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Considerable progress has been made over the past years to better understand the genetic nature and pathophysiology of brain AVM. For the actual review, a PubMed search was carried out regarding the embryology, inflammation, advanced imaging, and fluid dynamical modeling of brain AVM. Whole-genome sequencing clarified the genetic origin of sporadic and familial AVM to a large degree, although some open questions remain. Advanced MRI and DSA techniques allow for better segmentation of feeding arteries, nidus, and draining veins, as well as the deduction of hemodynamic parameters such as flow and pressure in the individual AVM compartments. Nonetheless, complete modeling of the intranidal flow structure by computed fluid dynamics (CFD) is not possible so far. Substantial progress has been made towards understanding the embryology of brain AVM. In contrast to arterial aneurysms, complete modeling of the intranidal flow and a thorough understanding of the mechanical properties of the AVM nidus are still lacking at the present time.

The cerebellum is historically implicated in motor coordination, but accumulating modern evidence indicates involvement in non-motor domains, including cognition, emotion, and language. This correlates with the symptoms observed in postoperative cerebellar mutism syndrome (CMS). Profound knowledge of cerebellar functional topography and tractography is important when approaching cerebellar tumors, as surgical trauma to relevant structures of cerebellar pathways plays a role in the pathogenesis of CMS. The aim of this systematic review is to provide a concise overview of relevant modern neuroimaging data and cerebellar functional tracts with regard to neurosurgical procedures.

The two burning questions regarding the management of cerebral aneurysms currently concern whether to use clip or coil and what to do with incidental aneurysms. Further issues that require continuing attention and research are primary and secondary damage following subarachnoid hemorrhage (i.e., delayed cerebral ischemia) and perhaps primary prevention of cerebral aneurysm formation by pharmaceutical treatment.

When operating early after subarachnoid hemorrhage, the anatomy may be much obscured by the cisternal and superficial blood accumulation and by the reactive swelling. It is of utmost importance to ensure sufficient brain relaxation prior to opening the dura. The ventricular or spinal CSF drain should be opened following craniotomy and 50–100 mL of CSF should be drained. It is important not to open the dura while it is still under tension, because doing so could result in brain prolapse and premature rerupture of the aneurysm. At this point, it is also important to check arterial pressure and communicate with the anesthesiologist. We recommend keeping the arterial pressure at a level corresponding to the preoperative value minus the preoperatively measured intracranial pressure (ICP). If preoperative ICP levels are not available, 10 mmHg is used as an average estimate, and arterial pressure during surgery should therefore be maintained at 10 mmHg lower than the preoperative value. This directive keeps the cerebral perfusion pressure steady, thus both avoiding ischemia and controlling the risk of premature rerupture of the aneurysm.

Aneurysms of the internal carotid artery (ICA) are subdivided according to their location along the ICA into proximal or paraclinoid aneurysms, aneurysms of the middle segment, and terminal aneurysms. Aneurysms may be related to branches of the ICA—that is, the ophthalmic artery, the posterior communicating artery (Pcom), or the anterior choroidal artery (AChA)—but a considerable proportion are unrelated to side branches. Aneurysms of the ICA can reach giant size and present with optic nerve compression.

Middle cerebral artery (MCA) aneurysms are fairly peripheral to the arterial tree, occurring close to the cranial surface. They are often broad based and rarely lead to a hematoma in the temporal lobe or Sylvian fissure. (Compare also Sect. 7.2.) These factors are in favor of the microsurgical approach, although many MCA aneurysms can technically also be controlled with modern endovascular systems.

Aneurysms of the posterior cerebral circulation account for only about 15 % of all intracranial aneurysms, and surgical treatment of these aneurysms was demanding until the introduction of endovascular therapy. The surgery-related morbidity and mortality—about 10 % in the best published series—was correspondingly high. One must assume that in the average series, the surgery-related morbidity and mortality may have been about 30 % or higher. Part of the high complication rate can be linked to the relative rarity of these aneurysms, because the particular approaches and techniques require special skills and awareness of specific pitfalls. Another reason for the unsatisfactory results of microsurgical treatment, however, has certainly been the highly eloquent territory supplied by the parent arteries of these aneurysms—that is, the brainstem. Drake and Peerless from London, Ontario, acquired the world’s largest experience in the surgical treatment of aneurysms of the posterior circulation.

More than 90 % of all saccular aneurysms arise from bifurcations or appear at the origin of small side branches (percentages are approximate): Middle cerebral artery main bifurcation (15–30 %) Anterior communicating artery (20–30 %) Internal carotid–posterior communicating artery (15 %) Basilar tip (5 %)

Haemangiomas are very frequent benign spinal tumours. However, pure epidural location is extremely rare. At present, only 52 cases have been reported in the literature during the last 10 years. We proposed to analyse clinical and radiological features of this rare entity treated in a tertiary care centre over the last 10 years.A study of a retrospective surgical series (2002-2012) was conducted. The clinic's electronic database was searched for "spinal" and/or "vertebral haemangiomas", which were treated by surgery and/or vertebroplasty. Clinical, radiological and histopathological data were analysed.In total, the series comprised 30 spinal haemangiomas. There were 6 epidural (20 %), 17 vertebral (57 %) and 7 intradural lesions (23 %). There were four men and two women, mean age 28.3 years, with epidural lesions. One patient presented with localised back pain only, two with radiculopathy and focal neurological deficit, two with radiculopathy only and one with isolated focal neurological deficit, respectively. The onset of symptoms was progressive in four cases over weeks to months and sudden in two cases. Preoperative MRI imaging revealed features of meningioma, neurinoma or metastasis.Epidural haemangiomas are extremely rare spinal lesions. They may mimic more common spinal tumours clinically and radiologically. The usual treatment is gross total resection confirming the diagnosis histologically.

Despite current treatment strategies cerebral arterial spasm still constitutes the dominant secondary complication following aneurysmal subarachnoid hemorrhage (SAH) and continues to be associated with high morbidity and mortality rates. In particular clot volume and clearance rate have been identified as independent predictors of vasospasm after aneurysmal SAH. Therefore investigators have tried to accelerate the rate of clot clearance in order to reduce the incidence of cerebral vasospasm.