Stimulation-related adverse effects

Stimulation-related adverse effects at levels of stimulation needed for tremor control usually occur due to suboptimal DBS lead location or failure to select the most optimally located electrode on the DBS lead for stimulation. Stimulation-related adverse effects for DBS in the region of the Vim include paresthesia, dysarthria, incoordination, pain, asthenia, abnormal thinking, and headache.^7,9

Tremor medication adjustments

If patients are treated with unilateral Vim stimulation, anti-tremor medications are usually maintained, if tolerated, to help treat tremor on the other side of the body. If the patient is treated with bilateral Vim DBS or if the tremor on the opposite side is not disabling, anti-tremor medications should be gradually tapered and discontinued.

Follow-up

Once optimal parameters are determined, patients are seen every 6–12 months for evaluation and minor adjustments, if necessary. Often, stimulation parameters remain remarkably stable over time and provide excellent tremor suppression for many years.

In a minority of cases, efficacy may wane over time, usually because the DBS lead location is not ideal. Some loss of tremor control can occur due to disease progression; however, this can often be corrected by a gradual increase in the amplitude of stimulation or addition of an extra active electrode.

Patient instructions

The neurostimulator can be turned off by the patient using the patient programmer. In addition, the patient programmer allows the patient to check the status of the battery and adjust the parameter settings if necessary.

To prolong neurostimulator battery longevity, ET patients are usually instructed to turn the device off at night, since their tremor will cease with sleep and respond quickly the following morning when the device is turned back on. In patients with bilateral treatment, if significant speech or gait abnormalities occur with both stimulators on, consider having the patient keep one side of stimulation off when speaking or walking to eliminate these adverse effects and both sides on while they are seated and working with both hands. Alternatively, in appropriate patients, they can be taught to toggle between different pre-programmed settings.

Management of other forms of tremor

Although Vim DBS is approved in the United States by the Food and Drug Administration only to treat tremor caused by ET and Parkinson’s disease, it has been used in an attempt to control other forms of tremor, such as that associated with stroke, multiple sclerosis, and traumatic brain injury.¹ In general, the management of these other forms of tremor is similar to that described for ET.