Effects of pulse width variations in pallidal stimulation for primary generalized dystonia.
BACKGROUND
Various pulse widths (from 60-450 mus) have been used for bilateral pallidal stimulation in generalized dystonia but, to date, no comparison of this parameter's effects is available.


OBJECTIVE
To provide an analysis of the differential effects of bilateral short, medium and long stimulus pulse width (PW) on clinical improvement in primary generalized dystonia.


METHODS
The most effective therapeutic stimulation parameters were recorded in 22 patients using bilateral pallidal stimulation. Six months after surgery, the effects of bilateral pallidal short (60-90 micros), medium (120-150 micros) and long (450 micros) PWs were studied in 20 of those patients. The effect of the stimulation was assessed by reviewing videotaped sessions by an observer blinded to treatment status (Burke-Fahn-Marsden movement score). Patients were tested on separate days, in random order, for the stimulation conditions (acute effect with the stimulation condition lasting 10 hours). The same contact was used for each stimulation condition. All the electrodes were set at 130 Hz (monopolar stimulation) and the intensity was set individually 10% below the side effect threshold.


RESULTS
Median PWs of 60 (short), 120 (medium) and 450 micros (long) were compared,with a mean intensity of 4.46, 3.45 and 2.47 V, respectively. This study failed to demonstrate any significant difference in the movement scale dystonia mean scores depending on PW.


CONCLUSIONS
According to our findings, short duration stimulus PWs are as effective as longer ones during a 10 hour period of observation. Confirmation of this finding for chronic use could be of importance in saving stimulator energy. Moreover, the use of smaller stimulus pulse widths are said to reduce charge injection and increase the therapeutic window between therapeutic effects and side effects.
Vercueil
Laurent
L
Neurology and Neurosurgery, CHU Grenoble, 38043 Grenoble, France. LVercueil@chu-grenoble.fr
Houeto
Jean Luc
JL
Krystkowiak
Pierre
P
Lagrange
Christelle
C
Cassim
François
F
Benazzouz
Abdelhamid
A
Pidoux
Bernard
B
Destée
Alain
A
Agid
Yves
Y
Cornu
Philippe
P
Blond
Serge
S
Benabid
Alim Louis
AL
Pollak
Pierre
P
Vidailhet
Marie
M
D046690:Deep Brain Stimulation / Q000379:methods*; D004307:Dose-Response Relationship, Radiation; D004311:Double-Blind Method; D004421:Dystonia / Q000628:therapy*; D005500:Follow-Up Studies; D005917:Globus Pallidus / Q000502:physiology*; D006801:Humans; D011446:Prospective Studies; D013997:Time Factors