Revision of vagal nerve stimulation (VNS) electrodes: review and report on use of ultra-sharp monopolar tip.
OBJECTIVE
As a result of the increasingly popularity of vagal nerve stimulation (VNS) for intractable seizures, neurosurgeons not uncommonly encounter cases which require electrode revision. We examine our experience of VNS revision and reports the use of the ultra-sharp monopolar tip for safe dissection and removal of the electrode from the vagus nerve.


METHODS
A retrospective review was performed from January 2000 to Dec 2009 reviewed eight cases of VNS revision.


RESULTS
The indications for VNS revision were device malfunction manifesting with increased seizures or increased impedance of the device and infection. The time from initial VNS implantation to revision ranged from 6 to 108 months (mean: 38 months). The entire VNS electrode system, was removed in seven cases and the helical coils were left in-situ in one case who did not derive any benefit from VNS and it was deemed unnecessary to subject the patient to the additional risk of vagal nerve injury. One case had dislodgement of the lower two coils and three cases had dense scarring to the vagus nerve causing high impedance and malfunction. The other three cases demonstrated no fibrotic scar tissue between the helical coils and the vagus nerve. Four cases had replacement of new VNS system but the case of infected VNS stimulator was not replaced as there was no benefit from the device.


CONCLUSIONS
VNS revision is normally performed in cases of device malfunction or infection and can be safely performed using a combination of ultra-sharp monopolar coagulation and sharp dissection.
Division of Neurosurgery, Suite 1503, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, Canada.
Wai Hoe
WH
Ng
Elizabeth
E
Donner
Cristina
C
Go
Amal
A
Abou-Hamden
James T
JT
Rutka
D000293:Adolescent; D002648:Child; D020878:Device Removal / Q000295:instrumentation* / Q000379:methods*; D004599:Electric Stimulation Therapy; D004566:Electrodes; D004827:Epilepsy / Q000628:therapy*; D004868:Equipment Failure; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D055536:Vagus Nerve Stimulation / Q000295:instrumentation; D055815:Young Adult