Brain-Nerve-Computer Interfaces in Otolaryngology Otolaryngologists are concerned with form and function of delicate, intricate structures. Until relatively recently, if a nerve could not be sewn back together or grafted, its function could not be restored. This issue of Otolaryngologic Clinics of North America, devoted to Cranial Nerve Stimulation in Otolaryngology and guest edited by Dr Michael Ruckenstein and Dr James Naples, looks at our specialty as it extends past cranial nerve deficits to reach new frontiers of reactivation, of incorporating biomedical technology to the patient experience.

Cranial Nerve Stimulation for Olfaction (Cranial Nerve 1) Like sensory maps in other systems, the sense of smell has an organizational structure based on converging projections of olfactory receptor neurons containing unique odorant receptors onto the olfactory bulb in synaptic aggregations termed glomeruli. This organizational structure provides the potential for electrical stimulation and restoration of smell. Prior animal and human studies support the feasibility of an olfactory stimulation device, encouraging ongoing work in development of olfactory implants.

Special Considerations in Patients with Cranial Neurostimulatory Implants Over the past 50 years, incredible progress has been made with implantable devices. Management can become complex, as unique issues arise with interaction of these devices with other devices and technologies. The cochlear implant (CI) is the most commonly implanted device in the head and neck. Because of its internal magnet, CIs can interfere with MRI, causing imaging artifacts, pain, and device complications. Other implants demonstrate similar issues with imaging and co-implantation. This article provides an overview of special considerations regarding neurostimulation devices within the head and neck. We focus on interactions between implantable devices and other technologies or devices.

Vagal Nerve Stimulation Vagal nerve stimulation (VNS) therapy is a surgical treatment that involves the implantation of a device to electrically stimulate the vagus nerve. It is indicated as an adjunctive treatment of epilepsy that is refractory to antiepileptic medications and for treatment-resistant depression. The exact mechanism by which VNS achieves its effects is not known, but various mechanisms have been proposed, including afferent vagal projections to seizure-generating regions of the brain and desynchronization of hypersynchronized cortical activity. The most common complications of VNS therapy include hoarseness, throat pain/dysphagia, coughing, and shortness of breath.

Concepts in Neural Stimulation Understanding the mechanisms of neural stimulation is necessary to improve the management of sensory disorders. Neurons can be artificially stimulated using electrical current, or with newer stimulation modalities, including optogenetics. Electrical stimulation forms the basis for all neuroprosthetic devices that are used clinically. Off-target stimulation and poor implant performance remain concerns for patients with electrically based neuroprosthetic devices. Optogenetic techniques may improve cranial nerve stimulation strategies used by various neuroprostheses and result in better patient outcomes. This article reviews the fundamentals of neural stimulation and provides an overview of recent major advancements in light-based neuromodulation.”

Vestibular Implantation and the Feasibility of Fluoroscopy-Guided Electrode Insertion Recent research has shown promising results for the development of a clinically feasible vestibular implant in the near future. However, correct electrode placement remains a challenge. It was shown that fluoroscopy was able to visualize the semicircular canal ampullae and electrodes, and guide electrode insertion in real time. Ninety-four percent of the 18 electrodes were implanted correctly (<1.5 mm distance to target). The median distances were 0.60 mm, 0.85 mm, and 0.65 mm for the superior, lateral, and posterior semicircular canal, respectively. These findings suggest that fluoroscopy can significantly improve electrode placement during vestibular implantation.

Cochlear Implant Cochlear implant is the first approved cranial nerve stimulator that works by directly stimulating the cochlear nerve. The medical and societal impact of this revolutionary device cannot be understated. This article reviews the evolving indications for cochlear implant, patient assessment, surgical approach, and outcomes for pediatric and adult cochlear implant that demonstrate its impact. Future concepts in cochlear implant are introduced briefly. This article covers a breadth of information; however, it is not intended be entirely comprehensive. Rather, it should serve as a foundation for understanding cochlear implant.

The Impact and Evolution of Cranial Nerve Stimulators in Otolaryngology As otolaryngologists, we specialize in the management of various individual organs within an anatomical region. This provides our specialty with a unique opportunity to address a breadth of disorders that are largely related to the special senses and often involve specific input from individual cranial nerves. As such, management of these disorders can be challenging because of the sensitive information being relayed and the complexities involved in cranial nerve signaling. When medical options fail to provide benefit, surgical options become available.

Recurrent Laryngeal Nerve Stimulator Electrical stimulation of the recurrent laryngeal nerve is a safe and promising therapeutic approach with the potentiality to overcome the shortcomings of conventional surgical glottal enlargement. Although aberrant or synkinetic reinnervation is commonly considered an unfavorable condition, particularly for recovery of vocal fold movement, its presence is essential to ensure the effective clinical performance of laryngeal pacemakers. Thus, the effective selection of patients who can profit from laryngeal pacemakers implantation demands the implementation of new diagnostic tools based on tests capable of reliably detecting the presence of viable reinnervation on at least one vocal fold.

Auditory Brainstem Implantation Auditory brainstem implants (ABIs) stimulate the auditory system at the cochlear nucleus, bypassing the peripheral auditory system including the auditory nerve. They are used in patients who are not cochlear implant candidates. Current criteria for use in the United States are neurofibromatosis type 2 patients 12 years or older undergoing first- or second-side vestibular schwannoma removal. However, there are other nontumor conditions in which patients may benefit from an ABI, such as bilateral cochlear nerve aplasia and severe cochlear malformation not amendable to cochlear implantation. Recent experience with ABI in the pediatric population demonstrates good safety profile and encouraging results.