Neuromuscular disorders

Question 1

What is Obstructive Sleep Apnoea Syndrome?

Answer 1

Recurrent episodes of upper airway obstruction leading to apnoea during sleep
Usually associated with heavy snoring
Typically unrefreshing sleep
Daytime somnolence /sleepiness
Poor daytime concentration

Question 2

Why is OSAS Important?

Answer 2

Impaired quality of life
Marital dysharmony
Increased risk of RTA’s
Associated with hypertension, increased risk of stroke and probably increased risk of heart disease.

Question 3

Obstructive Sleep Apnoea – Prevalence

Answer 3

2% adult men and 1% adult women approx

Question 4

How is OSAS diagnosed?

Answer 4

Clinical history and examination
Epworth Questionnaire
Overnight sleep study
pulse oximetry
limited sleep studies
full polysomnography

Question 5

Polysomnography components

Answer 5

Oronasal airflow
Thoracoabdominal movement
Oximetry
Body position
EEG
(Audiovisual recording)
EOG
EMG (peripheral muscle)
ECG

Question 6

OSA Severity

Answer 6

Desaturation rate / AHI:-

0-5 Normal
5-15 Mild
15-30 Moderate
>30 Severe

Question 7

Treatment of OSA

Answer 7

Identify exacerbating factors
weight reduction
avoidance of alcohol
diagnose and treat endocrine disorders e.g. hypothyroidism, acromegaly

Continuous positive airways pressure (CPAP)
Mandibular repositioning splint

Question 8

Driving

Answer 8

Advise patients with sleep apnoea and excessive daytime somnolence not to drive or restrict driving and to inform DVLA of their condition

Once satisfactorily treated should be allowed to drive

Question 9

Narcolepsy

Answer 9

Prevalence 0.05%
Familial
Associated with HLA - DRB11501 and HLA DQB1 0602

Question 10

Clinical features of narcolepsy

Answer 10

Cataplexy (sudden muscle weakness)
Excessive daytime somnolence
Hypnagogic / hynopompic hallucinations
Sleep paralysis

Question 11

Investigation for narcolepsy

Answer 11

PSG
MSLT (multiple sleep latency test) (>1 SOREM and mean sleep latency <8 min).
Low CSF orexin

Question 12

treatment of narcolepsy

Answer 12

Modafinil
Dexamphetamine
Venlafaxine (for cataplexy)
Sodium Oxybate (Xyrem)

Question 13

Chronic Ventilatory Failure

Answer 13

Elevated pCO2 (> 6.0 kPA)
pO2 < 8 kPA
Normal blood pH
Elevated bicarbonate (HCO3-)

Question 14

Aetiology - Chronic Ventilatory Failure

Answer 14

Airways disease
COPD
bronchiectasis
Chest wall abnormalities
kyphoscoliosis
Respiratory muscle weakness
motor neurone disease (ALS)
muscular dystrophy
glycogen storage disease (Pompe’s disease)
Central hypoventilation
obesity hypoventilation syndrome
congenital central hypoventilation syndrome (Ondine’s curse)

Question 15

Typical Symptoms of chronic ventilatory failure

Answer 15

Breathlessness
Orthopnoea
Ankle swelling
Morning headache
Recurrent chest infections
Disturbed sleep

Question 16

Examination Findings of chronic ventilatory failure

Answer 16

Reflects underlying disease
Particularly look for paradoxical abdominal wall motion in suspected neuromuscular disease
Ankle oedema (hypoxic cor pulmonale)

Question 17

Investigation - neuromuscular disease

Answer 17

Lung function
Lying and standing VC
Mouth pressures / SNIP

Assessment of Hypoventilation
Early morning ABG
Overnight oximetry
transcutaneous CO2 monitoring

(Fluoroscopic screening of diaphragms)

Question 18

Treatment of chronic ventilatory failure

Answer 18

Domicillary Non Invasive Ventilation (NIV)
Oxygen therapy
(t-IPPV)