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Pediatric Head Injuries







Oral and Maxillofacial Surgery Clinics, 2012-08-01, Volume 24, Issue 3, Pages 337-350, Copyright © 2012 Elsevier Inc.


Head injuries in children are common, comprising more than half of all injuries sustained. The mortality and morbidity associated with traumatic head injury in children is staggering, and the cumulative effect of such on the pediatric and general populations is propagated through related health care measures and subsequent socioeconomic burden. The majority of deaths due to trauma in children are caused by brain injury. This article reviews the evaluation and management of scalp injuries in the pediatric patient. The second portion addresses skull fractures, the specter of child abuse, management of acute fracture, and the phenomenon of growing skull fractures.

Key Points

  • Scalp and head injuries are more common and more potentially life threatening in children than in adults, because of the large area of exposure relative to body size in children.

  • Ischemic soft-tissue wounds will often improve with patient rewarming and correction of hypovolemia in children, resulting in salvage of complex avulsive wound flaps.

  • Most avulsive scalp wounds in children that result in tissue loss will require staged reconstruction through tissue expansion.

  • Initial diagnosis of pediatric skull fractures may be delayed owing to the desire to limit infant radiation exposure, making clinical follow-up critical.

  • A small proportion of pediatric cranial fractures may develop into a growing skull fracture, which presents as a widening skull fracture, pulsatile mass, and neurologic symptoms.

  • Computed tomography and magnetic resonance imaging are important tools in the workup of growing skull fractures, to delineate cranial and intracranial injuries.

  • Patients benefit from multidisciplinary surgical care, which requires wide scalp exposure, craniotomy access, intracranial debridement, dural repair, and cranial reconstruction.


Introduction

Head injuries in children are common, estimated by the American College of Surgeons (according to data over the last 10 years in the National Trauma Data Bank) to comprise more than half of all injuries sustained by children. The mortality and morbidity associated with traumatic head injury is staggering, and the cumulative effect of such on the pediatric and general populations is propagated through related health care measures and subsequent socioeconomic burden. The majority of deaths due to trauma in children are caused by brain injury.

Many children who sustain injury to the craniofacial region will have scalp injuries and underlying skull fractures. Although there are many data that reflect the high association of traumatic brain injury with head trauma, there are few data on the percentage of those children who have associated scalp injuries. And the converse is true: there are few data on the percentage of those children sustaining isolated scalp injury (no underlying fractures) who may have a brain injury. The mechanism of injury may point to the likelihood of sustaining a scalp injury in certain age groups: younger children in motor vehicle crashes and falls and older children (adolescents) in motor/recreational vehicular crashes and personal violence. Skull fractures in children are highly related to mechanism: vehicular crashes, falls, and abuse or violence.

This article reviews the evaluation and management of scalp injuries in the pediatric patient. The second portion addresses skull fractures, the specter of child abuse, management of acute fracture, and the phenomenon of growing skull fractures.


Scalp injuries

“I closed the scalp in 2 layers.” —Harvey Cushing. Neurosurgeon and Medical Educator

The child presenting to the emergency room (ER) with a scalp injury must be fully evaluated for other injuries, particularly to the intracranial compartment. Simultaneously, attention must be given to immediate control of hemorrhage because the scalp is rich in vascularity. Scalp vasculature is derived primarily from 4 main arterial sources, as shown in Fig. 1 . These major vessels then divide into many smaller branches that communicate with underlying arteries and arterioles running under the firm galea (aponeurosis), which tends to stent the vessels and not allow vessel constriction after injury. The scalp continues to ooze, often without being attended to or noticed by medical personnel who are perhaps focused on other injuries. If the wound lies to the back of the head or has been loosely bandaged in the field, these injuries can have devastating consequences of hypovolemia and shock in the younger child. Every effort must be made to thoroughly and quickly evaluate scalp wounds in children, particularly those with complex injuries and instability. Control of hemorrhage, via either a firm dressing or actual tamponade of the vessels with instrumentation or sutures in a whip-stitch fashion, should be undertaken.

Diagram of the 4 main arterial branches to the scalp. The supratrochlear and supraorbital arteries are branches of the ophthalmic artery (internal carotid); the superficial temporal, posterior auricular, and occipital arteries are branches of the external carotid.
Fig. 1
Diagram of the 4 main arterial branches to the scalp. The supratrochlear and supraorbital arteries are branches of the ophthalmic artery (internal carotid); the superficial temporal, posterior auricular, and occipital arteries are branches of the external carotid.

It is important to confirm and document medical status and immunization history. If there is a question as to tetanus prophylaxis in the past 5 years, a tetanus booster of Td or Tdap may be given, depending on the patient's immunization history. This action is particularly important with soil or agricultural contaminant exposure. After the child has been stabilized and cleared for further management, plans for wound closure should be made in the controlled environment of the operating theater. The patient can be adequately resuscitated, if necessary, and careful monitoring undertaken. Only the simplest of scalp wounds in older children should be repaired in the ER. Many scalp wounds, once cleared of matted hair, clots, and debris, are more complex than perhaps originally thought, and a thorough evaluation through direct observation and digital exploration is necessary. Mechanisms of injury, for example, striking the pavement or a tree, may suggest the need for opening a wound even further to adequately explore, debride, and retrieve foreign bodies ( Fig. 2 ). Gross contamination from soil, rotted vegetation, agricultural exposure, and so forth will necessitate a vigorous washout with pulse irrigation. The addition of antibiotics to the irrigant has not been shown to decrease the incidence of postoperative infection and wound breakdown.

Retrieving a foreign body from the scalp wound of an adolescent boy who was thrown into a wooden fence from an all-terrain vehicle.
Fig. 2
Retrieving a foreign body from the scalp wound of an adolescent boy who was thrown into a wooden fence from an all-terrain vehicle.

Initial Evaluation

When the child has been stabilized and other life-threatening injuries addressed, further evaluation can be undertaken. For any head injury in children involving a scalp wound, noncontrasted computed tomography (CT) should be obtained to rule out fractures or intracranial injury ( Fig. 3 ). Because of the rich vascularity to the calvarium and scalp, there may be a great deal of swelling accompanying scalp wounds, particularly if the wound is not completely open. Particular attention should be given to infants or young children with cranial trauma and swelling, to identify possible cause of abuse and also for suspect bleeding. In very young children with open sutures, a hematoma that crosses the suture lines is considered to be superficial to the pericranium, much like that seen in traumatic birth with caput succedaneum, whereas swelling (cephalohematoma) that is limited by the sutures is subperiosteal in nature.

CT image of skull fractures ( arrow ) and scalp (cephalo-) hematoma (X) after blunt injury.
Fig. 3
CT image of skull fractures (
arrow ) and scalp (cephalo-) hematoma (X) after blunt injury.

Once the primary and second surveys have been completed and the child stabilized, adequate exploration and management of head wounds is optimally performed in the operating theater. If a small open wound suggests further exploration because of swelling or mechanism, for example, striking a tree, post, or gravel surface, the wound should be opened to allow thorough evaluation, debridement, and evacuation of contaminant or hematoma, and cleansing before closure. An evacuated hematoma or subgaleal dead space needs to be closed with either a firm dressing (preferred in young children) or small drains judiciously placed and observed.


Small Wounds

Small scalp wounds with linear or limited segmental limbs and clean margins or small stellate wounds can be washed out and closed in layers. As already noted, any extent of injury beyond the wound margin mandates further exploration and irrigation. Most of these wounds can be closed with absorbable sutures. A topical antibiotic and dressing to protect the wound can then be placed.

A puncture wound of the scalp from a dog bite requires special attention. Some dog breeds, particularly pit bulls, have a tendency to bite the head and neck region, especially in children, and can puncture the skull in young children. If this is the case then CT examination is warranted and must be performed to rule out intracranial extent of injury. Dog-bite puncture wounds to the scalp with extension intracranially mandate hospitalization with intravenous antibiotics, neurosurgical consultation, and follow-up CT in 3 days to rule out early abscess formation.


Complex Wounds

Scalp wounds with various segmented or stellate limbs, macerated margins, gross contamination, or avulsive elements are considered complex. These wounds require careful attention to maintain tissue vascularity and integrity during and after repair to preserve viability of the scalp tissue. Segmented wounds with tenuous vascular integrity require immediate reorientation of the tissues to preserve viability. This intervention should be preferably addressed in the ER, as twisted pedicles will result in compromised blood flow and possible tissue loss if the segmented limbs are not correctly reoriented to their passive anatomic position and stabilized in that position. Often a small vascular pedicle in a flap of tissue will remain constricted until rehydration, patient warming, and anatomic repositioning has taken place. Children experience more heat loss through the head region, particularly after injury with open wounds, therefore every precaution should be taken to limit exposure time, maintain core temperatures, use warmed fluids for irrigation, and close wounds in a timely fashion.

Nearly all complex wounds deserve a thorough washing out with saline solution. The addition of antibiotics has not been shown to decrease the incidence of postoperative wound infection. Most complex scalp wounds need to have the surrounding hair removed to identify badly contused and macerated tissue margins and reveal areas of tissue necrosis. Proper wound cleansing and closure is made that much easier with the hair removed. Contaminated wounds that have been exposed to gross foreign-body impregnation or stagnant or soiled fluids should be thoroughly cleansed with pulse irrigation ( Fig. 4 ). The mechanical dislodgment of foreign-body material and bacterial contamination through pressure irrigation has been shown to significantly reduce bacterial colonization and subsequent wound breakdown or infection. As noted, these fluids should be warmed to decrease loss of body heat in children. Excessive pressure (<20 psi) with commercial irrigation devices should be avoided, to reduce barotrauma and shredding of compromised tissues.

( A, B ) Pulse irrigation of contaminated avulsive scalp wounds should be undertaken before definitive wound repair.
Fig. 4
(
A, B ) Pulse irrigation of contaminated avulsive scalp wounds should be undertaken before definitive wound repair.

Severely compromised, questionable, and obviously nonviable tissue should be sharply debrided under loupe magnification to obtain a precise and conservatively prepared margin for closure. There should be minimal use of electrocautery for hemostasis, as the thinner scalps of children are more prone to thermal injury of the hair follicles, leading to increased localized alopecia. Simple closure of the pericranium and galea will control most bleeding points in the loose tissue, and final closure of the skin will obtain good hemostasis of the entire wound margin. In general, absorbable sutures are placed because they are well tolerated in the scalp region and will not require subsequent removal, which in very young children can be a traumatic event, particularly after injury. If pexing or mattress-type suture placement is indicated to approximate wound margins, judiciously placed permanent nylon or prolene sutures may remain in place for up to 2 weeks before significant epithelial migration and increased scarring ensues ( Fig. 5 ).

Permanent sutures have been placed circumferentially at the wound periphery and across the wound to assist in serial reduction of the defect size. This procedure is performed over 2 to 4 weeks before planned definitive repair.
Fig. 5
Permanent sutures have been placed circumferentially at the wound periphery and across the wound to assist in serial reduction of the defect size. This procedure is performed over 2 to 4 weeks before planned definitive repair.

Support of the wounds and obliteration of dead space under a scalp tissue flap is obtained through the careful application of a head dressing. Antibiotic ointment and xeroform or petrolatum gauze strips are applied to the wound margins, and a firm gauze dressing placed to further protect the site as well as apply light pressure to the underlying dead space to discourage hematoma formation. A mesh stockinette is used to hold the dressings in place during the immediate postoperative healing period ( Fig. 6 ).

Stockinette mesh is placed over protective Vaseline and sterile gauze on the wound bed to secure the dressings and prevent wound desiccation and damage.
Fig. 6
Stockinette mesh is placed over protective Vaseline and sterile gauze on the wound bed to secure the dressings and prevent wound desiccation and damage.

Avulsive Wounds

Scalp wounds that have small avulsive defects can usually be primarily closed with a circumferential purse-string suture to approximate the wound margins. As the fibrotic aponeurosis does not allow for much stretching of the scalp, and because of the thin scalp in young children, full-thickness defects smaller than 2 cm 2 are generally the limit for primary closure in the author's (B.B.H.) experience without extended or additional incisions and rotational flaps. In avulsion defects of between 2 and 3 cm 2 , progressive closure of the wound can take place over a short period to approximate the wound margins. In most young children this kind of staged closure must take place under sedation or general anesthesia for reasons of patient comfort and parental anxiety associated with the procedure. Children younger than 3 years will experience further cranial vault expansion, therefore the scar will correspondingly increase in size and require final revision at a later age. The parents should be informed of this normal progression and maturation of scar.

Larger scalp wounds that have an avulsive component will require temporary tissue coverage. Underlying pericranium must be intact as a recipient site for the graft. If the avulsed portion of scalp tissue can be retrieved and adequately cleansed, it may be used as a temporary autologous free graft. Preparation of the tissue necessitates thorough debridement and washing with an antibiotic solution to conceivably decrease bacterial load. Similarly, commercial decellularized dermal grafts can be used to achieve temporary coverage of a full-thickness avulsion defect. Both tissue specimens are treated as temporary biological free grafts to provide for initial wound healing and stabilization. The free graft material is sutured into place providing for tie-over bolster sutures, “pie-crust” incisions are placed to allow exudative flow and discourage hematoma or seroma formation, and a firm bolster dressing of cotton and gauze placed over the graft ( Fig. 7 ). After a period of 3 weeks, the bolster dressing can be removed and the wound allowed to mature for several more weeks to obtain a firm adherence of the graft (which will turn into a dermal scar) to the underlying cranial surface in preparation for tissue expansion.

Series of photos of an adolescent girl who was thrown from her bicycle and struck her head on the pavement. ( A ) Avulsive scalp wound with full-thickness tissue loss. ( B ) After several weeks of wound-bed preparation (calvarial perforations were placed to encourage granulation tissue formation), a full-thickness skin graft is placed. ( C ) Tie-over bolster dressing in place for 3 weeks.
Fig. 7
Series of photos of an adolescent girl who was thrown from her bicycle and struck her head on the pavement. (
A ) Avulsive scalp wound with full-thickness tissue loss. (
B ) After several weeks of wound-bed preparation (calvarial perforations were placed to encourage granulation tissue formation), a full-thickness skin graft is placed. (
C ) Tie-over bolster dressing in place for 3 weeks.

Scalp Flaps

Closing defects of the scalp greater than 2 cm 2 may require recruitment of tissue to obtain final closure. Depending on the location of the defect, either bilobed or rotational advancement flaps or tissue expansion may be used to reconstruct the scalp defect. In general, defects at the vertex or upper parietal and occipital regions can be closed with rotational flaps of various designs, as demonstrated in Fig. 8 . Flaps generated from the temporal and occipital regions have slightly increased laxity and will rotate more than those from the top of the scalp. Rotational flaps of the scalp will require a 4- to 5-times distance in length as the width of the defect. This distance can be minimized by introducing 2 or 3 smaller rotational flaps in a circular or pinwheel fashion around the defect, as shown in Fig. 8 . Typically some standing cones (“dog ears”) will develop at the bases of the flaps, but with time these will flatten and not require excision. If there is some degree of tension at the leading border of the flap where it insets at the distalmost portion of the defect, a small back-cut incision can be made at the advancing base; however, caution should be exercised to keep this small, as it effectively reduces the width (hence vascularity) of the flap.

Smaller scalp defects can be closed with circular rotational flaps.
Fig. 8
Smaller scalp defects can be closed with circular rotational flaps.

Tissue Expansion


Patient preparation

Scalp avulsion injuries and their reconstruction in children may involve tissue expansion. In general, tissue expansion of the scalp should not be undertaken in children younger than 3 years, as the pressure exerted on the underlying cranium with potentially patent sutures may cause deformation, erosion, or remodeling. Preoperative CT scans will confirm such anatomic features of consequence. Expanders can be placed under the galea, distant from the avulsive defect area, in children with a developed diploë, usually around age 3 or 4 years. Thorough preoperative counseling should be undertaken with the caregiver of the child so that there is no misunderstanding as to the amount of cooperation necessary, treatment duration, potential travel involved, simultaneous discomfort and need for a second surgery (and possibly more) for removal, and so forth, which attends tissue expansion. Adolescents need to fully understand what tissue expansion involves, how it addresses treatment goals in reconstruction of their injury, and the necessity for strict adherence to expansion protocols and hygiene measures in caring for the expansion site. Time spent before implementation of tissue expansion will go a long way in preventing future frustration or misunderstanding on the patient's part during the expansion process which, in the author's (B.B.H.) experience, is inevitable.


Expander selection

The skin of the scalp region is thick and variable in texture compared with other body regions, even in children, therefore tissue expansion is slightly more prolonged and uncomfortable. Because of variable characteristics of scalp tissue, the tissue reservoir from which to recruit, and the defect to be reconstructed, there are several commercially available expanders of a variety of shapes and volumes. Rectangular, round, and crescent-shaped expanders (see Fig. 9 ) are available, but the most popular for scalp reconstruction is the crescent in 100- to 200-mL volumes. Studies have confirmed that an expander can be safely overinflated several times that of their reservoir volume, should that be necessary.

( A ) Midline scalp and forehead defect with plans for placement of bilateral crescent-shaped (250 mL) expanders. ( B ) Defect reconstructed with bilateral crescent-shaped expanders after four weeks of expansion.
Fig. 9
(
A ) Midline scalp and forehead defect with plans for placement of bilateral crescent-shaped (250 mL) expanders. (
B ) Defect reconstructed with bilateral crescent-shaped expanders after four weeks of expansion.

One must consider the area to be reconstructed and from where tissue recruitment will derive. Round or elliptical defects are most easily reconstructed with crescent-shaped expanders, and typically 2 are arranged at some proximity to the defect. The borders of the defect or the peripheral scar margin will be incorporated in the advancing expanded scalp and subsequently excised at advancement and inset of the flap. Gibney and van Rappard and colleagues have confirmed that the expander base should be roughly 2 to 3 times the area of the defect to be reconstructed.


Technique

Access incisions for insertion of the expander should be made near the junction of the defect (confirm that the scar is mature and not thin) and uninvolved scalp tissue. If the incision is made in thin or atrophic tissue, the possibility of dehiscence is greater, thereby jeopardizing exposure of the expander with subsequent infection and loss. The expander is placed in a well-dissected pocket in the subgaleal plane and above the pericranium. Great care should be exercised not to thin or perforate the overlying scalp during preparation of the expander pocket, which in young children is easy to do. If this occurs, a delay in expansion is necessary to allow for sufficient healing of the perforated tissue.

Placement of the injection port can usually be made through the expander access site if the port is to be buried. It is important to place the port a sufficient distance from the expander to allow for ease in identification and safe needle placement during expansion. Buried ports are desirable in older children (adolescents), who may be more active and will tolerate needle placement for expansion. Younger children (<10–12 years) will do better with external ports, which can be accessed easily and kept protected under a head or scalp dressing or clean garment during the expansion process. There are no reports of external ports being more prone than buried ports to infection, and this has been the author's (B.B.H.) experience as well. After expander placement, confirmation of position and contour of the expander is done with injection of normal saline; this also obliterates any dead space around the reservoir and achieves some degree of hemostasis by pressure. Some initial expansion can be done on the table, but blanching of the overlying scalp skin should be avoided to ensure vascularity. Permanent sutures are placed to firmly hold the access incision during the expansion process.

Expansion can begin about 2 weeks after initial expansion, and is accomplished with a 23-gauge needle placed through the injection port at right angles to avoid cutting or tearing the hub and increase chances of leakage from the port. Tissue expansion proceeds at 1- to 2-week intervals depending on the amount of expansion accomplished and the tolerance of the patient. Usually smaller injection amounts done on a weekly basis for younger children is better tolerated. The parents can administer an appropriate dose of acetaminophen or ibuprofen before the visit, which helps to alleviate any discomfort. Also, oral midazolam may be administered for the very frightened or anxious child. For patients living some distance from the surgeon's office, the parents can be instructed on fluid administration if there is an external port, and the entire procedure can be monitored nowadays via cell-phone video capture and immediate e-mail. After each expansion procedure the overlying skin must be confirmed to be viable, with adequate capillary refill; this is documented should there arise any question as to vascular compromise to the overlying skin with subsequent ischemia and tissue loss. Expansion will typically take about 4 to 8 weeks.

Site preparation for the expanded tissue necessitates excising the scar or tissue bed of the defect down to pericranium. It is important to try to integrate hair-bearing scalp with the margin of the recipient site. Obliteration of the scar will be enhanced by creating a geometric or w-plasty type margin at the leading edge of the flap, which will inset into a similar recipient margin. At removal of the expanders there will typically be a large amount of redundant tissue or folds of tissue, which will remain after the flap(s) has been inset ( Fig. 10 ). These folds will settle with time. To assist in obliteration of the dead space under an advanced flap, a small drain and a pressure dressing should be placed and left in position for several days. All sutures should be absorbable, to avoid the messiness of removal from a tangle of matted hair in an anxious child.

Temporal scalp defect in an adolescent boy. ( A ) At final expansion of parietal and vertex scalp. ( B ) Reconstruction of temporal defect and reestablishment of hairline after removal of expanders and flap advancement.
Fig. 10
Temporal scalp defect in an adolescent boy. (
A ) At final expansion of parietal and vertex scalp. (
B ) Reconstruction of temporal defect and reestablishment of hairline after removal of expanders and flap advancement.

Histologic changes

Tissue expansion has been shown to increase skin thickness through increased basal layer activity and net gain in donor tissue. The deeper dermis decreases in thickness, and this is directly related to the rate and degree (amount) of expansion: the faster the rate and amount, the thinner the dermis becomes. Collagen bundles in the reticular interstitium become more parallel and thin as well. Hair follicles become more sparsely spaced but the actual numbers remain the same. If there is rapid expansion, the phenomenon of hair shock may occur, with loss of hair, but the follicles remain viable and hair regrows after cessation of expansion. Lastly, expansion may stimulate melanocytic activity, resulting in hyperpigmentation of the overlying skin, particularly in darker pigmented children.


Pitfalls and complications of expansion

Postoperative hematoma or seroma formation may be seen following expander placement. This shortcoming will usually be avoided if expander inflation is undertaken at the time of placement to sufficiently obliterate dead space and achieve some small measure of skin pressure and mechanical vascular compression, albeit minimal.

The underlying calvarium is prone to thinning under an expander in younger children, therefore less expansion volume should be undertaken at each visit if possible. Usually cortical thinning occurs with rapid and aggressive expansion. Any “cupping” under an expander will resolve with time on removal. A plain radiograph taken at right angles to the expander will demonstrate any undue cortical thinning (risk of perforation); should this occur, expansion should be halted for a period of time before reinflation.

A capsule nearly always forms around tissue expanders. The longer the expansion process, the greater the chance of capsule formation and the more dense it will become. If a capsule forms, this should be minimally excised at the base or periphery of the expander but not overlying the expander, as this may compromise the flap vascularity. Most capsules will flatten and remodel with time.

Erosion of the overlying expanded skin is the most common complication of tissue expansion, either in the access incision site or through scarred and atrophic overlying tissue. Exposure of the expander can usually be managed by withdrawing some fluid, placement of reinforcement or bolster sutures, and allowing a period of initial healing before reinflation, now at a slower pace. If this occurs late in the expansion process, the surgeon can proceed with plans to remove the expander and complete the reconstruction of the defect. Exposure of the implant reservoir early in the process will necessitate removal of the expander; after allowing for a period of healing, one then proceeds with another expander, probably in an area distant from the perforation. Undoubtedly this latter event and complication is the one that should be thoroughly reviewed with the parents before undertaking expansion, as the delay in reconstruction and prolongation of treatment is a discomfiture to all involved. Exposure of a buried injection port is of no worrisome consequence; with excellent hygiene measures expansion can take place accordingly, now through an external port.


Summary

Scalp repair and reconstruction in children is optimally addressed through careful and meticulous debridement of contaminated wounds, appropriate tissue cleansing, and approximation of wound margins, and the proper closure of the scalp in 2 layers with postoperative support dressings. Many avulsive scalp wounds also have a closed head injury component, and this needs to be addressed in the triage of the injured child. It is important to decompress an avulsive or degloving type of scalp wound to prevent hematoma/seroma formation and provide for tissue viability. For wounds that cannot be primarily closed the wound bed should be prepared for future tissue expansion, which will restore hair-bearing scalp in a normal pattern and appearance for the child.


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