Information Technology Reference
In-Depth Information
Fig. 13.8: Minimum pulse width-amplitude combinations causing tremor suppres-
sion and onset of adverse side effects as found experimentally and reported by Volk-
mann et al. [152]. The
asterisk
shows the pulse width suggested by Volkmann, while
the voltage-doubling limit is a property of the Itrel II and Soletra stimulus generators
reported by Volkmann.
more localized stimulation that it provides [5, 14]. At 6 months postoperatively, the
stimulation parameters require only minor adjustments, as reported by Ashkan [5].
13.5.5 Side Effects
The undesirable side effects of DBS are primarily due to excess current leakage
into adjacent brain centers and include cognitive degradation and severe emotional
disturbances. However, other ill side effects may occur when DBS therapy is ad-
ministered in conjunction with unrelated methods of diagnosis or treatment. For
example, electrodes may be displaced by intense electromagnetic fields during MRI
sessions, thus causing damage to brain tissue and displacing the location of the ap-
plied stimulus. Also, temperatures may become dangerously high during the admin-
istration of therapeutic diathermy (tissue heating), thus resulting in massive trauma
or death [115, 131].
13.6 Biosignal Processing
All biological processes associated with perception and limb movement involve
measurable electrical phenomena. Moreover, depending on where and how a mea-
surement is taken, the recorded signal will exhibit particular characteristics [65,
144]. Typically, biosignal processing involves the analysis and classification of
