**4. Diagnosis**

Many diagnostic tools can be used, yet physical examination is very important. A through physical examination of the nose, oral cavity, pharynx and neck should be done. Endoscopy gives clinicians visual assessment to the upper airway and may show possible sites of collapse. Endoscopic Mullar maneuver is a useful procedure for OSA[6].The best results obtained by instructing the patient to lie down in supine position then inspire maximally then with closed nose and mouth, while placing the endoscope at the level of supraglottis, the examiner will be able to visualize the degree of pharyngeal collapse. Increase in negative pressure in the pharynx will demonstrate the point of collapse. Standardized performance and documentation is advocated to prevent any inter-investigator variability [7]. There are many classifications for upper airway obstruction; Fujita's classification system described patterns of upper airway obstruction in OSA patients in 1985. Fujita classified airway obstruction into 3 types namely:

**Type 1.** Isolated palatal obstruction,

**2nd stage** rapid eye movement (REM) stage will follow for 20 minutes. REM stage represents the deep sleep stage; it follows the non-REM stage with 20-25% of total sleep. During average night REM to non-REM ratio is 4:6 with intervals 60-90 minutes. Physiologic changes during REM are generalized muscle atonia except for ocular muscles, increase temperature, blood flow and oxygen use in the brain as well as increase in heart rate, blood pressure and respiration with dramatic fluctuations. Respiration is controlled by 2-control systems; metabolic and behavioral. Non-REM is predominantly controlled by the metabolic control system, which is influenced by hypoxia and hypercapnia. On the other hand during the REM sleep, behavioral control system is predominant. OSA usually occurs during stage 3, 4 and REM, which are the deep sleep stages, and that is because of blunt responses to hypoxia and hypercapnia along

with the generalized muscle atonia; pharyngeal wall muscles may collapse [1] [2].

could have one or more of the following anatomical variations:

394 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

There is a special surgical procedure for each site of obstruction.

Upper airway obstructions can occur anywhere in the nasopharynx, oropharynx and hypo‐ pharynx. Nasopharyngeal obstruction examples are nasal septum deviation, nasal polyps and rhinosinusitis; they can cause mild OSA [3]. Most common sites of airway collapse occur in the hypopharynx [4]. It extends from the soft palate to the epiglottis; anteriorly it is formed by the base of the tongue and soft palate, while pharyngeal constrictor muscles form the posterior borders. Studies show that tongue volume and lateral walls of the pharynx are independent risks to OSA. There are many craniofacial abnormalities that cause OSA. Even a minimal change in maxillary or mandibular position can lead to upper airway collapse. OSA patients

A retro-position of the mandible or the maxilla, micrognathia, long soft palate, increased thickness of the soft palate, macroglossia (large tongue) and differences in hyoid bone

The success of surgical treatment is depending on the recognition of the level of obstruction.

Many diagnostic tools can be used, yet physical examination is very important. A through physical examination of the nose, oral cavity, pharynx and neck should be done. Endoscopy gives clinicians visual assessment to the upper airway and may show possible sites of collapse. Endoscopic Mullar maneuver is a useful procedure for OSA[6].The best results obtained by instructing the patient to lie down in supine position then inspire maximally then with closed nose and mouth, while placing the endoscope at the level of supraglottis, the examiner will be able to visualize the degree of pharyngeal collapse. Increase in negative pressure in the pharynx will demonstrate the point of collapse. Standardized performance and documentation is advocated to prevent any inter-investigator variability [7]. There are many classifications

**3. Anatomy**

position [5].

**4. Diagnosis**

**Type 2.** Isolated retrolingual obstruction, and

**Type 3.** Palatal and retrolingual obstruction

Recently other modifications to Fujita classification were advocated by adding more details for the base of the tongue [8].

**Polysomnography** (PSG) is still the golden standard to establish OSA diagnosis. It can be used as a diagnostic tool as well as to assess therapeutic efficacy of a given treatment modality including weight loss, CPAP, oral appliances and MMA. It is usually done in a sleep clinic, as the patient should sleep at least for 4 hours, and the electroencephalogram (EEG), electroocu‐ logram (EOG), electromyogram (EMG), and electrocardiogram (ECG) will be monitored [9].

There are many imaging studies proposed to evaluate the upper airway such as CT, MRI, dynamic scanning protocols e.g. ultrafast CT or MRI [7]. In oral and maxillofacial clinics cephalometric x-ray is still one of the most common x-rays used to diagnose and to evaluate treatment along with orthopantomogram (OPG). Both are a simple 2D image commonly used by oral and maxillofacial surgeon. It helps to detect posterior airway obstruction caused by skeletal disharmony. Examples of some important cephalometric measurements are:


OPG is used before any skeletal surgery to estimate the location of vital structures such as inferior alveolar nerve, mental foramen and apices of anterior teeth [10].
