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Dentistry

Alencar, Dentistry 2013, 3:2http://dx.doi.org/10.4172/2161-1122.1000e112

Volume 3 Issue 2 1000e112DentistryISSN: 2161-1122 Dentistry, an open access journal

Open AccessEditorial

Chronic Orofacial Pain, Central Sensitization and Sleep Is There a Link?Francisco Alencar Jr*General Dental Sciences Department, TMD and Orofacial Pain, Marquette University School of Dentistry, Milwaukee, WI, USA

*Corresponding author: Francisco Alencar Jr. DDS, MS, MS, PhD, GeneralDental Sciences Department, TMD and Orofacial Pain, Marquette University School ofDentistry, Milwaukee, WI, USA, Tel: 414-288-5590; E-mail: docfalencarjr@yahoo.com,fguedes00@yahoo.com

Received November 04, 2013; Accepted November 06, 2013; Published November 08, 2013

Citation: Alencar F (2013) Chronic Orofacial Pain, Central Sensitization andSleep Is There a Link? Dentistry 3: e112. doi: 10.4172/2161-1122.1000e 112

Copyright: 2013 Alencar F. This is an open-access article distributed under theterms of the Creative Commons Attribution License, which permits unrestricteduse, distribution, and reproduction in any medium, provided the original author andsource are credited.

Pain has been cited in very ancient texts such as the Old and Newestament in the Bible. However, it was only dened in the scientic

literature in 1986 when the International Association or the Studyo Pain (IASP) provided officially their rst classication and paindescription [1].

Contrary to what one might think, pain cannot be dened onlyas an unpleasant sensation. Pain is a highly subjective experience thatinvolves the peripheral and central nervous system and is inuencedby previous experiences, emotional and cognitive actors. It haslong been appreciated that the experience o pain is highly variablebetween individuals. Pain results rom activation o sensory receptorsspecialized to detect actual or impending tissue damage (nociceptors).Nevertheless, a direct correlation between activation o nociceptorsand the sensory experience o pain is not always apparent. Even incases in which the severity o injury appears similar, individual painexperiences may vary dramatically. Emotional state, degree o anxiety,attention and distraction, past experiences, memories, and many other

actorscan either enhance or diminish the pain experience. Tis is whatwe call pain modulation [2].

Pain could also be viewed as a protective or de ensive mechanismthat sends the brain an alert so a protective behavior can be generated.Nevertheless in Chronic Pain this purpose is missing. When pain lastslonger than it is supposed afer healing has happened, it can in act turnto be an etiologic actor. Tere ore pain cannot be viewed only as a signor a symptom o a disease. Tis nding has a pro ound impact in theway Chronic Pain should be viewed by health care providers. Also itshould create a shif in patients behavior towards pain management.In other words, this means that treating pain is not only palliative orsupportive care. When managing pain properly we are in act treatingor controlling a potential or actual etiologic actor. Pain can causetransient or irreversible changes in the peripheral and central nervoussystem, clinically resulting in Myo ascial Pain, Neuropathic Pain andother complex pain syndromes.

Tere has been an extensive debate towards the length or durationo pain to be considered chronic. Usually 3 months or 6 months wouldbe considered the minimal pain duration. Te question is: Why isit important to differentiate between chronic and acute pain? Teimportance relies in the need to treat these patients with a differentapproach. Te difference is usually related to the presence o CentralSensitization, Sleep Dys unction and severe Psychological Issues.Tere ore the debate about time/duration becomes o a secondaryimportance since the presence o signs or symptoms o CentralSensitization and Poor Sleep quality becomes the key topics in ChronicPain denition and consequently management.

In order to understand Central Sensitization we need to considerpain not as a sign or symptom o a disease or pathological disorder.We need to see pain with a potential to cause damage to the CentralNervous System (CNS) according to its severity, intensity and duration.In other words, the longer the duration and the greater the painintensity, chances are that some sort o damage will occur in the CNS.Central sensitization represents an enhancement in the unction oneurons and circuits in nociceptive pathways caused by increases inmembrane excitability and synaptic efficacy. Te whole CNS becomesoversensitive and will respond not only to pain ul stimulations, but

rather to all sorts o excitations in a very different and peculiar way.Tis change may affect different autonomic, sensory and motor bers.

When affecting autonomic bers the patient can clinically mani estsigns and symptoms that will resemble an allergic or sinus in ection.Tese could be acial swelling, increase in skin temperature, redness,eye lacrimation, rhinorrhea, nasal congestion, sneeze and coughamong others. Sensory or sensitive bers may be affected and presentclinically as allodynea or secondary hyperalgesia. Motor bers caninitially present muscle protective co-contraction that i postergatedwill originate muscle myalgia and perhaps myo ascial pain. Interestingto note is that all these different clinical presentations are constantlymisdiagnosed and they are all caused by constant pain input.

It is not surprising that patients with chronic headaches have ahigher prevalence o myo ascial trigger points, and headache symptomsthat can be reproduced by stimulation o an active trigger point [3].Trough my research I have ound that the presence o trigger pointsmay be a contributing actor in the initiation and/or perpetuation ochronic headaches. Myo ascial pain can be the cause, along with theevidence o central sensitization, o atypical acial pain, with triggerpoints re erring pain to the teeth, gums, maxillary sinus, mandible,ears, ace, head and /or some kind o vision impairment [4].

When a re erred patient presents or an emergency consultindicating tooth pain, he could actually be suffering rom Myo ascialPain Disorder (MPD.) All practitioners who treat pain patients,especially chronic pain patients, need to study and better understand theetiology in order to come out with an adequate diagnosis. Consideringonly occlusion or psychological issues as potential etiologic actors to

MD or MPD is not considered evidence based Dentistry.

Patients have undergone invasive surgery procedures, includingteeth extractions and MJ surgery, when the diagnosis was myo ascialpain or neuropathic pain. Neuropathic pain etiology used to be linkedonly when some nerve damage had occurred. In act this can be oneo the causes o neuropathic pain, but inadequately managed chronicpain can lead to central sensitization and neuropathic pain as well. Tiscan be caused due to changes in the peripheral and central nervoussystem. It can be even more con using because it is usually describedas a burning, electrical shock like or throbbing pain. I this pain isbeing elt in some teeth or head, can be easily con used and diagnosedas odontogenic pain or migraine.

Evidence based Dentistry points in one direction or the managemento Chronic MD and other Oro acial Pain conditions. It is now known

http://dx.doi.org/10.4172/2161-1122.1000e110http://dx.doi.org/10.4172/2161-1122.1000e110

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Volume 3 Issue 2 1000e112Dentistry

ISSN: 2161-1122 Dentistry, an open access journal

Citation: Alencar F (2013) Chronic Orofacial Pain, Central Sensitization and Sleep Is There a Link? Dentistry 3: e112. doi: 10.4172/2161-1122.1000e 112

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that a combination o many actors contribute to this condition.Sleep quality, daytime posture, habits including work environment,posture during sleep, insufficient hydration, caffeine intake, nicotine

intake, daytime para unctions and sleep bruxism, anxiety, rustrationand depression, can all affect the Central Nerve System (CNS) andcause more pain or perpetuate the pain through central sensitization.Inadequate occlusion could be a consequence and not the cause oinammation in the temporomandibular joint. In multiple cases with

MD and/or MJ inammation the patient completed treatment witha much better an adequate occlusal relationship.

Chronically pain ul conditions are requently associated with sleepdisturbances, i.e. changes in sleep continuity and sleep architectureas well as increased sleepiness during daytime. A new hypothesis,which has attracted more and more attention, is that disturbanceso sleep cause or modulate acute and chronic pain. Since it is well-known that pain disturbs sleep, the relationship between the two has

since recently been seen as reciprocal. According to the majority o thestudies, sleep deprivation produces hyperalgesic changes. Furthermore,sleep deprivation can inter ere with analgesic treatments involvingopioidergic and serotoninergic mechanisms o action [5]. Tis is veryimportant in ormation that clinicians dealing with chronic pain shouldnever orget.

Laboratory based sleep deprivation studies have also suggested thatreductions in total sleep time are accompanied by increased sensitivityto noxious stimuli (secondary hyperalgesia) and by decrements inendogenous pain-inhibitory processes. Tis could also be a linkbetween chronic pain and central sensitization (CS), since secondaryhyperalgesia and other secondary excitatory effects specically relatedto CS could be related to a longer duration o the pain causing a

reduction o the sleep time. Alternatively, a relatively long sleep periodmay indicate poor sleep continuity (e.g., ragmented, or overly lightsleep), which has been associated with enhanced pain perception in

some laboratory studies o experimental sleep ragmentation [6].It is a very complex area due to the numbers o actors that can

be involved, the need or the clinician to study other areas not relateddirectly with Dentistry and the controversies in the literature mosto the times caused by grouping a lot o different subtypes o MDdiagnosis in one big group and call it MD.

It seems to be clear and evident that sleep and pain have a closerelationship. Also, chronic pain can cause sleep disturbances andcentral sensitization. Health care providers who treat patients in painmust be amiliar with these concepts as well as treatment modalities tomanage them.

References

1. Mersky H (1986) Classi cation of chronic pain: Description of chronic pain syndromes and de nition of pain terms. Pain 3: S1-226.

2. Ossipov MH, Dussor GO, Porreca F (2010) Central Modulation of Pain. J Clin Invest 120: 3779-3787.

3. Sanit PV, Alencar Jr FGP (2009) Myofascial Pain Syndrome as a contributing factor in patients with chronic headaches. Journal of Musculoskeletal Pain 17: 15-25.

4. Alencar Jr FGP (2010) The Puzzling Problems of Myofascial Pain. MarquetteUniversity Discover Magazine.

5. Lautenbacher S, Kundermann B, Jrgen-Christian Krieg (2006) Sleep deprivation and pain perception. Sleep Medicine Reviews 10: 357-369.

6. Everson CA, Szabo A (2009) Recurrent restriction of sleep and inadequate recuperation induce both adaptive changes and pathological outcomes. Am J Physiol Regul Integr Comp Physiol 297: 1430-1440.

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http://dx.doi.org/10.4172/2161-1122.1000e112http://dx.doi.org/10.4172/2161-1122.1000e112http://dx.doi.org/10.4172/2161-1122.1000e112http://www.ncbi.nlm.nih.gov/pubmed/3461421http://www.ncbi.nlm.nih.gov/pubmed/3461421http://www.ncbi.nlm.nih.gov/pubmed/21041960http://www.ncbi.nlm.nih.gov/pubmed/21041960http://www.massage-research.com/blog/?p=424http://www.massage-research.com/blog/?p=424http://www.massage-research.com/blog/?p=424http://www.researchgate.net/publication/7384287_Sleep_deprivation_and_pain_perceptionhttp://www.researchgate.net/publication/7384287_Sleep_deprivation_and_pain_perceptionhttp://www.ncbi.nlm.nih.gov/pubmed/19692662http://www.ncbi.nlm.nih.gov/pubmed/19692662http://www.ncbi.nlm.nih.gov/pubmed/19692662http://dx.doi.org/10.4172/2161-1122.1000e110http://dx.doi.org/10.4172/2161-1122.1000e110http://www.ncbi.nlm.nih.gov/pubmed/19692662http://www.ncbi.nlm.nih.gov/pubmed/19692662http://www.ncbi.nlm.nih.gov/pubmed/19692662http://www.researchgate.net/publication/7384287_Sleep_deprivation_and_pain_perceptionhttp://www.researchgate.net/publication/7384287_Sleep_deprivation_and_pain_perceptionhttp://www.massage-research.com/blog/?p=424http://www.massage-research.com/blog/?p=424http://www.massage-research.com/blog/?p=424http://www.ncbi.nlm.nih.gov/pubmed/21041960http://www.ncbi.nlm.nih.gov/pubmed/21041960http://www.ncbi.nlm.nih.gov/pubmed/3461421http://www.ncbi.nlm.nih.gov/pubmed/3461421http://dx.doi.org/10.4172/2161-1122.1000e112http://dx.doi.org/10.4172/2161-1122.1000e112