Ping Pong skull fracture

Clinical History

A six-month-old female patient presented to the emergency department after a fall from her mother’s hands onto a hard surface. She did not vomit or lost consciousness. The mother noted a skull deformity immediately after the fall.

Imaging Findings

Unenhanced axial volumetric CT of the head showed a large inward cranial indentation of the right parietal bone without associated fracture line, in keeping with ping-pong type depressed skull fracture. The fracture measured approximately 5 x 5 cm in diameter with an inward depth of 1.6 cm. There was no associated intracranial haemorrhage or other underlying brain abnormality (Fig.1, 2).

Post-operative unenhanced CT of the head showed evidence of craniotomy and elevation of the previously noted depressed skull fracture in the right parietal bone (Fig.3, 4).

Discussion

A ping-pong ball fracture or pond fracture is inward buckling of the calvarium and occurs in neonates and young children due to direct blunt trauma to the skull. It is primarily due to increased plasticity of the immature skeleton in young children. As a result of this malleability, blunt head trauma causes inversion of the normal outer convexity of the cranium to take a cup shape termed a "ping-pond ball or pond" fracture. This is equivalent to green stick fracture of the long bone and is rarely associated with any significant intracranial injury [1, 4, 6].

It can be classified into two main categories; congenital and acquired. Congenital fracture occurs either antenatally due to in utero pressure of the limbs on the skull surface, or during birth due to pressure from the mother’s sacral promontory or symphysis pubis against the skull. Acquired fractures are usually related to obstetric intervention or postnatal trauma [1, 2].

Clinically, the fracture appears as a deformity of the surface of the skull usually without associated symptoms unless there is associated intracranial injury. Plain x-ray may show focal skull deformity with inward indentation. Ultrasound of skull is a helpful in diagnosing the fracture and associated intra-cerebral hematoma, which is a rare association. CT is the gold standard examination for evaluating the extent and shape of the fracture and to rule out associated lesions. MRI is usually limited to cases with doubtful or incidental intracranial findings [1, 3].

This can be treated conservatively or surgically depending upon the severity of depression and presence of associated intracranial injury. Small fractures and those diagnosed at birth may resolve spontaneously. However, large fracturse (>3 cm) and those which occur following head injury are unlikely to resolve spontaneously and usually require intervention. There are many nonsurgical reduction techniques used to elevate the depressed fracture using digital manipulation and vacuum devices such as an obstetrical vacuum extractor. Complicated fractures require corrective surgery or minimally invasive borehole technique for reduction [1, 2, 4, 5].

In our case, in view of the patient’s age a mini borehole to elevate the fracture was initially attempted but was not successful. A craniotomy was therefore performed to elevate the bone flap. The post-operative outcome as shown on the follow up CT was excellent without any neurological problems.

Differential Diagnosis List

Final Diagnosis

Right parietal depressed skull fracture of ping-pong type with no intracranial injury.

URL:	https://eurorad.org/case/14346
DOI:	10.1594/EURORAD/CASE.14346
ISSN:	1563-4086