Obstructive sleep apnea syndrome (OSA) is a sleep disorder characterized by periods of respiratory arrest (Apnea) or decreased air-flow (hypopnea) leading to oxygen desaturation in the blood.
OSA affects approximately 4% of men and 2% of women aged between 30 and 60 years old. This percentage increases to 28 to 67% in older men compared to 20 to 54% in older women. An important discrepancy exists between the estimated prevalence of OSA and the patients accurately diagnosed and treated, where an estimated 80% of patients with moderate to severe OSA are not diagnosed.
Apneas occurring during sleep can take two forms: Obstructive apneas, are caused by an anatomical obstruction of the upper airway, central apneas are related to a decreased respiratory drive in the brain-stem during sleep and a mixed apnea can be a combination of both. Apnea itself is defined as absence of breathing for 10 seconds or more despite respiratory effort. Hypopnea is resultant to a reduction of 30 to 50 % of respiratory flow for at least 10 seconds with a resultant 3-4% oxygen desaturation. The severity of OSA is classified according to the Apnea Hypopnea index (AHI). AHI is the average number of apneas and hypopneas per hour of sleep. AHI of greater than 5 and less than 15 is mild OSA, while 16-30 is moderate and greater than 30 is severe.
The obstruction of the upper airways can happen at multiple levels; the nasal region, the retro-palatine region and the oropharynx. Obstruction at the level of the nasal region, can be caused by a deviated septum, hypertrophic lower turbinates or narrow nasal floor. The retro-palatine region is the most common site of obstruction in teenagers and kids due to hypertrophic adenoids and/or tonsils. Also, a hypoplatic maxilla can decrease the volume of the nasopharynx, especially in patients with cleft lip and palate who are at higher risk of developing OSA. The oropharynx or posterior airways space is largely affected by the anterio-posterior position of the mandible and tongue. A retrognathic mandible causes the tongue to be positioned posteriorly which can cause obstruction at the level of the oropharynx during sleep. Other risk factors for OSA include a macroglossia (Hypertrophic tongue), obesity (BMI > 34), advanced age, family history of OSA, excessive alcohol consumption and cigarette smoking. Men are at higher risk for OSA due to differences in the anatomical and functional characteristics of their upper airways' structures and the respiratory response to micoarousals.
OSA could be a lethal disease, and is associated with multiple comorbidities. OSA can also be associated with a decreased quality of life due to persistent fatigue and loss of alertness. Significant negative physiologic changes are seen with each obstructive episode like hypoxemia, hypercapnia, frequent arousals and increased respiratory efforts. These changes will lead to the development of hypertension, coronary artery disease, cerebrovascular accident, depression, type II diabetes, glaucoma, attention deficit disorder and increased risk for sudden death during sleep.
The diagnosis of OSA is based on a thorough history, physical examination, X-rays and a sleep study (Polysomnography). Screening indicators for the disease are snoring, respiratory arrest during sleep, daytime sleepiness, recurrent headaches, irritability and decreased libido. A questionnaire call the “Epworth sleepiness scale” is widely used to assess the severity of symptoms associated with OSA.
There are multiple treatment options for OSA including surgical and non-surgical options. The non-surgical options are: anteriorly positioning mandibular devices, CPAP (continuous positive airway pressure) and modification to sleep position. In all patients a decrease in alcohol consumption, drugs, tobacco, sedatives and weight loss are associated with improved OSA symptoms. The most commonly used device for treatment of OSA is a device that maintains the upper airways open during sleep called CPAP. Another non-surgical device is an oral appliance that can advance the mandible and is useful for treatment of mild to moderate OSA in patients that do not tolerate CPAP.
Several surgical procedures are currently offered to reduce the symptoms and severity of OSA. These procedures are divided into surgeries that can affect the maxillary-mandibular complex, nasal and paranasal spaces and oral pharynx. One of the most common and effective of these procedures is called maxillomandibular advancement surgery (MMA), which has been shown to be an excellent alternative to CPAP in patients with severe OSA. MMA procedures involve a movement of 10mm or more of the maxilla and mandible, effectively re-positioning the soft palate and tongue and opening the posterior airway space. Success rates in curing OSA with MMA procedures is reported at 90 to 100% of patients.
In conclusion, the American Academy of Sleep Medicine recommends the use of mandibular advancement devices for mild OSA. For moderate OSA, a mandibular advancement device or a CPAP are considered as initial treatment. Finally for severe OSA, the CPAP is a must. In cases where the patient is unable to tolerate the CPAP, a maxillofacial surgeon can offer maxillomandibular advancement surgery to improve the health and quality of life of patients with OSA.
References:
• Bagheri (2011). Current Therapy in Oral and Maxillofacial Surgery. United States: Saunders
• Lowe AA. Treating obstructive sleep apnea: The case for oral appliances. AJODO 2012 Oct:434
• Jacobson RL. Treating obstructive sleep apnea: the case for surgery. AJODO 2012 Oct: 435
