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FATIGUE

& CMT

Research is showing that fatigue, feeling tired and CMT are commonly misunderstood and misdiagnosed, which can have a dramatic impact on a person's day-to-day life.

A common symptom among people with CMT is a feeling of tiredness, which can range from needing to sit down after a brief walk, to an overwhelming wave of fatigue that can be hard to stave off, even with caffeine or other stimulants. Many people are told that feeling tired is a normal symptom of CMT due to a lack of muscle resulting in increased physical exertion, however, a growing amount of research is showing that sleep disorders and CMT may be linked, and it is important for people with CMT to understand the signs and symptoms of tiredness and other issues so a correct diagnosis and treatment can be found where necessary.

Fatigue or Daytime Sleepiness?

Feeling tired may sound like a simple concept, but medically there is a significant difference between the concepts of fatigue and daytime sleepiness

Fatigue

Daytime Sleepiness

Fatigue is medically defined as one of two things: 

  1. Weariness or exhaustion from labour, exertion, or stress

  2. The temporary loss of power to respond induced in a sensory receptor or motor end-organ by continued stimulation

In short, fatigue is what a person feels after they have undergone some sort of physical exertion, such as feeling tired after exercise. 

 

If you find yourself falling asleep during the day without having physically exerted yourself, or tired even after a perceived good night of sleep, this could be a sign of daytime sleepiness, also known as daytime somnolence. This is medically different from fatigue and defined as the inability to stay awake and alert during the major waking periods of the day, which results in unintended lapses into drowsiness or sleep [1]

Exhaustion as a Symptom of CMT

The experience of exhaustion in people with CMT is well known [2], with one study showing 64% of CMT patients interviewed reporting severe fatigue [3]. The reported levels of exhaustion seem to be much more intense than what would be normally expected from CMT-induced physical exercise, with people describing "overwhelming" exhaustion, regardless of how well the person slept, and unlinked to activity [2]

While more research is required to fully understand the connection between fatigue and daytime sleepiness in people with CMT, there has been some research done in the last few years that is uncovering a potential link between CMT and sleep disorders. In a 2001 family study of a family with a history of CMT-1A, 11 of 17 family members were found to have sleep apnoea syndrome [4] and a 2006 study of patients with CMT-2 found that restless legs and periodic limb movement during sleep is common, with 10 out of 27 (37%) of patients studied having one of the pre-mentioned sleep issues [5]. It's worth noting that sleep apnoea syndrome and restless leg syndrome do not seem to be neurologically related, but for CMT patients, the outcome is the same: a sleep disorder that impacts the quality of sleep and results in excessive daytime sleepiness.

Diagnosing Daytime Sleepiness

To determine if a person is suffering from daytime sleepiness, also known as hypersomnia or daytime somnolence, a doctor may have a patient undertake the Epworth Sleepiness Scale, a modern tool for evaluating a patients symptoms, or undergo a sleep study 

Sleep disorders usually cannot be diagnosed quickly or without evaluation of some kind from a medical professional. If you suspect you have a sleep disorder, seek advice from a medical professional. If they believe that your symptoms warrant further investigation, several steps may be taken to determine this, two commonly used ones are noted below:

The Epworth Sleepiness Scale

Recognising the need to be able to clinically evaluate a person's symptoms at the Sleep Disorder clinic in Epworth Hospital, Melbourne, Murray W. Johns, a doctor specializing in sleep disorders, created the Epworth Sleepiness Scale: a short questionnaire of eight questions about a person's likelihood of dosing in certain situations [6]. Since the publication of the Epworth Sleepiness Scale, it has become a common, internationally used tool to determine if a person may be showing signs of a sleep disorder, with the only change being made to the original scale being the range used to determine whether a person exhibits normal, borderline or abnormal results [7]. As an initial stage in evaluating whether a person is showing signs of excessive daytime sleepiness, the Epworth Sleepiness Scale can be used quickly and effectively. 

Sleep Study: Monitoring For Symptoms

If a person is showing signs of excessive daytime sleepiness, or other signs of a sleep disorder, then an overnight polysomnography study may be used to monitor a patient while they sleep [4]. It is a common diagnostic tool used to monitor multiple components that may be linked to poor sleep, such as limb movement, airflow, oxygen saturation as well as the quality of your sleep cycles. 

A medical professional is required to carry out the test, as well as interpret the results, due to the complexity involved as different electrodes are utilised to monitor numerous variables. 

Sleep Hygiene

The routine around a persons sleep is essential to a healthy nights sleep and shouldn't be ignored, even if a sleep disorder is diagnosed.

The Importance of a Healthy Routine

Sleep hygiene is the term associated with a set of behavioral and environmental recommendations intended to promote healthy sleep and was initially publicised in 1977 for use in the treatment of mild to moderate insomnia [8]. Since then, it has undergone decades of testing and scrutiny, with the current consensus being that sleep hygiene is important, although certain aspects of sleep hygiene have more of an impact on a person's sleep quality than others [9][10]. The basics of sleep hygiene are summarised below:

  1. Avoid caffeine

  2. Avoid nicotine

  3. Avoid alcohol

  4. Exercise regularly

  5. Manage stress

  6. Reduce bedroom noise

  7. Sleep at regular times

  8. Avoid daytime naps

While basic, these factors all help to contribute to a healthy sleep schedule and can modestly improve sleep quality and therefore shouldn't be overlooked. 

a quick fix for energy can be found in coffee, energy drinks, and other sources of caffeine, such as pre-workouts which tend to have a blend of different energy-inducing mixes.  However, for the long term, these are not solutions, and ultimately if you feeling that you may suffer from excessive daytime sleepiness rather than fatigue, seek advice from a medical professional. The discovery of sleep disorders linked to CMT is relatively new and therefore, not all practitioners may be aware of this link, resulting in a misdiagnosis of fatigue as opposed to daytime sleepiness. Getting a good night's sleep is vital for many different reasons, such as helping the immune system [11] and reducing depression and anxiety [12]

References

[1] Fan, Mengyu & Qi, Lu. (2020). Sleep, Genetics, and Human Health. 10.1016/B978-0-12-816658-1.00006-5. 

[2] Ramdharry GM, Thornhill A, Mein G, Reilly MM, Marsden JF. Exploring the experience of fatigue in people with Charcot-Marie-Tooth disease. Neuromuscul Disord. 2012;22 Suppl 3:S208-S213. doi:10.1016/j.nmd.2012.10.016

[3] Kalkman JS, Schillings ML, van der Werf SP, et al. Experienced fatigue in facioscapulohumeral dystrophy, myotonic dystrophy, and HMSN-I. J Neurol Neurosurg Psychiatry. 2005;76(10):1406-1409. doi:10.1136/jnnp.2004.050005

[4] Dematteis M, Pépin JL, Jeanmart M, Deschaux C, Labarre-Vila A, Lévy P. Charcot-Marie-Tooth disease and sleep apnoea syndrome: a family study. Lancet. 2001;357(9252):267-272. doi:10.1016/S0140-6736(00)03614-X

[5] Aboussouan LS, Lewis RA, Shy ME. Disorders of pulmonary function, sleep, and the upper airway in Charcot-Marie-Tooth disease. Lung. 2007;185(1):1-7. doi:10.1007/s00408-006-0053-9

[6] Johns MW. A new method for measuring daytime sleepiness: the Epworth sleepiness scale. Sleep. 1991;14(6):540-545. doi:10.1093/sleep/14.6.540

[7] Engleman HM, Douglas NJ. Sleep. 4: Sleepiness, cognitive function, and quality of life in obstructive sleep apnoea/hypopnoea syndrome. Thorax. 2004;59(7):618-622. doi:10.1136/thx.2003.015867

[8] Hauri P. Sleep hygiene. In: Hauri P, editor. Current concepts: the sleep disorders. Kalamazoo, MI: The Upjohn Company; 1977. p. 21e35.

[9] Mastin DF, Bryson J, Corwyn R. Assessment of sleep hygiene using the Sleep Hygiene Index. J Behav Med. 2006;29(3):223-227. doi:10.1007/s10865-006-9047-6

[10] Brown FC, Buboltz WC Jr, Soper B. Relationship of sleep hygiene awareness, sleep hygiene practices, and sleep quality in university students. Behav Med. 2002;28(1):33-38. doi:10.1080/08964280209596396

[11] Bryant PA, Trinder J, Curtis N. Sick and tired: Does sleep have a vital role in the immune system?. Nat Rev Immunol. 2004;4(6):457-467. doi:10.1038/nri1369

[12] Alvaro PK, Roberts RM, Harris JK. A Systematic Review Assessing Bidirectionality between Sleep Disturbances, Anxiety, and Depression. Sleep. 2013;36(7):1059-1068. Published 2013 Jul 1. doi:10.5665/sleep.2810