Surgical techniques

Preoperative planning

Inadequate preoperative preparation is often responsible for many avoidable intraoperative adventures. Coming to the operating room with a defined plan, as well as plans for the most common intraoperative problem scenarios is a necessity.

A substantial discussion should be conducted with the patient regarding the type of implant and location of any incisions and visible/palpable components such as a pump or generator. Locations for these should be simulated as best possible with the patient using models, if available. Factors such as belt line height and preferred side of sleeping and wallet pocket should be taken into consideration.

The author believes that imaging should be performed and reviewed preoperatively of any area of the nervous system into which a device implant is planned. The medicolegal community has a multitude of stories of previously asymptomatic anatomic variations/lesions (i.e., thoracic disc bulges, cervical spinal canal stenosis) that became symptomatic upon insertion of a neurostimulation lead or a low lying conus that was inadvertently punctured with a Tuohy needle during pump catheter implantation [ ]. The imaging should include the region of the final implant position as well as any path the implant will travel to reach that location. An MRI of the thoracic spine is adequate for a thoracic paddle lead implant but there should be thoracolumbar imaging for a percutaneous implant. When contemplating a revision of an existing neuromodulation system, a set of X-rays of the entire system is very useful in defining the locations and orientations of the components.

Operative positioning is an often overlooked aspect of preoperative planning. Can the procedure be done from a single position or does it require multiple stages with a position change in the middle? If the plan is for a single position, can the patient be positioned once in a manner that is advantageous for all aspects of the procedure or is there compromise of one aspect to the benefit of another? For instance, if an open approach needs to be performed for spinal lead/catheter implantation but the generator or pump will be placed in the abdomen, does the surgeon want to perform an open spinal approach in the lateral position just so only a single position needs to be used or would it be better to perform the spinal portion in the prone position and then tunnel and implant the abdominal device in a second stage in the lateral position?

Similar considerations drive decisions as to where to implant components such as generators. While no surgeon likes to believe that their implants will ever need substantial revisions, they do occur and initial implant planning should take into account the possibility of a future device revision (above and beyond a simple generator change). For example, if the generator for a cervical spinal cord stimulator is implanted in the anterior infraclavicular incision without use of extension wires, it is almost impossible to revise that device with the patient prone and will need to be done either in multiple stages or in the lateral position (which is difficult both for fluoroscopy of the cervical spine and for performing a revision procedure over the cervical spinal cord).

Importantly, if the procedure is performed under intravenous sedation with an unsecured airway, is the patient positioned adequately to avoid compromising the airway? Blanket rolls and gel rolls may work well to open the lumbar interlaminar space but may cause significant patient discomfort or skin breakdown if placed in certain locations. Patient feedback may be obtained if the procedure is done under sedation but extra care needs to be taken if general anesthesia is used. As the average patient has grown larger, positioning for some individuals on a standard width operating table has also become more precarious. Open spinal surgical tables may be necessary for these people.