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Frequently Asked Questions

Find answers to common questions about VNS Therapy®

Frequently Asked Questions

Intended Use / Indications

Epilepsy (US) The VNS Therapy® 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.

Depression (US) The VNS Therapy® System is indicated for the adjunctive long-term treatment of chronic or recurrent  depression for patients 18 years of age or older who are experiencing a major depressive episode and have not had an adequate response to four or more adequate antidepressant treatments.

What is the definition of drug-resistant epilepsy?

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.

Who are good candidates for VNS Therapy®?

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.

How many people have used VNS Therapy®?

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

What is the procedure like?

A small device (generator and lead) is implanted during a short, outpatient procedure that is performed under general anesthesia.  The new implant procedure typically takes about an hour.

How long does the procedure take?

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.

What benefits can patients expect with VNS Therapy®?

Many patients report fewer seizures, shorter seizures, less severe seizures, faster recovery times, 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.

Does the device work immediately?

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. Studies show that the benefits of VNS Therapy continue to improve over time, with efficacy seen as early as 3 months.

If patients have VNS Therapy®, will they still need to take medications?

VNS Therapy is not a replacement for medications, nor does it stop patients from trying new ones.  Some of your patients may be able to cut back on their medication number or dosages while on VNS Therapy.

What are the potential side effects of VNS Therapy®?

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.

Will patients be seizure free with VNS Therapy®?

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.

MRI Conditional Status and Labeling

Can all VNS Therapy® patients get a 3T MRI?

Yes, all VNS Therapy patients can get 1.5T and 3T MRI provided that specific guidelines are followed.

Can all VNS Therapy® patients get an MRI?

Yes, provided that specific guidelines are followed.

What is new and improved in the updated labeling?

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) or SenTiva® (Model 1000) implanted in the upper left chest, at or above armpit

Where can I find a copy of the MRI safety labeling and information?

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

Determining Scanning Requirements

What precautions must be taken for my patient to get an MRI?

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.

After performing diagnostics, if there is a suspected lead break or a patient has a lead left from a previous VNS Therapy® System explant, is my patient still eligible to receive an MRI?

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
Suspected Lead Break or Lead Only ≥ 2cm remaining
Lead Only ≤ 2cm remaining
Lead Only ≤ 2cm remaining
Exclusion Zone C7-T8 None
MR Conditional
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

Can my patient receive an MRI scan of the brain?

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.

Does the device need to be turned off before my patient gets an MRI?

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 (Model 1000 only)
How does the type of VNS Therapy® generator model and implant location affect a patient’s eligibility to undergo MRI?

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.

How do I prepare my patient for getting an MRI?
  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 (Model 1000 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.
How will my patients be able to identify themselves having an MRI conditional VNS Therapy system and which model they have been implanted with?

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

Where can I find information on the patient’s implanted generator model and implant location?

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.

Where can I find MRI scanning conditions and/or precautions information?

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

Will my patient be able to continue receiving VNS Therapy after an MRI?

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.

Radiology - MRI Conditional Status and Labeling

Can all VNS Therapy® patients get an MRI?

Yes, provided that specific guidelines are followed.

Is VNS Therapy MR Conditional?

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.

Where can I find a copy of the MRI safety labeling and information?

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

Radiology - Determining Scanning Requirements

Are chest x-rays required before the MRI to confirm VNS Therapy model, implant location, and to ensure no old leads are present?

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.

Are there any parts of the body that cannot be scanned (exclusion zones)?

Yes. For patients with VNS Therapy® generator model AspireHC® Model 105, AspireSR®  Model 106 and SenTiva® Model 1000 implanted in the upper left chest at or above armpit (above rib 4), the exclusion zone is C7 to L3. For all other VNS Therapy® System models and implant locations, the 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.

Are there guidelines for limiting SAR and other parameters?

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.

Does it matter what kind of coil we use?

For generator models Demipulse® (Model 103), AspireHC® (Model 105), AspireSR® (Model 106) and SenTiva® (Model 1000) 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.

Is there a limit to the number of times a patient can be scanned with VNS Therapy system?

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

Is there a time limit for the patient being in the MRI scanner?

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.

What precautions must be taken for my patient to get an MRI?

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.

Where can I find information on the patient’s implanted generator model and implant location?

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.

Would the VNS Therapy® Generator interfere with any other ferrous implants, like rods or joint implant?

Scanning patients who have multiple devices approved for MRI present is acceptable as long as the MR labeling conditions for all implants are satisfied.

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