**7.5 Alzheimer disease (AD)**

*Neurostimulation and Neuromodulation in Contemporary Therapeutic Practice*

DBS like hemorrhage and infection, such trials face ethical issues [40].

brain to thwart propagation of seizure [43].

of multiple sclerosis patients [46].

(dopaminergic therapy is the first). Instability in posture and freezing can be improved by DBS at pedunculopontine nucleus region of the brain [38].

Based on previous studies, there is a general concept of DBS that it can improve PD patients with advance kind of symptoms like motor fluctuation, dyskinesias secondary to chronic levodopa as well as those with refractory and marked tremor. But based on studies of EARLYSTIM findings, DBS can also improve early stages of PD [39]. Due to these advantages of DBS, it is now been under clinical trials for those patients who are eliminated from surgery due to age factor, along with those patients with motor fluctuations in whom medication is effective. Due to the inherent risk of

Earlier it was thought that DBS can switch open resective surgery in epilepsy, but after studies on DBS of the anterior nucleus of the thalamus (ANT), it was stifled. These researches imposed well on the efficacy of DBS but simultaneously also demonstrated that many patients did not attain seizure freedom after the DBS treatment [41, 42]. Closed-loop stimulation is a hopeful technology in epilepsy that can sense seizure activity with electrode and also can send electrical stimulations to

After various studies, DBS was recommended by FDA in 1997 for the initial tremor symptoms of the movement disorder [44]. Along with DBS, other therapies such as lesional surgery have also been used for the treatment of essential tremors. DBS is a better choice due to its safety as well as adjustability of the stimulation, which is not provided by the lesional therapy [45]. Thalamic DBS is used in tremors

DBS had played a crucial role in dystonia treatment [47, 48]. Pallidal DBS, for instance, is the first-line treatment in childhood generalized dystonic disease. The most significant determinant of results was age at which surgery was performed and the duration of disorder [49–51]. Genetic makeup of patients has also been important in evaluating the outcome, as individual with DYT1 dystonia are benefited more than the DYT6 dystonia [52]. Therefore, genetic testing of patients undergoing DBS treatment would suggest which candidate is going to be benefited more [53]. The posteroventral lateral GPi in dystonia is the utmost recognized target for DBS [54]. GPi stimulation offers significant recovery in dystonic patients with adversarial effects on low frequency. The STN and the thalamus are two other targets for DBS. Despite of positive outcomes of STN DBS, the therapeutic use is still restricted [55]. An additional important target is sensorimotor thalamus, which in the age of radiofrequency lesioning, was considered as standard target [56, 57]. The mode of action of DBS in clinical improvement is quite intricate because of delayed and progressive effect exhibited over a period of months. The underlying mechanism for this was hypothesized as the alteration of maladaptive plasticity, progressive motor learning, and modification in pathological oscillatory activity in basal ganglia circuitry [58]. Dystonia can recur within minutes to hours after discontinuation of stimulation during the initial postoperative period; the advantages from stimulation that has been administered for several years can persist for days and weeks after

**36**

**7.2 Epilepsy**

**7.3 Essential tremor**

**7.4 Dystonia**

AD is perhaps the most prevailing neurodegenerative disease but is characterized with years of gradual reduction in neurocognitive parameters. Many DBS strategies have been identified for AD, including areas anterior to the fornix, entorhinal cortex, and the nucleus basalis of Meynert (NBM). Several studies suggest that DBS can affect cognitive function in AD. Nonetheless, outcome influencing factors such as baseline neuroanatomical substrates, surgical technique, placement of lead, and target population choice are the challenges for DBS [62].
