Trigeminal Neuralgia
Trigeminal Neuralgia explained
Trigeminal neuralgia (TN) is an excruciating facial pain condition that affects one side of the face that comes in short bursts and can completely knock a person off their feet. According to the National Institute of Neurological Disorders and Stroke (NINDS), “The incidence of new TN cases is approximately 12 per 100,000 people per year.” Trigeminal neuralgia also occurs more commonly in women than in men.
Trigeminal neuralgia comes in two types:
Type I TN
Also called “classic” trigeminal neuralgia. In Type I TN, people describe their pain using words like “electrical”, “stabbing”, “sharp”, “shock-like”. Basic things like talking, chewing, touching their face, or brushing their teeth, can “trigger” a pain episode.
Type II TN
This type of TN is a bit different. Here, people describe the same “stabbing” or “electric shock” sensations on one side of the face, but they also have a more constant component to their story. Type II TN patients describe a “throbbing”, “burning”, or “numbness” on the same side of the face where they experience the more classic “stabbing” pains. Type II TN patients can also have triggers that they avoid to try and prevent a painful episode and control the pain.
Facial pain – What causes trigeminal neuralgia pain?
Trigeminal neuralgia is also called “tic douloureux”. This was the French name given to one-sided facial pain by Nicholas André in 1756 when he noticed that facial pain patients would contract one side of the face every time they had a severe pain episode, almost having a muscle spasm of one side of the face.
The Trigeminal Nerve – Just think of a Tree with 3 big branches
To begin to understand facial pain, you need to understand that we have 2 trigeminal nerves (1 of 12 pairs of cranial nerves); one trigeminal nerve feels the right side of the face and one feels the left side of the face. The trigeminal nerves are like trees in that they have a “trunk” and three larger “branches”. Each branch feels a part of the face (these divisions are called V1, V2 and V3).
Inside the nerve are hundreds of nerve fibers or “wires” that carry information from the face to the brain to tell us what is happening with our skin, eyes, teeth, etc.. Each wire carries a different kind of sensation. For example, there is a set of wires that feel hot and cold, and another set of wires that feel sharp pin-pricks and yet another that feels pressure on our teeth. These wires are bundled together like a cable in your home and are meant to send true pain signals to your brain. Like most electrical wires, they are surrounded by insulation (myelin). The myelin insulation keeps the sensory information flowing quickly to the brain while preventing the wires from “shorting out” on each other by mistake.
When someone experiences “electrical shocks”, “stabbing pain” and “sharp pain” that come in short bursts (1-3 seconds) and are triggered by eating, talking, chewing, or touching their face, trigeminal neuralgia is likely. Here, the wires inside the trigeminal nerve are starting to “short out” on each other. When a temperature sensor shorts out on a wire that is meant to feel sharp pain, cold water makes the pain wire fire by mistake. This is called “ephaptic transmission”. This happens when the insulation between wires breaks down in spots. When this happens, erroneous pain signals are sent to your brain in short bursts.
Inside the nerve are hundreds of nerve fibers or “wires” that carry information from the face to the brain to tell us what is happening with our skin, eyes, teeth, etc.. Each wire carries a different kind of sensation. For example, there is a set of wires that feel hot and cold, and another set of wires that feel sharp pin-pricks and yet another that feels pressure on our teeth. These wires are bundled together like a cable in your home and are meant to send true pain signals to your brain. Like most electrical wires, they are surrounded by insulation (myelin). The myelin insulation keeps the sensory information flowing quickly to the brain while preventing the wires from “shorting out” on each other by mistake.
When someone experiences “electrical shocks”, “stabbing pain” and “sharp pain” that come in short bursts (1-3 seconds) and are triggered by eating, talking, chewing, or touching their face, trigeminal neuralgia is likely. Here, the wires inside the trigeminal nerve are starting to “short out” on each other. When a temperature sensor shorts out on a wire that is meant to feel sharp pain, cold water makes the pain wire fire by mistake. This is called “ephaptic transmission”. This happens when the insulation between wires breaks down in spots. When this happens, erroneous pain signals are sent to your brain in short bursts.
The breakdown of the insulation is often the result of a blood vessel pressing on and heating up the trigeminal nerve at its “trunk”.
This situation is called “neurovascular conflict”. Breakdown of the myelin sheath (insulation) can also be seen in patients with multiple sclerosis (MS). MS is a condition where the myelin sheath tends to breakdown in specific locations and in this case, the myelin breaks down along the trigeminal nerve. As time progresses, the breakdown of insulation can increase and episodes of pain that used to be short and rare become more frequent and intense. Some patients can even progress to type II (atypical) trigeminal neuralgia over time.
Treatment Options for Trigeminal Neuralgia
There are a variety of treatment options for trigeminal neuralgia and facial pain. Once the diagnosis of trigeminal neuralgia has been made by an experienced expert, treatment options striving to result in pain relief most commonly include:
Microvascular decompression or “MVD” is a surgical procedure designed to create a buffer between the cranial nerve that’s “in trouble” and the blood vessel that is pushing on the nerve. MVD surgery is performed under general anesthesial. Patients are fully asleep during surgery. During an MVD, space is created by placing teflon sponges between the cranial nerve and the blood vessel. For trigeminal neuralgia, sponges are placed in between the SCA and the trigeminal nerve using an operative microscope.
MVD surgery is performed by an experienced neurosurgical team including a brain surgeon, neuro-anesthesiologist, surgical “scrub” technicians, operating room nurses and an experienced neurophysiologist. Throughout the surgical procedure, patients are kept safe by using special monitoring equipment to ensure that functions of the brain and brainstem are protected throughout the surgical procedure. Critical cranial nerves for facial movement, hearing, and swallowing are “in play”, so an experienced team is critical to preventing hearing loss, facial numbness, or other potential side effects. MVD surgery can be extremely safe and beneficial to patients. Long term, most successful MVD patients remain pain free and off medications.
Gamma Knife Radiosurgery (GKRS) is not traditional surgery. Rather, Gamma Knife Radiosurgery is a minimally invasive outpatient procedure designed to treat painful nerve disorders like trigeminal neuralgia without a knife. In the case of trigeminal neuralgia, a small “shot” of radiation is placed on the trigeminal nerve where the offending blood vessel is touching the nerve.
In many cases, this location is on the trigeminal nerve just before it plugs into the brainstem. GKRS is painless and general anesthesia is not required. Patients leave the Gamma Knife facility on the same day of treatment, often before lunch, and have very few restrictions after the procedure is complete.