Incidental MRI Findings in Children on the Rise

Pauline Anderson

April 09, 2015

With increasing use of ever more sophisticated brain and spinal cord diagnostic technology, more children are being referred to pediatric neurosurgeons for unexpected findings on MRI.

Incidental findings of such lesions as pineal cysts and brain tumors cause additional stress not only for patients and their families but often also for primary care doctors, said lead author Cormac Maher, MD, pediatric neurosurgeon, University of Michigan, Ann Arbor.

"It has opened up a number of challenging treatment decisions for referral specialists. The decision to treat or not to treat these incidental lesions is frequently controversial."

A clinical report from the American Academy of Pediatrics section on neurosurgery discussing these incidental findings is published in the April issue of Pediatrics.

Big Part of Practice

An incidental MRI finding might, for example, be a small aneurysm found when a child with migraine headaches is sent for an MRI, or a Chiari malformation on the scan of child with a concussion after falling off playground equipment, said Dr Maher.

These incidental findings are now quite common. "A big part of most pediatric neurosurgeons' practices now is just interpreting these MRI scans for families and trying to determine the right thing to do," said Dr Maher. "We're discovering things now that 10 years ago, 20 years ago, 30 years ago, we just didn't know about and would never have found out about."

In the United States, MRIs are being used diagnostically more than in most other countries. According the Organization for Economic Cooperation and Development, there were 97.7 MRIs per 1000 population in 2010, compared with, for example the 2010 rate of 40 per 1000 in Canada. The US rate has since gone up to 106.8 per 1000 in 2013.

The most common incidental findings referred for specialist evaluation are pineal cysts, arachnoid cysts, and Chiari malformations, all of which may be asymptomatic. "Those are the three big ones that are most likely to result in a neurosurgical referral, and the most likely to result in a family that is very worried," said Dr Maher.

And these particular incidental findings are causing the most controversy as to whether they should be treated, he said.

It's important to recognize that some patients with these conditions will have significant benefit from surgical treatment, said Dr Maher.

"The task of differentiating those who will benefit from surgery from those who will not is assuming increasing importance in neurosurgical practice. Surgeons need to be sensitive to the risks inherent in both undertreatment as well as overtreatment."

He used the case of the mother of a child with a Chiari malformation who in a blog expressed her extreme disappointment that the neurosurgeon recommended against surgery, "which was the right decision for that particular case in my opinion," said Dr Maher.

"We spend more time counselling families who we think should not have surgery than counselling families we think should have surgery. It's easy for families to understand that we are taking a condition seriously if we are planning to operate, but if we're not treating something surgically, we need to spend a lot of time educating families about the condition so that they understand that they're being taken care of."

Because so many MRI examinations are being done nowadays, the cysts and malformations are being detected whereas in the past, they were all but unheard of. "If you asked neurosurgeons about these conditions 30 years ago, they would say that they're very rare, but now if you ask pediatric neurosurgeons they would say that they are the most common things we see in our practice."

US physicians are under "subtle pressure" to order MRIs for the child who, for example, has a headache history or concussion, said Dr Maher. "When a patient is worried or parents are worried, then the easiest thing to do is order a scan and be sure you're not missing something. If you don't order a scan, there's a chance that the family or patient will be unhappy and will go somewhere else where they can order a scan."

Doctors might think that the child probably just has a migraine or a concussion, "but they think, what if I'm wrong?" said Dr Maher.

He points out that MRIs sometimes pick up a serious condition, such as a brain tumor, earlier, and that the technology has dramatically changed the practice of neurology.

Too Many Scans?

But some are wondering whether US doctors now order too many scans. There may be an opportunity for specialty society–supported standards that would make physicians feel more comfortable in their decision not to recommend tests or treatments that they view as unnecessary, said Dr Maher.

"Physicians would feel less vulnerable if they knew this was very much a standard where societies would back them up."

Interest in the issue of incidental findings on MRI has been gradually building. A well-attended seminar on the topic has been offered for the last 7 years at the annual meeting of the American Association of Neurological Surgeons, he noted.

In addition to pineal and arachnoid cysts, other incidental cysts discussed in the paper are choroid plexus cysts, choroidal fissure cysts, and perineural (Tarlov) cysts. Other incidental findings the authors outlined include the following:

  • Benign enlargement of the subarachnoid spaces (BESS): Seen on brain imaging indicated for macrocephaly, BESS is "a transient developmental phenomenon that is really a variant of normal," said the authors. Typically, the affected patient exhibits accelerated head growth in midinfancy but otherwise thrives. Despite the presence of macrocephaly, the fontanel is slack and there is no suture separation. The natural history of BESS "is resolution later in childhood" and from a clinical standpoint, the child's head circumference will likely "drift gradually back toward the top of the normal range over a period of years," the authors write.

  • Brain tumors, most of which are benign: The neurosurgeon may choose to observe lesions that appear to be benign glial tumors, which in childhood have a relatively favorable natural history, said the authors. "Malignant degeneration is rare among children, so withholding of treatment until imaging surveillance reveals growth is often a safe and attractive strategy."

  • Vascular lesions in the central nervous system, including arteriovenous malformations (AVMs), cavernous hemangioma, developmental venous malformation (DVMs), and telangiectasia: According to the authors, AVMs pose a lifelong risk for hemorrhage at arterial pressures, leading to high rates of neurologic disability and possible mortality. Cavernous hemangioma is a less-threatening lesion, and DVMs are recognized as nothing more than anomalous patterns of venous drainage of normal brain parenchyma. Telangiectasia is believed to pose no risk for hemorrhage and is not a common incidental finding in childhood.

  • Pituitary abnormalities: Unanticipated imaging findings involving the pituitary gland are so common they've been dubbed "pituitary incidentaloma," said the authors. As is the case with incidentally discovered brain tumors, there is no alternative to neurosurgical referral for these pituitary lesions but the general pediatrician can control expectations, they said.

Although the diagnostic process will always generate unexpected findings, rational use of imaging technology and subspecialty consultation can minimize confusing experiences for parents, the authors concluded.

Asked to comment, Nina Schor, MD, PhD, chair, Department of Pediatrics, University of Rochester Medical Center, New York, and president, Child Neurology Society, said these incidental findings "are not a new phenomenon."

"As imaging gets more available and more in demand by the nonmedical public and as imaging modality resolution and discernment get better, the likelihood that medically unnecessary imaging will be done and show incidental findings that lead to worry and more unnecessary imaging increases, too."

Dr Maher and other authors have filed conflict of interest statements with the American Academy of Pediatrics, and any conflicts have been resolved through a process approved by the Board of Directors.

Pediatrics. Published online March 30, 2015. Abstract


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