A term, appropriate-for-gestational-age female infant is delivered by forceps-assisted vaginal delivery. On the initial physical exam, a 3 cm x 4 cm depression of the skull is identified in the left temporoparietal region. The neurosurgery team is consulted, and a non-contrast computed tomography of the head is obtained (Figure 1).
Figure 1. Axial head computed tomography (A) and three-dimensional modeling (B) of the depressed area of the left parietal region. Image from: Villahermosa A,Lafuente M, Benchouia AR, Leary J, Gardner H, Tarasiewicz I. Depressed skull fracture in infants: The role of vacuum-assisted intervention. Neoreviews. 2024;25(12):e757–e764.1
Which of the following features is associated with this infant’s most likely condition?
- Isolated buckling of calvarial bones
- Leptomeningeal cyst formation
- Mutations in fibroblast growth factor genes
- Wormian bones
Answer: A: Isolated buckling of calvaria bones
Explanation:
Palpable bony defects of the skull in a neonate should raise suspicion for a skull fracture. Depressed skull fractures (sometimes referred to as “ping-pong” fractures) may develop due to in utero compression of the skull from ischial spines and pubic symphysis of the pregnant person or due to physical trauma during birth, such as with the use of forceps.2–4 Depressed skull fractures typically result from inward buckling of the calvarial bones (Option A).2 Diagnostic imaging with axial computed tomography (CT) imaging with three-dimensional reconstruction (Figure 1) can further define the injury, as well as intracranial complications, such as intracranial bleeding.2,3 Imaging with plain radiographs is limited by findings that can be mistaken for skull fractures, such as lacunar skull, soft tissue folds causing ripple lines, or vascular grooves.2 Additionally, plain films of the neonatal skull are difficult to interpret due to the normal suture width and decreased mineralization seen in neonatal crania.3 Depressed skull fractures in the neonate rarely require surgical intervention, as the depressed region can remodel over time, but the presence of bone fragments in the brain parenchyma, increased intracranial pressure, large hematomas requiring evacuation, and neurologic defects are indications for surgical repair.2,3
Mechanisms that induce depressed skull fractures in neonates can also result in other skull injuries such as linear skull fractures. Linear fractures primarily affect the parietal bones of the skull and may occur with uncomplicated spontaneous vaginal deliveries.2 Linear skull fractures also do not usually require surgical intervention, but can be complicated by the rare development of a mass known as a leptomeningeal cyst (Option B).2 Leptomeningeal cysts form at the fracture line, widen over time, and are accompanied by an expanding fluid-filled mass.2,4 Most patients are asymptomatic, but some may develop mass effect with associated neurological deficits, necessitating surgical intervention.2,3 The neonate in this case vignette did not have a linear skull fracture on imaging, making the development of a leptomeningeal cyst unlikely.
Craniosynostosis (Figure 2) involves the pathologic premature mineralization and fusion of one or more cranial sutures, the fibrous tissue that separates the individual flat bones of the cranial vault.5-7 Fusion of the sutures alters head shape and can result in both facial dysmorphisms and increased intracranial pressure.5,6 Craniosynostosis can have primary or secondary forms. Primary, or congenital, craniosynostosis is usually isolated or sporadic but can be associated with genetic syndromes.5,6 Mutations in the fibroblast growth receptor (FGFR) family are associated with syndromic causes of craniosynostosis, including Meunke (FGFR3), Apert (FGFR2), Crouzon (FGFR2), and Pfeiffer syndromes (FGFR2>FGFR1) (Option C).5 Secondary forms of craniosynostosis can be caused by rickets or thyroid disorders.5 Plain radiographs and CT imaging can be useful in distinguishing between cranial fractures and craniosynostosis in neonates with abnormal cranial shapes.
Figure 2. Anteroposterior (A) and lateral (B) radiographs of a patient with complex craniosynostosis involving the bilateral lambdoid sutures that resulted in flattening of the lower occipital region. Image adapted from: Hanford J, Anders A, Vachharajani AJ. A neonate with an abnormally shaped head. Neoreviews. 2021;22(5):e351–e355.6
Osteogenesis imperfecta (OI), also known as “brittle bone disease”, is a rare, heterogeneous group of disorders that most commonly affects the type 1 procollagen genes COL1A1 and COL1A2.7-10 Patients with OI can demonstrate bone deformities, osteopenia, and a predisposition for multiple fractures.7 Prevalence of OI ranges from approximately 1 in 15,000 to 20,000 births.8 The mode of transmission is generally autosomal dominant; however some forms can be inherited as autosomal recessive or X-linked traits.10 Over the past several years, the classification of OI has expanded to include nine types, with neonatal manifestations classified by the presence of biconcave vertebrae, slender gracile-appearing ribs, multiple fractures in various stages of healing with callus formation, diffuse osteopenia, and wormian bone formation of the skull.7,9 –10 Wormian bones (Option D) are small, irregularly shaped calvarial bones along suture lines that can be seen on plain radiographs (Figure 3).7 Secondary features of OI include conductive, sensorineural, or mixed hearing loss; dentinogenesis imperfecta; macrocephaly; and subtle facial dysmorphisms.10 Patients with milder forms of OI may not present until later childhood and can survive into adulthood.10 While Wormian bone and soft skulls are a feature of OI, these findings do not tend to present as a skull fracture at the time of delivery as with the patient described in this vignette.
Figure 3. Skull radiograph demonstrating Wormian bones of the skull, most prominent in the occipital region (white arrows), in a patient with osteogenesis imperfecta. Image from: Swarr DT, Sutton VR. Skeletal dysplasias in the newborn: diagnostic evaluation and developmental genetics. Neoreviews. 2010;11(6):e290 – e304.7
Did you know?
While depressed skull fractures usually do not require surgical intervention, the use of vacuum suction to assist in the fracture reduction is a newer procedure with a 95% success rate.1
Bonus question: What are the two primary modes of ossification, and at what weeks of gestation do they occur?
Find the answer in: Langston SJ, Krakow D, Chu A. Revisiting skeletal dysplasias in the newborn. Neoreviews. 2021;22(4):e216 – e227.8
NeoQuest December 2024 Authors:
Allison N. J. Lyle, MD, MA, University of Louisville
Lila S. Nolan, MD, Washington University School of Medicine in St. Louis
References:
- Villahermosa A,Lafuente M, Benchouia AR, Leary J, Gardner H, Tarasiewicz I. Depressed skull fracture in infants: the role of vacuum-assisted intervention. Neoreviews. 2024;25(12):e757–e764
- Akula VP. A newborn who has a depressed region over the right parietal bone. Neoreviews. 2005;6(7):e356-e358
- Merhar SL, Kline-Fath BM, Nathan AT, Melton KR, Bierbrauer KS. Identification and management of neonatal skull fractures. J Perinatol. 2016;36:640 – 642
- Rosenburg AA. Traumatic birth injury. Neoreviews. 2003;4(10):e270–e276
- Bautista G. Craniosynostosis: neonatal perspectives. Neoreviews. 2021;22(4):e250-e257
- Hanford J, Anders A, Vachharajani AJ. A neonate with an abnormally shaped head. Neoreviews 2021;22(5):e351–e355
- Swarr DT, Sutton VR. Skeletal dysplasias in the newborn: diagnostic evaluation and developmental genetics. Neoreviews. 2010;11(6):e290-e304
- Langston SJ, Krakow D, Chu A. Revisiting skeletal dysplasias in the newborn. Neoreviews. 2021;22(4):e216-e227
- Doctor PN, Sood BG, Natarajan G, Misra VK. Rib fractures in a term newborn with respiratory distress. Neoreviews. 2021;22(8):e559-e563
- Adel S, Farzeen M, Aiman S. A rare cause of fracture in a preterm infant. Neoreviews. 2024;25(10):e656–e659