Continuing Education Activity

Brachycephaly is an infant skull deformity characterized by a shortened anteroposterior skull length and a widened biparietal diameter. This condition may be non-synostotic (positional) or synostotic (craniosynostosis). Accurate diagnosis of the type of brachycephaly is paramount in determining the appropriate treatment options. Positional brachycephaly and/or plagiocephaly are the most common head-shape abnormality, affecting between 20% and 50% of infants in the United States. The incidence of infant positional skull deformities has been on the rise since 1992. This activity reviews the evaluation and management options for brachycephaly and highlights the role of the interprofessional team.

Objectives:

• Describe the etiology of positional brachycephaly.
• Summarize the pathophysiology of synostotic brachycephaly.
• Identify the indication for neck physiotherapy in infants with brachycephaly.
• Outline the importance of interprofessional team coordination in the management of patients with brachycephaly.

Introduction

The term "brachycephaly" is derived from the Greek words "brakhu" (short) and "cephalos" (head), which translates to "short head." Brachycephaly is an infant skull deformity characterized by a lower-than-normal ratio of the skull's length to its width.[1] Infants with this form of skull deformity have a flattening of the cranium's occipital aspect; consequently, there is an apparent shortening of the skull in the anteroposterior dimension (length).[2] Brachycephaly may be positional (non-synostotic) or synostotic. The incidence of infant positional skull deformities has been on the rise since 1992.[3][4] This appears to be related to the introduction of the measure of infant supine sleep positioning by the American Association of Pediatrics as a means to prevent sudden infant death syndrome (SIDS).[5][6] However, brachycephaly in infants can also occur due to the phenomenon of craniosynostosis.

The infant skull has the dual function of providing protection for the brain in addition to allowing for its volumetric growth and development. The cranial vault or calvaria in infants comprises several bones separated by fibrous joints or cranial sutures. There are two frontal bones separated by a metopic suture and two parietal bones separated from each other by a sagittal suture. A coronal suture separates the two parietal bones from the two frontal bones, which includes the anterior fontanelle (future bregma). Paired squamosal sutures separate paired temporal bones on either side of the calvaria from the two parietal bones, and a lambdoid suture which includes the posterior fontanelle (future lambda), separates a single occipital bone from the two parietal bones. The anterior fontanelle typically closes by 2.5 years of age, while the posterior fontanelle normally closes by 2 to 3 months of age. Craniosynostosis refers to the premature mineralization and fusion of one or more of these fibrous joints, which occur between the bones of the calvaria before the completion of brain growth and development in infants.

Etiology

Positional (non-synostotic)/Deformational Brachycephaly

The cranial sutures or fibrous joints that separate the cranium bones do not fuse or ossify at birth. This ensures the essential event of volumetric growth and development of the brain postnatally. As a result, a newborn skull retains its ability to mold in the initial months of life and is, therefore, susceptible to the deformational effects of external force. The frequent practice of placing an infant in a supine sleeping position can lead to a symmetrical flattening of the occipital bone resulting in positional or deformational brachycephaly.[7] 

A unilateral flattening of the occipital bone in infants may result in deformational plagiocephaly, a related positional skull deformity. Positional brachycephaly may also be observed at the time of birth in some infants. This may be attributable to prolonged labor or intrauterine fetal head constraint due to factors such as abnormal intrauterine position, multiple gestations, oligohydramnios, and congenital or acquired structural anomalies of the uterus.[8]

Brachycephaly Due to Craniosynostosis (Synostotic Brachycephaly)

The skull consists of the neurocranium and the viscerocranium (also known as splanchnocranium). The neurocranium forms a protective shell surrounding the brain and the brain stem, while the facial bones form the viscerocranium (or facial skeleton).[9] The neurocranium consists of the cranial vault (calvaria) and the chondrocranium (skull base). The bones that constitute the chondrocranium mineralize by endochondral ossification, which is the replacement of cartilage by the bone matrix. The bones of the calvaria are established by intramembranous ossification, which involves direct mineralization of mesenchymal connective tissue without the need for a transitional cartilaginous component.

Premature abnormal mineralization of the cranial sutures, which can occur between the calvaria bones, results in craniosynostosis. Bilateral premature mineralization of the coronal sutures leads to bi-coronal craniosynostosis, referred to as anterior brachycephaly.[10] Unilateral premature mineralization of the coronal suture in infants results in anterior plagiocephaly, a related skull deformity. Genetic abnormalities such as Fibroblast Growth Factor Receptor type-2 (FGFR-2), FGFR-3, twist homolog-1 (TWIST1), and ephrin-B1 (EFNB1) gene mutations may predispose an infant to craniosynostosis.[11] FGFR plays an integral in the abnormality, although the exact etiology remains unclear at this time. Fibroblast growth factors (FGFs) participate in the differentiation, cell proliferation, migration, and regulation of normal bone morphogenesis. These mutations may be clinically syndromic or non-syndromic.[10] Clinical syndromes with craniosynostosis include Crouzon syndrome, Apert syndrome, Pfeiffer syndrome, Saethre-Chotzen syndrome, Antley-Bixler syndrome, and Muenke syndrome. 

Epidemiology

Positional brachycephaly and/or plagiocephaly are the most common head-shape abnormality, affecting between 20% and 50% of infants in the United States.[1][12][13] Approximately 20% of cases of positional plagiocephaly may be observed at the time of birth, while 80% of the cases present within the first three months of life as an acquired postnatal cranial deformation.[14] Positional plagiocephaly is more common in male children.[14]

Up to 93% of infants with positional plagiocephaly will also have some degree of torticollis which is often underrated by the average physician.[15] Synostotic brachycephaly, resulting from bicoronal synostosis, occurs in around 3% of non-syndromic synostoses.[16] and has a higher prevalence of around 0.5 per 10000 live births in syndromic synostosis.[17] Lambdoid craniosynostosis is relatively rare, with a reported incidence of 1 to 9% of cases of craniosynostosis.[18]

History and Physical

It is essential to differentiate between non-synostotic (brachycephaly and/or plagiocephaly) and synostotic (bicoronal and/or bi-lambdoid synostosis) infant head shape abnormalities by taking a detailed history in combination with an astute physical examination. Important questions include:

• Family history of abnormal head shapes
• Prenatal exposure to teratogens
• When the abnormality was first observed
• History of intrauterine fetal head constraints
• Birth history

Physical examination should include measurement of the infant's head circumference, palpation of the sutures for evidence of ridging, and examining the fontanelles for assessment of elevated intracranial pressure. The infant's head should be assessed from the anterior view, posterior view, lateral view, and, importantly, from the vertex (top of the head). Anthropometric measurements using cranial calipers provide vital information on head length, width, and occipitofrontal transcranial diameters.

A complete neurological examination should also be performed. Indices such as the cephalic index (i.e., the ratio of maximum width to the maximum length of the skull) and the cranial vault asymmetry index (i.e., the percentage difference between the diagonal dimensions of the skull) may provide useful information on the degree of severity of an infant's head shape abnormality.

Positional brachycephaly is characterized by bilateral/symmetrical flattening of the occiput, widening of the posterior skull, bilateral temporal bossing, and a round face. There is usually evidence of sutural ridging (bi-coronal and/or bi-lambdoid craniosynostosis) with synostotic brachycephaly. In lambdoid craniosynostosis, there may be an associated sutural trough rather than an expected ridge. Bicoronal synostosis is often associated with turricephaly; the forehead appears somewhat towered with seemingly shallow orbits and a shortened nasal bone. Some infants with bicoronal synostosis resulting in brachycephaly may have peri-orbital findings, including Harlequin eye signs and exophthalmos.[10] 

The Harlequin eye sign is characterized by the affected side having a higher supra-orbital margin than the unaffected side. During the physical examination, it is important to determine whether or not other craniofacial or systemic abnormalities are present, including mid-face hypoplasia, abnormal facies, or limb abnormalities, which may indicate the presence of an associated syndrome.[19] Patients with syndromic craniosynostosis may also present with elevated intracranial pressure (ICP), obstructive sleep apnea, hearing disabilities, visual impairment, dental malocclusion, ventricular dilatation, and Chiari malformations.[20] It is also essential to determine whether urgent or elective treatment is required.[19]

Positional Plagiocephaly

Positional plagiocephaly produces a parallelogram head-shape deformity. There will be occipital flattening of the affected side and associated bossing of the ipsilateral frontal region and contralateral occipital region. The ear position will be pushed forward, and the mastoid will be of normal appearance. 

Posterior Plagiocephaly Secondary to Unilateral Lambdoid Craniosynostosis 

Posterior plagiocephaly produces a trapezoid head-shape deformity. Similar to positional plagiocephaly, there will be occipital flattening of the affected side. In contrast to positional plagiocephaly, there will be associated bossing of both the contralateral frontal and contralateral parietal regions. The ear position will be backward, and the mastoid will be bulging and downward. 

Bilateral Lambdoid Craniosynostosis 

The presentation of bilateral lambdoid suture craniosynostosis is that of brachycephaly, with both ears displaced inferiorly and anteriorly.[18]

Bicoronal Craniosynostosis 

The presentation of bicoronal craniosynostosis is turricephaly, with a towered forehead, seemingly shallow orbits, and a shortened nasal bone. 

Anterior Plagiocephaly

Anterior plagiocephaly is secondary to unilateral coronal suture craniosynostosis with contralateral forehead bossing. 

Evaluation

The physical examination is the most important aspect of the diagnosis of craniosynostosis. Radiological imaging studies are usually not required to diagnose positional plagiocephaly but may be helpful in unclear cases. 

Conversely, synostotic infant head shape abnormalities require radiographic evaluation of the abnormal sutures either by skull X-ray or computed tomography (CT scan of the head. CT imaging with three-dimensional image reconstruction is the imaging modality of choice. Other imaging modalities, such as ultrasonography prior to fontanelle closure or magnetic resonance imaging (MRI), may also be employed if there is a concern for intracranial abnormalities, such as hydrocephalus. In synostotic brachycephaly (bicoronal synostosis), CT imaging studies usually demonstrate the thickening of the sutures implicated. Skull x-rays will demonstrate a sclerotic margin along the suture of interest. In some instances, there may be non-visualization of these sutures. Genetic tests may be undertaken if affected infants present with additional features suggesting the presence of an underlying genetic syndrome. 

Treatment / Management

Positional (non-synostotic) brachycephaly and/or plagiocephaly are usually treated conservatively. The best management for positional plagiocephaly is prevention. Pediatrician counseling on tummy time beginning in infancy and early repositioning. If present, torticollis exercises should be utilized. Surgery is not indicated, given the absence of craniosynostosis. The parents of affected infants should be reassured, and attempts may be made to alternate the infant's head position for sleep (repositioning education). Other conservative treatment measures include massage therapy, physiotherapy (for torticollis), assistive devices, and helmet therapy. Helmets are expensive, require frequent visits to the orthotist every two weeks, and have their own set of complications, including pressure sores, subcutaneous abscess, and failure to correct the deformity.[21] Therefore, prevention and active repositioning should instead be the mainstay of therapeutic intervention in children. 

Synostotic infant head shape abnormalities require surgical intervention, with the timing of surgery being crucial. Infants with signs or symptoms of raised intracranial pressure require urgent interventions. Surgical repair of uncomplicated bicoronal synostosis is usually delayed until after the sixth month of life and is usually undertaken between the sixth and twelve months of life. Lambdoid synostosis should be repaired earlier, between the second and sixth months of life. Established surgical management strategies include sub-total or complete cranial vault remodeling, cranioplasty (spring-assisted), and endoscopic suturectomy with postoperative helmet therapy. Early referral is advised as delayed referrals may result in more extensive surgical interventions with higher risks of complications. The best outcomes for endoscopic surgery are between the ages of 0 to 6 months of age while the bone is still the most malleable. The benefits of endoscopic surgery include less observed patient discomfort, less blood loss, and shorter hospital stay.[22] 

Following endoscopic surgery, a helmet is often fitted 3-7 days following surgery and may be worn up to 1 year post-operatively.[23] In general, open surgical repair is often employed between 4 to 12 months of age. All open cranial vault reconstructions begin with a bicoronal skin incision. Lambdoid craniosynostosis requires bi-parietal craniotomies with barrel staving of the frontal and occipital bones. In cases of coronal craniosynostosis, anterior cranial vault remodeling with orbital rim advancement is used. This technique includes a bifrontal craniotomy, the creation of an orbital bandeau, and subsequent bifrontal advancement.[24]

Differential Diagnosis

Synostotic (bi-coronal and/or bi-lambdoid synostosis) brachycephaly in infants may be associated with multiple syndromic conditions. It is, therefore, essential to follow a standardized pattern of physical examination to avoid overlooking any vital etiological clues. Some of the common syndromes included in the differential diagnosis are as follows:

• Crouzon syndrome: Bicoronal synostosis resulting in brachycephaly, proptosis, hypoplasia of the midface with a characteristic underbite (mal-occlusion), and an upturned nose.
• Apert syndrome: Bicoronal synostosis with syndactyly of digits 2,3, and 4. May have mental retardation and mid-face hypoplasia. 
• Pfeiffer syndrome: Craniosynostosis, abnormally broad and medially deviated thumbs and great toes, varying degrees of protruding eyes, and conductive hearing loss.
  • Type 1: Turribrachycephaly, midface hypoplasia, high forehead, ocular hypertelorism, hypoplastic maxilla, and dental abnormalities. Intelligence is usually normal.
  • Type 2: Cloverleaf skull (or Kleeblattschadel type craniosynostosis), hydrocephalus, ocular proptosis, beak-shaped nose, and neurological problems due to severe involvement of the brain.
  • Type 3: Same as type 2 except for the absence of Cloverleaf skull. Additionally, there is a presence of natal teeth and an anterior cranial base.
• Saethre-Chotzen syndrome: Also called "acrocephalosyndactyly" - craniosynostosis and or syndactyly of certain digits and characterized by a low-set hairline and facial asymmetry. 
• Carpenter syndrome: Craniosynostosis, syndactyly of certain digits and/or polydactyly. May have short stature and congenital heart defects. 
• Antley-Bixler syndrome: Craniosynostosis, proptosis, low set ears, mid-face hypoplasia, radiohumeral or radioulnar synostosis, arachnodactyly, and joint contractures.
• Muenke syndrome: Coronal craniosynostosis, carpal synostosis, hearing loss, developmental delay, Cone-shaped epiphysis, and High narrow palate.
• Beare-Stevenson cutis gyrata syndrome: Craniosynostosis, cutis gyrata (furrowed and wrinkled appearance of skin and acanthosis nigricans), choanal atresia, abnormality of the pancreas, and aplasia/Hypoplasia of the earlobes.
• Jackson-Weiss syndrome: Craniosynostosis, midfacial hypoplasia, broad great toes, and/or malformation or fusion of certain bones within the feet.

Prognosis

Positional (non-synostotic) brachycephaly and/or plagiocephaly are the most common infant head shape abnormalities encountered in the primary health care setting. Parental reassurance and management with conservative measures such as repositioning education are usually sufficient, with improvements evident in most infants as they attain their developmental milestones.[13] 

Refractory cases of positional brachycephaly should be referred for helmet therapy, and any suspicious cases of craniosynostosis should be referred early for an opinion from an experienced craniofacial team. Early craniofacial referrals of synostotic brachycephaly may obviate the need for more extensive surgical interventions. Cosmetic outcomes following non-syndromic craniosynostosis repair are excellent for both open and endoscopic approaches with low redo rates.[25]

Complications

Positional brachycephaly primarily raises aesthetic concerns. Reliable evidence of its effect on the neurological development of affected infants is lacking. Conversely, untreated synostotic brachycephaly may impede volumetric brain growth and development, is associated with elevated ICP in infants, and has a high incidence of intracranial hypertension in older untreated patients.[26] 

Cognitive and behavioral difficulties in those affected have been previously suggested to have some relationship with elevated ICP.[10] However, no correlation was identified between both variables in several other studies.[27][28][29] The effect of craniosynostosis surgical repair and neurodevelopment remains widely debated.

Consultations

A pediatrician usually detects and diagnoses the condition of brachycephaly in infants. Specialist consultation with a craniofacial team, traditionally led by a pediatric neurosurgeon in concert with a craniofacial plastic surgeon and occasionally a geneticist, is necessary in cases of synostotic brachycephaly.

Deterrence and Patient Education

Parents with concerns about their infant's head shape should consult a pediatrician early. Further specialist consultation with a craniofacial team can be arranged by the pediatrician if there is suspicion of craniosynostosis. If the abnormal head shape is secondary to positional plagiocephaly, patient counseling can be provided. 

Enhancing Healthcare Team Outcomes

Brachycephaly can be diagnosed by history and physical examination. It is essential to distinguish between non-synostotic and synostotic brachycephaly. Most cases of non-synostotic brachycephaly improve with conservative measures. Refractory cases should be referred for consideration of helmet therapy. Cases of brachycephaly secondary to craniosynostosis should be referred early for craniofacial consultation and appropriate surgical management as part of an interprofessional team approach to care.