الفهرس Only 14 pages are availabe for public view
 |  | from | 153 |  |  |
| | | from | 153 | | |
Abstract
DBS is a reversible surgical procedure that involves stereotactic implantation of electrodes into the targeted brain regions, used to treat a number of neurological and psychiatric diseases. DBS today is routinely used to treat movement disorders, predominantly PD, ET, dystonia and refractory TS, also used for treating other neurological diseases like chronic pain, epilepsy and CH. Recent studies have demonstrated its importance for treating depression and OCD
DBS uses a surgically implanted medical device, similar to a cardiac pacemaker, to deliver carefully controlled electrical stimulation to targeted areas in the brain. It works by electrically stimulating specific structures that control movement and muscle function.
The mechanism of action of high-frequency DBS is still not clear. submechanisms are probably involved in producing functional inhibition: (1) a jamming of the neuronal message transmitted through the stimulated structure and desynchronisation of abnormal oscillations; (2) extinction or strong inhibition of neuronal firing, supported by direct observation of the decrease in discharge rate during stimulation; (3) dual effects, combining excitation and induction of high-frequency bursts; and (4) inhibition of the production or release of certain neurotransmitters and hormones.
There are two indications for treating PD with DBS: I) for the rare patient with disabling tremor when the VIM thalamus is the target. 2) in the patient with problematic motor fluctuations, including off time and dyskinesias that cannot be managed medically; the subthalamic nucleus is the preferred targetWhen motor fluctuations and dyskinesia cannot be adequately controlled with medications, also DBS of the globus pallidus interna improves all of the cardinal symptoms of PD (tremor, rigidity, bradykinesia) and markedly reduces dyskinesia.
Although pallidal DBS is safe and effective for primary dystonia. secondary dystonia due to brain injury seems to respond poorly, there have been exceptions, whereas other secondary dystonias such as, tardive dystonia has responded very well to pallidal DBS.
DBS has the potential to be an effective therapy in a carefully selected subset of adult patients with TS in which tics are severe and intractable to medical therapy.
DBS of the medial thalamic nuclei and GPi has been tried in the treatment of medically refractory TS
DBS in the VL thalamus, Vim thalamus are the most effective treatments for ET. and both STN- and GPi- DBS improve the tremor associated with PD.
DBS for epilepsy is a functional therapy that avoids many of the adverse effects associated with antiepileptic drug therapy and resective brain surgery.
Studies from the 1950s investigated the use of this therapeutic method for the treatment of chronic pain. However, recent advancements in the techniques of non-invasive brain stimulation have enhanced their modulatory effects and thus become a new, attractive alternative for chronic pain treatment.
DBS of the posterior hypothalamus was found to be effective in the treatment of drug-resistant chronic CH.
Despite the limited studies on the role of DBS for treatment resistant depression, their results have been positive and they have provided the base for future trials to investigate DBS as a treatment for resistant depression.
DBS of the unilateral right NA showed encouraging results in patients with treatment-resistant OCD.
In general, DBS is currently preferred surgical treatment of different intractable disorders, given the adjustability of stimulation parameters and potential reversibility of adverse effects and putatively lesser morbidity, especially in cases of bilateral surgery.