Microvascular anatomy of the medial temporal region

OBJECTIVE The authors investigated the microvascular anatomy of the hippocampus and its implications for medial temporal tumor surgery. They aimed to reveal the anatomical variability of the arterial supply and venous drainage of the hippocampus, emphasizing its clinical implications for the removal of associated tumors. METHODS Forty-seven silicon-injected cerebral hemispheres were examined using microscopy. The origin, course, irrigation territory, spatial relationships, and anastomosis of the hippocampal arteries and veins were investigated. Illustrative cases of hippocampectomy for medial temporal tumor surgery are also provided. RESULTS The hippocampal arteries can be divided into 3 segments, the anterior (AHA), middle (MHA), and posterior (PHA) hippocampal artery complexes, which correspond to irrigation of the hippocampal head, body, and tail, respectively. The uncal hippocampal and anterior hippocampal-parahippocampal arteries contribute to the AHA complex, the posterior hippocampal-parahippocampal arteries serve as the MHA complex, and the PHA and splenial artery compose the PHA complex. Rich anastomoses between hippocampal arteries were observed, and in 11 (23%) hemispheres, anastomoses between each segment formed a complete vascular arcade at the hippocampal sulcus. Three veins were involved in hippocampal drainage—the anterior hippocampal, anterior longitudinal hippocampal, and posterior longitudinal hippocampal veins—which drain the hippocampal head, body, and tail, respectively, into the basal and internal cerebral veins. CONCLUSIONS An understanding of the vascular variability and network of the hippocampus is essential for medial temporal tumor surgery via anterior temporal lobectomy with amygdalohippocampectomy and transsylvian selective amygdalohippocampectomy. Stereotactic procedures in this region should also consider the anatomy of the vascular arcade at the hippocampal sulcus.

Resection of a recurrent pineal region teratoma via a posterior interhemispheric transcallosal approach

The authors describe the unusual case of a 6-year-old boy presenting with decorticate posturing, diminished hearing, and an inability to open his eyes, despite being verbally responsive. He underwent a posterior interhemispheric transcallosal intervenous approach for resection of a pineal region mature teratoma, which recurred 2 years postoperatively. This video demonstrates his initial surgery and reresection, illustrating the value of this approach for more complex lesions that involve the internal cerebral veins (ICVs). At the time of recurrence, microsurgical dissection of the scarred interhemispheric fissure was required to facilitate removal of the multifocal recurrent teratoma, resulting in gross-total resection. The video can be found here: https://stream.cadmore.media/r10.3171/2021.4.FOCVID2134.

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.

Computed tomography angiography accuracy in brain death diagnosis

OBJECTIVEThe present study was designed to answer several concerns disclosed by systematic reviews indicating no evidence to support the use of computed tomography angiography (CTA) in the diagnosis of brain death (BD). Therefore, the aim of this study was to assess the effectiveness of CTA for the diagnosis of BD and to define the optimal tomographic criteria of intracranial circulatory arrest.METHODSA unicenter, prospective, observational case-control study was undertaken. Comatose patients (Glasgow Coma Scale score ≤ 5), even those presenting with the first signs of BD, were included. CTA scanning of arterial and venous vasculature and transcranial Doppler (TCD) were performed. A neurological determination of BD and consequently determination of case (BD group) or control (no-BD group) was conducted. All personnel involved with assessing patients were blinded to further tests results. Accuracy of BD diagnosis determined by using CTA was calculated based on the criteria of bilateral absence of visualization of the internal cerebral veins and the distal middle cerebral arteries, the 4-point score (4PS), and an exclusive criterion of absence of deep brain venous drainage as indicated by the absence of deep venous opacification on CTA, the venous score (VS), which considers only the internal cerebral veins bilaterally.RESULTSA total of 106 patients were enrolled in this study; 52 patients did not have BD, and none of these patients had circulatory arrest observed by CTA or TCD (100% specificity). Of the 54 patients with a clinical diagnosis of BD, 33 met the 4PS (61.1% sensitivity), whereas 47 met the VS (87% sensitivity). The accuracy of CTA was time related, with greater accuracy when scanning was performed less than 12 hours prior to the neurological assessment, reaching 95.5% sensitivity with the VS.CONCLUSIONSCTA can reliably support a diagnosis of BD. The criterion of the absence of deep venous opacification, which can be assessed by use of the VS criteria investigated in this study, can confirm the occurrence of cerebral circulatory arrest.Clinical trial registration no.: 12500913400000068 (clinicaltrials.gov)

Cerebral deep venous thrombosis and COVID-19: case report

Herein, the authors present the case of a 54-year-old male diagnosed with coronavirus disease 2019 (COVID-19) during a screening test. The patient was asked to self-isolate at home and report with any exacerbations of symptoms. He presented later with pneumonia complicated by encephalopathy at days 14 and 15 from initial diagnosis, respectively. MRI of the brain showed bithalamic and gangliocapsular FLAIR signal abnormality with mild right-sided thalamic and periventricular diffusion restriction. A CT venogram was obtained given the distribution of edema and demonstrated deep venous thrombosis involving the bilateral internal cerebral veins and the vein of Galen. CSF workup was negative for encephalitis, as the COVID-19 polymerase chain reaction (PCR) test and bacterial cultures were negative. A complete hypercoagulable workup was negative, and the venous thrombosis was attributed to a hypercoagulable state induced by COVID-19. The mental decline was attributed to bithalamic and gangliocapsular venous infarction secondary to deep venous thrombosis. Unfortunately, the patient’s condition continued to decline, and care was withdrawn.

Right Anterior Parasagittal Craniotomy and Interhemispheric Approach for Resection of a Falcontentorial Junction Meningioma: 2-Dimensional Operative Video

Falcotentorial meningiomas are rare lesions that occur along the midline at the junction of the falx cerebri and tentorium. When large, these lesions pose a surgical challenge because of the risk of neurologic deficits, including cortical blindness. Delicate structures at risk during resection of these lesions include the sagittal sinus, internal cerebral veins, vein of Galen, straight sinus, torcula, and fornix. Although there are a number of very reasonable approaches, including a supracerebellar infratentorial or occipital interhemispheric, we chose an anterior interhemispheric approach to provide the safest route for accessing the largest portion of the tumor while protecting the deep venous system. After identification of the falcine attachment, the tumor is debulked within the tumor capsule. In this case, the tumor was subtotally removed because of the adherence of a small segment of tumor along the vein of Galen. The patient gave informed consent for surgery and video recording. Institutional review board approval was deemed unnecessary. Used with permission from Barrow Neurological Institute.

Posterior transcallosal intervenous-interforniceal approach to a periaqueductal tumor

Described by Dandy in 1921, the posterior interhemispheric transcallosal approach provides an operative corridor to the pineal region, posterior third ventricle, and upper midbrain. Intervenous-interforniceal and paravenous-interforniceal variants have been utilized for midline and paramidline pathology, respectively. The intervenous-interforniceal variant capitalizes on the natural separation of the internal cerebral veins, which are found medial to the forniceal crura at this level, to provide a safe corridor to the tumor while minimizing the risk of injury to the fornices. Here, the authors describe a posterior interhemispheric transcallosal approach using the intervenous-interforniceal variant for resection of a periaqueductal pilocytic astrocytoma.The video can be found here: https://youtu.be/mtQKEXEveTg.

Surgical management of pineal region lesions

Lesions in the pineal region are topographically located in the centre of the brain in the diencephalic-epithalamic region. An area where the brain is bounded ventrally by the quadrigeminal plate, midbrain tectum, and in-between the left and right superior colliculi, dorsally by the splenium of the corpus callosum, caudally by the cerebellar vermis and rostrally by the posterior aspects of the third ventricle. Major anatomical and surgical challenges are the vein of Galen located dorsally, the precentral cerebellar vein caudally, the internal cerebral veins anteriorly and the basal vein of Rosenthal laterally. Most pineal region tumours can be safely removed by both approaches depending on the surgeon’s experience: the occipital transtentorial approach is recommended in presence of associated hydrocephalus or a steep straight sinus and low location of the tumour and the supracerebellar infratentorial approach for posterior third ventricle tumours.