Technique

Surgical Technique of theSupraorbital Key-Hole CraniotomyRobert Reisch, M.D., Axel Perneczky, M.D., Ph.D., and Ronald Filippi, M.D.Department of Neurosurgery, Johannes-Gutenberg University, Mainz, Germany

Reisch R, Perneczky A, Filippi R. Surgical technique of the su-praorbital key-hole craniotomy. Surg Neurol 2003;59:223–7.

BACKGROUNDThe enormous development of microsurgical techniquesand instrumentation together with preoperative planningusing the excellent preoperative diagnostic facilitiesavailable, enables neurosurgeons to treat more compli-cated diseases through smaller and more specificapproaches.METHODSThe technical details of the supraorbital key-hole crani-otomy are described in this article as it has been evolvingin our experience for more than 10 years. After an eye-brow skin incision with careful soft tissue dissection andsingle frontobasal burr-hole trephination, a supraorbitalcraniotomy is carried out with a diameter of about 1.5 �2.5 cm. As a real frontolateral approach, the supraorbitalcraniotomy avoids removal of the orbital rim, the lessersphenoid wing or the zygomatic arch.RESULTS AND CONCLUSIONSThe supraorbital craniotomy allows wide intracranial ex-posure of the deep-seated supra- and parasellar region,according to the concept of key-hole approaches. Thelimited craniotomy requires minimal brain retractionthus significantly decreasing approach-related morbidity.In addition, the short skin incision within the eyebrow,the careful soft tissue dissection, and the single burr holetrephination result in a pleasing cosmetic outcome. ©2003 Elsevier Science Inc.

KEY WORDSMinimally invasive neurosurgery, supraorbital craniotomy,surgical approach, surgical anatomy.

The first supraorbital, subfrontal approach forresection of a skull base meningioma was re-

ported by Fedor Krause in the first volume of hispioneering work Experiences in Surgery of the Brainand Spine, published in 1908 [11]. Since then, vari-ous authors have been describing different modifi-cations to enhance the exposure offered by thesubfrontal route [2,4–7,10,12,14–16,17,18]. How-

ever, in his pioneering description, Krause had al-ready realized the essence of the subfrontal su-praorbital exposure: the suprasellar anatomicstructures are free for surgical dissection from ananterior direction of view and the anterior part ofthe temporal lobe does not obscure the access todeep-seated areas.

In our institution, we have been using the su-praorbital subfrontal approach for more than 10years. During a 5-year period between January 1997and December 2001, there were 511 patients suffer-ing from a variety of tumors and vascular lesionswithin the anterior, middle, and posterior cranialfossa. In this report, we will describe the basicsurgical technique of our supraorbital key-hole cra-niotomy through an eyebrow skin incision.

Surgical TechniquePATIENT POSITIONINGThe patient is placed supine on the operating table;the head is fixed in a three-pin Mayfield holder. Thesingle pin of the head fixator should be placed in theopposite frontal area to allow free manipulation onthe ipsilateral side during the procedure. Position-ing of the head requires that the neck be extendedwith the head above the heart level to facilitatevenous drainage during surgery. Thereafter, thehead is rotated to the contralateral side, the degreeof rotation dependent on the precise location of thelesion. According to the individual pathoanatomicalstructures, for ipsilateral temporomesial lesions a15° rotation is sufficient; however, by choosing thecorrect angle between 30° and 60°, one can alsomake contralateral lesions visible. Note that right-handed surgeons performing a left-sided craniot-omy need more rotation to allow an ergonomicworking position. The maneuver of retroflexion sup-ports gravity-related self-retraction of the frontallobe, but is dependent on the precise anatomic andpathologic situation. Lesions in close proximity to

Address reprint requests to: Dr Robert Reisch, Neurochirurgische Klinikder Johannes-Gutenberg Universitat Mainz, Langenbeckstr. 1., D-55131,Mainz, Germany.

Received July 19, 2002; accepted August 20, 2002.

© 2003 by Elsevier Science Inc. 0090-3019/03/$–see front matter360 Park Avenue South, New York, NY 10010–1710 doi:10.1016/S0090-3019(02)01037-6

the frontal skull base, such as proximal aneurysms,require a retroflexion of 10–15°. Structures situatedmore cranially, such as lesions of the third ventri-cle, need more retroflexion. In addition, the headmay be lateroflected about 10° to the contralateralside, allowing an ergonomic working position forthe surgeon.

ANATOMIC ORIENTATION AND SKININCISIONFor the appropriate eyebrow skin incision the im-portant anatomic landmarks of the osseous skullsuch as the glabella, the frontal paranasal sinus, thesupraorbital foramen, the temporal line, the fronto-basis, the impression of the Sylvian fissure, and thezygomatic arch are precisely defined and markedwith a sterile pen (Figure 1). Special attentionshould be given to the course of the superficialneurovascular structures, such as the supraorbitalnerves and artery. Only then should the borders ofthe craniotomy be marked, taking into consider-ation the position of the lesion and the landmarksdrawn on the skin. After defining the craniotomy,the individual optimum line of the skin incision ismarked with the pen. Usually this skin incision isplaced lateral to the supraorbital nerve runningwithin the eyebrow and extends some millimetersbeyond the lateral edge of the eyebrow. To achievecosmetically acceptable results, the incision mayfollow the orbital rim and should not extend medialto the supraorbital nerve, thereby avoiding frontalnumbness.

DISSECTION OF SOFT TISSUESAfter skin incision, the skin flaps are temporarilyretracted with four stitches, exposing the frontalbelly of the occipitofrontal muscle and the orbicu-lar and temporal muscles (Figure 2). The frontalmuscles are incised with a monopolar electrodeknife parallel to the glabella; the temporal muscle isstripped from its bony insertion (Figure 3). Usingstrong stitches, the temporal muscle is retractedlaterally and the frontal muscle upwards. Note thatthe frontal and orbicular muscles should gently bepushed downwards to the orbit; careful dissectionand minimal retraction of this muscular layer isessential to prevent postoperative periorbitalhematoma.

CRANIOTOMY AND DURAL OPENINGUsing a high-speed drill, a single frontobasal lateralburr hole is placed posterior to the temporal line.Special attention must be given to the placement ofthis burr hole with regard to its relationship to thefrontal skull base and to the orbit. Note that correctplacement of the burr hole, but incorrect directionof drilling may penetrate the orbit and not the an-terior fossa. After minimal enlargement of the holewith fine punches and mobilization of the dura, ahigh-speed craniotome is used to saw a straight lineparallel to the glabella in a lateral-to-medial direc-

1 Artistic drawing presenting the most important an-atomic landmarks of the frontotemporal area such

as the structures of the osseous skull and the superficialneurovascular structures. Note the definition of the skinincision and the supraorbital key-hole craniotomy.

2 After eyebrow skin incision, the subcutaneous tis-sue is dissected upwards observing the frontolat-

eral muscular layer. The skin flap is retracted temporarilywith stitches achieving optimal exposure of the occipit-ofrontal, orbicular, and temporal muscles.

224 Surg Neurol Reisch et al2003;59:223–7

tion, taking into account the lateral border of thefrontal paranasal sinus. Thereafter a C-shaped lineis sawed from the burr hole to the medial border ofthe previous frontobasal line, thus creating a boneflap with a width of about 20–25 mm and a height ofabout 15–20 mm (Figure 4). An important step of thecraniotomy after removal of the bone flap is the

drilling of the inner edge of the bone above theorbital rim under protection of the dura using thehigh-speed drill (Figure 5). After careful removal ofthis inner bone edge, the angle of visualization andmanipulation can significantly increase. In somecases, small osseous extensions of the orbital roofshould also be removed carefully to allow excellentoverview and easy introduction of microinstru-ments into the site. The dura should be opened in acurved fashion with its base toward the supraor-bital rim. The free dural flap is fixed downwardswith two sutures (Figure 6). Other dural elevationsutures are not required.

INTRADURAL DISSECTIONAfter opening the dura mater the first step shouldbe drainage of cerebrospinal fluid by opening thechiasmatic and carotid cisterns. After removal ofsufficient cerebrospinal fluid, the frontal lobe sinksspontaneously, making significant retraction of thefrontal lobe unnecessary. Generally, the self-retaining spatula is left in place as a “brain protec-tor” rather than a brain retractor.

DURA, BONE, AND WOUND CLOSUREAfter completion of the intracranial procedure, thedural incision is closed watertight; interrupted orcontinuous sutures may be employed for this pur-

3 The temporal muscle is stripped from its bony in-sertion and retracted laterally, the frontal muscle is

dissected from the orbicular muscle and retracted up-wards with strong stitches. Note that the orbicular mus-cles should be gently pushed downwards to the orbit.

4 After burr hole trephination behind the temporalline, a straight line is cut with the craniotome from

the burr hole in a medial direction, just parallel to theglabella. Thereafter the craniotomy is completed with aC-shaped sawing line.

5 After removal of the bone flap, the inner edge of thebone should be removed above the orbital rim using

a high-speed drill. After careful removal of this inner boneedge, the angle for intracranial visualization and manip-ulation can significantly be increased. After craniotomy iscompleted, an opening with a width of about 10–25 mmand a height of about 15–20 mm is created.

225Supraorbital Craniotomy Surg Neurol2003;59:223–7

treat more complicated lesions through smaller andmore specific approaches [13,17]. Similar to thepioneering presentation on a small frontolateral ap-proach from Brock and Dietz in 1978 [2], the novelpublications on the subfrontal exposures describelimited skin incision and soft tissue dissection withlimited craniotomy and brain retraction, thus min-imizing the intraoperative trauma to eloquent intra-cranial structures while allowing optimal cosmeticresults [3,4,8,9,12,13,16,17].

In this report, we describe the surgical techniqueof the supraorbital key-hole craniotomy, based onour more than 10 years of experience. The de-scribed approach offers several advantages com-pared to standard craniotomies.

First, the limited supraorbital key-hole craniot-omy allows minimal brain exposure to nonphysi-ologic surroundings such as room air, irrigation,cover material, or spatula pressure. Brain retrac-tion is minimized or even eliminated, thus signifi-cantly decreasing approach-related morbidity andshortening hospitalization. With the key-hole con-cept, despite limited craniotomy and dural opening,deep-seated or even contralateral structures can beadequately visualized. The simple surgical explora-tion significantly reduces the length of the operationwith a dural opening of approximately 10 min afterskin incision. The short skin incision within the eye-brow and the single burr hole trephination behind thetemporal line with correct fixation of the small boneflap during wound closure offer pleasing cosmetic re-sults. Because of the limited skin incision and minimalsoft tissue retraction, the superficial frontotemporalneurovascular structures such as the supraorbitalnerve and artery, the frontal branch of the facial nerveand the superficial temporal artery are preserved. Inaddition, the minimal soft tissue and osseous dissec-tion reduces postoperative orbital and frontotempo-ral swelling, and the excellent blood supply of thesupraorbital area minimizes postoperative wound-healing disturbances.

We express special gratitude to Stefan Kindel for theartistic illustrations and to Janice Roberts for preparation ofthe manuscript.

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