Differential diagnosis for orofacial pain, including sinusitis, tmd, trigeminal neuralgia

Maxillary sinusitis

Maxillary sinusitis causes a constant boring pain with zygomatic and dental tenderness from the inflammation of the maxillary sinus.10 Acute maxillary sinusitis is defined by the International Association for the Study of Pain (IASP) as constant burning pain with zygomatic and dental tenderness from the inflammation of the maxillary sinus.10 In chronic cases there may be no pain or just occasional mild diffuse discomfort. Diagnostic criteria for maxillary sinusitis include:

The character of the pain of maxillary sinusitis is dull, aching, boring and tender, of mild to moderate severity, is usually continuous and may be either unilateral or bilateral commencing after an upper respiratory tract infection. The pain is triggered by bending forward, touching the area or biting on the upper teeth. Headache is located over the antral area. In the presence of the key diagnostic symptoms, investigations are not required but confirmation of the diagnosis can be confirmed by maxillary sinus radiographic examination (although this is not generally advised as, apart from showing possible fluid levels in acute sinusitis, it is not of great benefit), computerized tomography (CT) or magnetic resonance imaging (MRI).

Temporomandibular disorders

Temporomandibular disorders encompass pain affecting the masticatory muscles and/or temporomandibular joints (TMJs). They consist of muscular pain MSK (referred to by some as myofascial pain), TMJ disc interference disorders and TMJ degenerative joint disease; this latter rarely causes pain but results in limitation of opening.11 In the case of trauma, the pain is usually self-limiting but psychological aspects may contribute to chronicity of the pain, therefore it is important to manage it early. TMD (MSK) is more prevalent in females and the natural history is that of intermittent pain with continuation for many years.12 Tension type headaches can be mistaken for TMD. There is increasing evidence that TMD is linked to many other chronic pain conditions, such as headaches, migraine, post-traumatic stress disorder and fibromyalgia.13 The relationship between TMD pain and clenching habit or bruxism is far from simple^5,13,14, and daily variations in pain do not correlate with self-reports of clenching or grinding.15

Trigeminal neuralgia

Trigeminal neuralgia (TN) is defined by the International Association for the Study of Pain (ISAP) as a ‘sudden and usually unilateral severe brief stabbing recurrent pain in the distribution of one or more branches of the fifth cranial nerve’.16 Idiopathic and secondary forms are recognized and conditions such as multiple sclerosis, benign or malignant lesions being contributory factors. Categorization of TN into classical and atypical forms is based on symptoms and not aetiology.17 TN is being increasingly recognized with its annual incidence now being estimated around 12.8 per 100,000, with a peak incidence in 50–60-year-olds. TN symptoms arising in younger patients should alert the clinician to the possibility of an underlying cause, such as multiple sclerosis.

Classical TN presents with shooting, sharp, unbearable pain in the distribution of one or more branches of the trigeminal nerve, of moderate to intense severity, lasting seconds.^17,18 The right side of the face is affected in 60% of sufferers, it is unilateral in 97% of cases and rarely in first division only. It is precipitated by light touch, but may be spontaneous, and there are often associated trigger points. Patients may have periods of remission lasting days, weeks or longer.

Glossopharyngeal neuralgia (GPN)

Defined by the IASP as sudden severe recurrent pain in the distribution of the glossopharyngeal nerve, GPN is very rare, with an incidence of 0.7 per 100,000, and is more common in females and those aged over 50 years.19 Classic and secondary forms are recognized. Classic GPN is severe recurrent stabbing pain in the ear, base of tongue, tonsillar fossa or below the angle of the mandible. It is precipitated by swallowing, talking or coughing.

Secondary GPN presents with an additional ache that may persist between attacks and is secondary to a cranial lesion demonstrable by investigations or surgery. The pain is unilateral in location and there are no obvious motor neurological defects. Episodes of pain may last from weeks to months.

Although also rare, a syndrome known as Eagles syndrome should be considered in patients presenting with classical symptoms of GPN. Eagles syndrome describes symptoms related to an elongated styloid process impinging on adjacent anatomical structures and is associated with pain and dysphagia on chewing and on turning the head to the affected side.

Burning mouth syndrome (BMS)

BMS is characterized by continuous burning pain of the oral mucosa in the absence of any contributing local or systemic pathology.^20,21 There is an increasing number of studies suggesting that this is not just a psychological condition but is probably neuropathic.13

The symptoms of BMS include:

Most patients have continuous pain but it can vary throughout the day. Most patients do not associate food or drink with the onset of pain but some will describe the pain as being exacerbated by certain foods, such as spicy or acidic food, whereas others find feeding relieves their pain. Many BMS patients score high in tests for depression or anxiety, possibly because the condition is not recognized, patients are not believed and they are not given an adequate explanation.

When excluding an organic cause for BMS, a thorough, systematic soft tissue examination is important and recommended investigations include:

Trigeminal neuropathic pain

Trigeminal neuropathic pain or traumatic induced neuralgia is a form of chronic facial pain arising as secondary to injury to the trigeminal nerve, such as facial trauma or a dental procedure. It is rare but increasingly recognized and the pain is described as a continuous burning sensation localized to the injured area, but may be described as constant, dull, burning with or without intermittent sharp stabbing pain. Numbness and tingling may also be present due to nerve dysfunction. The pain symptoms may be classed under the following:

Proposed mechanisms for trigeminal neuropathy include peripheral or central sensitization, beta fibre reorganization and sympathetically maintained pain due to alpha receptor sprouting.19

Trigeminal neuropathy, with and without pain, is associated with a number of connective tissue disorders including:

The underlying pathology for trigeminal nerve dysfunction in these patients is unknown but could be related to a form of vasculitis.22

Atypical odontalgia (AO)

Considered by most as a form of trigeminal neuropathic pain, atypical odontalgia may in fact have both psychological and neuropathic origins. There is limited evidence on the incidence and prevalence of AO. Clinical features include persistent pain, often commencing in conjunction with some form of dental treatment, particularly root canal therapy or extraction. In fact, over 80% of patients relate the onset of their pain to dental treatment, including local anaesthesia.13 The most common site of pain is the molar and premolar region. The pain is intra-oral, well localized and not associated with radiation to adjacent areas or extra-orally. Several studies have reported associated features of hyperaesthesia and allodynia at the pain site, with a prolonged response to ethyl chloride.23

AO often results in repeated, and possibly unnecessary, dental treatment such as extractions, root canal therapy and apicectomies in the pursuit of pain relief.21 A patient presenting with such pain and giving a history of multiple extractions possibly preceded by root canal therapies should raise suspicions of AO. Diagnosis and management as early as possible is vital24 to avoid unnecessary invasive treatments.

Post-herpetic neuralgia (PHN)

PHN is persistent burning pain but can be an excruciating/severe pain accompanied by intermittent shooting sensation localized to the site of previous herpes zoster infection, occurring 3–6 months after resolution of the infection.19 Allodynia, hyperalgesia and numbness in the affected area have been reported. The neuralgia is dermatomal in location. Ramsay Hunt syndrome, also caused by herpes zoster infection, specifically of the geniculate ganglion of the VIIth cranial nerve,22 presents with facial pain, lower motor neuron palsy and ipsilateral vesicles, affecting the skin of the ear canal, auricle and/or mucous membrane of the oropharynx. The pain is usually localized, paroxysmal, deep within the ear, but can radiate externally and may become more dull and diffuse in nature. Unlike PHN, the onset of pain usually precedes the rash by several hours or days and the disease is self-limiting.

PHN is thought to affect 40% of patients and most patients are more than 70 years of age. Following initial exposure to the herpes zoster virus from chicken pox, the virus lies dormant in the trigeminal ganglion and, when activated, gives rise to the rash of shingles. PHN is the result of damage to the nerve by the virus.

Chronic idiopathic facial pain

Chronic (persistent) idiopathic facial pain (CIFP), previously atypical facial pain, is persistent facial pain which is poorly understood, but its persistence is likely to result in psychological distress. The pain is described as aching, heavy, nagging, sometimes throbbing or stabbing.25 It does not follow anatomical pathways and can be local or very extensive, radiating into the head and neck. The pain is often constant but with varying intensity.

Psychological stresses or fatigue may worsen the symptoms and it is therefore important to take a relevant psychosocial history and record associated stress-related factors. Information regarding marital status, family medical history, employment status, history of depression or anxiety and sleep problems are all relevant. Exploring patients' beliefs about their pain can be particularly enlightening. There are no specific relieving factors and the patient may also suffer irritable bowel syndrome, back and neck pain and poor sleep.

Migraine

Migraine affects one in four women and one in 12 men in the UK.26 It is a chronic headache disorder affecting the frontotemporal region. It often co-exists with TMD, which may exacerbate migraines. The headache is typically unilateral, severely disabling, usually lasting 4–72 hours and is associated with photophobia, phonophobia, nausea and/or vomiting. It may be preceded by an aura in 15% of cases, with visual disturbances being most common.3 It will not be discussed further here but the salient features of the condition are highlighted in Table 2. Changes in frequency, intensity and location are often found in women whose migraines are hormonally driven.

Tension type headache

Episodic and chronic forms of tension-type headache are recognized. The episodic form lasts from 30 minutes to days, with a pressing quality, of mild to moderate intensity, is bilateral, with less than 15 attacks per month and no aggravating factors or associated symptoms, unlike the chronic form which, although of similar character and location, occurs more than 15 times per month for at least 6 months with associated nausea, photophobia or phonophobia. The pathophysiology of this form of headache is not fully understood, its prevalence is quoted as 2.2% and is more common in females.27 It can mimic TMD MSK.

Giant (temporal) cell arteritis (GCA)

GCA is a form of vasculitis involving cell-mediated immune damage to blood vessel walls and mainly affects blood vessels in the head and neck region. It is rare under the age of 50 years and females are about 3 times more likely than men to develop this disease. The temporal artery is commonly affected giving rise to temporal arteritis. Symptoms include unilateral or bilateral headache of aching or throbbing quality, often intense and continuous. Patients may have features of scalp tenderness, visual changes and/or neurological changes.

Criteria stipulated by the International Headache Society (IHS) for a diagnosis of temporal arteritis is any new persistent headache in the temporal region, with either swollen tender scalp artery (Figure 3) and raised ESR or CRP, or temporal artery biopsy demonstrating giant cell arteritis.19 Major improvement or resolution of headache within 3 days of high dose steroid treatment also helps confirm the diagnosis.

GCA may be associated with polymyalgia rheumatica, jaw claudication, weight loss, altered sensation or loss of vision. Owing to the high risk of early visual loss as a result of anterior ischaemic optic neuropathy, prompt diagnosis and management is essential.

Trigeminal autonomic cephalalgias (TACs)

TACs are a group of headache syndromes incorporating short lasting severe unilateral headache attacks, accompanied by cranial autonomic symptoms. TACs is included in the International Headache Society classification of headaches28 and includes cluster headache, paroxysmal hemicrania and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT), all of which display trigeminal distribution pain and ipsilateral cranial autonomic features. The primary site of pain is in the distribution of the first division of the trigeminal nerve and autonomic features present. They are rare, not expected to be diagnosed in primary care and the main features are highlighted in Table 2.