TECHNICAL NOTE - NEUROSURGICAL TECHNIQUES

One-step tunneling of DBS extensions—a technical note

Paulo Linhares & Bruno Carvalho & Rui Vaz

Received: 10 November 2012 /Accepted: 18 February 2013 /Published online: 7 March 2013# Springer-Verlag Wien 2013

AbstractBackground Infection constitutes a serious adverse event indeep brain stimulation (DBS) surgery, being responsible fordifficult therapeutic decisions that may ultimately involvethe removal of implanted material. Some cases begin withskin erosion and wound dehiscence of the retroauricularincision, which is one of the most fragile points. Severaltechniques of rotation flaps and skin reconstruction, as wellas prolonged antibiotic regimens, have been proposed astherapeutic options. To prevent the onset of this complica-tion, the authors propose a one-step tunneling technique ofDBS extensions, avoiding the opening of the retroauricularspace.Methods We describe a surgical technique of a one-steptunneling of DBS extensions in 20 patients submitted tosubthalamic DBS for Parkinson’s disease, avoiding theopening of the retroauricular space.Results After implantation of the extensions using this tech-nique, we had no erosions of the retroauricular skin, with aconsequent reduction in the number of infections.Conclusions The authors describe an easy surgical tech-nique that allows reduction of wound and erosion compli-cations, with great benefits for DBS patients.

Keywords Deep brain stimulation . Skin erosion .

Infection . Parkinson’s disease . Complications

Background

Deep brain stimulation (DBS) is a routinely performedsurgery for treatment of a wide range of pathologies, includ-ing movement disorders, pain, psychiatric diseases and ep-ilepsy [1]. Complications may occur at each step of theprocedure [4]. The most frequent complications found inthe literature are infections, permanent neurological deficits,hardware complications, aborted procedures and periopera-tive mortality [16]. The infection rates are related to manyfactors, including patient’s general medical condition, sur-gical technique, nature of the hardware, duration of surgeryand antibiotic use [14].

Several authors have reviewed infectious complicationsof deep brain stimulator implantation, but the estimate ofinfection risk varies widely, from 0 to 15 % per patient or0 to 9.7 % per electrode [17]. Infection risk on a per-patientbasis was not predicted by patient age, diagnosis, surgeonexperience, or placement of leads in a staged versus simul-taneous manner [17]. Doshi reported an erosion and infec-tion rate of 4.5 % [5]. The most typical complication is thescar above the connection between the electrode and theextension cable (Fig. 1) and its ulterior infection [6, 9–12].The skin erosion exposing the implant is an important causeof infection, and could be related to the surgical technique.This occurs not only in the retroauricular area, but alsoalong the whole length of the DBS hardware, and weightloss and decrease in the subcutaneous fat are probably themajor causes of skin erosion. In our series of patients withskin erosions, this almost invariably began in theretromastoid area. Only a few cases have started in thefrontal area and in the implantable pulse generator (IPG)pouch.

The standard technique includes opening of the skin inthe retroauricular region to pass the tunneling set, and this isthe place where most erosion occurs. To avoid the skin

Prior publication/presentation: This work or any portion thereof has notbeen published or presented in any other journal, conference orseminar.

P. Linhares :B. Carvalho (*) :R. VazDepartment of Neurosurgery, Centro Hospitalar de São João,Alameda Prof. Hernâni Monteiro,4200-319 Porto, Portugale-mail: bmfcarvalho@gmail.com

Acta Neurochir (2013) 155:837–840DOI 10.1007/s00701-013-1667-3

erosion we decided to review the standard technique, andperform a one-step tunneling and describe the technique.

Material and methods

Surgical technique

Patients were put on general anesthesia and positioned indorsal decubitus with the head slightly rotated to the rightside. To allow the one-step tunneling, the left frontal incisionfor electrode placement should be larger and extended to thecoronal plane of the external acoustic meatus (Fig. 2). Theskin incision is made in an arciform fashion, starting in thefrontal parasagittal area, reaching the coronal plane of theexternal acoustic meatus and curving laterally to a planeposterior to the beginning of the medial incision, as shownin Fig. 2. This incision is slightly larger than the contralateralone, generally extending 2.5 cm further posteriorly. Thetunnelizer is passed in one-step, from the frontal incision tothe infraclavicular region, passing about 10 mm behind themastoid process. The muscular fascia reflection in theretromastoid area is the hardest part through which to pass

the tunnelizer. It is very difficult if the tunnelizer has to bebent, because in this situation, considerable strength has to beused. However, with the tunnelizer straight, tunneling be-comes easier, and the strength needed is the same as whenopening a linear incision in the retromastoid area. Indeed, tokeep the rectilinear path, it is essential that the frontal incisionis extended to the plane of the external acoustic meatus. Oncethe tunnelizer reaches the infraclavicular region, the skin isopen in a 10 cm linear incision, exposing the tip (Figs. 3 and 4).A pouch is created to accommodate the IPG.

Results

The 20 patients submitted to this technique showed no skinerosion, and consequently, no infection started at this local.Additionally, there was no reported postoperative neck painand discomfort.

Discussion

As DBS is expanding its indications and regularly beingperformed worldwide, increased recognition of hardware-

Fig. 1 Erosion of retroauricular skin exposing implanted DBS system

Fig. 2 Arciform skin incision starting in the frontal parasagittal areaand reaching the coronal plane of the external acoustic meatus,extending 2.5 cm further posteriorly compared to the contralateralincision

Fig. 3 One-step tunneling technique after extension of left frontalsemilunar incision to the coronal plane of the external acoustic meatus,avoiding retroauricular incision

Fig. 4 Extension cables in place after one-step tunneling technique

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related adverse effects demands new strategies for compli-cation avoidance and management.

As described by Hamani and Lozano [6], the most com-monly reported hardware-related complications are infec-tions (6.1 %), migration or misplacement of the leads(5.1 %), lead fractures (5.0 %), and skin erosion (1.3 %).Erosions may arise not only due to IPG pressure onsubclavicular area, but also from the large size extensionwires into the subcutaneous tunnel and from the parieto-occipital connections on the ipsilateral cranial side.

According to Peña et al. [13], most cases of erosion occurin either the skin along the extension cable tunnel pathwayor the skin over the IPG pocket. This occurs mainly due toprominent hardware and reduced skin and subcutaneoustissue thickness, and it frequently appears over the connec-tor of the IPG site [2, 3, 13]. In this regard, the retroauricularskin is one important susceptible area. Authors have pro-posed lowering the connector profile from scalp to themastoid, or deepening in the subcutaneous tissue behindthe ear; however, increased hardware fracture is a concern[15]. Using occipital bone grooves for extensions accommo-dation has also been reported [7]. Although low-profile con-nectors seemed to diminish the rate of skin erosions, this isstill an important reported complication that may lead toinfection and eventually require the removal of implantedDBS system. In the absence of infection, skin erosions maybe treated as described elsewhere with local surgical proce-dures, including rotation flaps for covering skin defects andwith scalp reconstruction in the area of system exposure.When infection develops, however, prolonged antibiotic treat-ment as well as exchange of system components, or even ofthe entire DBS system, may be required [8]. Of course, skinerosion is not the only and probably not the most importantcause of infection, but lowering this preventable factor isimportant in both clinical and cost-effectiveness.

Much has been written about the surgical techniqueconcerning the cranial part of the surgery. The tunneling hasbeen described as a two steps procedure with a retroauricularaperture, that in our opinion is a sensible area with greatpropensity to erode. This erosion is the first step of an infectionthat ultimately may imply the removal of all of the implantedsystem. In our series of 118 patients submitted to DBS forParkinson´s disease, we have a 5.6 % infection rate due to thissituation leading to the removal of the implanted material.

Taking into consideration the highmorbidity related to skinerosions and its close relationship with infection, we proposethis simplified one-step tunneling technique as a modificationto the classic standard approach, with stated advantages.

We consider that through refinements in surgical tech-nique and technological improvements, such as, for in-stance, antibiotic-coated DBS systems, these devastatingadverse effects may be minimized, allowing optimizationof functional therapeutic benefits.

Conclusion

The authors describe an easy surgical technique that allowsthe reduction of wound and erosion complications in DBSsurgery with great benefits for the patients. In our opinion,maintenance of skin integrity, avoiding areas of weaknessand potential entry sites for infectious organisms, as well asreducing the patient interference with the wound, representsa clear benefit. Despite the absence of retroauricular skinerosions with this method, the claimed reduction in infectionrates has to be confirmed in further prospective studies

Conflicts of interest None.

References

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2. Boviatsis EJ, Stavrinou LC, Themistocleous M, Kouyialis AT,Sakas DE (2010) Surgical and hardware complications of deepbrain stimulation. A seven-year experience and review of theliterature. Acta Neurochir 152:2053–2062

3. Carvallo J, Simpson R, Jankovic J (2011). Diagnosis andTreatment of Complications Related to Deep Brain StimulationHardware. Move Disord Vol. 26(No. 8)

4. Chou YC, Lin SZ, Hsieh WA, Lin SH, Lee CC, Hsin YL, Yen PS,Lee CW, Chiu WT, Chen SY (2007) Surgical and hardware com-plications in subthalamic nucleus deep brain stimulation. J ClinNeurosci 14:643–649

5. Doshi PK (2011) Long-term surgical and hardware-related com-plications of deep brain stimulation. Stereotact Funct Neurosurg89:89–95

6. Hamani C, Lozano AM (2006) Hardware-related complications ofdeep brain stimulation: a review of the published literature.Stereotact Funct Neurosurg 84:248–251

7. Hu X, Jiang X, Zhou X, Liang J, Wang L, Cao Y, Liu J, Jin A,Yang P (2010) Avoidance and management of surgical andhardware-related complications of deep brain stimulation.Stereotactic Funct Neurosurg 88:296–303

8. Lanotte M, Verna G, Panciani PP, Taveggia A, Zibetti M, LopianoL, Ducati A (2009) Management of skin erosion following deepbrain stimulation. Neurosurg Rev 32:111–114

9. Lyons KE, Wilkinson SB, Overman J, Pahwa R (2004) Surgicaland hardware complications of subthalamic stimulation: a series of160 procedures. Neurology 63(Suppl 4):612–616

10. Medtronic: global clinical study report: activa Parkinson’s diseasecontrol therapy 1999: N1-3169

11. Merello M, Cammarota A, Leiguarda R, Pikielny R (2001) Delayedintracerebral electrode infection after bilateral STN implantation forParkinson’s disease. Case report. Mov Disord 16:168–170

12. Oh MY, Abosh A, Kim SH, Lang AE, Lozano AM (2002) Long-term hardware related complications of deep brain stimulation.Neurosurgery 50(Suppl 6):1268–1274

13. Peña E, Pastor J, Hernando V, Gallego I, Pedrosa M, Carrasco R,Sola RG (2008) Skin erosion over implants in deep brain stimula-tion patients. Stereotact Funct Neurosurg 86:120–126

14. Real R, Linhares P, Fernandes H, Rosas MJ, Gago MF, Pereira J,Vaz R (2011) Role of T99mc-Sulesomab Immunoscintigraphy in

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the Management of Infection following Deep Brain StimulationSurgery. Neurol Res Int vol 2011:1–8

15. Sakas DE, Kouyialis AT, Boviatsis EJ, Panourias IG, Stathis P,Tagaris G (2007) Technical aspects and considerations of deepbrain stimulation surgery for movement disorders. ActaNeurochir Suppl 97:163–170

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Comment

The subcutaneous positioning of the so-called "extensions", cablesconnecting the impulse generator with the leads exiting at the frontalbone, is a simple, but time-consuming procedure. An incorrect tech-nique or a complication may compromise results of a complex

intracranial procedure, sometimes requiring several days of planning.More importantly, system infection is a complication leading to systemremoval and return to the preoperative disease status. For this, theauthors should be commended for raising the question of the bestway to perform this procedure. They suggest performing the position-ing of the cables in a one-step cranio-caudal passage. The procedurerequires pushing the tunnelizer for a long tract along the cervical regionto the sub-clavicular area. Due to the diameter of the tunnelizer, whichis large enough to allow the passage of two thick cables, this requires asignificant strength, especially at the level of the muscular fascia in theretromastoid area. It is possible to lose control of the instrument duringthis maneuver, going deep in the muscular plane. Furthermore, thepassage of the instrument in the supraclavicular area seems to be moredifficult this way.

This article has, however, the merit of focusing our attention on anoverlooked step of the DBS procedure. While awaiting for the productsof ongoing research on wireless or micro-impulse generators directlyimplantable on the skull, technical notes on this issue are of definiteinterest to the functional neurosurgery community.

Alfredo ContiMessina, Italy

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