Functional imaging in sleep medicine
The field of sleep relating breathing disorders has grown substantially in recent years. The increased awareness of sleep apnea hypopnea syndrome and the potentially serious consequences of this disease has resulted in better diagnosis and a growing number of treatments.
The most prevalent form of sleep relating breathing disorders is obstructive sleep apnea. This conditions is characterized by a repeated collapse of the upper airway during sleep, causing a frequent cessation of the airflow. This leads to oxygen desaturation and repetitive awakenings. Symptoms of obstructive sleep apnea include daytime fatigue, morning headache and concentration difficulties. Untreated sleep apnea can lead to high blood pressure, atherosclerotic plaque formation and even stroke or heart failure.
Obstruction of airflow during sleep caused by upper airway collapse
At present, the standard treatment for sleep apnea is continuous positive airway pressure or CPAP. This treatment involves sleeping with a nose of face mask connected to a CPAP device that increases the intraluminal pressure to prevent collapse. Although efficient in many cases, this therapy is not always tolerated well by the patients. Therefore a whole range of alternative treatments have been developed:
- oral appliances
- upper airway surgery
- tongue muscle stimulation
- maxillo mandibular osteotomy
A hallmark of these treatments is that they tend to work very well for a subset of patients but that the success rate over a general population is often limited. A good patient selection criteria is therefore crucial for the development of efficient alternatives to CPAP. Functional imaging using computer methods can be used to screen and characterise the patients and select appropriate therapies.