Artikel
Chronic dorsal column stimulation for medically intractable orthostatic tremor
Chronische Hinterstrangstimulation zur Behandlung des medikamentös refraktären orthostatischen Tremors
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Autoren
Veröffentlicht: | 23. April 2004 |
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Gliederung
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Objective
Primary orthostatic tremor (POT) is characterized by an intense sensation of unsteadiness and shaking of legs and trunk when standing still. The diagnosis is confirmed by a typical 14-16 Hz burst activation pattern in EMG recordings. If medical therapy fails, the patient's daily activities can become very limited. Here, we have studied the effects of chronic dorsal column stimulation (DCS) on POT as a new therapeutic option.
Methods
Quadripolar plate electrodes (Symmix, Medtronic) were implanted via a limited laminotomy approach with the patients in prone position under intravenous analgesia. Electrodes were externalized for test stimulation for several days. Two patients with POT, a 58-year-old woman and a 72-year-old man were selected for this study. The duration of POT was 10 years in patient 1, and 8 years in patient 2. Patient 1 also suffered from diabetic neuropathic pain. Medical therapy was not effective in both instances. The prospective study protocol included timed measures of the ability to stand still combined with EMG tremor recordings.
Results
Intraoperative electrical stimulation produced paraesthesias of both legs. There were no adverse events. Test stimulation showed that the abilty to stand still improved markedly in both patients. The electrodes were then internalized and connected to implantable programmable impulse generators (Itrel III, Medtronic). Stimulus parameters were gradually adjusted to maximum effect on unsteadiness. Patient 1, who was able to stand still for a maximum of 2 minutes preoperatively, became free of symptoms when standing (amplitude 1.0 V, frequency 100 Hz, duration 210 µs). In patient 2, the ability to stand still was 10 seconds preoperatively, and it increased to 150 seconds (3.7 V, 220 Hz, 210 µs). In both patients, clinical improvement was stable at 1-year follow-up.
Conclusions
Chronic DCS is useful in patients with medically intractable POT. Its effects may be mediated by the modulation of the oscillators responsible for POT via activation of the dorsal columns.