Tic Dolereux aka: Trigeminal Neuralgia

Pain is never a fun thing. Ever felt something hurt so bad that you said "the pain is killing me?" Well I guarantee you this disease is worse. Get ready for 'the Suicide Disease', Trigeminal Neuralgia:

Short 'n Sweet:
An dysfunction (disease state of impromper functioning) involving the Trigeminal Nerve either directly(rare) or indirectly(more often) which causes it to send a huge false pain signal chronicly.

Background Anat&Physio:
Lots of anatomy to get through :), let's learn how *pain* works.
Nerves are the body's way of sending signals (as we all know). For the most part, nerves that have to conduct over a long distance are myelinated, meaning they are covered in a sheath (of myelin) that effectively "insulates" their electrical signal and does not allow for "cross-talk between the wires". It's really the same concept as we see in the cables that hook up your TV - like an HDMI cable. A thick, electricity-proof, insulation prevents outside interference, in this case from other nerves or electrical impulses in the body.

Now pain is a complex sensation and the body has many different types of signals it can produce to transmit it. Your skin has multiple kinds of receptors for sensation (light-touch, vibration, etc.) as well as straight-up 'pain receptors' (a different kind of sensor). Organs (heart, lungs, liver, stomach, colon, kidneys, etc.) have visceral (greek for 'organ'-al) pain sensors as well, though they're less sensitive and fewer in number. All of these sensors send their signals to the nearby spinal cord segments via nerves. The spinal cord in turn transmits them up to the midbrain (lower part of the brain), which sends them to the cerebrum (the brain-proper) where the signals are dealt with, interpreted, and pain is actually "felt". This spinal pathway also has opiod receptors, special structures that allows the binding of opioids which can dull or even inhibit the sensation of pain. These receptors can react both to endgonously produced (made in the body) opiods/enkephalins as well as exogenously delivered ones (like morphine or heroin).

So that's how pain from the trunk on down is transmitted, but what about higher than that? Above the level of the neck, when we're passed the spinal cord, pain is transmitted via a few of the major nerves in the cranium (skull-bone) creatively termed the "Cranial Nerves". The Trigeminal Nerve (cranial nerve 5, or CN V) and the facial nerve (CN VII). Of these, CN V does more surface area and 'deeper' into the head, whereas CN VII works primarily with the face and superficial (ie: skin). Though nerves, veins, and blood vessels are totally separate from each other, it is quite common to see a set of all three traveling together in a membranous sheath. Like the way we have those Red/White/Yellow cables for TV's to give video, right-audio, and left-audio, but each cable is insulated separately.


What goes wrong?:
While there can be other causes, in trigeminal neuralgia (neuro = nerve/brain related, algia=pain) what happens is that the blood vessel that runs with the Trigeminal Nerve gets too big. As blood gushes through the blood vessel, it swells and presses against the adjacent trigeminal nerve, clamping down on it. This frictional rubbing of the blood vessel against the Trigeminal Nerve steadily disrupts its myelin sheath . . .leaving it more and more susceptible to nearby electric disturbance. Once it's thin enough, small irritations cause the trigeminal nerve to fire erratically and directly into the brain. Maybe every time the heartbeat goes up, so the CN V is pulsating a bit more. . . a new signal bursts through. What signal you might ask? Pain.

The signal sends "wave upon wave" of excruciating pain. I can't emphasize this enough -

the pain is really *REALLY* bad.This illness got the nickname "the suicide disease",

 because people would literally kill themselves at the pain's severity and consistency.

The thing that makes it so interesting though is that the pathway by which the pain is caused effectively short-circuits past all of the usual mechanisms! Patients will take painkillers like extra-strength Tylenol or Aleve to try to deal with it. Some will be put or harder stuff like morphine or codeine (opiods). But it will all have absolutely zero effect! Ordinarily, when you suffer an extremely massive injury, the pain dulls after a moment, and you go into shock. The spinal-cord pathways that would modulate an extreme pain signal (via endgoneous opiods) are ineffective here, and even some of the midbrain level stuff to modulate pain response is all being short-circuited past!

Treatment:
Treatment is tricky here; there are medications you can take, but they're not pain meds . . . they're anti-seizure meds! The idea is, since you can't dull the pain signal, kill all the signals. Some seizure meds dampen the excitability of nerves in the brain (like you'd want in a seizure setting) and try to target the trigeminal nerve (which still has plenty of spillover and bad side effects). Eventually, most these patients will opt for surgical correction of the problem.





So next time "it hurts so bad" just be glad it's not Trigeminal Neuralgia :) !