BACKGROUND
Vagal nerve stimulation has become an important treatment for patients with
intractable seizure disorders. Many of these patients will require magneti
c resonance imaging (MRIs) of the brain after the stimulator has been impla
nted to monitor underlying neurologic conditions. Functional MRI (fMRI) is
also being used in the evaluation of epilepsy. With the current recommended
implant techniques the magnetic field of the MRI will deactivate the pulse
generator while the patient is in the supine position for the scan. A simp
le change in positioning of the pulse generator will help to avoid deactiva
ting the device during an MRI. This will avoid exposing the patient to leng
thy time periods with a deactivated stimulator and also allow for the perfo
rmance of fMRIs and any other MRI scans needed to monitor underlying neurol
ogic conditions.
METHODS
A working model of the NeuroCybernetic Prosthesis (NCP(R)) pulse generator
was assessed with an oscilloscope and LED light connected to it that relate
d activation of the generator while in the MRI. This simulation was perform
ed with the device alone, in multiple positions. Then patients with implant
ed devices who could personally confirm the activation of their stimulators
were also studied.
RESULTS
A pulse generator placed with the electrode inputs parallel to the long axi
s of the body was not deactivated by the magnetic field of the MRI when the
patient was in the supine position.
CONCLUSION
Changing the implant position of a vagal nerve stimulator pulse generator w
ill help to prevent deactivation of the device while in the MRI, allowing f
or the performance of fMRIs while not exposing the patient to lengthy time
periods with a deactivated vagal nerve stimulator. (C) 2000 by Elsevier Sci
ence Inc.