Persistent Idiopathic Facial Pain Clinical Presentation

Persistent idiopathic facial pain (PIFP) is essentially a diagnosis of exclusion. Daily or near-daily headaches are a widespread problem in clinical practice. ^{[1, 4]} According to population-based data from the United States, Europe, and Asia, chronic daily headache affects a large number of patients (approximately 4-5% of the population). ^{[4, 6, 7]}

A careful history and physical examination, including a dental consultation, laboratory studies, and imaging studies, may be necessary to rule out occult pathology. Underlying pathology such as malignancy, vasculitis, infection, and central or peripheral demyelination may manifest early as neuralgia, and not until focal neurologic deficits, imaging abnormalities, or laboratory abnormalities are discovered does the diagnosis become evident. Rare cases of referred pain must also be considered.

It is important to distinguish PIFP from other chronic daily headache syndromes, including the following: ^{[4, 6, 7, 8, 9, 10]}

• Trigeminal neuralgia

• Postherpetic neuralgia

• Temporomandibular joint (TMJ) syndrome

• Chronic cluster headache

• Cluster-tic syndrome

• SUNCT (s hort-lasting, u nilateral, n euralgiform headache attacks with c onjunctival injection and t earing) syndrome

• Jabs and jolts syndrome

• Raeder syndrome

• Thalamic pain syndrome

• Hemicrania continua

• Side-locked migraine

The following are characteristic of other chronic facial pain syndromes from which PIFP should be differentiated.

Clinical features distinguishing other chronic facial pain syndromes from PIFP

Trigeminal neuralgia

Trigeminal neuralgia is characterized by severe bursts of lancinating pain in 1 or more branches of the trigeminal nerve. Bursts are quick, repetitive, electric shock–like sensations. Each pain episode is seconds in duration, occurs irregularly, and is not related to the patient’s pulse. Treatments include antiepileptic drugs (AEDs), antidepressants (eg, tricyclic antidepressants [TCAs], selective serotonin reuptake inhibitors [SSRIs], and norepinephrine reuptake inhibitors [NeRIs]), injections, and surgical intervention. ^{[11, 12]}

Postherpetic neuralgia

Postherpetic neuralgia is defined as pain that persists for 1-6 months after an acute herpes zoster infection. The pain is neuropathic in nature. It is associated with allodynia and hyperalgesia, most commonly affecting the V1 distribution of the trigeminal nerve. The mainstays of treatment are AEDs, TCAs, and SSRIs. ^[13]

Temporomandibular joint syndrome

TMJ syndrome is characterized by focal tenderness to one or both TMJs and is usually aggravated by chewing, talking, and jaw movement. The quality of the pain is similar to that of PIFP (ie, dull, aching, crushing, or burning). Treatment of TMJ syndrome is often directed either at the articular joint itself or at fatigue of the periodontal ligament and the temporalis.

Cluster headache

Cluster headache is characterized by the sudden onset of severe, boring, and burning pain. Episodes last 30-180 minutes. The pain awakens the patient from sleep and does not improve with rest. Many individuals pace, and some may even injure themselves because of the severity of the pain. Associated symptoms include ipsilateral conjunctival injection, tearing, and nasal congestion. The male-to-female ratio is 6:1.

Abortive treatment includes oxygen (8-15 L), sumatriptan injections, dihydroergotamine, or combinations thereof. Preventive treatment includes verapamil, lithium, divalproex sodium, and topiramate. ^[14]

Cluster-tic syndrome

Cluster-tic syndrome is a difficult diagnosis and is easily confused with other facial pain syndromes. The 3 types of pain include pain with clusterlike features, pain with trigeminal neuralgia features, and a combination of these 2 types. Treatment includes AEDs, TCAs, and SSRIs or NeRIs. ^[15]

SUNCT syndrome

SUNCT syndrome may be a variation of the cluster-tic syndrome. It is characterized by brief (15-120 seconds) bursts of pain in the eyes, temple, or face. The pain is usually unilateral and is described as burning, stabbing, or electric. It occurs frequently (>100 episodes) in a 24-hour period. Neck movements can trigger the pain. SUNCT syndrome is refractory to medical therapy. ^[16]

Jabs and jolts syndrome, primary stabbing headache, or icepick headache

In this setting, head pain occurs as a single stab or a series of stabs. The pain is exclusive to or predominantly felt in the distribution of V1. Stabs last for up to a few seconds and recur with an irregular frequency that ranges from once daily to many times a day. No other accompanying symptoms are noted, and the pain cannot be attributed to another disorder. This syndrome is refractory to medical treatment. ^[17]

Raeder syndrome

Raeder syndrome is characterized by a V1 distribution of a unilateral burning facial pain associated with hyperesthesia, ptosis, and miosis. The pain may be caused by trauma, a middle cranial fossa mass lesion, syphilis, or sinusitis. In the absence of these underlying conditions, the pain is self-limited. ^[18]

Thalamic pain syndrome

Thalamic pain syndrome is described as unilateral facial pain and dysesthesias and is attributed to a lesion of the ventral-medial thalamic nuclei. It is typically a severe, burning, or aching pain localized to the contralateral side of the face. The diagnosis can be made by means of imaging studies or can be based on the presence of other associated symptoms in the trunk or limbs.

Hemicrania continua

The rare condition known as hemicrania continua is characterized by unilateral headache and facial pain. The daily head pain is continuous (24 h/d, 7 d/wk), with pain exacerbation periods that occur with variable frequency (from multiple times per week to every third month or even less often). The pain at baseline is mild to moderate, and exacerbations are moderate to severe in intensity. It is associated with migraine or cluster features (eg, photophobia, nausea, aura, lacrimation, eye injection).

Hemicrania continua responds to indomethacin, and this response facilitates diagnosis. ^{[14, 19, 20]} Abortive treatment includes oxygen (8-15 L), sumatriptan injections, and dihydroergotamine. Preventive treatment includes verapamil, lithium, divalproex sodium, and topiramate. ^[14]

Migraine

Migraine is a common condition. The female-to-male ratio is 3:1. It is commonly unilateral but can be bilateral. The pain has a throbbing quality and feels as if it is associated with a pulse. Photophobia, phonophobia, and osmophobia are typical features, as is nausea. The pain worsens with exertion and improves with sleep. The patient may or may not experience aura.

Pharmacologic therapy includes abortive and preventive medications, depending on the frequency and severity of the headaches. Abortive agents include serotonin agonists, ergotamine, isometheptene, and anti-inflammatory drugs. Preventive agents include AEDs, beta-blockers, calcium channel blockers, TCAs, SSRIs or NeRIs, and angiotensin-receptor blockers.

As indicated by the definition of persistent idiopathic facial pain (PIFP), the findings from the general physical examination and the neurologic examination should be normal.

Pain evoked responses after stimulation are less common with PIFP than with trigeminal neuralgia. Palpation- and manipulation-induced tenderness of the TMJ is associated more closely with TMJ syndrome and less so with other cephalalgias or facial pain syndromes.