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The concept of seizure abortion after prompt detection by employing stimulation is a very appealing one. Several investigators in previous experimental and clinical studies have used stimulation of various anatomical targets with promising results. In this chapter, the authors present their experience with a novel, implantable, local closed-loop responsive neuro-stimulation system (RNS) (Neuropace, Inc., Mountain View, CA, USA). This system consists of a cranially implanted pulse generator, one or two quadripolar subdural strip or depth leads and an external programmer. The system components and technical characteristics are presented. The criteria for selecting candidates for implantation as well as the preliminary results of a clinical trial are also presented. Closed-loop stimulation system appears to be a safe treatment option with promising results for the management of patients with well-localized, focal medically-refractory epilepsy, who are not candidates for surgical resection.

Neurosurgical treatment for psychiatric disorders has a long and controversial history dating back to antiquity. Both enthusiastic reports and social outcry have accompanied psychosurgical practice, particularly over the last century. Frontal lobotomy has probably been the only medical advance which was first awarded a Nobel prize in medicine and then irreparably stigmatized by scientific rejection and public criticism. In the present paper, the historical milestones of psychosurgery are briefly overviewed. The particular circumstances of the rise and fall of frontal lobotomy are also discussed. Furthermore, the clinical and surgical considerations of the four major psychosurgical procedures which are still in practice are presented.

Over the last fifteen years, the advent of deep brain stimulation (DBS) methodology coupled with accurate stereotactic techniques and guided by elaborate neuroimaging methods have revolutionized neurosurgery, particularly for the alleviation of certain disabling movement disorders. Investigationally, chronic electrical stimulation of selected brain structures, clearly implicated in the pathophysiology of neuropsychiatric disorders, has already been applied with promising results. Given the tainted past of psychiatric neurosurgery, modern neuroscientists have to move forward cautiously, in a scientifically justified and ethically approved framework. The transition from the indiscriminate destruction of brain structures to the selected electrical modulation of neural networks lies ahead; contemporary neuroscientists would substantiate this aim but should remind the controversial history of the field.

Electrical stimulation (ES) in the brain is becoming a new treatment option in patients with treatment-resistant obsessive-compulsive disorder (OCD). A possible brain target might be the nucleus accumbens (NACC). This review aims to summarise the behavioural and physiological effects of ES in the NACC in humans and in animals and to discuss these findings with regard to neuroanatomical, electrophysiological and behavioural insights. The results clearly demonstrate that ES in the NACC has an effect on reward, activity, fight-or-flight, exploratory behaviour and food intake, with evidence for only moderate physiological effects. Seizures were rarely observed. Finally, the results of ES studies in patients with treatment-resistant OCD and in animal models for OCD are promising.

Neuromodulation of the inferior thalamic peduncle is a new surgical treatment for major depression and obsessive-compulsive disorder. The inferior thalamic peduncle is a bundle of fibers connecting the orbitofrontal cortex with the non-specific thalamic system in a small area behind the fornix and anterior to the polar reticular thalamic nucleus. Electrical stimulation elicits characteristic frontal cortical responses (recruiting responses and direct current (DC)-shift) that confirm correct localization of this anatomical structure. A female with depression for 23 years and a male with obsessive-compulsive disorder for 9 years had stereotactic implantation of electrodes in the inferior thalamic peduncle and were evaluated over a long-term period. Initial OFF stimulation period (1 month) showed no consistent changes in the Hamilton Depression Scale (HAM-D), Yale Brown Obsessive Compulsive Scale (YBOCS), or Global Assessment of Functioning scale (GAF). The ON stimulation period (3–5V, 130-Hz frequency, 450-msec pulse width in a continuous program) showed significant decrease in depression, obsession, and compulsion symptoms. GAF improved significantly in both cases. The neuropsychological tests battery showed no significant changes except from a reduction in the perseverative response of the obsessive-compulsive patient and better performance in manual praxias of the female depressive patient. Moderate increase in weight (5 kg on average) was observed in both cases.

Chronic high frequency stimulation (HFS) of the posteromedial hypothalamus (PMH) has been the first direct therapeutic application of functional neuroimaging data in a restorative reversible procedure for the treatment of an otherwise refractory neurological condition; in fact, the target coordinates for the stereotactic implantation of the electrodes have been provided by positron emission tomography (PET) studies, which were performed during cluster headache attacks. HFS of PMH produced a significant and marked reduction of pain attacks in patients with chronic cluster headache (CCH) and in one patient with short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT). The episodes of violent behaviour and psychomotor agitation during the attacks of CCH supported the idea that the posteromedial hypothalamus could be also involved in the control of aggressiveness; this has been previously suggested, in the seventies, by the results obtained in Sano’s hypothalamotomies for the treatment of abnormal aggression and disruptive behaviour. On the basis of these considerations, we have performed HFS of the PMH and controlled successfully violent and disruptive behaviour in patients refractory to the conventional sedative drugs. Finally, we also tested the same procedure in three patients with refractory atypical facial pain, but unfortunately, they did not respond to this treatment.

Treatment-resistant depression (TRD) is a major public health concern due to its high costs to society. One of the novel approaches for the treatment of depression is the vagus nerve stimulation (VNS). Therapeutic brain stimulation through delivery of pulsed electrical impulses to the left cervical vagus nerve now has established safety and efficacy as an adjunct treatment for medication-resistant epilepsy and has recently been approved as an adjunct long-term treatment for chronic or recurrent depression. There is considerable evidence from both animal and human neurochemical and neuroimaging studies, that the vagus nerve and its stimulation influence limbic and higher cortical brain regions implicated in mood disorders, providing a rationale for its possible role in the treatment of psychiatric disorders. Clinical studies (open-label and comparator with treatment in naturalistic setting) in patients with TRD have produced promising results, especially when the response rates at longer-term (one- and two-year) follow-up time points are considered. Ongoing research efforts will help determine the place of VNS in the armament of therapeutic modalities available for major depression.

The discovery of active mechanisms in the cochlea and the efferent auditory pathways from the brain to the cochlea demonstrated the existence of a modulation of the auditory input in the central nervous system (CNS). Otoacoustic emissions (OAEs) are weak signals that can be recorded in the ear canal and are considered a byproduct of an active process from the outer hair cells (OHCs) to the basilar membrane. The efferent auditory system plays an inhibitory role on the activity of OHCs; its stimulation reduces auditory nerve response, basilar membrane motility and OAEs amplitude. Indirect stimulation by contralateral sound is also inhibitory; a reduction of OAEs amplitude can be recorded and such an effect disappears after olivocochlear bundle section. The efferent system seems to play a role in detection of signals in noise, protection in noise-induced cochlear damage, development of hearing and processing of complex auditory signals. With respect to clinical application, OAEs suppression after contralateral auditory stimulation seems to be the only objective and non-invasive method for evaluation of the functional integrity of the medial efferent system, and, therefore, for evaluation of the structures lying along its course, at least up to the level of inferior colliculi.

The auditory implant provides a new mechanism for hearing when a hearing aid is not enough. It is the only medical technology able to functionally restore a human sense i.e. hearing. The auditory implant is very different from a hearing aid. Hearing aids amplify sound. Auditory implants compensate for damaged or non-working parts of the inner ear because they can directly stimulate the acoustic nerve. There are two principal types of auditory implant: the cochlear implant and the auditory brainstem implant. They have common basic characteristics, but different applications. A cochlear implant attempts to replace a function lost by the cochlea, usually due to an absence of functioning hair cells; the auditory brainstem implant (ABI) is a modification of the cochlear implant, in which the electrode array is placed directly into the brain when the acoustic nerve is not anymore able to carry the auditory signal. Different types of deaf or severely hearing-impaired patients choose auditory implants. Both children and adults can be candidates for implants. The best age for implantation is still being debated, but most children who receive implants are between 2 and 6 years old. Earlier implantation seems to perform better thanks to neural plasticity. The decision to receive an implant should involve a discussion with many medical specialists and an experienced surgeon.

In this article, the authors describe the current state of the auditory brainstem implant (ABI), comparing it to that of the cochlear implant (CI). The CI restores hearing by stimulating the cochlear nerve in the cochlea in patients whose deafness has been caused by inner ear disease; the ABI restores hearing by stimulating the cochlear nucleus of the brainstem in patients who are deaf because of bilateral cochlear nerve dysfunction. Up to now, about 500 patients worldwide have undergone ABI and had their hearing restored, most of whom suffer from neurofibromatosis type 2. Hearing performance, however, is not as good as that offered by the cochlear implant. To improve the quality of hearing, new techniques such as advanced coding strategies and penetrating electrodes, are now being introduced.

The purpose of the auditory brainstem implant (ABI) is to directly stimulate the cochlear nucleus complex and offer restoration of hearing in patients suffering from profound retrocochlear sensorineural hearing loss. Electrical stimulation of the auditory pathway via an ABI has been proven to be a safe and effective procedure. The function of current ABIs is similar to that of cochlear implants in terms of device hardware with the exception of the electrode array and the sound-signal processing mechanism. The main limitation of ABI is that electrical stimulation is performed on the surface of the cochlear nuclei, thereby making impractical the selective activation of deeper layers by corresponding optimal frequencies. In this article, we review the anatomical, and experimental basis of ABIs and the indications, and surgical technique for their implantation. To the best of our knowledge, we describe the first pathology images of the cochlear nucleus in a patient who had received an ABI.