Scott Cassar MD, Luann Jones MD, and P-L Westesson, MD, PhD, DDS
Clinical
Presentation:
A six-week-old female presented with a skull deformity and a questionable history of trauma. Clinically, a left-sided skull deformity is noted and a CT of the head was requested for evaluation of skull fracture.
Imaging Findings: The posterior part of the left parietal bone exhibits a skull depression, measuring approximately 3.5cm in diameter with an estimated depth of 8mm. No fracture line is noted and there are no secondary findings of an acute injury, such as soft tissue swelling, intracranial hemorrhage, or adjacent brain edema seen on the CT scan.
Figure 1: Scout film.
Figure 2: An axial image using bone windows to demonstrate the left parietal depression.
Figure 3: A posterior view of a 3D reconstruction.
Figure 4: Axial T2 image shows a linear hyperintense signal adjacent to the inner table vault.
Diagnosis: Infant skull depression fracture
Discussion: Neonatal and infantile skull depressions are extremely rare, with an incidence of about 1/10,000 in western countries. In infants and young children, where no fracture line can be found because of the resilient cartilaginous nature of the infant skull, depressed skull fractures have been called "Ping-Pong" fractures because of the similar appearance of a dented ping-pong. One third of depressed fractures are simple, one third are associated with dural laceration, and one fourth have cortical lacerations. Depressed skull fractures typically require surgical elevation if the depth of the depression is thicker than the calvarium.
These fractures in the neonate have been occasionally ascribed to trauma during delivery. Because of the cartilaginous nature of the fetal skull, compression applied by forceps, fetal limbs, or the maternal pelvis as the baby exits the birth canal can be causative.
The differential diagnosis includes faulty fetal packing. The term faulty fetal packing has been used to describe these concave depressions because they are believed to be caused by prolonged extrinsic pressure from a malpositioned limb in utero. It has also been reported that uterine leiomyomas have caused parietal bone compression. The skull deformity of faulty fetal packing is not permanent and will resolve with time.
Treatments of traumatic infantile skull depressions have included surgical elevation, elevation by digital pressure on the edges of the depression, vacuum extractor or breast pump, and watchful waiting. Multiple case reports confirm spontaneous resolution with conservative treatment as long as there is no intracranial involvement.
As in any case of an infant with a fracture, non-accidental trauma should be considered. Birth records did not report a skull defect, and this patient's clinically obvious calvarial defect was not present on two previous examinations by her pediatrician. Further discussion with family members revealed recent accidental trauma from a sibling's loose ball and this was not thought to represent non-accidental trauma on evaluation by the appropriate services.
References:
Glass RB, Fernbach SK, Norton KI, Choi PS, Naidich TP. The infant skull: a vault of information. RadioGraphics. 24:507-522, 2004. [Medline]
Hanlon L, Hogan B, Corcoran D, Ryan S. Congenital depression of the neonatal skull: a self limiting condition. Arch Dis Child Fetal Neonatal Ed. 2006 Jul;91(4):F272. [Medline]
Sherer DM, Schwartz BM, Mahon TR. Intrapartum ultrasonographic depiction of fetal malpositioning and mild parietal bone compression in association with large lower segment uterine leiomyoma. J Matern Fetal Med. 1999 Jan-Feb;8(1):28-31. [Medline]
