Vagal nerve stimulator (VNS) - implantation

Considerations

Preparation

- Ensure cardiac leads are in place and accurate.
  - If there is one on the anterior left chest, move it to the posterior shoulder.
- Place shoulder roll.
- Mark the two planned incisions, one on the left neck and the other on the left chest.
  - Neck incision is 4 cm, at the level of the hyoid medial to the SCM, and oriented horizontally within a neck crease.
  - Chest incision is 4 cm in the upper left in a Langer (tension) line.
    - The incision will be superolateral to the pocket that will house the generator.
    - For patients with little fat (ie young men), place this incision in an area where you think the generator will sit without much notice.
- Infiltrate the incisions with local anesthetic (lidocaine with epinephrine).
- Prepare and drape in usual sterile fashion with the neck and chest are in one field.
  - Dr. Tran and Dr. Rivero do not use Ioban.

Procedure

1. Make the neck incision with a 15 blade, through the platysma muscle.
2. Raise subplatysmal flaps superiorly and inferiorly, using skin hooks to tent the flap and Bovie cautery alternating with blunt dissection to lift it.
3. Insert a Weitlaner retractor to improve exposure.
4. Skeletonize/release the anterior border of the SCM to expose the deeper contents of the neck.
5. Identify the omoyhyoid muscle and ansa cervicalis nerve.
  1. In cases of difficult exposure, these may need to be transected.
6. Identify the carotid sheath and its contents.

- 1. The vagus nerve will be situated posterolateral to the carotid artery.

1. Dissect the fascia off the carotid sheath to better expose the vagus nerve.
2. Isolate 3 cm of the vagus nerve.
3. Place a silastic sheet underneath the nerve; this facilitates placement of the VNS electrode lead.

- - Use a nerve hook to lift the nerve up and allow the silastic sheet to slide under.

1. Anchor silastic sheet to the surrounding soft tissue with silk sutures x 2.
2. Place a moist sponge over the nerve, then turn your attention to the chest.
3. Incise the chest skin with a 15 blade.
4. Insert a Weitlaner retractor to improve exposure.
5. Carry the dissection down to the subcutaneous fat with Bovie cautery.
6. Dissect a pocket, inferomedially, between the fat and the pectoralis major muscle fascia.

- - Use an army-navy retractor for improved exposure.

1. Enlarge this pocket with finger dissection. The pocket should be large enough to accommodate the VNS generator.
2. Using a curved Schnidt, dissect a subcutaneous tunnel from the neck incision to the chest incision.
3. Pass the "bullet" into this tunnel, from the neck into the chest.

- 1. The "bullet" comes with the VNS equipment.
  2. It is designed to facilitate passage of the electrode wire from the neck to the chest.
  3. Twist the "bullet" cap off; this leaves you with the hollow tube.

1. Place the generator-end of the electrode into the hollow tube.
2. Pull the tube through the subcutaneous tunnel and exiting the chest. This brings the generator-end of the electrode into the chest.
3. Wrap the electrodes around the nerve, using two Gerald forceps.

- 1. There are three sets of coils on the electrode.
  2. Each of these coils has a string attached to each end.
  3. Handle the coils by the string, not the coil itself to avoid damaging it.
  4. Using these strings, wrap the vagus nerve with the coils.

1. Create relaxing loops of the electrode wire so that if it were to be tensed with body movement, this tension would not be transmitted to the coils or the vagus nerve.
2. Secure these relaxing loops with two "anchors" (comes with the VNS).

- - The anchor is placed around the electrode and then sutured to the surrounding muscle (strap, sternocleidomastoid) with Silk.

1. Attach the electrode to the generator.

- 1. The electrode tip should be seen in the transparent casing, just beyond the point where the screwdriver is inserted.
  2. Tighten the connection with the screwdriver that comes with the equipment.

1. Interrogate the device so that it is confirmed to have an acceptable impedance level and a current of zero.
2. Irrigate the chest pocket with antibiotic solution.
3. Place the generator into the pocket and interrogate again to ensure that it's tracking the heart rate appropriately. After this is shown to be acceptable, the device should be turned off by the interrogator.
4. Secure the generator to the surrounding muscle/fascia with Maxon suture.
5. Close the chest and neck incisions in layers, with a running subcuticular Biosyn for epidermal approximation.
6. Place steri-strips and a covered dressing.

Post-op

- Coordinate follow up with the neurologist for programming.
- Dr. Rivero
  - Postop abx not indicated
  - Keep the incisions dry for two days, then it is ok to get them wet.
  - Remove the Tegaderm after 2 days.
  - Keep the steri-strips on for 1 week.
- Dr. Tran
  - Duricef or similar antibiotic for 1 week.
  - Keep the incisions dry for three days, then it is ok to get them wet.
  - Remove the Tegaderm dressing if water accumulates under it.
  - Keep the steri-strips on for 1 week.
- CPT codes
  - 61885 - Insertion or replacement of cranial neurostimulator pulse generator or receiver, direct or inductive coupling; with connection to a single electrode array
  - 64570 - Removal of cranial nerve (eg, vagus nerve) neurostimulator electrode array and pulse generator

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Last updated 7/14/17 FAM.

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