Reconstruction of Scalp and Forehead Defects

Abstract

The scalp and forehead are a specialized area of skin that protects the skull, and they differ based on color, long hair, and esthetic appearance. The skull bone is a subcutaneous bone that gets exposed after trauma, electric burn, infection, and following scalp tumor excision. Long-term exposure to the skull may lead to life-threatening complications, such as brain abscess or meningitis. Options of coverage of scalp defects based on its location, depth, size, need for radiation, surrounding skin condition, and esthetic appearance. Partial or complete removal of skull bone may be required, depending on the bone’s condition and the disease’s nature. Options for cranioplasty rely on the size, location of the skull defect, and need for radiation. Most scalp defects can be managed with local scalp flaps with or without skin grafting at the donor site. Local flaps provide esthetic results because of their architectural similarity to the recipient site.

1. Introduction

The scalp and forehead are multilayered structures covering the skull. Physically, it protects the cranium from external forces, controlling the temperature, and is esthetically vital due to the presence of long hairs and involvement in facial expression. Defects in this region may be superficial, leaving intact pericranium, for example, trauma, avulsion injuries, thermal burn, skin infection, and following excision of benign skin lesions [1, 2]. Avulsion injury of the scalp is common in female workers because of long hair [3]. The high vascularity of the pericranium allows coverage with a skin graft in the superficial defects. Deep wounds usually occur after electric contact burn, excision of malignant skin tumors, high forced avulsion injuries with exposure of skull bone, or even loss of bone segment with exposure of dura or brain. Reconstruction of these deep wounds is challenging for plastic surgeons, neurosurgeons, and oncosurgeons. Because of the thick galea layer, even primary closure of small scalp defects is difficult, so surgeons should have experience with all reconstructive procedures [4]. Reconstructive options for coverage include primary closure, secondary healing, skin grafting, local flaps, regional flaps, tissue expansion, and free tissue transfer [5]. Essential factors, such as defect size, location, components, need for radiation, hairy or non-hairy nature of skin, surrounding tissue condition, and the potential for hairline distortion should be considered while selecting the coverage technique [6, 7, 8]. In addition, the basic knowledge of vascularity, innervation, components, and skin mobility in different areas is necessary while dealing with tissue loss in this region. Priority should be reconstruction with local flap with primary closure of donor site or grafted donor site placed in the less cosmetic area, resulting in a better esthetic outcome. Free tissue transfer is a time-consuming procedure and carries higher donor site morbidity than local flaps, unsuitable for high-risk patients.

2. Anatomy of the scalp and forehead

The scalp and forehead are usually considered a single unit but differ in color, texture, esthetic subunit, hair growth length, and pattern. The layers of tissue are almost similar in both areas except the galea layer of the scalp, replaced by the frontalis muscle in the forehead. The knowledge of vascular and nerve supply is helpful during the planning of reconstructive techniques without damaging the motor and sensory supply, especially in the forehead area, and identification of the recipient’s vessel for free tissue transfer.

2.1 Scalp

The scalp is formed by five layers, which can be remembered by the mnemonic SCALP: Skin, subcutaneous fat, galea aponeurotica, loose areolar tissue, and pericranium. Scalp skin is thickest in the body and carries long hairs, posing difficulties while reconstructing with similar tissue. The subcutaneous fat layer contains the hair follicles, blood vessels, and fibrous septa, which connect the skin to the galea. Any dissection superficial to galea causes damage to hair follicles and excessive bleeding. Galea aponeurotica connects the frontalis muscle anteriorly and the occipital muscle posteriorly. Laterally, it continues as temporoparietal fascia and is confluent with the superficial musculoaponeurotic system of the face. Loose areolar tissue beneath galea aponeurotica allows the avascular plane for dissection. The temporal branch of the facial nerve runs in the temporoparietal fascia and gets protected while raising the bicoronal flap in this loose areolar plane [9]. The pericranium is the deepest layer covering the skull bones except at the temporal region, where it is fused with the deep temporal fascia, which covers the temporal muscle. The calvaria comprises eight bones formed by intramembranous ossification (frontal, paired parietal, and paired temporal bones) and endochondral ossification (occipital, ethmoid, and sphenoid bones). These bones are fused by four sutures named metopic, coronal, sagittal, and lambdoid. The calvaria has three layers: an outer table, a diploic space, and an inner table. The superior sagittal sinus is the most superficial sinus that runs in the midline under the sagittal suture and needs care while doing bony debridement in this region.

2.2 Forehead

The forehead is the upper part of the face, bounded superiorly and laterally by the anterior hairline and inferiorly by the supraorbital margin. It contains the paired frontalis muscle, which elevates the eyebrows and blends with the procerus medially, the corrugator centrally, and the orbicularis oculi laterally. A temporal branch of the facial nerve innervates the frontalis and corrugator muscles, whereas the deep buccal branch of the facial nerve innervates the procerus.

2.3 Arterial supply

The scalp and forehead supply blood from paired supraorbital, supratrochlear, superficial temporal, posterior auricular, and occipital arteries. Supraorbital and supratrochlear arise from the ophthalmic artery, the first branch of the internal carotid artery, and other arteries are branches of the external carotid artery.

2.4 Venous drainage

Supraorbital and supratrochlear veins form the angular vein and drain into the facial vein. The superficial temporal and maxillary veins form the retromandibular vein, which divides into anterior and posterior divisions. The anterior division combines with the facial vein and includes a common facial vein, which drains into the internal jugular vein. The posterior division combines with the posterior auricular vein and forms the external jugular vein, which drains into the subclavian vein. The occipital vein drains into the suboccipital plexus.

2.5 Sensory supply

The paired sensory nerves of the scalp and forehead include supratrochlear (V1), supraorbital (V1), zygomaticotemporal (V2), auriculotemporal (V3), lesser occipital (C2–C3), and greater occipital (C2) nerves. The supraorbital and supratrochlear nerves supply the forehead and frontoparietal region of the scalp. The zygomaticotemporal nerve supplies the region laterals to the brow and the temporal area of the scalp up to the temporal line. The auriculotemporal nerve supplies the lateral scalp region, and the greater and lesser occipital nerves supply the occipital region.

2.6 Lymphatic drainage

The part anterior to the ear drains into preauricular and parotid lymph nodes, whereas the part posterior to the ear drains into postauricular and occipital lymph nodes.

2.7 Etiology

The scalp and forehead defects usually arise after traumatic injury, including avulsion, tumor resection, congenital, electric, thermal burn, infection, and post-radiation [10]. Trends of traumatic injuries are increasing due to the rise in roadside accidents and workplace injuries. Total or partial scalp avulsion injuries are more common in females because of long hairs [3]. The scalp and forehead are also common skin cancer sites because they are directly exposed to sunlight [5]. Many benign and congenital pathologies require excision followed by reconstruction. High voltage electric burn over the scalp is common in developing countries, causing exposure of skull bone. Radiation following tumor excision of the scalp or brain causes dehiscence of the suture line and ulceration, even exposure to implants [11].

2.8 Esthetic consideration of the scalp and forehead

The scalp is a single esthetic unit having thick hair-bearing skin demarcated by the anterior and temporal hairline. Preserving the hairline is a must while doing local flaps to cover the scalp and forehead defects. The direction of hair growth varies in the different anatomical areas of the scalp, so incisions should be planned parallel to them, and minimum use of electrocautery to prevent visible scarring. The frontal, parietal, and vertex are more of a cosmetic concern than the temporal and occipital areas. Historically, the forehead has been subdivided into one central unit, two temporal units posterior to the anterior temporal crest, and two eyebrow units along the supraorbital rims. Recently, the forehead has been subdivided into paramedian, lateral, and lateral temporal subunits [12].

2.9 Assessment of the defect and treatment planning

A detailed history and local examination are essential before selecting a reconstructive technique. Associated medical conditions, such as diabetes, hypertension, smoking, coronary artery disease, and asthma, should be assessed along with previous surgery and radiation history. In clinical examination, defect size, location, depth, surrounding skin condition, hairy or non-hairy nature of skin at the defect site, and potential for hairline distortion should be kept in mind. Defects following trauma and benign lesion excision are primarily superficial and can be managed with skin grafting if not able to closed with similar local tissue. Oncological resection is usually deep and requires the removal of bone, which may be reconstructed immediately along with a flap cover or in the second stage. Long-standing exposure of skull bone in electric contact burn also necessitates the removal of partial or complete bone followed by flap coverage [13]. Dural defects must be repaired with artificial patches or a non-vascularized fascial graft. Small defects at the forehead and scalp are manageable with primary closure or local flaps. Mobility of skin and availability of arc of rotation is less in the central region, which necessitates the closure of the medium-sized defects by a double rotation flap compared to the peripheral area, where a single rotation flap can cover. A skin graft is acceptable for the defect at the non-hairy scalp. Coverage of large scalp defect with a transposition flap necessitates skin grafting at the donor site, which should be kept in a less esthetic place (temporal, occipital) so that nearby long hairs can cover the skin-grafted area. In avulsion injuries, you may sometimes find an injured vascular pedicle, necessitating using a vein graft or arterio-venous loop to use recipient vessels outside the trauma zone for reimplantation or free tissue transfer (Table 1).

Wound characteristics	Consideration
Location of the defect	Forehead; Central; Lateral; Scalp; Frontal; Parietal; Vertex; Temporal; Occipital; Combined
Size of defect	Small (<4 cm^2); Medium (4–50 cm^2); Large (50–200 cm^2); Very large (>200 cm^2)
Depth	Subcutis; Pericranium; Bone/implant; Dura; Brain
Surrounding structure	Nearby scarring; Hairy or non-hairy skin; Hairline and brow position

Table 1.

Factors determining selection of graft.

3. Reconstructive options

3.1 Primary closure

The scalp wound up to 3 cm in diameter is considered amenable to primary closure [14]. The galeal layer is a rigid structure with limited mobility, so wide skin undermining is required to close the defect primarily in a tension-free manner. Galea scoring perpendicular to the line of maximum tension and parallel to the subaponeurotic blood vessel is also helpful in facilitating tension-free closure [15, 16].

The forehead skin is mobile, and slight undermining in the subcutaneous plane results in the primary closure of the small defects. The horizontal scar along the natural crease is cosmetic appealing but has the risk of upliftment of brow position. Vertical closure avoids this problem but decreases the distance between eyebrows when tried in the glabellar region. The Limberg flap maintains the inter-eyebrow distance, transposing the nearby skin at the defect site (Figure 1). Linear closure after elliptical excision has a long scar, which can be avoided using “M” plasty.

Figure 1.

A. Scarring over forehead following Bindi application; B. Excision of scar and coverage with Limberg flap.

3.2 Secondary healing

Healing by secondary intention can be allowed for very small scalp defects without exposure to the bone in a hairless area [14]. However, most reconstructive surgeons do not consider this method as it causes bald scars. Superficial burns and abrasions usually heal by secondary intension, but daily dressing is needed for an extended period. Conservatively managed post-traumatic and burn wounds over the forehead produce a shift of hairline and eyebrow position due to wound contraction (Figure 2). The upward shift of the eyebrow may pull the eyelid tissue. A vacuum-assisted closure device helps to fasten the wound contraction in chronic nonhealing wounds with continuous discharge (Figure 3).

Figure 2.

A. Postburn scarring on the left side of forehead causing eyebrow and lid upward pull; B. Correction of lid deformity by Z plasty at lateral canthal region and skin grafting after the release of brow pull.

Figure 3.

A. Infected wound over the scalp with recurrent dehiscence; B. Promoting secondary healing by vacuum-assisted closure device.

3.3 Skin grafting

Skin grafting may be considered for large-sized defects at the forehead and scalp area, which cannot be covered by local flaps with primary closure of the flap donor site. The lateral forehead, temporal, and occipital regions are of less cosmetic importance (Figure 4), and defects in this region can be resurfaced with skin grafting. Preservation of pericranium is a prerequisite for skin grafting. The disadvantage of this procedure are scar alopecia, instability in the long term, and not suitable for radiation therapy. These skin-grafted areas can be replaced by expanded flaps from nearby areas later for cosmetic reasons. Skin grafting suits patients with comorbidities who can not tolerate major surgeries. A free split-thickness skin graft can be done after drilling down to the diploic layer of bone to improve the granulation process for coverage of broad defects more significant than 100 cm² with loss of pericranium when other options are not feasible [17]. The use of a dermal regenerative template has also been described after removing the external table to improve the cosmetic outcome and durability of the graft [18, 19]. However, the increased cost of treatment and risk of infection are there. Combined vacuum-assisted closure dressing and a dermal regenerative template can improve wound beds when vital structures are exposed to scalp wounds [20].

Figure 4.

A. Scalp avulsion injury over the occipital region with a defect size of 12 × 10 cm; B. Skin graft application over intact pericranium.

3.4 Local flaps

Local scalp tissue arrangement can cover small- to medium-sized defects with donor area closure. Defects up to 50 cm² in the peripheral (temporal, parietal, and occipital) region allow coverage with a single rotation flap (Figure 5) because making a wide arc of rotation is possible [13]. Planning of double opposing rotation flaps (Figure 6) is needed for the similar-sized defects at the vertex regions. The arc of the rotation flap must be marked at the periphery four to five times the defect margin, ensuring primary closure of the donor area. The rotation flap requires a wide undermining and long incision and is time-consuming compared to the transposition flap. Therefore, it should be avoided in unstable patients. Injecting an adrenaline solution of 1:200,000 dilution at the marking site reduces blood loss, and the flap is elevated in the avascular plane with the preservation of the pericranium. Backcut at the pivot point toward the flap base and galea scoring is advisable for tension-free closure.

Figure 5.

A. Benign skin lesion at right parietal region; B. Excision of the lesion and coverage with a single rotation flap.

Figure 6.

A. Exposed skull bone following post-electric contact burn; B. Debridement and coverage with double rotation flap.

The central forehead defects need coverage with an O-T flap with a transverse incision along the hairline when defects are located at the middle and upper parts (Figure 7). For defects at the lower part of the forehead, transverse incisions need to be made just above the eyebrow to avoid approximation of the medial end of the eyebrows. Lateral forehead defects can be covered with a worthen flap [21] or temporoparietal fascia flap with an overlying skin graft (Figure 8). The temporoparietal fascia flap has a wide arc of rotation from the postauricular region to the lateral forehead. This fascial flap is supplied by a temporal branch of the superficial temporal artery, which runs just under the surface of the fascia. The plane of dissection between skin and fascia is demanding; too superficial dissection and excessive use of electrocautery may result in postoperative alopecia. Temporoparietal fascia with the temporal skin strip can be used for eyebrow reconstruction where the skin is scarred and not suitable for hair grafting (Figure 9). The temporalis muscle, supplied by the deep temporal artery, is a valuable flap for resurfacing the orbital cavity following exenteration. A piece of bone can be elevated along with the temporalis muscle, with its deep fascial extension used in various facial reanimation procedures.

Figure 7.

A. Mid forehead defect of size 5 × 5 cm following excision of an unstable scar; B. Coverage with O-T flap.

Figure 8.

A. Basal cell carcinoma at right lateral forehead; B. After excision of the lesion defects size of 7 × 6 cm and exposed bone; C. Raised temporoparietal fascia flap; D. Coverage of the defect with fascial flap and overlying skin graft.

Figure 9.

A. Postburn eyebrow loss with surrounding scarring; B. Brow reconstruction with temporoparietal fasciocutaneous flap.

There are large defects where the donor site cannot be closed using a rotation flap; a transposition flap is suggested. The length of the transposition flap should be from the flap’s pivot point to the defect’s farthest point with a length-to-width ratio of up to 1:1 to 1:3 with the named vessel at the pedicle base. When the length-to-width percentage increases more than 1:3, or the flap distal margin crosses the midline, planning a bipedicle flap is advisable to increase the flap’s vascularity. The bipedicle fronto-occipital (Figure 10) and temporo-temporal (Figure 11) flaps are supplied by named vessels at both ends and have a wide coverage scale. The dog ear at the flap base in the transposition flap should not be excised immediately because it would narrow the pedicle and decrease its blood supply. The donor site of the transposition flap needs skin grafting. The donor site of the transposition flap at the less cosmetic and bald area (Figure 12) provides acceptable results [13].

Figure 10.

A. Necrotic scalp skin following avulsion injury left temporoparietal region; B. Debridement and coverage with bipedicle fronto-occipital flap with skin graft at the flap donor site for defect size of 18 × 10 cm.

Figure 11.

A. Post-electric contact burns with exposed skull bone at frontoparietal region; B. Defect covered with bipedicle bucket handle flap and skin graft at the flap donor site.

Figure 12.

A. Squamous cell carcinoma on the right parietal region; B. 8 × 8 cm size defect after wide local excision; C. Coverage with transposition flap from the bald area; D. 3 months postoperative result.

The galeopericranial, pericranial, and galeal flaps are highly reliable and versatile for anterior skull base defect reconstruction to prevent cerebrospinal fluid leaks and brain herniation [22, 23]. The pericranial flap is routinely used to obliterate the nasofrontal duct following cranialization of the frontal sinus (Figure 13). These flaps are designed to have a base toward the defects. They are elevated during the bicoronal flap elevation. Split calvarial bone grafts with pericranial flap have been described for reconstructing large anterior skull base defects.

Figure 13.

A. Cranialization of the frontal sinus and elevation of the pericranial flap; B. Fixation of the anterior table after blockage of the nasofrontal duct with pericranial flap.

3.5 Regional flaps

Due to limited reach, the regional flap is restricted to the occipital and lateral forehead regions. Expanded flap from face usually advanced to lateral forehead in managing the postburn scarring. Extended supraclavicular, pectoralis major, and latissimus dorsi flap have been described to cover the lateral face and forehead. A lower trapezius musculocutaneous flap is commonly performed to protect the occipital defects with exposure of bone and implants. These distant pedicle flaps, such as trapezius, pectoralis, and latissimus dorsi myo-cutaneous flaps, are marked on the distal point of flap territory to maximize the reach, which also increases the chances of flap ischemia. Other disadvantages of distant flaps are non-hairy, poor skin color match, thick pedicle, and bulky skin paddle [24].

3.6 Microvascular reconstruction

Local and regional flaps cannot cover extensive scalp defects >200 cm² area. In these conditions, free tissue transfer is indicated for the best outcome. Free tissue transfers are mainly required after post-tumor resection with loss of pericranium or calvarial defect with exposed dura. Other indications are extensive avulsion injury and electric contact burn of the scalp and forehead. Latissimus dorsi muscle flap, anterolateral thigh flap, para scapular flap, rectus abdominal flap, radial forearm flap, etc., are some commonly used free flaps for scalp and forehead reconstruction [25, 26, 27]. Among the free flaps, muscle flaps with an overlying skin graft are less bulky than fasciocutaneous flaps and provide better contour. Free latissimus dorsi is a workhorse flap in scalp reconstruction (Figure 14) with a broader scale of coverage and acceptable donor site morbidity. Fasciocutaneous free flaps are preferred when the calvarial bone is reconstructed using titanium mesh implants because there are no chances of atrophy, scarring, and better postoperative radiation toleration [28]. Fasciocutaneous flaps are also preferred for forehead reconstruction and when secondary cranioplasty is planned. The esthetic outcome of free flaps is lower when compared to local flaps but more than skin grafting.

Figure 14.

A. Near total scalp avulsion with exposed skull bone; B. Coverage with free latissimus dorsi muscle flap and overlying skin graft; C and D. 6 months follow-up results.

3.7 Scalp replantation

Scalp replantation is the standard treatment for complete and partial scalp avulsion injury. No other procedure can give results, such as replantation. Loose areolar tissue allows subgaleal dissection during the entrapment of scalp hair in a moving machine. Many times, some parts of the pericranium are also lost. The first patient should be stabilized hemodynamically. If the avulsed part is in good condition, repair of the single artery can survive the whole avulsed skin. Two team approaches can need to work simultaneously to shorten the surgery duration. The superficial temporal artery and vein are the most used recipient vessels for anastomosis. Two veins should be repaired to prevent the risk of venous congestion. A vein graft may be required if recipient vessels are injured. Nerve repair is indicated for recovery of sensation.

3.8 Calvarial reconstruction

The different etiologies of calvarial defects are traumatic loss, post-oncological resection, removal of dead bone, and craniectomy defect following intracranial surgeries. Immediate reconstruction of calvarial defects after craniectomy determined by the size and location of bone defects and expected intracranial pressure. Indications of cranioplasty are protection from trauma, cosmesis, and the putative “syndrome of trephined.” Small- to medium-sized bone defects (≤5–7 cm) in cosmetic and pressure-sensitive areas, such as the forehead or occipital region indicate cranioplasty. Morselized bone grafts for small-size defects and calvarial or rib grafts for medium-size defects are advisable [27]. However, large-size bony defects require a vascularized rib graft with a free latissimus dorsi muscle flap cover [29]. But nowadays, titanium mesh is an excellent alternative to autograft in all types of defects. Non-vascularized bone grafts and prosthetic material are not advisable when postoperative radiotherapy is planned. Bone resorption, exposure, and infection are the most common complications following cranioplasty, leading to revision surgery [30].

4. Summary

Local scalp flaps can cover small- to medium-sized scalp and forehead defects. Primary closure of the donor area or skin grafting at a less cosmetic area results in better esthetic outcomes. Large-sized defects, the need for postoperative radiation, and coverage after bony reconstruction indicate free tissue transfer. A single or double rotation flap selection depends on the defect’s location and the donor area’s availability rather than the size. Single or bipedicle transposition scalp flaps have a wider coverage scale, are less time-consuming, and are advisable in high-risk patients. Debridement of the outer surface of the cranium is needed in long-standing exposed bone or to promote granulation before skin grafting.

Conflict of interest

The authors have no conflicts of interest relevant to this article.