known as the common vertical trunk (CVT). We retrospectively examined whether the presence of a CVT increased surgical complications after clipping of short M1 aneurysms in 164 cases of unruptured MCANs (153 patients) clipped by the same surgeon. The 21 aneurysms located proximal to the limen insulae were defined as short M1 aneurysms. The 164 patients were divided into a short M1 group (n=21) and a non-short M1 group (n=143). The short M1 group was further divided into a CVT group (n=6) and a non-CVT group (n=15). The short M1 group showed a significantly (p＜0.001) longer operative time and higher rates of lacunar infarction and symptomatic (modified Rankin score ≥1) infarction than the non-short M1 group. The CVT group had higher rates of lacunar infarction and symptomatic infarction (50.0% and 16.7%, respectively) than the non-CVT group (26.7% and 6.7%, respectively). The CVT obstructed the view of the aneurysm neck behind the CVT, where the lenticulostriate arteries were located. The presence of a CVT in cases of short M1 aneurysms may be a risk factor for ischemic complications after clipping surgery.

Cytogenomic characterization of 1q43q44 deletion associated with 4q32.1q35.2 duplication and phenotype correlation

BackgroundMicrodeletion of 1q43q44 causes a syndrome characterized by intellectual disability (ID), speech delay, seizures, microcephaly (MIC), corpus callosum abnormalities (CCA) and characteristic facial features. Duplication of 4q is presented with minor to severe ID, MIC and facial dysmorphism. We aimed to verify the correlation between genotype/phenotype in a patient with 1q43q44 deletion associated with 4q32.1q35.2 duplication.Case presentationWe report on a 3 year-old female patient with delayed motor and mental milestones, MIC and facial dysmorphism. She is a child of non-consanguineous parents and no similarly affected family members. CT brain showed abnormal gyral patterns, hypogenesis of corpus callosum and bilateral deep Sylvian fissure. Electroencephalogram showed frontotemporal epileptogenic focus. Her karyotype was revealed as 46,XX,add(1)(q44). Fluorescence in situ hybridization (FISH) using whole chromosome paint (WCP1) and subtelomere 1q revealed that the add segment was not derived from chromosome 1 and there was the deletion of subtelomere 1q. Multiple ligation probe amplification (MLPA) subtelomere kit revealed the deletion of 1q and duplication of 4q. Array CGH demonstrated the 6.5 Mb deletion of 1q and 31 Mb duplication of chromosome 4q.ConclusionThe phenotype of our patient mainly reflects the effects of haploinsufficiency of AKT3, HNRNPU, ZBTB18 genes associated with duplication of GLRA3, GMP6A, HAND2 genes. Patients presented with ID, seizures, MIC together with CCA are candidates for prediction of 1q43q44 microdeletion and cytogenomic analysis.

Hybrid surgery for an arteriovenous malformation fed by an accessory middle cerebral artery and drained by a developmental venous anomaly: A case report and literature review.

An accessory middle cerebral artery (AMCA), which mainly acts in the collateral circulation of the middle cerebral artery (MCA), is a rare anatomic malformation. Similar to other intracranial vessels, cerebrovascular disease can occur in the AMCA. However, the development of an arteriovenous malformation (AVM) in the AMCA is very rare, especially in conjuction with developmental venous anomalies (DVAs). Here, a rare case of an AMCA combined with an AVM and a DVA was reported. The patient was a 47-year-old female with intracranial hemorrhage at symptom onset. CT and MRI showed lesions in the left Sylvian fissure and insula accompanied by hemorrhage. DSA suggested a left AMCA; an AVM of the AMCA was located in the deep Sylvian fissure. The AVM was diffusely developed and drained into the DVA. The operation was performed in a hybrid operating room. The major feeding artery of the AVM, which was derived from the AMCA, was clipped, then the AVM and DVA were subsequently removed. Intraoperative DSA showed that the AVM and DVA were radically removed. A pathological examination confirmed the presence of an AVM. The patient recovered well and was discharged. Therefore, as highlighted in this case report, rare AVMs can be found in AMCAs and can even occur simultaneously with a DVA. Hybrid surgical treatment can be used to remove AVMs and can lead to an improved prognosis.

MR画像（MRAおよびT2WI）による未破裂中大脳動脈分岐部瘤に対する手術アプローチの選択

We performed clipping surgeries for patients with unruptured middle cerebral artery (MCA) bifurcation aneurysms and used preoperative magnetic resonance (MR) imaging (T2-weighted image; T2WI) and MR angiography (MRA), intraoperative findings, and postoperative computed tomographic scans to investigate 1) whether the subfrontal approach (SFA) with frontal lobe retraction or the transsylvian approach (TSA) can secure a minimum surgical field by less invasive procedures and 2) which site in the Sylvian fissure (SyF) is it the most effective for entering via TSA. TSA is classified into 1) the transproximal Sylvian approach (proximal TSA) by opening the proximal SyF, 2) transmiddle Sylvian approach (middle TSA) by opening the middle SyF, and 3) transdistal Sylvian approach (distal TSA) by opening the distal SyF. Determinants of selecting each approach are not only the length of the horizontal portion of the MCA (M1) and size and location of aneurysms in the deep SyF, but also the width of the anterior operculoinsular compartment (A-OpIC) of the SyF exposed by resection of the sphenoidal ridge and deep sphenoidal compartment (SphC) of the SyF. In conclusion, 1) the SFA is speculated to be appropriate for cases wherein M1 is hidden by aneurysms deeply located inside the narrow SphC; 2) the proximal TSA, for cases wherein M1 and aneurysms are located at the border of the wide SphC and A-OpIC; 3) the middle TSA, for cases wherein M1 and aneurysms are located at the lateral part of the wide A-OpIC; and 4) the distal TSA, for cases wherein long M2 and aneurysms are located in the OpIC.

The butterfly pattern in a patient with chromosome 7 deletion.

The butterfly pattern in a patient with chromosome 7 deletion.

Short communication: sclerosing meningioma in the deep sylvian fissure

Sclerosing meningioma is a rare type of meningeal tumor with extensive collagen depositions. Deep sylvian meningioma, a tumor that is unattached to the dura mater, is also unusual. The biological activity of both is controversial, as are therapeutic strategies. A heterogeneous contrast-enhanced mass in the right sylvian fissure of a 10-year-old boy with a 3-year history of epilepsy was identified via magnetic resonance imaging. The patient underwent partial surgical resection because the tumor was hard and contained numerous perforators arising from the right middle cerebral artery. The tumor was histologically diagnosed as sclerosing meningioma. Twelve months after surgery, the patient was asymptomatic and did not require any additional therapies. This case is the first report of a sclerosing meningioma arising in the deep sylvian fissure. We discuss the therapeutic dilemma of this case with respect to the current literature.

Temporal Lobe Epilepsy Caused by Dermoid Cyst

A 15-year-old boy presented with a dermoid cyst in the left temporal lobe manifesting as complex partial seizures. Magnetic resonance imaging demonstrated a tumor with mixed signal intensity in the left anterior temporal subdural area, but no evidence of rupture. Intraoperatively, the tumor was located mainly in the deep sylvian fissure, adjacent to the amygdala, and had compressed the hippocampus. Intraoperative electrocorticography (ECoG) showed sporadic interictal spikes in both the adjacent areas of the tumor and over the anterior segment of the hippocampus. Total removal of the tumor and gliotic area of the surrounding tissue including the amygdala was performed. The hippocampal epileptic region was treated by transection of the pyramidal layer to preserve verbal memory function. Histological examination showed the dermoid tumor was closely attached to the brain parenchyma. The complex partial seizures ceased completely after surgery. Intraoperative recording of ECoG from the hippocampus and other limbic structures was very important to determine the epileptogenic area even if the tumor did not directly invade the hippocampus.

Anatomical relationships between Sylvian fissure and the sphenoid ridge

During pterional craniotomy, the sphenoid ridge is resected to facilitate the dissection of the arachnoid in the Sylvian fissure. It is a common intra-operative perception that a deep sphenoid ridge often accompanies a shallow fissure. We explored this unique relationship between the sphenoid ridge and the Sylvian fissure. We studied 46 fresh adult cadavers and measured the depth of both the sphenoid ridges and the Sylvian fissure. The deepest portion of the sphenoid ridge was determined and its depth measured by using a narrow ruler with a sliding gauge. The depth of the Sylvian fissure was measured from the middle cerebral artery bifurcation perpendicularly to the surface of the temporal pole where the arachnoid was cut. An inverse relationship exists between the Sylvian fissure and the sphenoid ridge. The depth of the sphenoid ridge averages 7.28 mm ± 0.3 mm while the depth of the Sylvian fissure averages 9.0 mm ± 0.4 mm. Approximately 25% of studied population have deep ridges, i.e. greater than 10 mm, and approximately 25% have shallow ridges, i.e. less than 4 mm. The extent to which the sphenoid ridge projects into the Sylvian fissure determines the depth of the Sylvian fissure thus explaining their inverse relationship. Importantly, encountering a shallow sphenoid ridge during surgery most likely will result in the dissection of a deep Sylvian fissure while a deep ridge predicts a shallow fissure. [Neurol Res 2001; 23: 645-646]

Deep Sylvian Fissure Meningioma without Dural Attachment in an Adult

Deep Sylvian Fissure Meningioma without Dural Attachment in an Adult

Selective Amygdalohippocampectomy: Which Route Is the Best?

Four different approach routes have been used to perform the selective amygdalohippocampectomy for the surgical treatment of epilepsy: transcortical through the middle T2 gyrus [1], translyvian through the deep sylvian fissure, transcortical subpial through the anterior T1 gyrus [2] and transcortical through the first temporal sulcus [3]. The choice between them, based on the advantages and disadvantages of each one, depends upon the different view angles they allow, and the parenchymal and vascular relationships they involve. This requires accurate knowledge of the microsurgical anatomy of this region and its features along the different acceding routes. The authors made an experimental study on 80 adult cerebral hemispheres they randomly submitted to selective amygdalohippocampectomy through these four alternative approach routes. They measured the dimensions of the major temporal limbic structures, namely the amygdala and the hippocampus, and their distances from the brain convexity and the deep sylvian fissure along those acceding routes; they also registered the main distinct microsurgical features of each. The results emerge as anatomical guidelines useful to decide for each case which way is preferable to make amygdalohippocampectomy complete, safer and easier.

Source modelling of the rolandic focus

In rolandic epilepsy, consideration of the stereotyped ictal symptomatology suggests that the epileptic zone is likely to be in the same cortical structure in different patients. Routine EEG tracings of the interictal spike activity suggests a deep Sylvian fissure location. On the basis of the predominantly tangential potential field at the peak spike negativity seen in this group of patients, the inferior bank of the Sylvian fissure appears to be a good candidate. Without invasive studies, little refinement to this rather imprecise localization can be made as there is neither neurologic deficit nor lesion to provide a marker on radiological imaging. However, the application of source modelling technique using a simple single-dipole spherical head model has resulted in improved understanding of the generator behaviour, and facilitated the generation of new ways of analyzing spikes (e.g., stability index). Review of newer quantitative approaches including matrix and singular value decomposition of the dataset, spatial-temporal constrained source estimates etc. suggest other fruitful approaches. At least in some patients with partial epilepsy, the source characteristics of interictal scalp spikes appear to contain information of the ictal generator. Under certain circumstances, such derived information which is not otherwise available from routine electrophysiology may influence clinical management and prognosis. This is an additional bonus to the primary objectives of quantification and data reduction.