Trigeminal Neuralgia (TN) is a neurological syndrome characterized by excruciating pain to the face. It is chronic and progressive. While remissions of up to 6 months in length are reported by up to 50% of TN patients, it usually returns and most often becomes more frequent and severe over time. While a fortunate subset of patients with typical TN are able to achieve long-term and/or permanent pain relief with a procedure called microvascular decompression (MVD), for many others there is no cure.
The annual incidence of TN has been reported to be anywhere from 5.1-12.6/100,000 per year, but if less strict definitions including other facial pain syndromes are included, this incidence rises to as high as 26.8/100,000/year. However, estimates may be under-reported due to misdiagnosis. It is more common in adults, though it sometimes strikes children.
TN is caused by a malfunction of the trigeminal nerves, the largest of the cranial nerves, which provide information to your brain about all forms of facial sensation. Typically the pain of TN strikes very suddenly and seems to “come out of nowhere.” The pain can also be triggered by other trigeminal nerve sensory stimuli such as hair in the face, breezes, toothbrushing, showering, eating, or talking. Most often, TN is limited to one side of the face, but it can be on both sides.
In less than 5% of cases the syndrome can be caused by multiple sclerosis, brain stem strokes, tumors, cysts, or rare vascular lesions including aneurysms and arteriovenous malformations. In approximately 95% of patients the syndrome is caused by vascular compression of the trigeminal nerve root in the space between the brain stem and the skull. While the first category can be routinely diagnosed by neuro-imaging such as a magnetic resonance (MR) scan, unfortunately, vascular compression is often missed on MR scans, even utilizing specialized cranial nerve protocols.
Two Types of TN
Type I (TN1) is characterized by sudden, brief, episodic bursts of high intensity pain in the face, specifically the cheek, chin, and/or forehead. These attacks can last for seconds or minutes, and can continue repeating for hours. They are often described as “lightning bolts,” “ice pick stabs,” and worse. For TN1, if any constant, aching, throbbing, or burning pain is present, it represents <50% of the overall syndrome, with the sharp, stabbing, shock-like pain dominating overall.
Type II (TN2) still has a sharp, stabbing shock-like component to the overall syndrome. However in this syndrome constant, aching, throbbing, or burning pain in the same trigeminal nerve distribution represents >50% of the patient’s overall suffering.
Atypical Facial Pain, Trigeminal Neuropathic Pain of Unknown or Obscure Etiology, etc., is not technically TN. It is however usually a severe facial pain syndrome, and it is often treated with interventions developed for TN. With this syndrome patients have only constant, aching, throbbing, or burning facial pain without any sharp, stabbing, shock-like pain component.
Other Overlapping Facial Pain Syndromes
There are a host of other over-lapping facial pain syndromes that can be erroneously diagnosed as TN. By default, many of these syndromes may be treated by interventions developed for TN, but many of them also have specific differing treatments that often work. Thus, accurate diagnosis and differentiation is critical. Among others, these syndromes include:
- Geniculate Neuralgia (Episodic Otalgia or Nervus Intermedius Neuralgia)
- Glosspharyngeal Neuralgia
- Anesthesia Dolorosa
- Trigeminal Deafferentation pain
- Paroxysmal Hemicrania
- Temporal arteritis
- Occular Migraine
- Cluster headache
- SUNA (Short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms)
- SUNCT (Short-lasting unilateral neuralgiform headache with conjunctival injection and tearing
- CRPS (Chronic Regional Pain Syndrome)
- Post-herpetic neuralgia
- Burning Mouth Syndrome
- Post-traumatic Trigeminal Neuroma
- TMJ (temporal mandibular joint) Syndrome
- Atypical Odontalgia
- Trigeminal perineural spread of cancer
Pronunciation of Trigeminal Neuralgia:
BMJ talk medicine: Trigeminal neuralgia – the evidence base for medical and surgical treatments
Mayo Clinic for Medical Education and Research. Trigeminal Neuralgia
The Patient’s Journey Through Trigeminal Neuralgia – IASP (International Association for the Study of Pain)
Trigeminal Neuralgia – NORD (National Organization of Rare Disorders)