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Skull Radiography

Although skull radiography is of limited value in assessing patients with head injuries, skull X-rays are extremely valuable for studying abnormalities of the base of the skull and the cranial vault, congenital and perinatal anomalies, and systemic diseases that produce bone defects of the skull. For more accurate assessment of head injuries as well as of skull and head abnormalities, non enhanced computed tomography studies of the head are done.

Skull radiography evaluates the three groups of bones that comprise the skull: the calvaria (vault), the mandible (jaw bone), and the facial bones. The calvaria and the facial bones are closely connected by immovable joints with irregular serrated edges called sutures. The bones of the skull form an anatomic structure so complex that a complete skull examination requires

Purpose

• To detect fractures in patients with head trauma.
• To aid diagnosis of pituitary tumors.
• To detect congenital anomalies.

Patient preparation

• Explain to the patient that his head will be immobilized and that several X-rays of his skull will be taken from various angles.
• Tell him that this test helps determine the presence.
• Explain that a radio logic technician will perform the test. Describe where it will take place (usually the radiology department).
• Explain that he needn't restrict food or fluid before the test.
• Tell him to remove glasses, dentures, jewelry, or any metal objects that would be in the X-ray field

Procedure and posttest care

• Have the patient recline on the X-ray table or sit in a chair.
• Tell him to remain still during the procedure.
• Use foam pads, sandbags, or a head­band to immobilize the patient's head and increase comfort.
• Five views of the skull are routinely taken: left and right lateral, anteroposterior Townes, posteroanterior Cald-well, and axial (or base).
• Films are developed and checked for quality before the patient leaves the area.

Normal findings

A radiologist interprets the X-rays, evaluating the size, shape, thickness, and position of the cranial bones as well as the vascular markings, sinuses, and sutures. All should be normal for the patient's age.

Abnormal findings

Skull radiography is often used to diagnose fractures of the vault or base, although basilar fractures may not show on the film if the bone is dense. This test may confirm congenital anomalies and may show erosion, enlargement, or decalcification of the sella turcica that result from increased intracranial pressure (ICP). A marked rise in ICP may cause the brain to expand and press against the inner bony table of the skull, yielding visible marks or impressions.

In conditions such as osteomyelitis (with possible calcification of the skull itself) and chronic subdural hematomas, X-rays may show abnormal areas of calcification. The X-rays can detect neoplasms within brain substance that contains calcium (such as oligodendrogliomas or meningiomas) or the midline shifting of a calcified pineal gland caused by a space-occupying lesion.

Radiography may also detect other changes in bone structure, for example, those that arise from metabolic disorders such as acromegaly or Paget's disease.

Interfering factors

• Improper positioning of the patient and excessive head movement (possible poor imaging).
• Failure to remove radiopaque objects from the X-ray field (possible poor imaging).