Diagnostic Evaluation of Sleep Disorders

Module Summary

This module covers the clinical evaluation and diagnostics of sleep disorder patients across the spectrum of all sleep related pathologies. As Obstructive Sleep Apnea is the most common sleep malady seen and treated by Otolaryngologists, learning objectives focus mainly on the details of the polysomnogram and the sleep apneic patient. Presented with a clinical perspective, the module also includes content covering Drug Induced Sleep Endoscopy, the current role of imaging, and the appropriate use of less commonly utilized tests like the Multiple Sleep Latency Test.

Anatomy

List the anatomic abnormalities on Head & Neck exam that are associated with Obstructive Sleep Apnea.
- Craniofacial Structure
  - Kids: Syndromic facies (Pierre Robin sequence, Treacher Collins)
  - Adults: Several anatomic abnormalities are associated with OSA:
    - Retrognathia
    - Micrognathia
    - Overjet
    - High arched palate
    - Neck circumference (averages 43.7 +/- 4.5cm for those with, 39.6 +/- 4.5cm for those without); >40cm+ sens 61% and spec of 93% for OSA gender regardless
    - Obesity (most commonly observed risk factor)
    - Suspicion if BMI >30 kg/m2
    - Neck circ and BMI predictive value is not large except in extreme cases
Name the components of head and neck anatomy that are necessary to evaluate in snoring and sleep disordered breathing patients.
- Should examine nasal patency, oropharyngeal anatomy, and craniofacial structure
- Septum, turbinates, polyps, lesions, etc.
- Soft palate, uvula, BOT, tongue, tonsil size, for oropharynx
List and describe two classification schemes that provide utility in staging oropharyngeal crowding:
- Mallampati and Friedman classifications for staging oropharyngeal crowding 105 – numeric scale that grades size of, and relationship among, sp, u, tonsil pillars, and BOT.
  - Crowding of the OP has been shown to be related to presence and severity of OSA, but in and of itself has limited value for predicting presence of OSA (Likelihood ratio range 1.4 to 1.6)
Describe the Meuller maneuver’s ability to assess potential obstructive sites and patterns in the upper airway for patients with suspected or confirmed OSA.
- Meuller maneuver (inspiratory effort against an obstruction) has limited validity as an assessment of site and nature of upper airway obstruction.
Describe the anatomic factors that determine upper airway patency:
- craniofacial structure
- extent of surrounding soft tissue
- intrinsic properties of the upper airway
- neuromuscular function of the upper airway
List four screening snoring and sleep disordered breathing questionnaires that have been validated in specific populations:
- Berlin Questionnaire
- STOP-BANG
- Stanford Sleepiness Scale
- Epworth Sleepiness Scale
List the eight questions in the STOP-BANG questionnaire and how to interpret the assumed risk:
- Snore loudly?
- Tired during the daytime?
- Observed you stop breathing?
- Pressure (HTN?)
- BMI > 35?
- Age > 50?
- Neck circumference > 40cm?
- Gender – male?
- Low risk 0-2, high risk 3+
Describe the Stanford Sleepiness scale.
- 7-point subjective measure of perception of sleepiness at a given time (from wide awake, vital, and alert to unable to remain awake with sleep onset imminent)
Describe the Epworth Sleepiness Scale and how it is scored:
- Eight-item measuring person’s general propensity to fall sleep in various situations in recent times
- Chances of dozing (0 – never, 1 – slight, 2 – moderate, 3- high)
- 0-9: normal, 10+ = sleepiness present, referral recommended

References:

Kryger M, Roth T, Dement WC. Principles and Practices of Sleep Medicine, 6th ed. Philadelphia: Elsevier; 2017.

Patient Evaluation

Describe the constellation of signs and symptoms which are correlated with a higher likelihood of patients having OSA documented on formal Sleep Study:
- Neck circumference greater than 40cm, habitual snoring, HTN, bed partner report of apnea
- No one single symptom or sign appears sufficiently predictive of OSA, including snoring, sleepiness, morning HA
Appreciate positive review of system findings that may increase the likelihood of OSA.
- Signs of neuropathy or neuromuscular disease
List four screening snoring and sleep disordered breathing questionnaires that have been validated in specific populations:
- Berlin Questionnaire
- STOP-BANG
- Stanford Sleepiness Scale
- Epworth Sleepiness Scale
List the eight questions in the STOP-BANG questionnaire and how to interpret the assumed risk
- Snore loudly?
- Tired during the daytime?
- Observed you stop breathing?
- Pressure (HTN?)
- BMI > 35?
- Age > 50?
- Neck circumference > 40cm?
- Gender – male?
- Low risk 0-2, high risk 3+
Describe the Stanford Sleepiness scale.
- Seven-point subjective measure of perception of sleepiness at a given time (from wide awake, vital, and alert to unable to remain awake with sleep onset imminent)
Describe the Epworth Sleepiness Scale and how it is scored:
- Eight-item measuring person’s general propensity to fall sleep in various situations in recent times
- Chances of dozing (0 – never, 1 – slight, 2 – moderate, 3- high)
- 0-9: normal, 10+ = sleepiness present, referral recommended

References:

Kryger M, Roth T, Dement WC. Principles and Practices of Sleep Medicine, 6th ed. Philadelphia: Elsevier; 2017.

Diagnostic Testing

Name the Gold standard diagnostic tool for the diagnosis of Obstructive Sleep Apnea.
- Polysomnogram
Define in layman’s terms what a polysomnogram is:
- Literally the recording of multiple physiologic variables during sleep
- Indicated for sleep disordered breathing when apnea is suspected, for suspected movement disorders, and complex sleep behavior
List eight common variables included in a diagnostic Polysomnogram
- Electroencephalogram (EEG)
- Recording of eye movements (Electrooculogram EOG)
- Recording of muscle activity (Electromyogram EMG)
- Electrocardiogram (ECG)
- Nasal and oral airflow
- Breathing effort (measured at chest and abdomen)
- Oximetry
- Microphone (snoring)
Report the variables that comprise the structure, continuity, and quality of a patient’s sleep pattern on diagnostic Polysomnogram:
- EEG, EOC, and EMG are foundation for accurate assessment of other recorded variables.
Describe what constitutes PSG tracings:
- All represent electrical activity.
- When obtained directly form the patient’s body, these are: bioelectrical potential recordings.
  - Tiny voltage fluctuations occurring within the cerebral cortex (EEG)
  - Voltage generated by muscle fibers (EMG)
  - Voltage shifts caused by movements of the eyes (EOG)
  - Voltage generated by the heart (ECG)
Demonstrate a working knowledge of the challenge of obtaining clean electrical signals:
- Most challenging aspect of recording bioelectrical potentials is electrical interference from body, equipment, or surrounding environment:
- Examples: 60Hz powerline frequency, DC voltages from pt’s skin, ECG voltages throughout body, and various mixed frequencies (“noise”)
- Reduced by common mode rejection
- Role of differential amplifier
- Electrodes need to be properly applied and tested for low and relatively equal impedances
Describe the basic characteristics and names of the electrical impulses that appear as waveforms on a PSG:
- Frequency, amplitude, and morphology.
- Shape of certain waveforms is important for identifying characteristic features of various sleep stages
  - Vertex waves, K-complexes, sleep spindles, and sawtooth waves.
List factors influencing the quality and accuracy of recorded PSG data:
- Electrode application: care with which they are applied is the most important factor in the quality and accuracy of the recorded data.
Describe the role of the Sleep technician involved in PSG:
- Troubleshoot, quality of data, behavioral observation, and patient safety
Define the following terms: Apnea, Hypopnea, and Respiratory Effort Related Arousal (RERA):
- Apnea: BOTH of the following occur:
  - Drop in peak signal excursion by >90% of pre-event baseline using oronasal thermal sensor or nasal pressure (best)
  - Duration of the >90% drop is > 10 seconds
  - Obstructive if it is associated with continued inspiratory effort throughout the duration of the episode, central if not, mixed if both
- Hypopnea: ALL of the following criteria:
  - Drop in peak signal excursion by >30% of pre-event baseline using nasal pressure
  - Duration is > 10 seconds
  - There is a >3% (or >4%) desaturation from baseline, or the event is associated with an arousal
  - This definition was meant to increase the sensitivity of PSG to detect OSA in pts with sleep fragmentation and daytime impairment but without significant desaturations.
- RERA:
  - Sequence of breaths lasting > 10 seconds characterized by increasing resp effort or by flattening of the insp portion of the nasal pressure waveform leading to arousal from sleep when the sequence of breaths does not meet criteria for an apnea or a hypopnea
Name the diagnostic criteria for Obstructive Sleep Apnea:
- OSA (first AND second, or third):
  - 1 - Presence of 1+ of:
    - Sleepiness, nonrestorative sleep, fatigue, or insomnia symptoms
    - Wakes with breath holding, gasping, or choking
    - Bed partner reports habitual snoring, breathing interruptions, or both during sleep
    - Patient has been dx’ed with HTN, a mood d/o, cognitive dysfunction, coronary heart disease, stroke, CHF, Afib, or DM2
  - 2 - PSG or Out-of-center sleep testing demonstrates:
  - Of note, because of hypopnea / RERA challenges and imperfect reliability of PSGs, interpretation of PSG reports remains more complicated and may not be definitive, esp in borderline cases.
    - 5+ obstructive rep events (i.e. obstructive or mixed apneas, hypopneas, or RERAs per hour of sleep during PSG or OCST
  - 3 – PSG or OCST demonstrates:
    - 15+ obstructive rep events (i.e. obstructive or mixed apneas, hypopneas, or RERAs per hour of sleep during PSG or OCST
Describe the limitations of the PSG that if not realized could trigger unnecessary treatment or deprive pts from effective treatment:
- Results cannot of PSG cannot be reliably interpreted by those w/o experience in sleep medicine
- Results cannot be summarized by any given single number
- Results cannot be applied to patient care without careful use of additional clinical data
List the four Types or categories of sleep studies available:
- Type 1: in-lab PSG full
- Type 2: out-of-center portable study with minimum seven variables
- Type 3: unattended portable recording with minimum 4 variables (add resp effort)
- Type 4: unattended portable study with minimum 3 variable HR, oximetry, and resp analysis
Describe the advantages and limitations of Out of Center Sleep Tests (OCST) or “home” sleep studies
- Advantages:
  - Lower cost
  - Offer greater accessibility for patient evaluation
  - Some studies show no significant differences in outcomes vs. formal PSG
- Limitations:
  - Diagnostic value of OCST may be reduced
  - No behavioral observations
  - Inability to standardize recording conditions
  - Inability to address technical problems
  - Cannot distinguish between OSA and Central Sleep Apnea
  - Should not be done for patients with significant cardiovascular comorbidities
List the parameters necessary for an OCST or home sleep studies to be of diagnostic quality:
- O2 saturation
- Airflow
- Resp effort
- HR/pulse
- Body position
List the Sleep Disordered Breathing (SDB) diagnoses other an Obstructive Sleep Apnea that can be diagnosed effectively with polysomnogram:
- Pathologically enhanced resp chemoreflexes result in a spectrum of PSG breathing patters and disorders, including: CSA, periodic breathing (Cheyne-Stokes breathing), high-altitude sleep apnea, and treatment emergent CSA.
- Opiate use causes disintegrative CSA d/o with unique PSG features
Describe the basic purpose of the Drug Induced Sleep Endoscopy (DISE) procedure:
- Developed as a screening tool to help determine suitability for surgery and the type of surgical procedure to be undertaken based on the site(s) and pattern(s) of upper airway obstruction or collapse.
Explain the depth of anesthesia necessary for effective DISE and how this is typically obtained:
- Anesthesia provider providers IV drugs (more commonly propofol or dexmedetomidine; less commonly midazolam, ketamine) to produce sedation and sleep-like relaxation including snoring and upper airway obstruction.
- Only useful when sleep itself supervenes or sedation is deepened to a level at which consciousness is lost through a direct drug effect.
List the four collapsible segments or anatomic levels of obstruction that are typically noted on DISE:
- Velopharynx (soft palate)
- Oropharynx (palatine tonsils and lateral oropharyngeal walls)
- Tongue base level
- Hypopharynx (epiglottis and the hypopharyngeal walls)
Describe how the degree and pattern of obstruction are typically noted on DISE reports:
- Degree (None, partial, complete, or not evaluable)
- Pattern (AP, Lateral, Concentric)
Name the most common application of DISE today:
- Used as a patient selection tool for use of Upper Airway Stimulation therapy for OSA (the absence of complete concentric collapse at the level of the palate).
Understand that research and standardization are needed in order to optimize the utility of DISE, as the literature currently carries no consensus on method of sedation, depth of sedation, patient position, use of airway anesthetics, duration of observation, standard DISE classification system or quantification of degrees of collapse or obstruction.

References:

De Vito A et al. European position paper on drug-induced sedation endoscopy (DISE). Sleep Breath. 2014 Sep;18(3): 453-65
Vroegop AV, et al. Observer variation in drug-induced sleep endoscopy: experienced versus nonexperienced ear, nose, and throat surgeons. Sleep. 2013 Jun 1;36(6):947-53
Butkov N. Atlas of Clinical Polysomnography. Vol I. Ashland: Synapse media, Inc.; 1996.
Kryger M, Roth T, Dement WC. Principles and Practices of Sleep Medicine, 6th ed. Philadelphia: Elsevier; 2017.

Imaging

Describe the anatomic findings on lateral cephalometry that have been studied to correlate with increased severity of Obstructive Sleep Apnea:
- Smaller airway dimensions, particularly those involving maxilla and mandible
- Mandibular retrognathia
- Decreased posterior airspace
- Inferiorly placed hyoid bone
- Increased soft palate dimensions and length
Understand and articulate the different landmarks and variables involved in interpreting lateral cephalometry films:
- Landmarks
  - Pns (posterior nasal spine)
  - H (hyoid bone)
  - MP (mandibular plane)
- Variables
  - SPl (length of soft palate)
  - Spw (Width of soft palate)
  - Tl (legth of base of the tongue)
  - Tw (width of the tongue)
  - H-Ph (distance from hyoid bone to post wall of pharynx)
  - H-Pns (distance from hyoid bone to posterior nasal spine)
  - H-MP (distance from hyoid bone to mandibular plane)
  - SPAS (upper posterior pharyngeal space)
  - IPAS (lower posterior pharyngeal space)
Identify the potential role of functional brain imaging in the four main categories of sleep and arousal disorders – insomnias, hypersomnias, rhythm disruptions, and parasomnias:
- Initiating and maintaining sleep – INSOMNIAS
  - Insomnia – no known role
  - PLMD & RLS
    - Shown decrease in dopamine binding in areas of the basal ganglia compared with normal subjects
  - Fatal familial insomnia
    - FDG/PET shows thalamic hypometabolism, and this is major characteristic of the disease
  - Disorders of excessive somnolence – HYPERSMONIAS
    - Narcolepsy
      - Finding of increase in number of post-synaptic dopamine receptors. Long term medication the cause?
      - fMRI may be useful to study attentiveness / wakefulness
    - OSA – no known role
  - Disorders of the sleep/wake cycle (RYTHYM DISRUPTIONS) – no known role
  - Behavioral dysfunctions associated with sleep, sleep stages, or partial arousals (PARASOMNIAS) - no known role
Recognize that brain imaging technology has helped the field of sleep medicine to explore more precisely the relation between wake-sleep and sleep disturbances and their relation to cognitive function.
List findings on MRI that are correlated with the diagnosis of Obstructive Sleep Apnea:
- wider mandibular divergence
- smaller mandibular length
- smaller area at the mandibular plane

References:

Kryger M, Roth T, Dement WC. Principles and Practices of Sleep Medicine, 6th ed. Philadelphia: Elsevier; 2017.

Pathology

Describe how non-OSA sleep disorders such as Insomnia, hypersomnias (like narcolepsy), parasomnias, RLS, and circadian rhythm disorders are typically diagnosed:
- INSOMNIA
  - Diagnosis usually by history alone
  - Insomnia Severity Index (7 item self-report instrument typically used in insomnia research.
    - Score of 10+ : Sens 86% Spec 88%
  - Sleep logs
    - Sleep Onset Latency (SOL): 20, 30 minutes used as cut-offs
    - Wake After Sleep Onset (WASO)
    - Not necessary to establish presence of insomnia but can help define severity and facilitate identification of causes of inadequate sleep hygiene, cycle issues, etc.
  - Actigraphy
    - Not typically used for insomnia
  - PSG:
    - Not indicated for routine eval of insomnia, but used when H&P, other signs / symptoms suggest SDB, PLMD, paradoxical insomnia, or uncertain cases, it can be an aid.
- HYPERSMONIA – Narcolepsy
  - History, Multiple Sleep Latency Test (MSLT) and the Maintenance of Wakefulness Test
- PARASOMNIA
  - With exception of REM Sleep Behavior Disorder (RBD), diagnosis of parasomnias are done by history alone.
- RLS
  - Dx made by clinical hx of:
    - Urge to move legs
    - Worse at rest
    - Better with movement
    - Worse at evening / nighttime
  - Instruments are available (used in research mostly)
  - Exam
    - Consider neuro conditions (neuropathy, MS, Parksinsons) and psych referral
  - Labs: iron and ferritin
  - PSG: not needed
- CIRCADIAN RHYTHM DISORDERS
  - Discrepancy between desired times for sleep / wake and circadian propensity for times of sleep / wake
    - Ask: “What time of day do you feel most alert?” “When do you perform the best?”
  - Questionnaires evaluating circadian preferences aka chronotype:
    - Horne-Ostberg Morningness-Eveningness Questionnaire (MEQ)
      - 19 item, most widely used, evals personal preferences
    - Munich Chronotype Questionnaire (MCTQ)
      - Measures actual (not preferred) sleep times.
  - Sleep logs and Actigraphy
    - AASM recommends use of sleep logs and whenever possible actigrpahy for 7-14 days to evaluate suspected CR sleep-wake disorders.
    - Vacation time, days-off: where the money is at!
  - PSG / MSLT – not super useful in dx this d/o.
  - Objective markers
    - ICSD: endogenous markers of circadian phase can confirm some diagnoses
      - DLMO (Salivary Dim-Light melatonin onset) or urinary (6-sulfatoxymelatoniin, MT6s) can be used, role in ambulatory collection needs more study
List the steps involved in a Multiple Sleep Latency Test (MSLT):
- For two weeks prior, patient avoids stimulants, TCAs, monoamine oxidase inhibitors, and other meds. Sedatives, hynpotics, and antihistamines should also be avoided.
- PSG one night (documents adequate sleep and rules out any other sleep pathology), and MSLT the next day.
- 1st nap is 1.5 – 3 hours after terminated PSG and changing into street clothes
- Minimum of four daytime naps at two hour intervals is required
- 30 minutes prior to each nap no tobacco as well as no vigorous activity
- Sleep Latency: moment of lights out until 1st epoch of sleep
- REM Latency: first epoch of sleep until first epoch of REM sleep in minutes
- Test is terminated when 1st epoch of REM sleep is completed or 15 minutes after establishing 1st epoch of sleep
  - Nap also terminated if 20 minutes have passed after lights out and there has been no sleep
Describe the diagnostic criteria for narcolepsy on a MSLT:
- Sleepiness is pathologic if MEAN SLEEP LATENCY < 5 minutes across four naps
- Presence of two sleep-onset REM episodes in a series of five sleep latency tests is diagnostic of narcolepsy
Describe the Maintenance of Wakefulness Test (MWT):
- assesses the patient’s ability to stay awake for 40 minutes in dark environment in comfortable chair
List the clinical indications for use of the MSLT and WMT:
- MSLT is indicated as part of the evaluation of patients with suspected narcolepsy and may be useful in the evaluation of patients with suspected idiopathic hypersomnia.
- Not routinely indicated in the initial eval and dx of OSA, or in assessment of change following treatment with CPAP.
- Not routinely indicated for evaluation of sleepiness in medical and neurological disorders other than narcolepsy, insomnia, or circadian rhythm disorders.
- MWT may be indicated in assessment of individuals in whom the inability to remain awake constitutes a safety issue, or in patients with narcolepsy or idiopathic hypersomnia to assess tx response with medications.

References:

Chokroverty S, Heming WA, Walters AS. Sleep and Movement Disorders. Philadelphia: Butterworth Heinemann publishers; 2003.
Kryger M, Roth T, Dement WC. Principles and Practices of Sleep Medicine, 6th ed. Philadelphia: Elsevier; 2017.
Littner MR et al. Practice Parameters for Clinical Use of the Multiple Sleep Latency Test and the Maintenance of Wakefulness Test. Sleep. 2005 Jan;28(1):113-21

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Diagnostic Evaluation of Sleep Disorders

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