Split calvarial fracture: A rare cause of hypovolemic shock in an infant.

The present report describes a rare type split fracture of a calvarial bone, causing hypovolemic shock in an infant. The infant responded well to resuscitative measures. The authors discuss the possible mechanisms behind such a calvarial fracture.

Introduction

Closed skull fractures circumspect all infective complications, usually observed with open/compound skull fractures. These fractures are mere radiological findings and carry little clinical significance. The pediatric skull is highly flexible and usually shows a linear or “diastatic” fracture after sustaining trauma. “Ping-pong“ fractures of the pediatric skull are an extrapolation of greenstick calvarial fractures.[1] The authors describe a unique type of calvarial fracture in an infant where calvarial bone got split open and chiseled by the adjoining calvarial bone.

Case Report

After an accidental fall from a two-wheeler, a 2-month infant presented with massive scalp swelling and traumatic shock. On examination, child was looking around and had spontaneous movements of all limbs. There was local scalp swelling over the right frontoparietal region, but no laceration or skin breech. Pupils were equal in size and reacting to light. There was tachycardia, with a heart rate of 186 beats/min and hemogram of 5.6 g/dL. Computerized tomography scan of the head revealed a split fracture of a right parietal bone at the anterior end, chiseled by the posterior margin of right frontal bone [Figures 1 and 2]. The examination did not reveal any other site of trauma, including long-bone and abdominal solid organ injury. The infant was resuscitated with packed red blood cell concentrate and was kept under observation for 48 h. On the 7th posttrauma day, scalp swelling had subsided, and the infant was discharged in a stable state.

Figure 1

(a) Clinical picture of the infant showing scalp swelling at frontoparietal region. (b) Bone window of computerized tomography scan showing splitting of right parietal bone

Figure 2

(a and b) Computerized tomography scan (axial section) showing split right parietal bone and stripping of underneath dura, causing sequestration of blood. Left sided over-riding of frontal bone over parietal bone is seen

Discussion

In adults, cranial bone and suture have similar properties, and the adult calvaria deforms very little prior to fracture. In contrast, pediatric cranial bone is 35 times stiffer than pediatric cranial suture. In addition, pediatric cranial suture deforms 30 times more before failure than pediatric cranial bone and 243 times more than adult cranial bone.[23] For a given energy, the impact of the skull with a complaint interface caused less damage for skulls aged <18 months.[4] Henceforth, the ability of pediatric skull to undergo dramatic shape changes before the fracture is obvious.

In the present case, a possible mechanism of injury could be a direct impact over the right side of forehead causing posterior displacement of the bifrontal bone complex, which was more pronounced on the right side. The posterior displacement of the right frontal bone caused massive pressure over the anterior edge of the right parietal bone, leading on to its chiseling and opening up of the two cortices (an elevated and a depressed segment of parietal bone). Bilateral frontal bones’ posterior end was abutting against parietal bones, obliterating the sutural space, producing a situation contrary to “diastatic fracture.” Right parietal bone had split, with outer cortex getting elevated and inner table getting depressed. The depressed segment had stripped off the duramater, causing significant blood sequestration at the fracture site. The subgaleal and extradural hypo-dense blood collection had caused a significant drop in circulating blood volume resulting in hemorrhagic and hypovolemic shock.[5] Slight overriding of frontal bone over parietal was also noted on the left side, indicating disparity of impact over frontal bone.

Conclusion

The present case highlights the compliant nature of pediatric calvaria and demonstrates a unique variety of infantile skull fracture. Such split calvarial fractures point toward significant frontal energy impact and unequal over-riding at frontoparietal sutures indicate directional preponderance of impact. These findings may be of help in guiding future studies from forensic case files.

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Conflicts of interest

There are no conflicts of interest.