Cortex: Gross Anatomy

The cerebral cortex consists of 2 hemispheres, the left and the right. These are divided by the falx cerebri, a dural-derived structure. The cerebral cortex receives input from various subcortical structures, often connecting through the thalamus and from other areas of the cortex by association fibers. The cortex then projects back to wide regions of the central nervous system, including the cortex, thalamus, basal nuclei, cerebellum, brainstem, and spinal cord. The types of fibers connecting areas of the central nervous system are designated according to the regions they connect. For instance, the fibers connecting the cortex to subcortical structures are called projection fibers. The fibers connecting 1 hemisphere to the opposite hemisphere are called callosal fibers, and the fibers connecting areas within the same hemisphere are called association fibers. Fibers connecting the cortex to the thalamus are designated corticothalamic fibers.

Hemorrhagic angiomatous meningioma: what we know. Case report and review of the literature

Meningiomas are the most common benign intracranial tumors and rarely present with spontaneous bleeding. We report on a case of hemorrhagic angiomatous meningioma that was treated surgically (the first case described in Brazil) and present a review of the literature. The patient wasa 38-year-old female with progressive headache and vomiting. She also had a previous history ofchronic headaches and refractory depression. Imaging studies showed a large left frontal extra-axialtumor, with intense contrast enhancement and hyperperfusion/hypervascularization. There was anextensive intratumoral and pericapsular hemorrhagic region, with dilation of the middle meningealarteries and falx cerebri vessels. The lesion was compatible with hemorrhagic meningioma. Thepatient underwent bifrontal craniotomy and tumor devascularization, followed by total resection.Histopathological and immunohistochemical analyses led us to conclude that this was a case of angiomatous meningioma. Subsequently, the patient’s headaches and depression improved. Noresidual or recurrent neoplastic lesion was observed during the follow-up.

First documented case of intracranial falcine malignant peripheral nerve sheath tumor: illustrative case

BACKGROUND The authors reported the first documented case of intracranial extraaxial nonneurofibromatosis type 1–related nontriton malignant peripheral nerve sheath tumor (MPNST) originating from the falx cerebri. OBSERVATIONS A 34-year-old man with headache, short-term memory deficit, postural instability, and blurred vision presented with a large heterogenous contrast-enhanced intraventricular cystic lesion originating from the free margin of the falx cerebri. The patient received surgery using the right posterior interhemispheric approach. Gross total resection was performed, and the inferior border of the falx cerebri was resected. The postoperative course was uneventful. Histological examination revealed hypercellular foci of neoplastic spindle cells with hyperchromatic and wavy nuclei. Hence, a diagnosis of MPNST was made based on concomitant immunochemistry findings, including mouse double minute 2 homolog focal positivity and geographic loss of H3K27me3. The patient received adjuvant radiotherapy, and recurrence was not observed. LESSONS Intracranial MPNSTs are extremely rare tumors, typically originating from the cranial nerves in the posterior cranial fossa. An even rarer variant of these tumors, referred to as malignant intracerebral nerve sheath tumors, may directly arise from the brain parenchyma. The authors reported the first case of an intracranial MPNST originating from the dura mater of the falx cerebri, acting as an extraaxial lesion with prevalent expansion in the right ventricle.

Posterior interhemispheric occipital transtentorial approach for resection of a falcotentorial meningioma

Falcotentorial meningiomas arise along the junction of the falx cerebri and the tentorium cerebelli. The authors present a woman in her 60s with an incidentally discovered falcotentorial meningioma, approximately 3 cm in diameter, resected with a torcular craniotomy and posterior interhemispheric approach. The galenic complex was dissected away from the tumor. In the final view, the bilateral internal cerebral veins and basal veins of Rosenthal were seen. A Simpson grade I resection was achieved. The patient experienced transient contralateral hemianopsia and was discharged home. At 1-year follow-up, her neurological examination findings were unremarkable, and there was no radiographic evidence of tumor. The video can be found here: https://stream.cadmore.media/r10.3171/2021.4.FOCVID2125.

Calcification of Falx Cerebri between Male and Female Patients: A Comparative Study

Objectives: The aim of this paper is to study the calcification that occurs in the inter−hemispheric fissure to compare between male and female patients. Materials and Methods: The level of density and size of these calcifications were collected and analyzed in 30 patients randomly. Results: The result of this study showed that there is a relation between falx cerebri and gender since its more common in female patients. The density of the calcifications is higher in males and the calcifications are longer on the AP axis, while the falx cerebri calcifications are wider in the coronal axis in females. Conclusion: There is a relation between Calcification of falx cerebri and gender.

A rare appearance of the trigeminocardiac reflex during resection of posterior parasagittal meningioma

Background: Although a well-recognized phenomenon of the tentorium and posterior fossa, the trigeminocardiac reflex (TCR) has been rarely reported during surgery involving the posterior falx cerebri. Case Description: We present the case of a 63-year-old woman who underwent repeat resection of an atypical parasagittal meningioma involving the posterior falx. During resection, TCR was repeatedly elicited during manipulation and coagulation of the falx. Air embolism and cardiac etiologies were initially considered while TCR was not suspected, given the location. Ultimately, TCR was recognized when asystole self-resolved upon cessation of stimulus and due to its reproducibility. Conclusion: Awareness by the anesthesiologist and neurosurgeon of the possibility of TCR during falcine procedures can help with rapid identification to avoid a potentially catastrophic outcome.

Giant chondrosarcoma of the falx in an adolescent: A case report

Background: Intracranial chondrosarcomas are slowly growing malignant cartilaginous tumors that are especially rare in adolescents. Case Description: A 19-year-old woman with no medical history presented with symptoms of intermittent facial twitching and progressive generalized weakness for 6 months. The patient’s physical examination was unremarkable. Imaging revealed a large bifrontal mass arising from the falx cerebri, with significant compression of both cerebral hemispheres and downward displacement of the corpus callosum. The patient underwent a bifrontal craniotomy for gross total resection of tumor. Neuropathologic examination revealed a bland cartilaginous lesion most consistent with low-grade chondrosarcoma. Her postoperative course was uneventful, and she was discharged to home on postoperative day 3. Conclusion: This is an unusual case of an extra-axial, non-skull base, low-grade chondrosarcoma presenting as facial spasm in an adolescent patient.