Surgical management of skull base tumors

AimTo present a review of the contemporary surgical management of skull base tumors.BackgroundOver the last two decades, the treatment of skull base tumors has evolved from observation, to partial resection combined with other therapy modalities, to gross total resection and no adjuvant treatment with good surgical results and excellent clinical outcomes.Materials and methodsThe literature review of current surgical strategies and management of skull base tumors was performed and complemented with the experience of Barrow Neurological Institute.ResultsSkull base tumors include meningiomas, pituitary tumors, sellar/parasellar tumors, vestibular and trigeminal schwannomas, esthesioneuroblastomas, chordomas, chondrosarcomas, and metastases. Surgical approaches include the modified orbitozygomatic, pterional, middle fossa, retrosigmoid, far lateral craniotomy, midline suboccipital craniotomy, and a combination of these approaches. The selection of an appropriate surgical approach depends on the characteristics of the patient and the tumor, as well as the experience of the neurosurgeon.ConclusionModern microsurgical techniques, diagnostic imaging, intraoperative neuronavigation, and endoscopic technology have remarkably changed the concept of skull base surgery. These refinements have extended the boundaries of tumor resection with minimal morbidity

The Relational Bottleneck as an Inductive Bias for Efficient Abstraction

A central challenge for cognitive science is to explain how abstract concepts are acquired from limited experience. This effort has often been framed in terms of a dichotomy between empiricist and nativist approaches, most recently embodied by debates concerning deep neural networks and symbolic cognitive models. Here, we highlight a recently emerging line of work that suggests a novel reconciliation of these approaches, by exploiting an inductive bias that we term the relational bottleneck. We review a family of models that employ this approach to induce abstractions in a data-efficient manner, emphasizing their potential as candidate models for the acquisition of abstract concepts in the human mind and brain

Left retrosigmoid craniotomy for cavernous malformation of the middle cerebellar peduncle.

We present a 25-year-old female with a history of multiple intracranial cavernous malformations complaining of vertigo. Imaging is significant for increasing size of a lesion in her left cerebellar peduncle. Given the proximity to the lateral border of the cerebellar peduncle, a retrosigmoid approach was chosen. After performing a craniotomy that exposed the transverse-sigmoid sinus junction, the dura was open and reflected. The arachnoid was sharply opened and cerebrospinal fluid was aspirated to allow the cerebellum to fall away from the petrous bone. The cerebellopontine fissure was then opened to visualize the lateral wall of the cerebellar peduncle. The cavernous malformation was entered and resected. The video can be found here: http://youtu.be/P7mpVbaCiJE

Left retrosigmoid craniotomy for cavernous malformation of the middle cerebellar peduncle

We present a 25-year-old female with a history of multiple intracranial cavernous malformations complaining of vertigo. Imaging is significant for increasing size of a lesion in her left cerebellar peduncle. Given the proximity to the lateral border of the cerebellar peduncle, a retrosigmoid approach was chosen. After performing a craniotomy that exposed the transverse-sigmoid sinus junction, the dura was open and reflected. The arachnoid was sharply opened and cerebrospinal fluid was aspirated to allow the cerebellum to fall away from the petrous bone. The cerebellopontine fissure was then opened to visualize the lateral wall of the cerebellar peduncle. The cavernous malformation was entered and resected. The video can be found here: http://youtu.be/P7mpVbaCiJE

Advanced Imaging Modalities in the Detection of Cerebral Vasospasm

The pathophysiology of cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH) is complex and is not entirely understood. Mechanistic insights have been gained through advances in the capabilities of diagnostic imaging. Core techniques have focused on the assessment of vessel caliber, tissue metabolism, and/or regional perfusion parameters. Advances in imaging have provided clinicians with a multifaceted approach to assist in the detection of cerebral vasospasm and the diagnosis of delayed ischemic neurologic deficits (DIND). However, a single test or algorithm with broad efficacy remains elusive. This paper examines both anatomical and physiological imaging modalities applicable to post-SAH vasospasm and offers a historical background. We consider cerebral blood flow velocities measured by Transcranial Doppler Ultrasonography (TCD). Structural imaging techniques, including catheter-based Digital Subtraction Angiography (DSA), CT Angiography (CTA), and MR Angiography (MRA), are reviewed. We examine physiologic assessment by PET, HMPAO SPECT, 133Xe Clearance, Xenon-Enhanced CT (Xe/CT), Perfusion CT (PCT), and Diffusion-Weighted/MR Perfusion Imaging. Comparative advantages and limitations are discussed

Three Dimensional CT Angiography Versus Digital Subtraction Angiography in the Detection of Intracranial Aneurysms in Subarachnoid Hemorrhage.

INTRODUCTION: Ruptured intracranial aneurysms are responsible for over 90% of cases of spontaneous subarachnoid hemorrhage (SAH). Conventional digital subtraction angiography (DSA) remains the gold standard for diagnosing the source of SAH. A prospective study is presented wherein SAH patients underwent three dimensional CT angiography (CTA) prior to DSA in order to assess the specificity and sensitivity of this non-invasive modality to detect aneurysms. METHODS: 179 consecutive patients with spontaneous SAH presented over 36 months, as identified by screening CT and CTA. Patients with negative CTA findings underwent DSA within 24 h of presentation. All patients who were determined to have angiographically negative SAH underwent follow-up DSA 2 weeks later. RESULTS: Of the 179 patients screened by CTA, 13 (7%) were negative for aneurysms or other vascular lesions (arteriovenous malformation or dural fistula) on CTA and underwent DSA. No new lesions were identified on six vessel angiography, resulting in a 0% false negative rate (sensitivity 100%, predictive value 100%). MRI to rule out thrombosed aneurysms and repeat angiography at the 2 week follow-up were negative. CONCLUSIONS: Sensitivity and specificity were higher than previously reported, suggesting that CTA may be used as an initial screening tool in lieu of DSA. Further studies are necessary to determine if CTA can supplant DSA in ruling out all forms of vascular disease in idiopathic SAH

Prospects of Photo- and Thermoacoustic Imaging in Neurosurgery

The evolution of neurosurgery has been, and continues to be, closely associated with innovations in technology. Modern neurosurgery is wed to imaging technology and the future promises even more dependence on anatomic and, perhaps more importantly, functional imaging. The photoacoustic phenomenon was described nearly 140 yr ago; however, biomedical applications for this technology have only recently received significant attention. Light-based photoacoustic and microwave-based thermoacoustic technologies represent novel biomedical imaging modalities with broad application potential within and beyond neurosurgery. These technologies offer excellent imaging resolution while generally considered safer, more portable, versatile, and convenient than current imaging technologies. In this review, we summarize the current state of knowledge regarding photoacoustic and thermoacoustic imaging and their potential impact on the field of neurosurgery