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The Diagnosis of Narcolepsy and the MSLT

Narcolepsy is one of the most interesting of Sleep Disorders in the International Classification of Sleep Disorders (ICSD-3). It is characterised by the classic tetrad was Excessive Daytime Sleepiness, Cataplexy, Sleep Paralysis and Hypnagogic Hallucinations. The addition of Sleep disruption makes the Narcolepsy pentad. The most often used test for this diagnosis is the in-hospital Multiple Sleep Latency Test (MSLT).

Whilst the symptom of sleepiness is helpful, sleepiness is a symptom of many sleep disorders. Some Narcoleptics are not aware of how sleepy they really are. Objective testing is crucial.

A Multiple Sleep Latency Test (MSLT) involves an overnight sleep study, followed by timed nap opportunities the following day. A urinalysis is also part of the testing process. Depending on the overnight and subsequent-daytime testing, and in the absence of another sleep disorder, a diagnosis of Narcolepsy (or Idiopathic Hypersomnia) can be confidently made.

A home sleep study (also known as an ambulatory sleep study) will never be able to diagnose Narcolepsy.

Measuring CSF Hypocretin levels are useful when an MSLT is not possible.

Here at Adelaide Sleep, we look after all aspects of Narcolepsy including the counselling, diagnosis, and treatment of all Narcolepsy symptoms. If you’d like to know whether you have Narcolepsy or one of the Narcolepsy-like conditions, call us now and see one of our doctors.

© APSS 2018

The History of Narcolepsy – Excessive sleepiness in evolution

Central Disorders of Hypersomnolence encompass conditions including Narcolepsy and Idiopathic Hypersomnia – at here at the best Adelaide Sleep clinic in Adelaide, we manage all these conditions.

Narcolepsy was first described the 1870’s were it was associated with Cataplexy and Postencephalitic Narcolepsy. With these reports from over a century ago, it was the first known primary sleep disorder to be described, identified and the symptomatology reported. It was from here that the classic tetrad was Excessive Daytime Sleepiness, Cataplexy, Sleep Paralysis and Hypnagogic Hallucinations was coined. Fragmented sleep is also a common symptom that is often overlooked.

Our understanding of Narcolepsy progressed with the development of treatments such as Methylphenidate in the 1950’s – known to ameliorate some Narcolepsy symptoms.

In the following decade of the 1960’s came tricyclic antidepressants (TCAs) and their use in cataplexy, at around the time we discovered sleep-onset REM periods (SOREMPs).

The first consensus for the definition fo Narcolepsy was ratified in the 1970’s under the International Classification of Sleep Disorders (ICSD). The following decade saw the first documented association of Human Leukocyte Antigen (HLA)-DR2 and Narcolepsy (Honda et al, Sleep 1986).

With the 1990’s came the discovery of Hypocretin 1 and the Hypocretin Receptor 2 Gene. Today we can diagnose Narcolepsy with the Multiple Sleep Latency Test (MSLT) and CSF Hypocretin levels.

At Adelaide Sleep, we have experts who are trained in specifically counselling, diagnosing, and treating Narcolepsy and all Sleep Disorders. We treat the whole spectrum fo sleep disorders, and pride ourselves on being able to differentiate and treat each of these separately.

If you believe you may have Narcolepsy or one of the Narcolepsy-like conditions, we can help. Call us now for an appointment.

© APSS 2018

2017 Nobel prize winners : the first to be awarded in the field of Sleep Medicine!

Congratulations to the 2017 Nobel Prize Winners in Physiology or Medicine : Jeffrey C. Hall, Michael Rosbash and Michael W. Young. Their work was in discovering molecular mechanisms crucial to control of the circadian rhythm (body clock).

Hall, Rosbash and Young used fruit flies as specimens, isolating a gene that controlled the fly’s daily biological rhythm. From their work, this has led to a much better understanding of biological rhythms in other species… including humans.

Circadian Rhythm Disturbances (CRD) comprise a large proportion of Sleep Medicine, and accounts for a notable number of sleep disorders – particularly in childhood an adolescents.

At Adelaide Sleep, we loudly congratulate Hall Rosbash and Young for their ever-enduring work, and amazing accomplishments! Thankyou!

© APSS 2017

Diaphragm pacing for Central Sleep Apnoea

Treatments for Central Sleep Apnoea (CSA) are limited – that’s why we’re excited about the potential for new treatments such as Transvenous Neurostimulation… essentially, pacing the diaphragm to help you breathe.

Obstructive Sleep Apnoea (OSA) is the upper-airway closure resulting in a drop in oxygenation (oxygen saturations). Central Sleep Apnoea (CSA) is when there is a lack of air flow (breathing) but because of no effort. IE, the muscles moving your chest wall and diaphragm do not proceed as one would expect.

CSA can occur in many circumstances, including :

  • Heart failure ** (the most common cause)
  • Strokes
  • Opioid use (methadone, morphine)
  • Myotonic dystrophy
  • Renal failure
  • High altitude.

Whilst OSA is almost always treated with CPAP, the success in treating CSA with CPAP is limited. With the departure of ASV as an option in heart failure patients (Serve-HF trial results), diaphragmatic pacing comes at an opportune time.

Costanzo et al (1) looked at those with almost all kinds of CSA (but mainly heart failure), offering them diaphragmatic pacing vs. no-pacing.

At 6 months, more than half (51%) of those with pacing managed to reduce their CSA events by 50%, compared to 11% in those without pacing. There was also an improvement in the Quality of Life Scores, their sleepiness (ESS), and oxygenation.

These very promising results will hopefully one day allow us to provide an alternative treatment for those with CSA.

If you have a Sleep Disorder and would like to see one of our Medical Specialists, give us a call for an appointment now.

1. Costanzo et al. Lancet 2016; 388: 974–82

© APSS 2017

Rapid Access to Sleep Services

We’re delighted to announce that our Adelaide Sleep clinic and sleep study services have been extended!

We now have more sessions available and can consult you within days.

Similarly, our sleep study (polysomnography) sessions have increased to almost every night of the week. We can accommodate your schedule much easier and sooner.

With our Rapid Access Sleep Services, we’ll be able to see you, study your sleep, and start treatment immediately.
And for our country patients travelling into Adelaide, we can even see you the following morning with your sleep study results, and start treatment that same day.

For local Adelaideans, your Sleep Study reports are often released to yourself and / or your referrer within 24-48hours of your sleep study.

At Adelaide Sleep, we don’t think it’s fair to make you wait days, weeks, months to have your sleep study. You shouldn’t have to wait for your results either. See us now.

© APSS 2016

Does REM-dependent OSA matter? In Hypertension, it does!

Whilst we know that Severe OSA is associated with cardiovascular risk, a significant ‘grey area’ exists. This grey area is where the evidence for cardiovascular risk is less obvious…

OSA is usually worse in REM : it’s a well known phenomenon. REM sleep is associated with more hypotonia (less muscle tone) and your tongue base will be more prone to collapsing… and that will lead to worsening oxygen desaturations (drop in oxygen levels).

When OSA occurs entirely in REM, does it lead to worse health outcomes?

Mokhlesi et al (1) looked at the association between OSA during REM Sleep and Hypertension (high blood pressure). Sleep Data from the Wisconsin Sleep Cohort was analysed, in conjunction with ambulatory blood pressure monitoring.

Those with higher REM-AHI (worse OSA in REM) were more likely to develop hypertension.

OSA outside of REM was not a significant predictor of hypertension.

• Take-home message : REM-dependent OSA is associated with Higher blood pressure issues down the track.

If you have high blood pressure, we’d recommend an in-hospital sleep study. Ring us for an appointment now.

1. Mokhlesi et al. Am J Respir Crit Care Med. 2014.

© APSS 2016

OSA and Congenital long QT syndrome

We’ve long known OSA has been associated with a higher prevalence of AF, and worsening AF control. We now know it’s also associated with many Cardiac Arrhythmias, including deadly Congenital long QT syndrome (LQTS).

LQTS is characterised by prolonged ventricular repolarization and increased risk of torsades de pointes. Those with LQTS usually present with seizures, syncope, even sudden cardiac death (SCD).

Shamsuzzaman (1) looked at patients with LQTS and performed sleep studies in them, and (not un-expectedly) they concluded that OSA in these patients were asscoiated with a worsening of their LQTS.

•  OSA worsens QTc
•  Worsening QTc is a biomarker for sudden cardiac death
•  This worsening in their QTc was during wake, as well as sleep!

OSA has a profound impact on your Cardiac burden.

Adelaide’s resident Specialist Cardiologists at the Centre for Heart Rhythm Disorders (2) agree that it’s time we all acknowledged OSA’s impact on Cardiac Arrhythmias.

If you have a cardiac problem, whether it be a rhythm problem or otherwise, see us now.

1. Shamsuzzaman et al. Sleep 2015.
2. Dr Rajeev Pathak, Dr Rajiv Mahajan, Dr Dennis Lau, Prof Prashanthan Sanders. Sleep 2015

© APSS 2015

Don’t forget Depression and OSA!

A poor night’s sleep can affect anyone’s mental state, and can lead to depression and anxiety. Being excessively sleepy during the day can also lead to depression. We’ve realised this for a long time, and this is why we’re keen on fixing your sleep for your physical and mental wellbeing.

A recent Australian trial has found that one of the most common sleep disorders (Obstructive Sleep Apnoea, OSA) and Excessive Daytime Sleepiness (EDS) is independently associated with Depression.

Lang et al (1) looked at almost 2000 community-dwelling Australian men over a period of 5-years.

Of these, 857  random participants without previously diagnosed OSA underwent a sleep study and performed the Epworth Sleepiness Scale questionnaire. Lang found that if you had previously undiagnosed OSA you were almost 2x as likely to have depression (adjusted OR 1.9), even after adjusting for confounders.

Being sleepy during the day (EDS) made you almost 2.5x more likely to have depression (adjusted OR 2.4).

Having both OSA and EDS meant a 4.2 times higher risk of developing depression.

So in summary :

•  Having OSA, EDS, or a combination of OSA+EDS increases your risk of depression
•  Those with depression have a high chance of having undiagnosed OSA

We should all be mindful of checking for both comorbid diseases (depression and OSA) as they can both negatively impact each other. Call us now for an appointment.

(1) Lang et al. Am J Respir Crit Care Med. 2015.

© APSS 2015

CPAP prevents Atrial Fibrillation (AF) in OSA

Previously we described how those with Obstructive Sleep Apnoea (OSA) have a 4-fold increased risk of Atrial Fibrillation (AF)… and how it also significantly increases the risk of recurrence to AF even after procedures such as cardioversion and cardiac ablation.

There is now evidence that treating OSA with CPAP can significantly decrease AF recurrence.

Shukla et al performed a meta-analysis across seven large cardiac studies, totalling over 1000 patients with OSA+AF. If you have OSA+AF, and use CPAP, then your relative risk (RR) is reduced by a tremendous 42%. This was completely independent of whether or not you underwent cardiac ablation!

This confirms our understanding of why OSA is such an important and underestimated condition. CPAP prevents atrial fibrillation recurrence in those with OSA.

We recommend that everyone with AF should consider an in-hospital sleep study.

Contact us now if you’d like to discuss this further.

1.Shukla et al. JACC Electrophysiol. 2015.

© APSS 2015

Blue light and Body Clock Problems

Does your body clock feel as though it isn’t running at 24hours? Are you sleeping too early, too late, or all over the place? Then perhaps you have a Circadian Rhythm Disturbance (CRD) and blue light therapy may be able to help you.

Your body clock (Circadian Rhythm) runs at slightly longer than 24hours, but most of us can realign our body clock if needed, with the help of external cues called zeitgebers. When your central body clock generator malfunctions, or those external cues do not help as well as they should, then you could develop a Circadian Rhythm Disturbance (CRD).

The commonest CRD is Delayed Sleep Phase and is commonly seen in the young. Free Running Rhythm (now known as Non-24-Hour Sleep Wake Rhythm) and Advanced Sleep Phase can also disrupt your sleep.

If you can’t control your sleep-time, or wake-time, you’ll arise unrefreshed and subsequently become tired, sleepy, and performing at school or work will be difficult.

The typical adolescent with a CRD will be difficult to rouse in the morning, sleeps in often, falls asleep at school, under-performs during testing, and won’t go to sleep at an appropriate time.

Realigning your body clock is easy, and includes the use of sleep timing methods, blue light therapy, and Melatonin. This re-entrainment program should only be performed after exclusion of other sleep disorders, and under the direction of a Specialist in this field. A home sleep study or use of a CPAP machine won’t be able to address Circadian Rhythm problems.

If you think that your Circadian Rhythm isn’t what it should be, call us for a consultation.

© APSS 2015