Neuromonitoring and Neuromodulation

Among neuroelectrophysiological examinations frequently used by neurosurgeons for topographical or functional monitoring, the blink reflex (BR), which is electrically elicited by stimulation of the supraorbital nerve, is discussed here. The BR consists of an early response (R1) and bilateral late responses (R2; ipsilateral R2 and consensual R2). The late responses are generated by activity of the trigeminal spinal tract and the bilateral ascending branches of the lateral reticular formation. Based on the abnormal R2 patterns, the location of a brainstem blockage could be presumed in the case of a pontine lesion or C-P angle tumor. Different types of BR clinical studies are described. Neuromodulation has recently focused on the treatment of functional disorders such as movement disorder, medically refractory epilepsy and intractable pain. A new substitute therapy for medically refractory epilepsy with vagus nerve stimulation (VNS) using a neurocybernetic prosthesis (NCP) is described. NCP consists of a helical electrode that is planted onto the left cervical vagus nerve and a pulse generator that is placed into a skin pocket over the left chest. VNS therapy is, therefore, less invasive than conventional epilepsy surgery. VNS therapy for epilepsy has resulted in 50% seizure reduction in 50-60% of all patients treated with an NCP system in clinical trials. The mechanism by which VNS acts to reduce epileptic seizures is also described