WHEN CRANIAL C.T SCAN IS INDICATED?
A 2 years old boy fell off a chair 3 days before; he vomited once after falling, cried for few minutes, still complaining of pain in the scalp and vomits once daily. There was no other symptom. On physical exam, he was active, alert and there was a soft painful swelling of scalp on left lateral side, neurologic exam was within normal limit. Skull x-ray showed evidence of non depressed fracture and CT scan of the Brain showed temporo-parietal subdural hematoma (acute to sub-acute) with minimal left uncal displacement. He was treated conservatively by Neurosurgeon and the repeated CT scan on follow up showed resolution of the hematoma. Child is doing well on follow up.
Occasionally, we see children usually aged below 1-2 years old with history of fall which is usually from bed, kitchen table, chair, or some time involved in an accident. Many of these with history of fall usually don’t need any aggressive work up but some of them needs more attention and the question that arises is when to order a CT scan of the brain which in the majority is not needed and has the risk developing malignancies in future.
A good history and a thorough physical examination are very helpful for the physician to find his way through and make the right decision. Mental status, scalp hematoma except frontal, loss of consciousness, palpable scalp fracture, activity of the child, repeated vomiting, looking weak after the fall, and any signs of basal scalp fracture, are all determining factors for making decision for a CT scan of the brain because of the risk of malignancies associated with doing CT scan in children. If your child is more than a year of age, has not lost consciousness and is alert and behaving normally after the fall, you can watch your child carefully at home for 1 day and if notice any change call your doctor but if your child has lost consciousness even briefly or if won’t stop crying, complaining of head or neck pain or vomit several time or won’t awaken easily or not talking or walking normally, you should call your doctor.
Like x-ray, CT scan uses ionizing radiation which can damage DNA and is implicated as the cause of lethal malignancies. Two other technologies, MRI and ultrasound do not use radiation. It is estimated that the potential rate of lethal malignancies from pediatric Cranial CT is around 1/1000, with a maximum incidents of one case of cancer for every 500 people who are scanned. This highlights the need to obtain CT studies with appropriate clinical indication and to limit the amount of radiation to be as low as possible during the procedure and for this reason the CT scan should be done in a general hospital or a pediatric hospital where they are able and more familiar with the exposure of children to radiation. There is no low dose radiation threshold for inducing cancer, in other word no amount of radiation should be considered safe especially in children and age weight and the scanner setting all are be considered when receiving radiation.