HCP 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.

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 including 35,000 children worldwide have used VNS Therapy, a proven long-term solution for people with uncontrolled seizures.

A small device (generator and lead) is implanted during a short, outpatient procedure that is performed under general anesthesia. The implant procedure lasts from about 1 to 2 hours.

Many patients report fewer seizures, shorter seizures, less severe seizures, faster recovery times after seizures, and a decrease in dosage or number of medications. People on VNS Therapy also report improvements in mood, alertness, and memory with an overall improved quality of life. 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) are available here. 

The goals of VNS Therapy use are fewer seizures, shorter seizures, and faster 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.

Yes, provided that specific guidelines are followed.

The updated labeling allows the use of a body coil for MRI, provided the specific guidelines are followed.

The MRI safety information and Instructions for Use (IFU) are available here.

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

1. Implanted generator model
2. Implant location of the generator

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 Model	Normal Operating Mode**	Normal Operating Mode**
Max Spatial Gradient	≤3000 Gauss/cm	≤3000 Gauss/cm
Max Skew 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 seizure detection to OFF
4. Turn off any other optional device features (Models 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.

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 seizure detection to OFF
   4. Turn off any other optional device features (Models 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.

Information on the type of generator model implanted in the patient can be found on the VNS Therapy programmer displayed after interrogation of the patient’s generator in the device history.

To determine implant location, X-ray may be used to identify the generator position if it is not easily visualized or palpated.

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

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.

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.

The MRI safety information and Instructions for Use (IFU) are available 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.

Please refer to MRI Guidelines for more information. 

There is an SAR limit with regards to the conditions of use: ≤ 3.2 W/Kg for Transmit head coil, ≤ 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 Duo™ (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 recommended.

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 active scan 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 type of scan and the location of the scan that are allowed vary based on:

1. Implanted generator model
2. Implant location of the generator