Facial pain

Facial pain is pain below the orbitomeatal line, anterior to the ears and above the neck. Most cases are dental, sinogenic or musculoskeletal, but the neuropathic and vascular causes carry the highest risk of delayed or missed diagnosis.

Anatomy. Sensory supply is from the trigeminal nerve (ophthalmic, maxillary and mandibular divisions), with contribution from the glossopharyngeal and nervus intermedius branches of the facial nerve, and upper cervical roots. Brainstem trigeminal nuclei extend into the upper cervical cord, which explains referral of pain between face, head and neck.

Classification. Paroxysmal neuropathic (trigeminal, glossopharyngeal and nervus intermedius neuralgia), continuous neuropathic (post-traumatic, post-herpetic, persistent idiopathic facial pain), trigeminal autonomic cephalalgias, odontogenic, sinogenic, musculoskeletal, vascular, and referred.

Trigeminal neuralgia. Unilateral paroxysms of electric shock pain lasting from a fraction of a second to 2 minutes, in one or more trigeminal divisions (mostly maxillary and mandibular), triggered by innocuous stimuli, with a refractory period after each attack. Classical trigeminal neuralgia is caused by neurovascular compression of the root; secondary trigeminal neuralgia arises from a structural lesion; idiopathic cases have no cause on imaging.

Temporal patterns. Paroxysmal, continuous, or continuous with superimposed paroxysms.

History. Describe pain quality (electric, stabbing, burning, aching), duration of each episode, frequency, trigger zones (touch, brushing teeth, chewing, talking, cold wind), laterality, divisional distribution, and progression. Ask about autonomic features, jaw claudication, jaw pain on exertion (angina), vesicular rash, preceding dental work, sinus symptoms, hearing change, previous neurological episodes (multiple sclerosis), cancer history including skin cancer of the face, and diabetes.

Examination. Sensory testing in all three divisions with light touch and pinprick, corneal reflex, masseter and jaw jerk, other cranial nerves, temporomandibular joint palpation, mouth opening and clicking, teeth (percussion tenderness, caries, gingival swelling), oral mucosa, sinuses, ears, parotid glands, temporal arteries, skin of the face, cervical nodes, and cardiovascular examination if jaw pain is exertional.

Red flags

• Sensory loss or abnormal corneal reflex in the painful distribution
• Onset under age 40, bilateral trigeminal neuralgia, or other cranial neuropathy
• Hearing loss, facial weakness, or new neurological signs
• Continuous progressive pain between paroxysms
• Jaw claudication, scalp tenderness, or visual symptoms
• Exertional jaw pain
• Diabetes or immunosuppression with facial pain, black nasal discharge or facial swelling
• Weight loss, cancer history, or neck mass
• Recent head injury

Special groups. Older adults: trigeminal neuralgia and giant cell arteritis are both more frequent. Pregnancy: carbamazepine is teratogenic and needs specialist input. Region specific: HLA-B*1502 testing before carbamazepine in people of Han Chinese, Thai or other South East Asian ancestry.

Neuropathic

• Classical trigeminal neuralgia
• Secondary trigeminal neuralgia: multiple sclerosis, cerebellopontine angle tumour (meningioma, vestibular schwannoma, epidermoid), vascular malformation, aneurysm
• Painful post-traumatic trigeminal neuropathy
• Acute herpes zoster of the trigeminal nerve and post-herpetic neuralgia
• Perineural tumour invasion (skin, nasopharyngeal or parotid carcinoma)
• Glossopharyngeal neuralgia and nervus intermedius neuralgia
• Persistent idiopathic facial pain and burning mouth syndrome

Trigeminal autonomic cephalalgias

• Cluster headache, paroxysmal hemicrania, SUNCT and SUNA
• Facial migraine

Dental and oral

• Pulpitis, apical abscess, cracked tooth, dry socket, gingival disease

Sinogenic and ENT

• Acute and chronic rhinosinusitis
• Rhino-orbital mucormycosis (diabetic ketoacidosis, immunosuppression)
• Nasopharyngeal carcinoma
• Otitis media, mastoiditis, otitis externa
• Salivary gland stone, sialadenitis, parotid tumour

Musculoskeletal

• Temporomandibular disorder
• Eagle syndrome (elongated styloid process)
• Cervicogenic facial pain

Vascular and other

• Giant cell arteritis
• Carotid artery dissection
• Cavernous sinus lesion, Tolosa Hunt syndrome
• Angina referred to the jaw
• Acute angle closure glaucoma and optic neuritis

Reasoning. First separate paroxysmal from continuous pain, then look for a local cause (teeth, sinuses, ears, salivary glands), and then decide on neurological investigation.

Classical trigeminal neuralgia is a clinical diagnosis. Every new case needs MRI brain with thin slice 3D T2 sequences (to show neurovascular contact) plus contrast sequences and MR angiography to exclude tumour, demyelination or vascular malformation. Neurovascular contact occurs in asymptomatic people, so its presence alone does not confirm the diagnosis and its absence does not exclude it.

Other tests by suspicion

• Dental panoramic or periapical radiograph for odontogenic pain.
• CT sinuses for severe, persistent or complicated sinus disease; nasal endoscopy with biopsy for suspected mucormycosis (urgent).
• ESR and CRP for age over 50, with temporal artery ultrasound or biopsy.
• ECG, and troponin if the jaw pain is exertional or accompanied by other cardiac symptoms.
• Vesicle swab for varicella zoster virus PCR.
• HbA1c and glucose.
• Blood tests before carbamazepine: sodium, full blood count, liver function.
• Audiometry for suspected cerebellopontine angle lesion.

Trigeminal neuralgia

• Carbamazepine 100 mg orally twice daily (or 100 to 200 mg once daily in older adults), increased by 100 to 200 mg every 2 to 3 days to the lowest effective dose; usual 400 to 800 mg daily in divided doses; maximum 1.6 g daily. Check sodium, full blood count and liver function at baseline and at 2 to 4 weeks. Adjust: start low and go slow in older adults and in renal or hepatic impairment. Warnings: Stevens Johnson syndrome (highest risk in the first 3 months and with HLA-B*1502), hyponatraemia, enzyme induction (reduces efficacy of hormonal contraception, warfarin and many other drugs), teratogenicity.
• Oxcarbazepine 300 mg orally twice daily, increased by 300 mg every 3 days or weekly to a usual 600 to 1,800 mg daily; maximum 2.4 g daily. Monitor sodium. Halve the starting dose when creatinine clearance is under 30 mL/min.
• Second line add on or alternatives: baclofen 5 mg orally three times daily, increased by 5 mg every 3 days to 20 mg three times daily (maximum 100 mg daily; reduce in renal impairment; do not stop suddenly); lamotrigine with slow titration; gabapentin 300 mg at night increased every 3 days (adjust to creatinine clearance).
• Refractory pain: referral to neurosurgery for microvascular decompression or percutaneous destructive procedures.
• Review the response at 2 to 4 weeks. After 3 to 6 months of remission, try a slow dose reduction.

Acute herpes zoster, ophthalmic or facial. Valaciclovir 1 g orally three times daily for 7 days, started within 72 hours of the rash (also if later with new vesicles or ophthalmic involvement). Adjust: creatinine clearance 30 to 49 mL/min, 1 g every 12 hours; 15 to 29 mL/min, 1 g daily; under 15 mL/min, 500 mg daily. Same day ophthalmology for any ophthalmic division involvement. Post-herpetic neuralgia: amitriptyline 10 mg at night increased by 10 mg weekly to 25 to 75 mg, or gabapentin titrated to effect.

Giant cell arteritis. Prednisolone 40 to 60 mg orally each morning, started immediately when suspected, with aspirin 75 mg daily, and same day specialist review. If visual symptoms, methylprednisolone 500 mg to 1 g IV daily for 3 days.

Cluster headache and other trigeminal autonomic cephalalgias. Oxygen 100 percent at 12 to 15 L/min for 15 minutes and sumatriptan 6 mg subcutaneously (maximum 12 mg in 24 hours). Indomethacin 25 mg three times daily with food, increased to 50 mg three times daily if needed, for suspected paroxysmal hemicrania or hemicrania continua. Specialist referral.

Dental and sinus causes. Dental referral for abscess or pulpitis. Antibiotics for sinusitis only if severe, persistent beyond 10 days or with deterioration after initial improvement. Amoxicillin 500 mg orally three times daily for 5 days (adjust in renal impairment; avoid in penicillin allergy).

Temporomandibular disorder. Ibuprofen 400 mg orally three times daily with food for up to 2 weeks (maximum 2.4 g daily), soft diet, jaw rest, heat, and dental or physiotherapy review.

Emergency. Suspected rhino-orbital mucormycosis: immediate ENT, ophthalmology and infectious disease referral; liposomal amphotericin B 5 mg/kg IV daily (up to 10 mg/kg with CNS disease), glycaemic control and urgent surgical debridement. Suspected angle closure glaucoma: same day ophthalmology.

Monitoring. Sodium, blood count and liver function during carbamazepine and oxcarbazepine; pain diary and function.

Referral and escalation. Neurology for all new trigeminal neuralgia and for any red flag; neurosurgery for refractory pain; urgent ophthalmology, ENT or oncology when relevant.

Admission and discharge. Admit for uncontrolled pain with inability to eat or drink, suspected mucormycosis, suspected giant cell arteritis with visual loss, and complications of infection. Discharge others with follow up in 2 to 4 weeks. Safety net for new numbness, visual loss, weakness, or fever.