MRI Sleep Studies Advance Treatment of Obstructive Sleep Apnea
Obstructive sleep apnea (OSA) ransacks the lives of nearly 2 million children in the United States. For some of these sleep-deprived patients, an innovative MRI technique combining static and moving images of the airway can now help determine treatment.
Lane Donnelly, MD, of the Cincinnati Children's Department of Radiology and Medical Imaging, helped pioneer this technique, referred to as "MRI sleep study" or "cine MRI." Developed in 2001, MRI sleep studies are a combination of techniques where static anatomic images are combined with movies of the airway. The joint images allow physicians to see the tissues around the airway as well as the motion of the airway. "Through the combination of these images and pattern of motion, we can suggest one or more diagnoses and base surgical treatment on these findings," says Dr. Donnelly, radiologist-in-chief. "Information from these studies affects management decisions in more than 50 percent of cases." Furthermore, he notes, OSA has shown to significantly decrease when using these MRI sleep studies to guide surgical decisions.
Development of this technique did not come without challenges. Because OSA symptoms are present only during sleep, patients must be sedated for the evaluation. "It is against everyone's best instinct to sedate kids with airway problems," Dr. Donnelly says. "To do this and to get people to agree to it was a big culture change." Five years later, the evidence shows an excellent safety record. Physicians at Cincinnati Children's now use this technique in about 200 clinical cases a year, mainly for a select group of OSA patients with complex problems.
Lessons Learned
A team of specialists comes together to view the images and evaluate for surgical planning. Team members range from those in Radiology to experts from Otolaryngology/Head and Neck Surgery (Sally Shott, MD), Pulmonary Medicine and the Sleep Disorders Center (Maninder Kalra, MD, Raouf Amin, MD, and Barbara Chini, MD).
Working together, these specialists use results from the MRI sleep studies to guide future treatment of patients. Some new concepts in patients with persistent OSA despite prior tonsillectomy and adenoidectomy have come out of this work. These include the following:
- a high recurrence of the adenoid tonsils,
- enlargement of the lingual tonsils as a cause of OSA, particularly in obese children and children with Down syndrome, and
- abnormal characteristics of the tongues of patients with Down syndrome.
"It's important for community pediatricians to know that kids with Down syndrome, obesity and decreased muscular tone, such as cerebral palsy, are more likely to have OSA," Dr. Donnelly says. He emphasizes that evaluation in the Sleep Disorders Center at Cincinnati Children's can reveal important details to aid treatment of these patients.
More Studies Underway
Findings from these MRI sleep studies have led to further research by Cincinnati Children's investigators. Dr. Kalra of Pulmonary Medicine and colleagues are using the technique to look into the parameters that cause obstructive sleep apnea in obese patients. Dr. Kalra also is leading an effort to learn more about the effect of weight loss on OSA. Additionally, he has partnered with the University of Cincinnati in studying airflow through the airway (see sidebar).
As the MRI sleep study technique begins to spread throughout the nation, the researchers tackle questions of controversy around the safety of sedation. One alternative to sedating patients might be a technique developed by Dr. Kalra where anesthesia is sprayed on the throat to simulate sleep, whereby sedation could be avoided altogether. In the meantime, the researchers maintain strict guidelines for when MRI sleep studies are indicated, and they show an excellent safety record over a large volume of cases.
Dr. Donnelly is professor of radiology and pediatrics. Recent studies on cine MRI by Dr. Donnelly and colleagues have appeared in American Journal of Roentgenology (183[1]:175- 181, 2004 July), Radiology (2005; 236[3]:768-78) and Pediatric Radiology (2006; 36:518-523).
