Pineal gland for a long time aroused the interest of scholars' philosophical and religious current of thought.Its history started in China in 2697BC and in the Indu culture it was considered the centre of spiritual forces or the centre of vital energy. Herophilus (325-280) studied the pineal gland with anatomical dissection and considered the gland as the valve that permitted the flow of the vital "pnuema."Descartes (1596-1650), a French philosopher, gave a great impulsion to the studies on the role of the pineal gland. The location of the soul in the pineal gland was again proposed as it acts in the control of the human body. The human intellectual soul was characterized by the immortality, the free will, and the reason that characterize the power of imagination, the intellectual elaboration, and the faculty of commemoration, respectively.Ahlborn and Rabl-Ruckhardt (1839-1906) showed the similarity between the nonmammalian pineal gland and the primary optic vesicles. The visual function of the pineal gland was reported also by Helena Blavatsky (1831-1891) and a new era for its role started.In 1958 the hormone of the gland, the melatonin, was discovered by Lerner. Successively it demonstrated a variability of the production of the hormone in function of the exposition to light or dark and the implication in the control of the circadian rhythm. The theory of function of the internal clock of the pineal and the control of the circadian rhythm of an organism began to take form.At the same time the classification of the pineal tumor started and the first surgical approaches were proposed. The development of anesthesiology and the surgical tools in the last years permitted to make surgery accessible for patients reducing the rate of sequels and mortality.To know the "history" of the pineal gland and of pineal tumors, treatment permits to understand the evolution and the development of ideas concerning the diagnosis and treatment of these rare tumors.

Although the role of melatonin in many biological functions, foremost among them the regulation of circadian rhythms and sleep, has been widely demonstrated, the definition of a specific disorder linked to melatonin deficiency remains debated. As the main function of the pineal gland is to secrete melatonin, pineal lesions and pinealectomy provide insightful models for understanding the effect of acute and chronic suppression of melatonin secretion ("pinealoprive syndrome"). In pineal parenchymal cell tumor, melatonin levels are usually normal/high, whereas impaired secretion is thought to reflect parenchymal destruction and thus tumors with malignant profiles. Following pinealectomy, low or undetectable levels of melatonin are observed, suggesting that melatonin assay may be used to monitor complete tumoral and pineal gland resection. However, the link between melatonin depletion in this context and the objective/subjective quality of sleep remains unclear. Likewise, while melatonin is involved in a large number of physiological functions, damage to the pineal gland does not appear to have any clear extra-neurological effects. This paradox might be explained by the presence of extra-pineal melatonin secretion sites. In addition, it is possible that the effects of melatonin depletion are long term, in real-life situations, and fluctuate according to the season. Importantly, most evidence relies on very small samples due to the rarity of pineal gland lesions. Further prospective longitudinal studies on wider cohorts are needed, to definitively conclude on the impact of pineal gland-related melatonin on health in general and sleep in particular. There is therefore no recommendation for melatonin supplementation after pinealectomy. Pragmatically, in the presence of melatonin deficiency and sleep disorders in the context of pineal gland tumor/pinealectomy, and given the safety of melatonin as a medication, it seems reasonable to propose exogenous melatonin, with a chronobiotic or sedative purpose depending on the type of disorder.

Cystic anomalies of the posterior fossa constitute an important chapter of the malformations of this region. Their interpretation is largely based on the existence of a pouch described by Joseph Blake in 1900. We have reviewed the ancient literature on which this description is based. All human data were obtained from only three fetuses. The histological and embryological analysis of these observations leads us to remain very cautious as to their significance. Indeed, this region of the posterior fossa is very fragile and subject to numerous technical artifacts. In addition, errors in fetal age lead us to believe that one of the observations cannot be used. It is therefore appropriate to be very careful when using this old literature. All these elements justify the need to revisit this problem in order to determine the normal development of this region in humans.

Values-based medicine (VsBM) is an ethical concept, and bioethical framework has been developed to ensure that medical ethics and values are implemented, pervasive, and powerful parameters influencing decisions about health, clinical practice, teaching, medical industry, career development, malpractice, and research. Neurosurgeons tend to adopt ethics according to their own values and to what they see and learn from teachers. Neurosurgeons, in general, are aware about ethical codes and the patient's rights. However, the philosophy, concept, and principles of medical ethics are rarely included in the training programs or in training courses. The impact of implementing, observing the medical ethics and the patients' value and culture on the course, and outcome of patients' management should not underestimate. The main principles of medical ethics are autonomy, beneficence, nonmaleficence, justice, dignity, and honesty, which should be strictly observed in every step of medical practice, research, teaching, and publication. Evidence-based medicine has been popularized in the last 40-50years in order to raise up the standard of medical practice. Medical ethics and values have been associated with the medical practice for thousands of years since patients felt a need for treatment. There is no conflict between evidence-based medicine and values-based medicine, as a medical practice should always be performed within a frame of ethics and respect for patients' values. Observing the principles of values-based medicine became very relevant as multicultural societies are dominant in some countries and hospitals in different corners of the world.

Pediatric epilepsy has a worldwide prevalence of approximately 1% (Berg et al., Handb Clin Neurol 111:391-398, 2013) and is associated with not only lower quality of life but also long-term deficits in executive function, significant psychosocial stressors, poor cognitive outcomes, and developmental delays (Schraegle and Titus, Epilepsy Behav 62:20-26, 2016; Puka and Smith, Epilepsia 56:873-881, 2015). With approximately one-third of patients resistant to medical control, surgical intervention can offer a cure or palliation to decrease the disease burden and improve neurological development. Despite its potential, epilepsy surgery is drastically underutilized. Even today only 1% of the millions of epilepsy patients are referred annually for neurosurgical evaluation, and the average delay between diagnosis of Drug Resistant Epilepsy (DRE) and surgical intervention is approximately 20years in adults and 5years in children (Solli et al., Epilepsia 61:1352-1364, 2020). It is still estimated that only one-third of surgical candidates undergo operative intervention (Pestana Knight et al., Epilepsia 56:375, 2015). In contrast to the stable to declining rates of adult epilepsy surgery (Englot et al., Neurology 78:1200-1206, 2012; Neligan et al., Epilepsia 54:e62-e65, 2013), rates of pediatric surgery are rising (Pestana Knight et al., Epilepsia 56:375, 2015). Innovations in surgical approaches to epilepsy not only minimize potential complications but also expand the definition of a surgical candidate. In this chapter, three alternatives to classical resection are presented. First, laser ablation provides a minimally invasive approach to focal lesions. Next, both central and peripheral nervous system stimulation can interrupt seizure networks without creating permanent lesions. Lastly, focused ultrasound is discussed as a potential new avenue not only for ablation but also modulation of small, deep foci within seizure networks. A better understanding of the potential surgical options can guide patients and providers to explore all treatment avenues.

Posterior fossa decompression for symptomatic Chiari malformation is an effective and frequently performed procedure, but it does carry risks of significant complications including cerebrospinal fluid leak and craniocervical instability. Patients sometimes do not improve or worsen after decompression, which may discourage neurosurgeons from performing Chiari decompression surgery. In this chapter, management strategies and surgical approaches are discussed that minimize the risks of complications and maximize favorable outcomes in Chiari malformation surgery.

Spondylolisthesis is defined as the displacement or misalignment of the vertebral bodies one on top of the other. It comes from the Greek spondlylos, which means vertebra, and olisthesis, which means sliding on a slope. The nomenclature used to refer to spondylolisthesis consists of the following elements: vertebral segment (vertebrae involved), degree of sliding of one vertebral body over the other, the position of the upper vertebral body with respect to the lower one (anterolisthesis/retrolisthesis), and finally the etiology [1].

Pineal lesions represent less than 1% of all brain tumors (Villani et al., Clin Neurol Neurosurg 109:1-6, 2007). The abysmal location and critical neurovascular structures remain a surgical challenge, despite the advent of microneurosurgery. The classical wide surgical suboccipital craniotomy with the supracerebellar infratentorial approach, described by Sir Victor Horsley (Victor, Proc R Soc Med 3:77-78, 1910), is infamous for its considerable surgical morbidity and mortality. This was later upgraded microneurosurgically by Stein to improve surgical outcomes (Stein, J Neurosurg 35:197-202, 1971).Ruge et al. reported the first purely endoscopic fenestration of quadrigeminal arachnoid cysts via this corridor (Ruge et al., Neurosurgery 38:830-7, 1996). A cadaver-based anatomical study by Cardia et al. demonstrated the viability for endoscope-assisted techniques (Cardia et al., J Neurosurg 2006;104(6 Suppl):409-14). However, the first purely endoscopic supracerebellar infratentorial (eSCIT) approach to a pineal cyst was performed in 2008 by Gore et al. (Gore PA et al., Neurosurgery 62:108-9, 2008).Unlike transventricular endoscopy, eSCIT approach poses no mechanical risk to the fornices and can be utilized irrespective of ventricular size. More vascular control and resultant reduction in uncontrolled hemorrhage improve the feasibility of attaining complete resection, especially around corners (Zaidi et al,, World Neurosurg 84, 2015). Gravity-dependent positioning and cerebrospinal fluid (CSF) diversion aid cerebellar relaxation, creating the ideal anatomical pathway. Also, angle of the straight sinus, tentorium, and tectal adherence can often influence the choice of approach; thus direct endoscopic visualization not only counteracts access to the engorged Galenic complex but also encourages sharp dissection of the arachnoid (Cardia et al., J Neurosurg 104:409-14, 2006). These tactics help provide excellent illumination with magnification, making it less fatiguing for the surgeon (Broggi et al., Neurosurgery 67:159-65, 2010).The purely endoscopic approach thwarts the dreaded risk of air embolisms, via simple copious irrigation from a small burr hole (Shahinian and Ra, J Neurol Surg B Skull Base 74:114-7, 2013). The tiny opening and closure are rapid to create, and the smaller wound decreases postoperative pain and morbidity. Recent literature supports its numerous advantages and favorable outcomes, making it a tough contender to traditional open methods.

The treatment of pathologies located within and surrounding the orbit poses considerable surgical challenges, due to the intricate presence of critical neurovascular structures in such deep, confined spaces. Historically, transcranial and craniofacial approaches have been widely employed to deal with orbital pathologies. However, recent decades have witnessed the emergence of minimally invasive techniques aimed at reducing morbidity. Among these techniques are the endoscopic endonasal approach and the subsequently developed endoscopic transorbital approach (ETOA), encompassing both endonasal and transpalpebral approaches. These innovative methods not only facilitate the management of intraorbital lesions but also offer access to deep-seated lesions within the anterior, middle, and posterior cranial fossa via specific transorbital and endonasal corridors. Contemporary research indicates that ETOAs have demonstrated exceptional outcomes in terms of morbidity rates, cosmetic results, and complication rates. This study aims to provide a comprehensive description of endoscopic-assisted techniques that enable a 360° access to the orbit and its surrounding regions. The investigation will delve into indications, advantages, and limitations associated with different approaches, while also drawing comparisons between endoscopic approaches and traditional microsurgical transcranial approaches.

Enhanced recovery after surgery (ERAS) proposes a multimodal, evidence-based approach to perioperative care. ERAS pathways have been shown to help reduce complications, hospital length of stay (LOS), 30-day readmission rates, pain scores, and ultimately surgical costs, while improving patient satisfaction scores and outcomes in multiple surgical subspecialties [1-6]. Numerous specialties have implemented ERAS programs across the globe, providing a foundation for spine surgeons to begin the process themselves. Over the last few years, a significant number of papers have been addressing ERAS pathways for spinal surgery [7-19]. The majority have addressed the lumbar spine [9, 20-26]. The number of cervical ERAS pathways has been limited [27-29]. Many spine programs have begun the implementation of ERAS pathways, incorporating principles and interventions to various spine surgical procedures. Although differences in implementation across programs exist, there are a few common elements that promote a successful enhanced recovery approach [11, 16, 23, 25, 30-33]. All spinal ERAS pathways have three major elements, which are preoperative, perioperative, and postoperative phases. Within these phases some common elements include preoperative and intraoperative surgical checklists. Intraoperative checklist in addition to the "surgical time out" has been integrated into the workflow of most hospitals doing surgeries and have become a standard of care. The surgical checklist is designed to help reduce surgical errors and prevent wrong site/patient surgeries. Several surgical checklists have been developed throughout the years. Despite these safety protocols wrong site/level and other surgical errors continue to occur. Many cases of wrong level spine surgery (WLSS) still occur even when intraoperative imaging is performed [34, 35]. One survey reported that about 50% of spine surgeons have performed at least one WLSS during their career [36, 37]. Another survey reported that 36% of spine surgeons had performed at least one WLSS that was not recognized intraoperatively [38]. On a similar account, about 30% of spine surgery fellows have experienced wrong-site surgery [39]. From raw incidence rates, WLSS may seem rare, but these surveys show that the experience of WLSS is rather common among spine surgeons. WLSS is not yet a "never event." This may be due to poor quality of the intraoperative images, hindering subsequent level identification [34, 35, 38, 40]. Errors in interpretation of the imaging may also occur, including inconsistency in numbering vertebrae, inconsistency in landmark usage for level counting, and problems with numbering vertebrae due to lumbosacral transitional vertebrae (LSTV) and other anatomical variants [34, 38, 41-43]. This chapter will describe a framework for the development and implementation of ERAS pathway for patients undergoing spine surgery. In addition, we will propose preoperative imaging guidelines and a comprehensive spine surgical checklist to incorporate into the perioperative phase to help reduce further surgical errors and WLSS.