Volume 5, Case 9
Loren G. Yamamoto, MD, MPH
Kapiolani Medical Center For Women And Children
University of Hawaiʻi John A. Burns School of Medicine
Plain film radiographs of the skull are obtained in limited circumstances. In most instances, CT scanning of the head is more useful. Some hospitals and clinics do not have easy access to CT scanning and hence, they rely more on the use of clinical assessment, plain film skull radiographs, and judicious referral to a center with a CT scanner. Interpreting skull radiographs in infants can be difficult since their skulls have many normal lucencies. Sutures are generally sinusoidal in appearance and in their standard anatomic locations (coronal, sagittal, and labdoidal). Fractures are rarely sinusoidal. Fractures are usually linear, stellate, or depressed.
View normal skull radiograph.
Four standard views are often obtained. An AP view, a Towne's view, and two lateral views. The Towne's view is an AP view with the neck flexed forward. Two lateral views can be more optimal than a single lateral view to permit the film to focus on one side at a time.
Locate the coronal, sagittal, and lambdoidal sutures on these skull radiographs. In addition to these major sutures, the anterior fontanelle is often visible. A suture extends from the anterior tip of the anterior fontanelle into the frontal bone. Two smaller sutures on each side of the skull are present in the lower skull adjacent to the mastoid; the parietomastoid suture and the occipitomastoid suture.
View the locations of these sutures.
C - Coronal
S - Sagittal
L - Lambdoidal
P - Parietomastoid (squamosal)
O - Occipitomastoid
The anterior fontanelle is outlined in the broken line. Note that a suture extends anteriorly into the frontal bone from the anterior tip of the anterior fontanelle.
Linear skull fractures are rarely associated with the need for neurosurgical intervention. They will often present to an acute care clinic or emergency department several days after the injury with a subgaleal hematoma (soft swelling on the side of the head) as a chief complaint. These are benign and should not be aspirated unless an infection is present.
Parietal skull fractures which cross the path of the middle meningeal artery or other major vessels may be associated with epidural or other types of intracranial hemorrhage. In young children, the middle meningeal artery does not groove into the bone as it does in adults and thus, laceration of the middle meningeal artery is less likely to occur (compared to adults) with a parietal skull fracture. Roughly half of the epidural hematomas in children occur in the absence of skull fractures. Thus, plain film skull radiographs should not be used as a routine screening measure to determine risk of intracranial hemorrhage. CT scanning is more effective at ruling out cerebral hemorrhages.
Neither CT nor plain film skull radiographs are highly reliable in ruling out a basilar skull fracture. Such fractures are difficult to see on CT scans and plain film skull radiographs. This diagnosis is often made clinically (nasal CSF leak, CSF otorrhea, hemotympanum, Battle's sign, etc.) and then confirmed on fine or angled CT cuts, or MRI.
Widely separated linear skull fractures (widely diastatic) are associated with a higher risk of subdural hematoma and an increased risk of developing leptomeningeal cysts. The follow-up radiograph one month later may show a "growing" fracture that results from a meningeal laceration. This results in a bulging leptomeningeal sac that causes erosion of the overlying skull and an eventual skull defect if it is not repaired.
Depressed skull fractures may be evident on plain radiographs, however, CT scanning is better able to determine the extent of depression.
View the plain film skull radiographs to test your skill in interpreting these radiographs.
View Case B.
This 11-month old infant fell and struck his head on a hard surface.
Case B Interpretation:
Linear fracture of the posterior portion of the right parietal bone extending across the lambdoidal suture into the occipital bone.
View Case C.
The history in this case is that this 2-month old fell off a bed twice. It should be noted that this history is highly suspicious. A 2-month old infant cannot move about very much. While it may be possible for this 2-month old infant to have fallen off a bed once, it is very unlikely that any parent would have allowed this to occur twice on the same day.
Case C Interpretation:
Right parietal skull fracture.
View Case D.
The mother of this 2-month infant fell onto a hard surface while she was carrying her infant.
Case D Interpretation:
Linear fracture of the right occiput.
View Case E.
This 13-month old infant was noted to have a soft swelling on his head two days following an episode of head trauma following which, his behavior was normal.
Case E Interpretation:
Horizontal hairline fracture (very subtle) running across the left temporal bone which extends posteriorly to the level of the labdoidal suture.
View Case F.
Case F Interpretation:
There is a depressed skull fracture over the posterior right parietal bone. The hyperdense (sclerotic) appearance of the skull abnormality indicates the presence of a depressed skull fracture.
View Case G.
Case G Interpretation:
There is a 3 cm angled fracture in the right parietal bone which communicates with the labdoidal suture.
View Case H.
Case H Interpretation:
Linear skull fracture of the right parietal bone extending from the labdoidal suture to the parietomastoid suture.
View Case I.
Case I Interpretation:
There is a short parietal skull fracture (very subtle) near the vertex of the skull. It is difficult to lateralize on the frontal views. It is probably on the left.
View Case J.
Case J Interpretation:
There is a fracture of the lower portion of the left parietal bone.
View Case K.
Case K Interpretation:
Long linear left parietal fracture extending from the vertex to the labdoidal suture.
View Case L.
Case L Interpretation:
Linear fracture extending the length of the right parietal bone.
View Case M.
Case M Interpretation:
Biparietal skull fractures.
View Case N.
Case N Interpretation:
Linear fracture of the posterior left parietal region.
View Case O.
This is a CT scan image. While this case has focused on plain skull radiographs, CT scans are often ordered in cases of significant head trauma. Radiologists will usually read CT scans. Identification of the sutures versus fractures on CT can be difficult without the knowledge of the usual appearance and location of sutures.
Case O Interpretation:
The top set of scans focuses on the brain which appears to be normal. Extensive soft tissue swelling exterior to the skull is evident on this set of scans.
The lower set of scans is contrasted to view the bones (bone windows). There are bilateral fractures of the parietal region (arrows). The lambdoidal (L), coronal (C), and sagittal (S) sutures are identified. Note that the fracture is not seen in the lower cuts.
View Case P.
This is another CT scan case.
Case P Interpretation:
The top set of scans focuses on the brain which appears to be normal. A skull depression is visible on the right.
The lower set of scans is contrasted to view the bones (bone windows). There is a depressed skull fracture of the upper portion of the right parietal bone (arrows). The lambdoidal (L) and coronal (C) sutures are identified.
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