International Trigeminal Neuralgia awareness day takes place annually on 7 October to raise awareness about Trigeminal neuralgia (TN or TGN) a chronic pain disorder which affects the trigeminal nerve. This nerve is responsible for sensory data such as tactition (pressure), thermoception (temperature), and nociception (pain) originating from the face above the jawline; it is also responsible for the motor function of the muscles of mastication, the muscles involved in chewing but not facial expression. Trigeminal neuralgia was first described by physician John Fothergill and treated surgically by John Murray Carnochan, both of whom were graduates of the University of Edinburgh Medical School. Historically TN has been called “suicide disease” due to studies by Harvey Cushing involving 123 cases of TN during 1896 and 1912.
The trigeminal nerve is a paired cranial nerve that has three major branches: the ophthalmic nerve (V1), the maxillary nerve (V2), and the mandibular nerve (V3). One, two, or all three branches of the nerve may be affected. Trigeminal neuralgia most commonly involves the middle branch (the maxillary nerve or V2) and lower branch (mandibular nerve or V3) of the trigeminal nerve.
There are two main types: typical and atypical trigeminal neuralgia. The typical form results in episodes of severe, sudden, shock-like pain in one side of the face along the trigeminal nerve divisions which can last for seconds to a few minutes. Groups of these episodes can occur over a few hours. The episodes of intense pain may occur paroxysmally. To describe the pain sensation, people often describe a trigger area on the face so sensitive that touching or even air currents can trigger an episode; however, in many people, the pain is generated spontaneously without any apparent stimulation. It affects lifestyle as it can be triggered by common activities such as eating, talking, shaving and brushing teeth. The wind, chewing, and talking can aggravate the condition in many patients. The attacks are said by those affected to feel like stabbing electric shocks, burning, sharp, pressing, crushing, exploding or shooting pain that becomes intractable. The atypical form results in a constant burning pain that is less severe. Episodes may be triggered by any touch to the face. Both forms may occur in the same person. It is one of the most painful conditions, and can result in depression.
The exact cause is unclear, but believed to involve loss of the myelin around the trigeminal nerve This may occur due to compression from a blood vessel as the nerve exits the brain stem, multiple sclerosis, stroke, or trauma Less common causes include a tumor or arteriovenous malformation. It is a type of nerve pain. Diagnosis is typically based on the symptoms, after ruling out other possible causes such as postherpetic neuralgia. It was once believed that the nerve was compressed in the opening from the inside to the outside of the skull; but leading research indicates that it is an enlarged or lengthened blood vessel – most commonly the superior cerebellar artery – compressing or throbbing against the microvasculature of the trigeminal nerve near its connection with the pons which can injure the nerve’s protective myelin sheath and cause erratic and hyperactive functioning of the nerve. This can lead to pain attacks at the slightest stimulation of any area served by the nerve as well as hinder the nerve’s ability to shut off the pain signals after the stimulation ends. Causes vary from aneurysms (an outpouching of a blood vessel); by an AVM (arteriovenous malformation);tumor; such as an arachnoid cyst or meningioma in the cerebellopontine angle; or a traumatic event such as a car accident.
Short-term peripheral compression is often painless. Persistent compression results in local demyelination with no loss of axon potential continuity. Chronic nerve entrapment results in demyelination primarily, with progressive axonal degeneration subsequently. trigeminal neuralgia is therefore associated with demyelination of axons in the Gasserian ganglion, the dorsal root, or both.Further compression may be related to an aberrant branch of the superior cerebellar artery that lies on the trigeminal nerve. Further causes, include, multiple sclerosis or cerebellopontine angle tumor, a posterior fossa tumor, or brainstem diseases from strokes
Treatment includes medication or surgery. The anticonvulsant carbamazepine or oxcarbazepine is usually the initial treatment, and is effective in about 80% of people. Other options include lamotrigine, baclofen, gabapentin, and pimozide. Amitriptyline may help with the pain, but opioids are not usually effective in the typical form. In those who do not improve or become resistant to other measures, a number of types of surgery may be tried. It is estimated that 1 in 8,000 people per year develop trigeminal neuralgia. It usually begins in people over 50 years old, but can occur at any age.Women are more commonly affected than men.