Tip Of Temporal Lobe Research Articles

Alterations in Sphenoid Anatomy in Craniosynostosis: Implications for Fronto-orbital Advancement

OBJECTIVE: Fronto orbital advancement (FOA) requires the removal of the fronto-orbital bandeau via an anatomically challenging osteotomy that passes from the anterior cranial fossa to the middle fossa. During the intracranial portion of the osteotomy, visualization of the saw blade is lost as it passes through the fronto-orbito-sphenoid junction, prior to entering the middle cranial fossa. This places the temporal lobe dura and parenchyma at risk of injury. The aim of this study is to provide a 3-dimensional analysis of the space surrounding this osteotomy, and determine differences amongst different types of craniosynostosis. METHOD: 18 head CT scans of patients from ages 2 to 24 months with craniosynostosis (6 Metopic, 6 nonsyndromic Bicoronal, and 6 Unicoronal) were reconstructed to 3D skulls using Mimics 24.0 (Materialise NV, Lueven, Belgium). Unicoronal skulls were mirrored as necessary to be right sided. These skulls were landmarked with 47 cephalometric points. Measurents and volumetric analysis was performed to determine differences in sphenoid anatomy between the 3 craniosynostoses. RESULTS: For the 3 craniosynostosis groups, metopic, bicoronal and unicoronal, the average distance from the lateral orbital rim to temporal lobe tip was significantly different (17.37mm, 10.15mm, 14.76mm, respectively (p<0.05)). The mean depth of the temporal lobe tip from the edge of the sphenoid was also significantly different (16.23mm, 27.5mm, 22.8 mm respectively, p<0.05). The thickness of the fronto-orbito-sphenoid junction at the level of the supraorbital rim was significantly different between the three groups as well (7.75mm, 3.60mm, 8.04mm; p=0.01). Distances from the cornea to the lateral orbital rim, anteroposterior depth of the lateral orbit, and overhang of the lesser sphenoid wing over the middle cranial fossa were not significant between groups. CONCLUSION: Sphenoid shape and the zone of the fronto-orbital-sphenoid junction differs between types of craniosynostosis. Bicoronal craniosynostosis has the most unfavorable anatomy in this area, with minimal distance between the orbit and the anterior portion of the temporal lobe, a vertically deep middle cranial fossa, and thin bone at the fronto-orbital sphenoid junction, all of which make retraction and protection of the temporal lobe more challenging. Careful understanding of the patient’s specific anatomy is necessary to perform this osteotomy safely.

Temporal lobe epilepsy and focal cortical dysplasia in children: A tip to find the abnormality.

To demonstrate an association between magnetic resonance imaging (MRI) findings and pathologic characteristics in children who had surgery for medically refractory epilepsy due to focal cortical dysplasia (FCD). We retrospectively studied 110 children who had epilepsy surgery. Twenty-seven patients with FCD were included. Thirteen had temporal lobe epilepsy (TLE) and 14 had extra-temporal lobe epilepsy (ETLE). Three patients had associated mesial temporal sclerosis. Preoperative 3T MRIs interleaved with nine controls were blindly re-reviewed and categorized according to signal alteration. Pathologic specimens were classified according to the 2011 International League Against Epilepsy (ILAE) classification and compared to MRI studies. Rates of pathology subtypes differed between TLE and ETLE (χ2 (3) = 8.57, p = 0.04). FCD type I was more frequent in TLE, whereas FCD type II was more frequent in ETLE. In the TLE group, nine patients had temporal tip abnormalities. They all exhibited gray-white matter blurring with decreased myelination and white matter hyperintense signal. Blurring involved the whole temporal tip, not just the area of dysplasia. These patients were less likely to demonstrate cortical thickening compared to those without temporal tip findings (χ2 (1) = 9.55, p = 0.002). Three of them had FCD Ib, three had FCD IIa, two had FCD IIIa, and one had FCD IIb; MRI features could not entirely distinguish between FCD subtypes. TLE patients showed more pronounced findings than ETLE on MRI (χ2 (1) = 11.95, p = 0.003, odds ratio [OR] 18.00). In all cases of FCD, isolated blurring was more likely to be associated with FCD II, whereas blurring with decreased myelination was seen with FCD I (χ2 (6) = 13.07, p = 0.042). Our study described associations between MRI characteristics and pathology in children with FCD and offered a detailed analysis of temporal lobe tip abnormalities and FCD subtypes in children with TLE. These findings may contribute to the presurgical evaluation of patients with refractory epilepsy.

Possible involvement of the tip of temporal lobe in Landau–Kleffner syndrome

Landau–Kleffner syndrome (LKS) is a childhood disorder of unknown etiology characterized by an acquired aphasia and epilepsy. We have performed comprehensive neurofunctional studies on an 8-year-old girl with typical LKS, with the aim of identifying lesions that may be responsible for her condition. 18F-fluoro- d-glucose (FDG) positron emission computed tomography (PET), 11C-Flumazenil (FMZ) PET, 99mTc- hexamethylpropyleneamine oxime single photon emission computed tomography (SPECT) and magnetoencephalography were performed before and after changes to the patient’s medication led to a clinical improvement. Interictal SPECT showed hypoperfusion in the left frontal, left temporal, and left occipital lobes. 18F-FDG PET demonstrated a decrease in glucose metabolism medially in both temporal lobes and superiorly in the left temporal lobe. 11C-FMZ PET revealed a deficit in benzodiazepine receptor binding at the tip of the left temporal lobe. Magnetoencephalography demonstrated equivalent current dipoles located superiorly in the left temporal lobe. Our results suggest that the tip of the left temporal lobe plays an important role in the pathogenesis of LKS in our patient.

Neocortical Gliosis in Temporal Lobe Epilepsy: Gender‐Based Differences

Sex hormones can influence the timing and frequency of seizure activity. In addition, gender may influence the age of epilepsy onset and hemispheric location of focal epilepsy. Whether gender alters temporal lobe pathologies differentially is not clear. In this study, we assess if neocortical or hippocampal pathologies from patients who underwent en bloc anteriomedial temporal lobectomy (AMTR) for medically refractory epilepsy differ by gender. Consecutive en bloc AMTR resections (n = 128), including hippocampal tissues, were systematically studied. Cortical and intracortical gliosis from a standardized location, 1.5 cm from the temporal lobe tip, was assessed for quantifiable gliotic change. Corresponding hippocampal sections were characterized according to Watson grade. These outcomes were then compared by gender. Other correlates such as age of epilepsy onset, age of risk exposure, and duration of epilepsy were similarly compared. Subpial and intracortical gliosis was more pronounced in women (p = 0.02, p < 0.01). Cortical thickness was reduced in women compared to men (p < 0.05). No similar gender effects were seen in Watson grade of hippocampal sclerosis or CA1-4 neuronal dropout. Gender may differentially influence neocortical pathologies in patients with refractory temporal lobe epilepsy. No gender effect was seen when studying hippocampal pathologies.

Microsurgical Anatomy and Quantitative Analysis of the Transtemporal-Transchoroidal Fissure Approach to the Ambient Cistern

Surgical approaches to ambient cistern lesions are complex. We investigated the microanatomy of the transtemporal-transchoroidal fissure approach to the ambient cistern with emphasis on exposure of the posterior cerebral artery. Dissections were performed bilaterally in five silicone-injected cadaveric heads. Critical anatomic distances, specifically with reference to the P2 segment of posterior cerebral artery in relation to the inferior choroidal point and P2-P3 junction, were measured with digital calipers. Other landmarks (temporal lobe tip, points from the temporal base to the choroidal fissure) were included for quantitative analysis. The transtemporal-transchoroidal fissure approach provided adequate exposure of the ambient cistern, minimized temporal lobe retraction, and allowed assessment of regional microanatomy. The mean distance from the temporal base to the choroidal fissure measured 18.09 mm (range, 16.9-21.9 mm). The distances from the choroidal fissure to P2 varied at the coronal plane of the inferior choroidal point (mean, 6.96 mm; range, 3.6-12.0 mm) and the P2-P3 junction (mean, 6.02 mm; range, 4.3-6.9 mm), respectively. The transtemporal-transchoroidal fissure approach provides a corridor to the ambient cistern and P2-P3 junction while minimizing temporal lobe retraction and avoiding interruption of temporal lobe venous drainage. Because of widely variable vascular anatomy, access to posterior cerebral artery lesions using this approach requires preoperative imaging to identify the specific location of the P2-P3 junction.

脳動脈瘤手術における頭蓋底外科手技

For giant or large aneurysms on and around the basilar artery bifurcation, the (Cranio) orbito-zygomatic osteotomy is quite helpful for approach in multiple directions. Preservation of the bridging vein coming off the temporal lobe tip is preferable; for this purpose as well as for ample working space, the author often cuts the basal polar portion of the temporal lobe.For usual sized aneurysms around the high placed basilar bifurcation, the arch of the zygomatic bone is removed, but orbitotomy is not needed except for the lateral rim. If the lateral superior portion of the orbit disturbs the trajectory to the basilar tip, the cavernous carotid or the anterior communicating artery aneurysm, this portion of the orbital bone is removed at those stages of the operation. Removal of the supraorbital bar, including the nasal bone, is also helpful for approaching the anterior communicating artery aneurysm interhemispherically.Preservation of the olfactory nerves and the frontal sagittal bridging veins are constantly achieved through the basal interfalcine approach. The craniotomy for the basal interfalcine approach involves the frontal sinus. The outer table is incorporated to the craniotomy, but the inner table is discarded, the mucous membranes are removed, and the fronto-nasal duct is closed.

The Subarachnoid Spaces in Craniosynostosis

A review of 85 patients with various forms of craniosynostosis showed predictable patterns of dilatation of the subarachnoid spaces in regions of compensatory skull growth. The characteristic pattern in sagittal synostosis (43 patients) included dilatation of the frontal and occipital subarachnoid spaces associated with the elongation of the anteroposterior dimension of the skull and widening of the interhemispheric fissure. In 11 patients with unilateral coronal synostosis, dilatations of the subarachnoid spaces over the contralateral frontal lobe, the sylvian regions, and the ipsilateral temporal lobe tip were consistent with the skull changes of contralateral frontal bossing, increased bitemporal dimension, and elevation of the sphenoid wing, respectively. Four patients with bilateral coronal synostosis also had enlarged subarachnoid spaces high over the convexities of the brain consistent with the towering configuration of the skull. Four patients with true lambdoid synostosis had dilatation of the subarachnoid space only over the ipsilateral frontal lobe associated with compensatory bossing of the frontal bone. Ten of 14 patients with lambdoid deformities had bilateral enlargement of the subarachnoid spaces suggesting brain atrophy and an underlying motor delay accounting for the position-induced skull changes. The findings suggest that focal hydrodynamic mechanisms are involved in the compensatory skull changes seen in craniosynostosis.

Radiosurgery for palliation of base of skull recurrences from head and neck cancers.

Seven patients received stereotaxic radiosurgery for 10 lesions at the base of the skull (BOS) from recurrent head and neck malignant neoplasms. A radiation dose of 17.5-35.0 Gy was delivered as a single fraction. Follow-up ranged from 1 to 14 months. Nine lesions were symptomatic, and the symptoms improved in five and stabilized in four lesions. In addition, a significant radiographic response was observed in 4 of 10 recurrences. Cranial nerve signs developed in two patients, and an area of asymptomatic necrosis developed in one patient in the temporal lobe tip. From their brief experience, the authors conclude that stereotaxic radiosurgery may be a promising treatment in locally controlling recurrent head and neck cancers that involve the BOS.

The subarachnoid spaces in craniosynostosis.

A review of 85 patients with various forms of craniosynostosis showed predictable patterns of dilatation of the subarachnoid spaces in regions of compensatory skull growth. The characteristic pattern in sagittal synostosis (43 patients) included dilatation of the frontal and occipital subarachnoid spaces associated with the elongation of the anteroposterior dimension of the skull and widening of the interhemispheric fissure. In 11 patients with unilateral coronal synostosis, dilatations of the subarachnoid spaces over the contralateral frontal lobe, the sylvian regions, and the ipsilateral temporal lobe tip were consistent with the skull changes of contralateral frontal bossing, increased bitemporal dimension, and elevation of the sphenoid wing, respectively. Four patients with bilateral coronal synostosis also had enlarged subarachnoid spaces high over the convexities of the brain consistent with the towering configuration of the skull. Four patients with true lambdoid synostosis had dilatation of the subarachnoid space only over the ipsilateral frontal lobe associated with compensatory bossing of the frontal bone. Ten of 14 patients with lambdoid deformities had bilateral enlargement of the subarachnoid spaces suggesting brain atrophy and an underlying motor delay accounting for the position-induced skull changes. The findings suggest that focal hydrodynamic mechanisms are involved in the compensatory skull changes seen in craniosynostosis.