Trigeminal Neuralgia (TN) is defined by the International Association for the Study of Pain (IASP) as sudden, usually unilateral, severe, brief stabbing or lancinating, recurrent episodes of pain in the distribution of one or more branches of the trigeminal nerve (Merskey et al.). Less often patients may have a constant, aching or burning sensation. A tingling sensation or aching may also precede the pain episodes. Vibration or contact with the face may trigger the intense flashes of pain. The attacks usually last several seconds to a couple of minutes, and repeat over hours to weeks. The episodes then disappear for months to years before recurring. It can be bilateral, but does not involve both sides simultaneously. Rarely does the pain occur at night when the patient is sleeping. It tends to affect females slightly more than males at a ratio of 1.5:1, and increases slightly with age. Attacks can worsen over time, and the latent periods become more infrequent and shorter.
The cause of trigeminal neuralgia is the compression of the trigeminal nerve root. Causes of compression are tumors (vestibular schwannoma or meningioma), epidermoid cyst, or aneurysm (out pouching of a blood vessel). The compression then leads to damage of the protective covering of the nerve, called myelin. As a result, the nerve acts in an erratic manner, causing pain signals to be sent sporadically at the trigger of light touch, chewing, or brushing the teeth. Rarely, traumatic injuries of the trigeminal nerve, such as a car accident, can lead to similar damage. Multiple sclerosis is a condition where the loss of myelin in one or more of the trigeminal nerve nuclei can also cause trigeminal neuralgia.
Diagnostic criteria for classic trigeminal neuralgia have been developed and published by the International Headache Society (IHS),
- Attacks of pain lasting from a fraction of a second to two minutes, affecting one or more of the subdivisions of the trigeminal nerve
- Pain has at least one of the following characteristics:
- Intense, sharp, superficial, or stabbing
- Precipitated from trigger areas or by trigger factors
- Attacks are stereotyped in the individual patient
- There are no clinically evident neurologic deficit
- Not attributed to another disorder
It can be difficult to diagnose TN and the Pain Physicians at Arkansas Pain have received extra training to examine and diagnose your painful condition. The physician may be able to demonstrate the trigger zones, while the neurological examination is normal. Most neurologic deficits indicate an alternative cause of pain. The physician may also order radiological imaging depending on his clinical suspicion and the history obtained. Other causes of facial pain can be differentiated by these factors:
- Post herpetic pain – has persistent, typical rash that tends to involve the ophthalmic branch.
- Migraine – pain is more prolonged and often throbbing.
The standard medical approaches are anti-inflammatory, anticonvulsant, and antidepressant medications. If these fail, local anesthetic blocks are attempted. Lastly, percutaneous or open procedures may be done. Peripheral nerve stimulation may be a viable option earlier in the treatment of chronic facial pain. In patients not responded to medical treatment, there are several options for surgical procedures (Jannetta and Nurmikko et al).
These surgeries include:
- Microvascular decompression – an invasive procedure involving removal or separation of vasculature, which is often the superior cerebellar artery, away from the trigeminal nerve.
- Balloon compression – a balloon catheter is inflated and used to compress the gasserian ganglion.
- Gamma knife radiosurgery – a noninvasive treatment that creates lesions by using focused gamma radiation. The radiation is targeted at the proximal trigeminal root with the aid of stereotactic frame and MRI.
- Electrolytic rhizotomy – a percutaneous procedure that creates a lesion in the gasserian ganglion of the trigeminal nerve by using the heat of radiofrequency.
- Linear accelerator radiosurgery – a noninvasive approach similar to gamma knife, but uses a different form of radiation, linear acceleration.
- Peripheral neurectomy – an incision, radiofrequency lesioning, alcohol injection, or cryotherapy is used on a peripheral branch of the trigeminal nerve.
- Chemical rhizotomy – an injection of glycerol into the trigeminal cistern. Tingling or burning is felt in the face, and pain relief is usually immediate, but may take up to a week.
All of the above mentioned treatments have a high recurrence of pain.
Here at Arkansas Pain, your physician may talk to you about peripheral nerve stimulation (PNS) or spinal cord stimulation (SCS) of the nucleus caudalis for severe facial pain. These treatments may offer the potential for long-term management of the pain and may offer obvious benefit and less risk than neuro-destructive procedures. Because there is a trial period for SCS or PNS the procedure is often less invasive, reversible, adjustable, and testable for patients in pain.
- Headache Classification Subcommittee of the International Headache Society. The International Classification of Heachache Disorders: 2nd edition. Cephalalgia 2004; 24 (Suppl1):9. Janneta, PJ.
- Microsurgical management of trigeminal neuralgia. Arch Neurol 1985; 42:800. Lance, JW.
- Mechanism of and management of headache, Butterworth Heinemann, Oxford 1993, p. 260. Love, S, Coakham, HB. Trigeminal neuralgia: pathology and pathogenesis. Brain 2001; 124:2347.
- Merskey, H, Bogduk, N. Classification of chronic pain. Descriptions of chronic pain syndromes and definitions of pain terms, IASP Press, Seattle 1994, pp. 59-71. Nurmikko, TJ, Eldridge, PR.
- Trigeminal neuralgia—pathophysiology, diagnosis and current treatment. Br J Anaesth 2001; 87:117. Rozen, TD, Capobianco, DJ, Dalessio, DJ.
- Cranial neuralgias and atypical facial pain. In: Wolff’s Headache and Other Head Pain, Siblerstein, SD, Lipton, RB, Dalessio, DJ (eds), Oxford University Press, New York 2001, pp. 509. Slavin, KV, Wess C.
- Trigeminal branch stimulation for intractable neuropathic pain: technical note. Neuromodulation 8:7-13, 2005