Surgical Placement of Leads for Occipital Nerve Stimulation

Abstract

Occipital electrode placement into the subcutaneous tissues, innervated by and adjacent to the greater, lesser, and/or third occipital nerves from the C2-3 nerve roots for intractable occipital headache syndromes, continues to be an evolving methodology since the first cases were performed in 1993 and reported in 1999. These initial cases described a percutaneous method of wire electrode lead placement, which has been verified and modified among implanters for almost 25 years. Various paddle electrode designs have been implanted with more open techniques in an effort to minimize issues with migration and erosion and maximize tissue contact and electrical conduction into the subcutaneous tissues and adjacent affected nerves. Using text and pictures, traditional percutaneous placement, paddle electrode implantation, and wireless electrode placement will be described and discussed in this chapter.

Keywords

Electrodes, Occipital electrode placement, Occipital nerve stimulation, ONS implantation techniques, Paddle electrode implantation, Percutaneous placement, Wireless electrode placement

Outline
Introduction 529
Trial Stimulation 529
Permanent Implant – Percutaneous Wire Electrodes 530
Permanent Implant – Paddle Electrode 533
Wireless Trial and Permanent Implants 533
Conclusion 534
References 535
Further Reading 535

Introduction

Occipital electrode placement into the subcutaneous tissues, innervated by and adjacent to the greater, lesser, and/or third occipital nerves from the C2-3 nerve roots for intractable occipital headache syndromes, continues to be an evolving methodology since the first cases were performed in 1993 and reported in 1999 ( ). These initial cases described a percutaneous method of wire electrode lead placement, which has been verified and modified among implanters for almost 25 years. Various paddle electrode designs have been implanted with more open techniques in an effort to minimize issues with migration and erosion and maximize tissue contact and electrical conduction into the subcutaneous tissues and adjacent affected nerves ( ). Using text and pictures, traditional percutaneous placement, paddle electrode implantation, and wireless electrode placement will be described and discussed.

Trial Stimulation

Almost all potential candidates for occipital nerve stimulation (ONS) implantation undergo a percutaneous trial electrode placement of up to 1 week or longer to demonstrate initial efficacy and pain control to both the patient and the implanter, thereby justifying a permanent implant. This procedure is usually performed in an outpatient setting with short-acting and/or local anesthesia to minimize patient discomfort. Various insertion methods using Tuohy, Coude (Epimed), or angiocatheter needle devices have been used to place electrodes in the region of affected nerves. A distinct tissue plane is usually readily identifiable below the dermis and above the fascial layer of the upper cervical and skull base musculature. Insertion points can be midline to either side of the suboccipital region, lateral to midline, or lateral to beyond midline to cover the areas of innervated by the occipital nerve tributaries. Traditional starting insertion points has been at the level of C1, extending laterally; however, many implanters now angle the electrode tip toward the mastoid processes to maximize coverage of the various occipital nerve components ( ). Electrode placement typically is seated somewhat beyond the areas of maximal pain complaint in the occipital region so that, when tested for patient response to stimulation during the procedure, the wire(s) can be gently retracted toward the insertion point to maximize subcutaneous paresthesia coverage. The electrodes are then sutured to the skin, covered with watertight dressings for the trial period, and connected to the supplied transmitter ( Fig. 39.1 ).

Following the trial period, the electrodes are removed in the office setting, the patient is interviewed, and a decision is reached regarding permanent implantation. The wounds should be given at least a couple of weeks to heal before an incision is made in the area for permanent implantation to minimize risks of infection. Alternatively, permanent electrodes can be placed and tunneled with extension wires for a trial period, then converted to a total implant with generator placement (implantable pulse generator (IPG)).

Permanent Implant – Percutaneous Wire Electrodes

Most implants are bilateral lead placements at or near the level of C1 with trajectories ranging from zero (straight lateral) to almost 90 degrees toward the vertex of the occipital scalp. The most reasonable placements appear to be at a 30-degree angle, extending superiorly from a horizontal base point. Patient positioning is usually lateral or prone with the head resting on a suitable horseshoe or donut head holder. The issue of airway protection under sedation in some patients will require the lateral position, though generator placement in the lower lumbar/upper buttock region with linear tunneling is most attractive with the patient prone. There is a relatively high incidence of electrode migration ( ), mostly due to tethering of the electrode to a distally placed IPG. Forward bending can produce up to several centimeters of stretch within an electrode system, thereby increasing the risk of backward migration. Though there are no studies regarding IPG placement, reduced migration by IPG implantation into the upper chest region similar to pacemaker placements might be a reasonable alternative. Even more appealing is the development of wireless electrodes without an IPG, which are externally powered via regional radiofrequency connectivity and do not require tunneling ( ). Additionally, newer iterations of IPG technology might allow placement of a smaller, rechargeable IPG in the scalp region, also avoiding significant tunneling and electrode strain.

As of this writing, the use of peripheral nerve stimulator (PNS) implants such as described remains off-label for indications of the craniocervical region.

A stepwise implant method with percutaneous electrode placement is as follows: