Frequently Asked Questions

The International League Against Epilepsy (ILAE) defines drug-resistant epilepsy as the failure of adequate trials of two appropriately chosen and tolerated anti-seizure medications (whether as monotherapies or in combination) to achieve sustained seizure freedom.

The VNS Therapy™ System is indicated for use as an adjunctive therapy in reducing the frequency of seizures in patients 4 years of age and older with partial onset seizures that are refractory to antiepileptic medications. If your patients have been prescribed multiple medications and are still having seizures, VNS Therapy™ might be right for them. If multiple medications have not given your patients acceptable seizure relief, or they have side effects that are difficult to tolerate, you should consider VNS Therapy™.

Over 125,000 people worldwide have used VNS Therapy™, a proven solution for people with uncontrolled seizures.

A small device (generator and lead) is implanted under the skin in the chest and connected to the left vagus nerve in the neck. This procedure is a short, outpatient procedure that is performed under general anesthesia. The new implant procedure typically takes about 1 to 2 hours.

The procedure typically takes about an hour. It is a short, outpatient procedure which involves two small incisions and is typically performed under general anesthesia.

Many patients report fewer seizures, shorter seizures, less severe seizures, and improved post-ictal recovery time after seizures. People on VNS Therapy also report improvements in mood, alertness, and memory with an overall improved quality of life. 

Doctors have been able to reduce the dose of seizure drugs for some patients. Individual results will vary.

Response to treatment varies for each person. It is recommended that there is a 2-week period before stimulation is turned on. Then a healthcare provider will adjust the settings during routine office visits.The benefits of VNS Therapy™ are not always seen right away. In fact, seizure activity may improve slowly over the first 2 years of treatment. Long-term results from clinical studies suggest that the effects of VNS Therapy™ are significant and last over time.

The VNS Therapy™ system is an adjunctive therapy to existing (prior to device implantation) antiepileptic medications. Physicians are encouraged to keep all antiepileptic medications stable for the first three months of stimulation before attempting to reduce or change a patient's medication.

The most common side effects are voice alteration, increased coughing, pharyngitis, paresthesia, dyspnea, dyspepsia, and nausea. Infection is the most common adverse event of the surgical procedure. The Instructions for Use (IFU) is available here.

The goals of VNS Therapy use are fewer seizures, shorter seizures, and improved post-ictal recovery after seizures.  A small percentage of people (8%) report lasting seizure freedom with VNS Therapy.  Individual results will vary.

Yes, all VNS Therapy patients can get 1.5T and 3T MRI provided that specific guidelines are followed. For more details, please refer to the MRI instructions for use.

Yes, provided that specific guidelines are followed. For more details, please refer to the MRI instructions for use.

The updated labeling enables the use of a body coil for imaging*, which all MRI centers are equipped with, therefore a patient can safely undergo an MRI at any center of their choice.

* For VNS Therapy System Demipulse™ (Model 103) AspireHC™ (Model 105), AspireSR™ (Model 106), SenTiva™ (Model 1000), or SenTiva™ Duo (Model 1000-D) implanted in the upper left chest, at or above armpit

The MRI safety information and Instructions for Use (IFU) can be downloaded here.

All VNS Therapy™ patients can safely undergo an MRI provided that specified guidelines are followed.
The scan conditions and location vary based on:

1. Implanted Generator Model
2. Implanted generator location

In addition to verifying implant generator model and location, the device stimulation needs to be turned OFF which means all output currents set to 0.0 mA for all therapy modes before the patient can get an MRI.

For more details, please refer to the MRI Instructions for Use.

Yes the patient can still receive an MRI. The following guidelines and scan conditions need to be followed:

	Suspected Lead Break or Lead Only ≥ 2cm remaining	Lead Only ≤ 2cm remaining
Exclusion Zone	C7-T8	None
MR Conditional	Yes	Yes
Static Magnet Strength	1.5T or 3T	1.5T or 3T
Operating Mode	Normal Operating Mode**	Normal Operating Mode**
Max Spatial Gradient	≤3000 Gauss/cm *For Model 100 and 101, ≤720 Gauss/cm	≤3000 Gauss/cm *For Model 100 and 101, ≤720 Gauss/cm
Max Slew Rate	200 T/m/s	200 T/m/s
RF Coil	Transmit-receive head or extremity coils only	Transmit: Body or transmit-receive head or extremity coils Receive: No restrictions
Max SAR	Transmit-receive head coil: 3.2 W/kg	Transmit head coil: 3.2 W/kg Transmit body coil: 2.0 W/kg

For more details, please refer to the MRI Instructions for Use.

* Equivalent to clipping the lead at the anchor tether.
** Normal Operating Mode: Transmit Head Coil: 3.2 W/kg, Transmit Body Coil: 2.0 W/kg, Transmit/Receive Head Coil: 3.2 W/kg

Yes. VNS Therapy™ patients can receive an MRI scan of the brain. Refer to the MRI Instructions for Use to see the conditions that apply.

Yes. Prior to getting an MRI, turn device stimulation OFF by programing all output currents to 0.0 mA for all therapy modes:

1. Normal Output Current (mA): 0.0
2. Magnet Current (mA): 0.0
3. AutoStim Current (mA): 0.0 and tachycardia detection to OFF
4. Turn off any other optional device features (Model 1000 and 1000-D only)

MRI scan conditions are based on the type of generator model implanted in the patient and implant location.
The VNS Therapy System (generator and lead) is typically located between C7 and T8 vertebrae in the left chest area. This is the area that must not be scanned. Refer to the MRI instructions for use for more details on Group A and Group B exclusion zones. 

1. Download a copy of the Patient MRI Form. This will help ensure that the radiology center has all information necessary to safely perform an MRI.
2. Interrogate the VNS Therapy™ generator and record the generator settings
3. Perform System Diagnostics to ensure proper operation of the generator
4. Turn device stimulation OFF by programing all output currents to 0.0 mA for all therapy modes:
   1. Normal Output Current (mA): 0.0
   2. Magnet Current (mA): 0.0
   3. AutoStim Current (mA): 0.0 and tachycardia detection to OFF
   4. Turn off any other optional device features (Model 106, 1000, and 1000-D only)
5. Fill out and sign the Patient MRI form. Instruct the patient to bring the following materials to the MRI center on the day of the scan:
   1. The completed Patient MRI Form: Identifies scan conditions
   2. VNS Therapy patient implant card: Identifies implanted components
6. Instruct the patient to notify the MR system operator of any discomfort during the procedure
7. Schedule a follow-up clinical visit after the MRI procedure to program the patient’s therapeutic settings as they were before the MRI procedure.

The patient implant card or the Patient MRI Form will indicate what VNS Therapy model the patient has been implanted with.

The patient’s implanted generator model and implant location can be determined from the Patient MRI Form.
This form, completed by the patient's healthcare professional, provides information about the patient’s implanted VNS Therapy™ system such as implant model and serial number, implant location, and when the device stimulation was turned OFF by programing all output currents to 0 mA.

Input the model number and implant location in the Determining MRI Scan Conditions Tool or refer to the MRI Instructions for Use to determine scan conditions before proceeding with MRI.

The most up to date MRI safety information, guidelines, and precautions are available in our MRI Resource Center.

Yes. After the MRI procedure, an appropriate healthcare professional with access to a VNS Therapy programming system should reprogram the VNS Therapy generator to the patient’s therapeutic parameters as they were before the MRI procedure.

Yes, provided that specific guidelines are followed. For more details, please refer to the MRI instructions for use.

Yes. All VNS Therapy implant models are MR conditional and therefore MRI can be safely performed on patients with VNS Therapy System provided that specified guidelines are followed. For more details, please refer to the MRI instructions for use.

The MRI safety information and Instructions for Use (IFU) can be downloaded here.

Chest x-ray is not required unless generator model type is unable to be determined or there is a suspected history of lead fracture or break.

Yes. For patients with VNS Therapy™ DemiPulse™ generator Model 103, model AspireHC™ Model 105, AspireSR™  Model 106, SenTiva™ Model 1000, and SenTiva™ Model 1000-D implanted in the upper left chest at or above armpit (above rib 4), the isocenter exclusion zone is C7 to L3. For all other VNS Therapy™ System models and implant locations, the isocenter exclusion zone is C7 to T8. VNS Therapy™ System (consisting of generator and lead) located between C7 and T8 vertebrae must not be exposed to the radio frequency (RF) field.

There is a SAR (specific absorption rate) limit with regards to the conditions of use: ≤ 2.0 W/Kg for Transmit Body Coil, and ≤ 3.2 W/Kg for Transmit/Receive head coil for Normal Operating Mode.

For generator models Demipulse™ (Model 103), AspireHC™ (Model 105), AspireSR™ (Model 106), SenTiva™ (Model 1000), and SenTiva™ (Model 1000-D) implanted in the upper left chest area (above rib 4), a body coil or local transmit-receive coils can be utilized for transmitting the RF signal.
There are no restrictions on the type of RF coil used for receiving RF signal.

For all other generator models and implant locations, the use of local transmit-receive coils for imaging of the head or of the extremities is required.

There is no limit as to the number of times that a VNS Therapy patient can be scanned.

There are no restrictions on the use of local transmit/receive coils or transmit only coil for imaging of the head or extremities. For transmit body coil, the exposure time should be ≤ 15 minute of active scan time within a 30 minute window.

All VNS Therapy™ patients can safely undergo an MRI provided that specified guidelines are followed.
The scan conditions and location vary based on:

1. Implanted Generator Model
2. Implanted generator location

In addition to verifying implant generator model and location, the device stimulation needs to be turned OFF which means all output currents set to 0.0 mA for all therapy modes before the patient can get an MRI.

For more details, please refer to the MRI Instructions for Use.

The patient’s implanted generator model and implant location can be determined from the Patient MRI Form.
This form, completed by the patient's healthcare professional, provides information about the patient’s implanted VNS Therapy™ system such as implant model and serial number, implant location, and when the device stimulation was turned OFF by programing all output currents to 0 mA.

Input the model number and implant location in the Determining MRI Scan Conditions Tool or refer to the MRI Instructions for Use to determine scan conditions before proceeding with MRI.