Volume 1 • Issue 1 •1000e102 Pain Manage Med, an open access journal Lavano, Pain Manage Med 2015, 1:1 Editorial Open Access Intracranial Neurostimulation for Central Pain Relief Angelo Lavano* Department of Neurosurgery, School of Medicine and Surgery, University “Magna Graecia” of Catanzaro, Avenue Salvatore Venuta-88100, Catanzaro, Italy *Corresponding author: Angelo Lavano, Professor, Department of Neurosurgery, School of Medicine and Surgery, University “Magna Graecia” of Catanzaro, Avenue Salvatore Venuta-88100, Catanzaro, Italy, Tel: +39 09613647389, +39 09613647385; Fax: +3909613647118, +3909613647092; E-mail: lavano@unicz.it, angelolavano@gmail.com Received October 15, 2015; Accepted October 15, 2015; Published October 22, 2015 Citation: Lavano A (2015) Intracranial Neurostimulation for Central Pain Relief. Pain Manage Med 1: e102. Copyright: © 2015 Lavano A. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Editorial Central pain is an expression of a primary or secondary lesion or dysfunction of central nervous system and represents a very difcult condition to treat. Ofen pharmacotherapy allows a beneft clinically important only in a limited number of patients and clinical use of some drugs is rendered problematic by their poor handling and tolerability. Intracranial neurostimulation represents a reversible method of functional neurosurgery, adaptable and free of major side efects, indicated in cases of intractable chronic pain when other conservative treatment modalities have been exhausted. Currently two types of intracranial neurostimulation are commonly used for control pain: deep brain stimulation (DBS) and motor cortex stimulation (MCS) [1]. Te relief of pain with chronic electrical stimulation of deep sensory thalamic nuclei (DBS) was frst reported by Mazars et al. and Hosobuchi et al. [2,3]. Although Europe and the United States over the past 20 years have been several interventions of deep brain stimulation for the treatment of chronic pain syndromes, this method over the years has been gradually replaced by less invasive as spinal cord stimulation, intrathecal infusion pumps and epidural cortical stimulation. Despite this trend, some conditions of chronic pain refractory to drugs still represent a valid indication. DBS may be employed for a number of nociceptive and neuropathic pain states, including cluster headaches, chronic low back pain, failed back surgery syndrome, peripheral neuropathic pain and facial deaferentation pain. Patients are selected for DBS for pain if they experienced chronic pain unresponsive to medical or surgical therapies over many years and to treatment administered during an admission to a pain clinic [4]. Pain pathways are very complex and DBS can modulate these mechanisms of transmission. Te frst pathway is composed of the spinothalamic tracts connecting the dorsal horn of the spinal cord to the ventral nuclei of the thalamus which project to the somatosensory cortices. Te second pathway consists of tracts connecting the spine to the thalamus through the brain stem and the limbic system. Studies on deep brain stimulation for chronic pain in humans increased in the last years, thanks to the efcacy reported in various aetiologies including phantom limb pain [5,6], brachial plexus injury [7,8], central post- stroke pain [7,9], face pain [10,11], spinal injuries or failed back surgery syndrome [7,8]. DBS targets for pain are the septal region [12], the sensory thalamus (VPL and VPM) [6,7], the periventricular grey (PVG) and periaqueductal grey (PAG) [13], the internal capsule, the posterior hypothalamus, the nucleus accumbens [9] and the anterior cingulate cortex (ACC) [8]. Sensory thalamic stimulation is mainly used with varying efectiveness in several chronic pain syndromes with the VPM particularly targeted in facial pain. Te VPM is found between the wall of the third ventricle and the internal capsule. Te VPL is targeted 2-3 mm medial to the internal capsule for the arm pain, and 1-2 mm for the leg pain [10]. Te PVG is placed 2-3 mm lateral to the third ventricle at the level of the posterior commissure and it is targeted for nociceptive pain states. Stimulation of this site also induces some changes of autonomic functions [14]. Te stimulation of ACC is chosen in case of hemi- or whole-body post-stroke pain, although changes in psychological and motor functions have been observed. Tis surgical target is located 20 mm posterior to the anterior tip of the frontal horns of the lateral ventricles. Parameters of stimulation of PAG/PVG and sensory thalamus at low frequencies (<50 Hz) are generally analgaesic and at higher frequencies (>70 Hz) exacerbate pain [15]. Te best parameters of stimulation of ACC are found to be 130 Hz, 450 µs, 4-6.5 V [8]. Te mechanisms of action of DBS in the treatment of pain remain unclear : DBS might act , depending on the structure stimulated, either through inactivation by block neuronal depolarization or through a neuronal activation with increased release of inhibitory neurotransmitters . Whatever the mechanism of analgesia is, the efect of the stimulation is similar to the lesion, except for its reversibility and adaptability. In the stimulation of the somatosensory thalamic nuclei, electrical stimulation inhibits the abnormal neuronal activity that occurs in the VPM/VPL following their deaferentation. Moreover VPM stimulation may work through non-opioid mechanisms and ofer some relief in central pain. In the stimulation of PVG (periventricular gray)/ PAG (periaqueductal grey), stimulation of these neuronal substrates leads to increased CSF levels of endogenous opioids (opioidergic mechanism) [16]. Side efects can occasionally occur in some DBS patients, including seizures, oculomotor symptoms (diplopia, vertical gaze paresis, blurred vision, oscillopsia) and headaches. Infections are also described. Te majority of organisms were Staphylococcus species. Technical problems were reported in all studies, including migration of the electrode, skin erosion and fracture of the insulation. However the rate of these complications has decreased with the redesigned electrode [1,17,18]. A meta-analysis of the literature has shown that 50% to 60% of DBS patients report at least moderate levels of pain relief and/or have continued stimulator use at one year follow-up. Te stimulation of the thalamus is overall less efective while allowing better results in neuropathic pain as that of PVG/PAG has a greater efciency (up to 79%) above the nociceptive pain. Te major indication for DBS is cancer pain and FBSS (67-78% of long-term efcac) while recent data moderately support the use of DBS for post-stroke pain (long-term efcacy no more than 35) [19]. Chronic stimulation of the motorl cortex (MCS) for the treatment of pain was frst reported by Tsubokawa in 1991 [20,21]. Aferwards MCS Journal of Pain Management & Medicine J o u r n a l o f P a i n M a n a g e m e n t & M e d i c i n e