TECHNICAL NOTE - FUNCTIONAL

A sine-wave-shaped skin incision for insertingdeep-brain stimulators

Bilgehan Solmaz & Necati Tatarlı & Davut Ceylan &

Yaşar Bayri & M. İbrahim Ziyal & Aşkın Şeker

Received: 13 April 2014 /Accepted: 30 April 2014# Springer-Verlag Wien 2014

AbstractBackground The sine-wave-shaped skin incision is a tech-nique that minimizes skin-related complications near burr holecaps after electrode placement for deep-brain stimulation(DBS).Methods Between 2011 and 2013, 54 DBS electrodes wereimplanted in 27 consecutive patients with Parkinson’s disease(PD), essential tremor, or dystonia. The sine-wave incisionwas used in 26 patients and conventional bilateral linear scalpincisions were used in one patient.Results None of the patients whose operations involved sine-wave-shaped incisions developed hardware-linked complica-tions such as skin infection or skin erosion. The one patientwho underwent conventional bilateral linear scalp incisionsdeveloped a skin infection.Conclusion By preserving the vascular anatomy of the scalpand reducing skin tension at the wound site, the sine-wave-shaped incision promotes wound healing.

Keywords Deep-brain stimulation . Scalp incision .

Neurosurgery . Surgical technique .Wound healing

Introduction

Deep-brain stimulation (DBS) is a surgical method commonlyused to treat Parkinson’s disease (PD), dystonia, essentialtremor, chronic pain, and some psychiatric disorders [4].Some skin incisions that surgeons currently use to place theelectrodes (implants) for DBS can lead to complications. Suchproblems include infection and skin erosions that may neces-sitate removal of DBS implants, and this is especially unfor-tunate when a patient is experiencing clinical improvementafter successful targeting procedures.

This article describes our experience with a sine-wave-shaped skin incision for inserting DBS implants.

Methods

Between July 2011 and July 2013, 54 DBS electrodes wereimplanted in 27 patients at Marmara University Institute ofNeurological Sciences, Turkey. Twenty-two patients had PD,three had dystonia, and two had essential tremor. Convention-al bilateral linear scalp incisions were used in the first patient.After this patient developed a skin infection, we used the sine-wave-shaped incision (see technique description below) forthe remaining 26 patients. Informed consent was obtainedfrom all patients prior to the procedures.

Surgical technique for sine-wave-shaped incision

Ceftriaxone 2.0 g is administered intravenously 30 minutesbefore the skin incision is made. After fixing the frame to thepatient’s head, obtaining magnetic resonance images, and

B. SolmazDepartment of Neurosurgery, Istanbul Education and ResearchHospital, Istanbul, Turkey

N. TatarlıDepartment of Neurosurgery, Dr.Lütfi Kırdar Kartal Education andResearch Hospital, Istanbul, Turkey

N. Tatarlı :Y. Bayri :M. İ. Ziyal :A. Şeker (*)Institute of Neurological Sciences, Marmara University, MarmaraÜniversitesi Nörolojik Bilimler Enstitüsü, P.K.53Başıbüyük-Maltepe, 34840 İstanbul, Turkeye-mail: askinseker@hotmail.com

D. CeylanDepartment of Neurosurgery, Sakarya University School ofMedicine, Sakarya, Turkey

Y. Bayri :M. İ. Ziyal :A. ŞekerDepartment of Neurosurgery, Marmara University School ofMedicine, Istanbul, Turkey

Acta NeurochirDOI 10.1007/s00701-014-2123-8

planning the implant-insertion procedure, the patient is placedin the supine position and the frame is fixed to the operatingtable. The scalp is shaved and cleansed with ethyl alcohol andpovidone iodine solution. A LeksellMultipurpose StereotacticArc (Elekta AB, Stockholm, Sweden) is fixed to a Leksell®Coordinate Frame (Elekta AB, Stockholm, Sweden). Thelocations of the burr holes through which leads will be placedare marked on the scalp bilaterally with the arc ring, usingcoordinates obtained with Medtronic’s FrameLink™ softwarefor the StealthStation® S7® Navigation System (Medtronic,Minneapolis, MN, USA).

A vertical line is drawn at the midline and two straightvertical lines are drawn parallel to midline through the dots thatmark the burr holes (Fig. 1). An incision line resembling a sinewave is then drawn on the skin surface such that the peaksintersect the vertical lines above the burr holes (Fig. 1). Initially,prilocaine 2% is injected to achieve total neural blockade of thescalp, including zones supplied by the supratrochlear, supraor-bital, zygomaticotemporal, auriculotemporal, greater occipital,and lesser occipital nerves. Once this block has taken effect,prilocaine 2 % is injected subcutaneously along the incisionline. Sterile clear plastic drapes are used to prevent infection andto allow communication between the patient and the neurolo-gist. The surgical site is covered with a sterile iodine drape toprevent postoperative wound infection. The incision is thenmade.

The sine-wave shape of the skin incision avoids damage tothe supratrochlear, supraorbicular, frontal, and parietalbranches of the superficial temporal arteries (Fig. 1). Oncethe incision is made, Raney scalp clips are applied to preventbleeding, as opposed to vigorous coagulation of subcutaneousblood vessels using bipolar forceps. The periosteum is

elevated and the location of each burr hole (left and right) ismarked on the surface of the calvarium. Initially, a 14-mmburr hole is drilled on the left side using a Midas Rex® MR7High-Speed Pneumatic Drill system (Medtronic,Minneapolis,MN, USA). The dura mater is incised in a cruciate pattern.Then, to avoid unnecessary cerebrospinal fluid leakage, thedura is attached to the pia mater at four points using bipolarcoagulation. Themicroelectrodes are then inserted through theburr hole and the cerebral cortex is coagulated as necessaryusing bipolar forceps. Once the left implants are placed, thesteps are repeated for the right side. After all microelectrodesare in position, fibrin glue (TISSEEL VH Fibrin Sealant,Baxter AG, Deerfield, IL, USA) is applied to the dural defectto prevent leakage of cerebrospinal fluid. A pulse generator(Soletra 7426 Medtronic, Inc., Minneapolis, MN, USA) isalso implanted the same day.

Results

The median age of the 27 patients was 58.4 years (range, 25–87 years) and the median follow-up time was 9.14 months(range, 3–26 months). During follow-up, only the single pa-tient who underwent conventional bilateral, linear skin inci-sions developed skin infection. There were no skin-relatedcomplications in the 26 patients who underwent the sine-wave-shaped incision.

Discussion

Patients who undergo the insertion of implants for DBS fre-quently develop skin erosions with or without infection at theburr-hole cap area [12]. Such complications may also occur atother sites, such as along the routes of cables, at the connectorsite near the mastoid, and in the area of the pocket where theinternal pulse generator is placed. The literature documents avariety of techniques that are aimed at avoiding skin-relatedcomplications at the burr-hole cap area. Today, the incisionmost commonly used for DBS implant insertion is a bilaterallinear scalp incision, and alternatives are curvilinear, singlesemi-linear, double C-shaped incision, and S-shaped incisions[6, 7, 10].

Clinical studies have revealed no identifiable risk factorsfor skin-related complications after insertion of DBS elec-trodes [9, 13]; however, wound healing involves a complexseries of events that require adequate vascular supply, andnumerous factors can affect the healing process. The scalp issupplied by five pairs of arteries (Fig. 1). Oxygenated bloodreaches the scalp via the external carotid arteries that branchinto the occipital, posterior auricular, and superficial temporalarteries, and via the internal carotid arteries that branch intothe supratrochlear and supra-orbital arteries [7, 8]. This part of

Fig. 1 Figure showing incision lines. A vertical line is drawn at themidline and two straight vertical lines are drawn parallel to midlinethrough the dots that mark the burr holes

Acta Neurochir

the vascular system is a centripetal network made up of largesubcutaneous trunks; therefore, dissection in the subgaleal andsubpericranial plane spares blood vessels and allows largeflaps to be elevated safely. It is widely believed that the scalphas a superabundant blood supply and, thus, is forgiving ofsurgical dissections [11]; however, we developed the sine-wave-shaped skin incision with attention to zones of vascularanastomosis. Our aim in developing this technique was tocreate a specific pedicled skin flap that is supplied by a namedvessel, as opposed to random pattern flaps. This preservesoptimal vascularity for wound healing.

One important barrier to wound healing is excessive ten-sion on closure. When the rubber cap is placed over the burr-hole ring, this causes the scalp to bulge approximately 3 or4 mm [10]. The resultant stretching and continuous compres-sion of the skin caused by the caps and connectors impairsblood supply, predisposing to wound breakdown and infec-tion. Linear scalp incisions, in particular, have been shown tobe associated with higher rates of spontaneous wound dehis-cence and infection because these devices lie directly beneaththe incision [3]. In contrast, a sine-wave incision facilitates amore extensive skin flap over the burr-hole caps and leads,and avoids significant stretching of the skin upon closure.There is less tension at the flap edges on closure, whichfacilitates more efficient wound healing.

Wound healing depends on systemic factors as well as localfactors, and nutrition is an important systemic factor. Ade-quate energy, protein synthesis, micronutrients, and local andsystemic anabolic stimulation are needed for wound healing,but patients with neurodegenerative disorders, such as PD, arefrequently undernourished. Studies have revealed that patientswith PD suffer involuntary weight loss and have lower bodyweight than matched control populations [1]. According to arecent large-scale prospective study, weight loss in PD pa-tients cannot be attributed to decreased energy intake [2].Other research has demonstrated that weight loss in this pa-tient group is primarily due to a loss of fat tissue [1]. Whateverthe reason, these patients lack subcutaneous fat and this couldexplain why PD patients are more likely than other patients todevelop skin complications after placement of DBS implants[5]. Considering these issues, it is important to protect subcu-taneous fat tissue during these procedures, and one way to dothis is to avoid the need for vigorous coagulation with bipolarforceps.

One criticism of the sine-wave-shaped incision is thatthis incision might facilitate extension of an infection fromone side of the scalp to the other; however, most microor-ganisms that cause skin infection are thought to be spreadvia instruments or devices, as in ventriculoperitoneal shuntinfection.

Conclusions

The risk of skin-related infections with the sine-wave-shapedincision technique is no greater than with other incision tech-niques. Further, this method provides wider exposure, makingit easier for neurosurgeons to manipulate and place the DBSelectrodes. The sine-wave shape also results in reduced skintension at the wound site and helps maintain good vascularsupply for wound healing by preserving arteries that supplythe scalp.

Conflicts of interest None.

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