Orofacial pain – A review of common clinical entities and treatment modalities

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facial painThe orofacial region is significant for us because we express ourselves using facial expressions and from the time we are born, we take in air and food using the orofacial structures. Pain in this region can therefore be displeasing and not only effect the function but also the emotional and mental state. Clinically, orofacial pain is a significant and challenging condition from diagnosis point of view as it is mostly misdiagnosed and commonly associated  purely with TMJ. Successful management of  orofacial pain requires teamwork of various clinical specialities. The purpose of this article is to review the various causes of orofacial pain, associated signs and symptoms and common treatment modalities for orofacial pain.

Pain is defined as an unpleasant sensory or emotional experience associated with actual or potential damage or described in terms of such damage. Few of the terms associated with pain are allodynia (pain due to stimulus which does not normally provoke pain), hyperalgesia (an increased response to a stimulus which is normally painful), hyperaesthesia (increased sensitivity to a stimulus), hypoalgesia (diminished pain in response to a normally painful stimulus – associated with increased threshold level), analgesia (absence of pain in response to a normally painful stimulus) and hypoaesthesia (decreased sensitivity to a stimulus).

The common mnemonic SOCRATES for the history of pain applies to orofacial pain as well. The points which  should be investigated for an effective history which will help to establish correct diagnosis of the cause of orofacial pain are:  Site (Unilateral/ bilateral, referred pain), Onset (Paroxysmal pain which is strong and develops rapidly, evoked pain which occurs after stimulation, spontaneous pain which occurs on its own, triggered pain whose response is out of proportion to the stimulus and progressive pain which gets stronger over time), Character (Sharp/ electric e.g. in trigeminal neuralgia, burning pain which can occur in neuropathy, throbbing pain characteristic of neurovascular disease),  Radiation of pain which mostly indicates that the pain is severe,  Associations (swelling, redness, sweating, rhinorrhea, ptosis, nausea, photophobia, dizziness are some of the associated factors which might accompany some types of orofacial pain), Time (e.g morning, midday, evening, monthly, yearly), Exacerbating and relieving factors (e.g intake of cold/ hot eatables, air, chewing, bending down, stress, rest, analgesics) and severity.

The next step in the diagnosis of orofacial pain includes examination of the orofacial area extraorally and intraorally. Extraoral examination should include head and neck examination along with the lymph nodes of the head and neck, inspection of the TMJ to rule out any swelling or deviation of mandible on opening or closure, palpation of TMJ to rule out any tenderness or clicking sound during opening or closure. Intraoral examination should include dental examination to rule out any dental cause for the orofacial pain and examination of orofacial soft tissues to check for any swelling/ ulcer or any suspicious lesion which could be the cause of orofacial pain. Confirmatory radiographs are necessary to support the diagnosis.

Inorder to diagnose the cause of the orofacial pain accurately, it is necessary to know the distinguishing signs and symptoms of the common types of orofacial pain. The four major clinical entities of orofacial pain are dental, neurovascular, musculoskeletal and neuropathic.

Musculoskeletal orofacial pain might be due to TMJ, masticatory apparatus (in which case it is called masticatory myofacial pain) or tension type headache. If the orofacial pain is localized to the temporomandibular joint, the musculoskeletal orofacial pain is related to TMJ. Such pin is associated with click/ crepitation of TMJ, deviation of the mouth towards the affected joint while opening and a painful TMJ on palpation. In contrast if the pain is diffuse then the musculoskeletal orofacial pain is due to the muscles of mastication and is regarded as masticatory myofacial pain which is associated with muscle fatigue on chewing or yawning and limited range of jaw movements due to pain.. Bilateral pain at temples and occipital areas associated with anorexia and nausea is said to be tension type headache.

The neurovascular orofacial pain might commonly present as migraine, cluster headache or chronic paroxysmal hemicranias. Migraine is characterized by strong unilateral pain which is of throbbing type and is mostly associated with photophobia, phonophobia, nausea and vomiting. Relieving factors of migraine include rest in dark and quiet places. Distinguishing features of cluster headache include periorbital unilateral throbbing pain mostly once a year with a typical duration of 45-60 min and associated with rhinorrhea (involving the nostril of the affected side), redness, ptosis and miosis of the affected eye. The third neurovascular orofacial painful condition is chronic paroxysmal hemicranias involving periorbital and temporal region of one side with strong pain of short duration sometimes triggered by head movements and associated with sleep disturbance.

The neuropathic orofacial pain presents mostly as the neuralgia of the trigeminal nerve. Orofacial pain is associated mostly with the trigeminal nerve because this nerve provides most of the craniofacial sensory innervations. Typical trigeminal neuralgia presents for very short duration as an electric shock like pain in the region innervated by trigeminal nerve and is triggered by stimuli which are not usually painful e.g. light touch.

The dental entity of orofacial pain is wide deending on the dental cause present contributing to the orofacial pain. Most of the times it is irriversable pulpitis which cause orofacial pain. In such condition, the patient complains of continuous, spontaneous, severe throbbing pain which radiates to the head and ear and is aggravated by bending or changing posture at night. In such case endodontics (root canal treatment) or exodontias (tooth extraction) is the treatment of choice. Orofacial pain is also associated with post root canal treatment due to over instrumentation causing periodontal inflammation. This can be used by using various intracanal medicaments (which can be placed in the pulp canal of tooth) and have anti-inflammatory and sedative properties e.g. corticosteroids (triamcenolone acetonide). Post operative dental pain is also a cause of orofacial pain presenting as severe throbbing pain radiating to head. In such cases, treatment of dry tooth socket follows as irrigation of the open socket and then placement of sedative dressing e.g. of zinc oxide/ eugenol. For postoperative orofacial pain after extraction of third molar (wisdom tooth), ketorolac tromethamine combined with codeine is an effective method with the additional benefit of reducing the amount of codeine required for pain control and thereby reduces the adverse effects of codeine as well.

The major goals of the treatment of orofacial ain should be to relieve pain and at the same time prevent the abuse of analgesics and restore the function. Treatment of masticatory myofacial pain is non invasive and limited to restriction of mandibular function, simple muscle relaxation therapies, medication including muscle relaxants and antiinflammatories and physical therapy. On the other hand, patients of musculoskeletal orofacial pain due to TMJ have been treated by administering  glycosamine hydrochloride and chondroitin sulphate and studies have shown that effective administration of these agents for approximately 3-4 months have helped in reducing symptoms e.g. joint sounds and also has reduced the number of analgesics required in patients of TMJ pain.

Neurovascular orofacial pain presenting as migraine is primarily managed by avoiding precipitating factors which may include alcohol, citrus fruits, pickled foods, monosodium glutamate, stress etc. The next level in migraine management includes use of analgesics e.g. acetaminophen or NSAIDs. Triptans and ergotamine are involved in the treatment when migraine doesnot respond to analgesics. Beta blockers, serotonin antagonists and amitryptaline are used in cases of frequent migraine attacks. Cluster headache on the other hand is managed primarily by oxygen inhalation. Sumatriptan can be given subcutaneously will relieve the symptoms of cluster headache. Recent treatment introductions for cluster headache include intranasal administration of capsaicin. Cases of paroxysmal hemicrania have successfully been treated with indomethacin which causes total pain remission.

Some studies have divided the neuropathic pain into three categories according to the nature of pain and its pharmacological treatment. The sequence of medication in the group of sharp, stabbing, lancinating neuropathic orofacial pain is anticonvulsants, tricyclic antidepressants, antispasmodics and local anesthetics while in a group of burning neuropathic pain it is tricyclic antidepressants, gabapentin, local anesthetics and steroids. The group of neuropathic orofacial pain presenting as tingling sensation or numbness responds to antispasmodics, anticonvulsants and steroids. Trigeminal neuralgia responds well to anticonvulsants e.g. carbamazepine when used prophylacically and not when the attack starts. Incase of medical failure, surgery is the next available option (surgical division, cryosurgery). However there is always a chance of recurrence. Incase of failure or recurrence, intracranial neurosurgery is the next available option as percutaneous trigeminal ganglion compression or  microvascular decompression.

While the destructive human life style and behavioural patterns continue to increase various medical conditions, expeditious research work is being carried out so as to bring forth new treatment options both in the field of medicine and surgery which are more effective, comfortable for patients, increase patient’s compliance and provide long term positive results with less chances of recurrence. The research work carried out in regards to orofacial pain is vast and beyond the scope of this article. However on the other hand, understanding the fact that pain management is palliative, can  prevent aggressive treatment by the patients.