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manner could be successfully treated in other ways [2–5]. In any case, patients
coming from a sleep specialist are diagnostically evaluated with qualitative and
quantitative assessment of sleep-disordered breathing. A technically adequate and
manually scored sleep study record can provide information on OSA severity, point
to the number and level of obstructions and positional dependence, and possibly
yield other important information. However, potential shortcomings of sleep studies
and the resulting possibility of misjudging a patient’s condition when relying solely
on them should be kept in mind.
The training of ENT specialists emphasizes the morphological rather than the
functional assessment of UA.Recognizing the extent to which both of these factors
are present in each individual patient might be the key to successful treatment but is
often difcult to determine. When gathering information about a patient’s clinical
condition, we usually consider the possibility of surgical treatment. In this regard,
the key question to be constantly kept in mind is whether we can signicantly
improve or cure OSA and its consequences; if not, we should aim to facilitate or
enable other treatments. As surgical procedures are irreversible and associated with
possible complications, non-surgical approaches have, as a rule, traditionally taken
precedence over surgical ones. In recent years, protocols have been on the rise that
take into the account the heterogeneity of OSA and encourage the identication of
specic phenotypes, i.e., sets of morphological and other characteristics that may
allow a more personalized approach. In certain cases, invasive procedures are preferred, based on the claim that anatomic considerations should be taken as the true
prognosis factor for OSA surgery, rather than merely the severity of the disease [6–8].
Routine pre-operative drug induced sleep endoscopy (DISE) investigations have
conrmed that obstructions often occur at the level of the epiglottis and it is now
recognized as one of the predominant sites affecting treatment success [9].
Nevertheless, to date, no reliable system has been established that could help us
identify patients with obstruction at this level during clinical examination. As a relatively recently discovered entity, epiglottis obstructions are still associated with
many unresolved issues related to classication, diagnosis, and treatment.
M. Delakorda and B. Maver
6.2 History
History taking remains a fundamental part of OSA patient assessment. It can take
place in different clinical settings, often during routine appointment when other
complaints are being evaluated and OSA symptoms or typical clinical features are
detected. Sometimes, only a few simple screening questions can start revealing an
undiagnosed OSA. These patients might need more extensive workup, and the
ENT specialist sets the sequence of medical treatment. A systematic approach to
history taking should be established to acquire all necessary information. In this
respect, tools like sleep questionnaires can be very helpful. With high clinical suspicion, the patient is sent to a sleep study and is expected to return for further
workup. In this case, a sleep surgeon should be familiar with the contraindications
for unattended sleep studies—severe pulmonary disease, neuromuscular disease,
congestive heart failure, hypoventilation, chronic opioid use, history of stroke, or
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severe insomnia. [10] An alternative clinical setting is when the patient is suspected to have OSA or has already been positively tested and is referred to an ENT
specialist. Once again, a full comprehensive history is required, even though we
anticipate that a thorough assessment has already been performed. With growing
incidence and awareness of the disease, we can expect a substantial increase in
OSA patient inux to clinics. An effort should be made to educate colleagues of
other specialties about the disease, since their role in recognizing sleep disorders is
not negligible.
OSA patients are usually not able to evaluate their own respiratory events.
Therefore, it is helpful if their bed partner is present at the ofce while taking history or during follow-up. Quite often, the main reason a patient seeks help is socially
disruptive snoring leading to partner’s sleep deprivation. They can provide information on snoring loudness, disturbance, position dependency, breathing route, etc.
Such observations are valuable in evaluating the outcome of any potential treatment,
and it is therefore advisable to describe and quantify them with questionnaires
employing a visual analogue scale. To avoid bias, these questionnaires should be
lled out in advance and without the presence of medical staff.
OSA-oriented history involves the evaluation of typical symptoms, divided into
daytime and nighttime. The most common symptoms are presented in Table 6.1.
Pang etal. found a strong correlation between patient’s self-perception and OSA
severity [11]. However, we must be cautious when assessing objectivity of selfreported symptoms. A precise description of the sleeping pattern is important, so it
is advisable for the patient to keep a sleep diary documenting sleep and its features
over a period of several weeks. We must also address abnormal behavior during
sleep (e.g., strange movements of limbs, catathrenia), personal habits (drinking,
smoking, and consumption of stimulants), drugs abuse (sedatives, antidepressants,
anxiolytics), and occupational and social history.
Many questionnaires were developed for the assessment of sleep quality, OSA
symptoms, and risk factors. In the English literature alone there are already more
than 30. The Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index
(PSQI), and STOP BANG are among the most commonly used. The ESS is used to
assess excessive daytime sleepiness in different sleep disorders. Patients rate the
probability of falling asleep in diverse real-life scenarios [12]. It is regularly used in
clinical practice; however, with low test–retest reliability and poor sensitivity (46%)
Table 6.1 Daytime and nighttime OSA symptoms
Daytime symptoms Nighttime symptoms
Unrefreshing sleep
Morning headache and dry/sore throat Witnessed apneas
Excessive daytime sleepiness or fatigue
Cognitive decits Insomnia
Decreased vigilance Restless sleep
Sexual dysfunction Nocturia
Irritability
a
PSQI
b
STOP, BANG
c
ESS
a
a,b,c
a,b
Snoring
Gasping and choking sounds
a
a,b
a
a
a
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and specicity (60%), it is not a good OSA predictor [13–15]. PSQI is a good tool
for assessing sleep quality, although it is not specic to any primary sleep disorders
and it is not indicated for screening patients with a high risk of OSA [16–18]. It
focuses on sleep quality, efciency, duration and latency, daytime symptoms, and
the use of sleeping medications. Currently, the most utilized questionnaire is the
STOP BANG; the abbreviations stand for snoring (S), tiredness (T), observed apnea
(O), high blood pressure (P), body mass index (B), age (A), neck circumference (N),
and male gender (G) [19]. It is easy to use and shows a high sensitivity (90%) and
moderate specicity (46%) for detecting OSA [20]. In contrast to other questionnaires, it can be used as an efcient screening tool for OSA [21].
It is important to recognize the risk factors for OSA, such as obesity, increased
neck circumference, airway abnormalities, hypertension, and family history of
OSA, and therefore, relevant questions addressing them should not be omitted. The
points of interest include cardiovascular (arterial hypertension, congestive heart
failure, arrhythmias, ischemic heart disease, pulmonary hypertension), endocrine
(hypothyroidism), metabolic (diabetes type 2, gout), neurological (epilepsy, stroke,
headaches), pulmonary (asthma, emphysema, chronic bronchitis), gastroesophageal, and psychiatric diseases (depression, anxiety, bipolar disorder) [22, 23]. All
signs, symptoms, and OSA-related comorbidities should be recorded to aid our
diagnostic process and to provide therapy outcome measures for re-evaluation in
addition to sleep studies’ results.
M. Delakorda and B. Maver
6.3 BMI
Excess body weight is the most important risk factor for the development of OSA
with incidence increasing rapidly at values of body mass index (BMI) above 30kg/
m2 [24]. At such values, the likelihood of multilevel obstructions increases as well
[25]. Changes in BMI affect OSA severity in both positive and negative ways [26,
27]. Fat accumulation in soft tissues of the neck, especially in the tongue, causes
reduction of the pharyngeal lumen and greater collapsibility of the walls [28].
Paradoxically, according to some studies, lower BMI patients are more prone to
obstructions at the level of the tongue base and epiglottis when compared to others
[29–31]. On the other hand, Kuo etal. observed no difference in BMI between epiglottis collapse and non-epiglottic collapse groups [32].
6.4 Gender
Historically, OSA has always been considered a male disease [33]. Previous estimations showed that male-to-female ratio of OSA prevalence in general population
ranged from 3:1 to 5:1, while in clinical study groups, the ratio was between 8:1 and
10:1 [34–36]. It is believed that sex difference in OSA prevalence is linked to different fat distribution, length of the upper airway, pharyngeal collapsibility,
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neuromuscular control, arousal threshold, and sex hormones [37]. Women tend to
express differently when describing symptoms, and according to Young, 40% of
women with an apnea–hypopnea index greater than 15 did not report any typical
OSA symptoms, while in men this share was 20% [38]. The difference in collapsibility of retroglossal airway in women and men has not been proven, although
Whittle etal. have shown by means of MR imaging that women have greater fat
deposition and a narrower airway in this area [39]. Signicant differences in the
epiglottis cross- sectional area (CSA) and oropharyngeal airway length (OPAL)
between men and women with severe OSA were noticed in a study by Ma etal.
OSA males had increased CSA and longer OPAL [40]. Another study showed that
male gender is positively related to a thicker epiglottis, which could attribute to its
collapsibility [41].
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6.5 Age
Aging is a risk factor for OSA, although the mechanisms are still not elucidated
completely. A study by Zhao showed that aging increases the probability of multilevel obstructions [42]. On the other hand, some authors observed no correlation
between age and obstruction at the level of the epiglottis [29, 31, 32]. Two anatomic studies have conrmed age-related changes in the medial hyoepiglottic ligament with decreased level of elastin and collagen bers that could cause the
posterior displacement of the epiglottis as well as its instability during breathing
[43, 44]. Additionally, it was discovered with electromyography that age-related
weakening with remodeled motor units is present in the genioglossus muscle of
individuals above 55years, which may have implications in tongue base collapsibility [45].
6.6 Craniofacial Features andCephalometry
A physician should be aware of the connection between certain craniofacial skeletal
features and OSA, as they can be an important predisposing factor for the development of the disease [46–48]. Mandibular and maxillary hypoplasia, inferior position
of the hyoid bone, narrowed posterior air space, and a greater exion of the cranial
base are the most frequently observed features linked to OSA [49–51]. We must also
not forget about the importance of narrowed maxilla in the transverse plane [52].
For objectivization we can use the multi-detector computer tomography or 2D lateral cephalogram, with the latter being simpler, cheaper, and less harmful due to the
radiation. Probably the most important feature in assessing/diagnosing an OSA
patient is the position of the hyoid bone. In a study by Neelapu, it was shown that
inferiorly placed hyoid bone in relation to the mandible and sella, strongly correlated to OSA patients [51]. It also plays a role in EC, as it determines the position of
the tongue and epiglottis.
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M. Delakorda and B. Maver
6.7 Upper Airway Evaluation
After we use medical history and initial clinical evaluation to identify patients with
a high risk for OSA, a detailed physical examination of UA should be the next step.
Most clinicians dealing with surgical treatment of OSA agree that determining the
level and conguration of obstructions are important to help in planning adequate
treatment and identify patients who could benet from surgery [53–55]. In this
regard, information obtained from sleep and radiologic studies can be very helpful
(see Chaps. 7 and 9). While observing the anatomy, we should keep in mind that at
least 70% of OSA patients have multilevel obstructions and that the number of
obstructions tends to increase with OSA severity [56–58]. When describing observations during UA assessment, it makes sense to use classication systems, as they
enable standardized reporting, improved interpretation, and comparison of research
results. Many grading systems are available for describing and scoring the affected
sites during ofce examination, although their actual clinical value is still
questionable.
Inferring the importance of different observations during clinical examination is
complicated by the fact that UA characteristics can differ considerably between
wakefulness and sleep. This is especially true for the level of the larynx and hypopharynx, where awake assessment frequently underestimates the degree of obstructions [59, 60]. Despite this fact, traditional methods of UA examination are regularly
performed by sleep surgeons when they tend to rely on anatomical traits. Such
evaluations are performed in a relatively static airway, but some techniques to evaluate dynamic changes have been introduced. Muller’s maneuver was rst described
by Borowiecki and Sassin in 1983 with an initial intent to select patients suitable for
uvulopalatopharyngoplasty [61]. Although still used by many clinicians, there are
many controversies about the investigation [11, 62]. After literature review, Mattos
Soares etal. came to a conclusion that Muller’s maneuver has low reproducibility,
that it is not a good predictor of disease severity or oropharyngeal surgery success,
and that it does not reliably detect the site of upper airway collapse [63]. In a study
from Sung etal., no epiglottis collapse was noted during the Muller’s maneuver in
any of the patients with isolated epiglottis collapse detected with DISE [30].
Radiological methods allowed the rst clear conclusions that patients with OSA
have, on average, smaller pharyngeal cross-sections compared to the healthy population [64]. A clear proof that obstructive respiratory events during the sleep should
be viewed as dynamic phenomena is the fact that they never occur in wakefulness.
In accordance with this, it makes sense to distinguish visible sites of UA narrowing
(obstructions) from collapses resulting from increased tissue compliance and/or
intraluminal pressure. The pharyngeal airway collapse follows the principle of the
“tube law,” with gradual lumen narrowing dependent on transmural pressure and
tissue compliance. Unlike these structures, the epiglottis behaves as a one-way
valve with obstructions occurring abruptly and intermittently, exclusively during
inspiratory phase [65–67]. The displacement of such valve-like structures is determined by the driving pressure, as well as the shape and position (angle). The epiglottis is located low in the upper respiratory tract and therefore, when assessing its
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stability, it is necessary to look for the primary ow-limiting site that may be located
at a higher UA level [68]. This multifactorial dependency is probably one of the
reasons why it is difcult to predict the success of epiglottis surgery [69, 70].
In most studies, the determination of the level of obstruction (topodiagnosis) is
based on and conrmed with DISE.It is known that some medications used for
sedation can affect the tone of the genioglossus muscle, the main pharyngeal dilator,
and thus affect the position of the tongue base and consequently also the epiglottis
[71, 72]. This might explain the disagreement between surgical plans based on the
DISE ndings and those based on awake techniques, with epiglottis surgery being
more frequently indicated after DISE [73, 74]. Also, the prevalence of epiglottis
obstructions requiring surgery seems to be lower than that found during DISE [70].
Therefore, we can reasonably suspect that at least a part of obstructions detected at
this level may be due to the effect of sedating agents. Accordingly, results of DISE
should be evaluated with some care and interpreted with a degree of doubt. It also
means that DISE should be combined with awake examination as a complementary method.
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6.7.1 The Nose
The role of the nose in the development of obstructive sleep disorders has not been
denitively elucidated. Nasal patency can inuence OSA pathogenesis in several
ways. Although nasal resistance represents around half of the total airway resistance
in the awake state, this share is much lower during sleep. While many studies have
conrmed that treating nasal obstruction does not substantially affect OSA severity
in terms of respiratory events, it has an important effect on subjective outcome measures [75–78]. Consequently, a complete sinonasal symptoms evaluation and thorough exam of the nasal cavity are necessary in any patient with OSA. Nasal
obstruction can affect the epiglottis in two ways: either through posterior displacement of the tongue base during oral breathing or by contributing to higher downstream negative pressures (see Chap. 12).
When examining the patient, we should obtain information on nasal patency,
discharge, previous facial trauma, or surgery (endoscopic sinus surgery, esthetic
rhinoplasty, septoplasty, turbinate reduction, adenoidectomy). Tools like the Nasal
Obstruction Symptom Evaluation scale (NOSE) can be of great help when evaluating a patient’s perception of nasal obstruction or treatment outcome [79]. Some
authors even consider it a screening tool for patients with a high risk of OSA [80].
Assessment begins with the inspection of the outer nose. In case of a collapsible
nasal alae, we can perform Cottle’s maneuver to assess nasal valves’ collapse. In our
experience, patients with a long soft palate often complain of sensations of nasal
obstruction when in the supine position. The examiner should also be aware of the
negative effects of the supine body position on nasal congestion [81]. We proceed
with anterior rhinoscopy and systematically evaluate the nasal mucosa, turbinates,
and septum. Any pathological discharge, septal deviation, perforation, synechiae,
crusting, nasal polyps, and turbinate hypertrophy should be described. In case of
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M. Delakorda and B. Maver
clinical suspicion, we can additionally perform endoscopy that can reveal pathologic processes in the nasopharynx, such as enlarged adenoids, antrochoanal polyps, and neoplasms.
6.7.2 The Oral Cavity (Skeletal Frame)
There are several important skeletal characteristics in the dental/maxillofacial area
that a sleep surgeon should notice when assessing a patient [47, 82]. OSA is a
known risk factor for bruxism, so teeth should be checked for signs of dental wear
[83]. Then, one should proceed with the assessment of the upper and lower jaws.
Angle’s classication of malocclusion is widely accepted and divides the patient
into three groups (classes I, II, and III). Retrognathia (class II) is a condition where
the mandible is decient in growth and lies more posteriorly (Fig.6.1). It is commonly associated with a narrower airway at the retroglossal area [83–85].
Cephalometric studies have shown that in addition to mandible position, other factors in OSA etiopathogenesis include retro-positioned maxilla, extrusion of teeth,
proclined incisors, and open bite [50]. Another important feature is the shape of the
hard palate. The narrow maxilla and high-arched hard palate are associated with a
history of mouth breathing, and are commonly seen in people with OSA [52]. Often,
a long and ptotic soft palate is co-observed (Fig.6.2). Discrepancy between the size
of the tongue and bony skeletal frame can result in a scalloped tongue that in turn
may be a useful clinical indicator for OSA [86]. Oral devices are widely used, but
we should assess the appropriate candidates for such treatment. Suitable patients
should have stable dentition and usually at least six healthy teeth per arch with
adequate jaw mobility, with the ability to protrude the mandible for at least
6mm [87].
Fig. 6.1 OSA patient with
class II malocclusion
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Fig. 6.2 OSA patient with
a high-arched hard palate
and a long, ptotic soft
palate
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6.7.3 The Pharynx
The pharynx lacks skeletal support and is the primary obstruction site in OSA
patients, so a clinical evaluation of this part is an essential part of UA inspection.
When accessing the tongue base, one should keep in mind that obstructions at the
level of the epiglottis can be primary, where the epiglottis closes the airway independently (trap door or oppy epiglottis), or secondary, where it is pushed back by
the base of the tongue. Identifying the difference between both options is important
as it affects the choice of treatment [88].
The tongue base and larynx can be examined either indirectly or by means of
endoscopy that can be either transnasal exible or transoral rigid. Each of these
techniques has its advantages and disadvantages. Indirect examination with a laryngeal mirror can be quite demanding in people with pronounced pharyngeal reex,
as it can cause the tongue base and the epiglottis to move forward. Due to the activation of the pharyngeal muscles, an altered shape of some soft tissues, e.g., tongue
base position, the curvature of the epiglottis, or their interrelationship may occur.
Additionally, when the patient is asked to regulate breathing or hold a breath, variable degrees of laryngeal closure can be noticed [89]. Some authors suggest to evaluate UA at end expiration to eliminate the possible effect of dynamic collapse from
negative intraluminal pressure [90]. During early inspiration in the awake state, a
small increase of the pharyngeal lumen occurs, but during the rest of the respiration
cycle, it remains constant, which points to phasic dilator activity [91]. All of the
above may affect our assessment of UA; therefore, a gentle use of transnasal exible
endoscopy is advisable in sensitive patients.
When examining the tongue base and the larynx, we should be aware that the
head position can also have an impact on the pharyngeal lumen and hence inuence our judgement on possible obstruction sites. With indirect laryngoscopy,
using laryngeal mirror, the patient’s head is usually tilted backward, i.e., the neck
is extended. This position makes the retroglossal pharyngeal lumen wider.
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Fig. 6.3 (Video 6.1) Video showing the effect of oral positioning on UA
(► https://doi.org/10.1007/000-bf4)
M. Delakorda and B. Maver
Contrary, any head exion with the chin tucked in, which can occur during transnasal laryngoscopy, causes a posterior shift of anterior pharyngeal structures in
combination with shortening of the distance from the epiglottis to the posterior
pharyngeal wall. Mouth opening has a similar effect on the size of the pharyngeal
lumen. While opening the jaw slightly can increase the size of the pharynx by
providing more space for the tongue, progressive opening leads to a posterior
movement of the mandible, the tongue, and hyoid, thereby narrowing the pharyngeal airway [91, 92]. A similar effect on the enlargement of the lumen behind the
epiglottis can sometimes be noticed with the protrusion of the tongue.
Nevertheless, paradoxical patterns can occur in a substantial share of patients
[93] (Fig.6.3).
When assessing a patient preoperatively, the pharynx is one of the anatomical
regions where we can use well-established grading systems. Fujita was the rst to
classify upper airway obstructions, as follows: type 1 (soft palate), type 2 (soft palate and tongue base), and type 3 (tongue base and hypopharynx) [94]. Friedman’s
tongue position staging is used for the estimation of pharyngeal obstruction and
describes tongue position relative to the soft palate and uvula. The staging system is
based on the Mallampati score introduced in 1983. It was proposed as a non- invasive
method for assessing difcult intubation [95]. In 1999 Friedman etal. added two
parameters and named it the modied Mallampati score that was later renamed to
the Friedman tongue position grade (FTP). Mallampati classication has three
grades and evaluates the position of the protruded tongue relative to the soft palate
[96]. So far, two classications of lingual tonsils have been introduced, one by
Friedman etal. and the second by Sung etal. Both consist of grades from 0 to 4,
with 0 indicating absent lymphoid tissue and 4 hypertrophied lymphoid tissue
spreading toward the epiglottis (Fig.6.4) [97, 98].
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Fig. 6.4 Friedman grade 4
lingual tonsils
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6.7.4 The Larynx
To date, quite a few clinical models for predicting the presence or the degree of OSA
have been presented, but they generally do not include the epiglottis [11, 99]. On the
other hand, considerable research has been conducted on the role of the base of the
tongue and epiglottis in glottis visualization when assessing the difculty of intubation. Majority of this research was performed by anesthesiologists who mostly concentrated on the position of the epiglottis relative to the tongue base during examination
under general anesthesia [100, 101]. In 1984, Cormack and Lehane were the rst to
describe the laryngeal view during direct laryngoscopy to predict the ease of endotracheal intubation. Since then, the grading system they proposed became the anesthesiologist’s gold standard for UA classication, with some modications [102, 103].
However, despite the widespread use, some studies question its validity [104–106]. In
a study conducted by Uzun etal. in 2005, a classication was proposed based on different types of epiglottis shapes evaluated during general anesthesia. They concluded
that free edges of the omega-shaped epiglottis could prevent total obstruction at this
level by leaning onto the posterior wall of the hypopharynx when the tongue base
moves posteriorly. Additionally, they observed that leaf-shaped or at epiglottises had
a exible character with a tendency to collapse and close the laryngeal inlet [107].
Nowadays, it is widely accepted that OSA and difcult intubation are related
[108]. Moreover, a connection between some epiglottis characteristics and the presence of OSA has been established. Ma etal. conducted a study with magnetic resonance imaging of the upper airway in awake OSA patients lying in a supine position.
They investigated the relation between epiglottis position and OSA severity. The
distance between the hard palate and the tip of the epiglottis increased with OSA
severity, while a signicantly reduced cross-sectional area behind the tip of the epiglottis appeared only in severe OSA cases [40]. A similar conclusion on the connection of the lower laryngeal position and OSA severity was published by Yamashiro
and Kryger. Airway length from the hard palate to vocal cords as well as to the base
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