Trigeminal nerve
introduction
The trigeminal nerve is one of the cranial nerves, i.e. one of the twelve nerves that originate in the brain. It is the fifth and largest cranial nerve and has many different functions. The trigeminal nerve is also called the triplet nerve, as it produces three nerves in its course to supply the face. On the one hand it has motor functions, i.e. it is responsible for movements, on the other hand it also contains sensitive fibers that convey information to the brain about the touches and pain in the face.
course
The trigeminal nerve has its Origin in the brain, more precisely in different cranial nerve nuclei in the brain. These are created in pairs so that the trigeminal nerve is present on both sides of the brain. At the place of origin you can two nerve roots distinguish. One leads motor fiberswho have favourited other the sensitive fibers. In the area of the so-called bridge (a special area of the brain) the trigeminal nerve leaves the brain and breaks through the hard meninges near the temporal bone.
In a duplication of the meninges (Dura mater) the trigeminal nerve forms the so-called Trigeminal ganglion out. This is a thickening caused by a Accumulation of many nerve cells arises.
Here the trigeminal nerve divides into his three terminal branches on. These pull as their own nerves to their respective target areas and leave the skull through various openings.
There is Eye branch (Ophthalmic nerve), the Maxillary branch (Maxillary nerve) and the Lower jaw branch (Mandibular nerve).
The eye branch pulls towards the eye socket in order to divide there into its terminal branches. The branch of the maxilla leaves through a hole in the underside of the skull (Foramen rotundum) the skull and pulls towards the upper jaw, where it divides into its terminal branches. The branch of the lower jaw pulls together with the motor fibers to the lower jaw and gives off the end branches there.
Since the trigeminal nerve is a very large nerve and therefore supplies a large part of the head with nerve fibers, it is accompanied on some sections by other nerves that use it as a guide structure.
tasks
The motor fibers of the trigeminal nerve are mainly responsible for the To innervate the masticatory muscles. In addition, they also supply small muscles of the palate, which are important for the swallowing process, and of the ear to protect it from loud noises. Also Muscles of the floor of the mouth are innervated by this nerve. These are also relevant for the swallowing process.
The sensitive fibers of all three branches of the nerve are used for the sensation of touch and pain throughout the face. The eye branch is responsible for the eye socket, the nasal cavity and the forehead area, the upper jaw branch for the middle face and also for parts of the nasal cavity, as well as for the upper jaw with gums and teeth. The branch of the lower jaw supplies the lower face, the oral cavity and parts of the tongue.
paralysis
Trigeminal palsy or trigeminal paralysis can manifest itself in various symptoms. This depends on where the lesion occurs and which branch of the nerve is affected.
Is the Branch affectedso it happens Sensory disturbances in the upper face. Also is Eyelid closing reflex weakened or even no longer triggerable. Then the eye is no longer closed reflexively when a foreign body touches the cornea.
In the case of paralysis of the Branch of the maxilla the sensation in the central area of the face is impaired.
Also a paresis of the Branch of the lower jaw manifests itself in sensory disturbances in the corresponding area. In addition, however, there is one Loss of function of the masticatory muscles. In the case of one-sided paralysis, this causes the lower jaw to deviate from the paralyzed side.
The individual branches are often paralyzed by the Pressure increase on the affected nerves, for example through a Brain tumor or by a Aneurysm. Also Circulatory disorders and Inflammation of the nerves can lead to these symptoms.
Paralysis of the entire trigeminal nerve, on the other hand, is caused by the complete severing of the nerve. This is where all the symptoms come together.
A paralysis can be both one-sided as well as bilateral occur. If there is paralysis of the lower jaw branch on both sides, chewing is impossible and if this paralysis lasts for a long time, the masticatory muscles recede.
irritation
In some cases it does permanent irritation of the trigeminal nerve. The nerve is responsible, among other things, for transmitting facial pain to the brain. The trigeminal nerve reports in the event of permanent irritation strong pain to the brain, although no damage to the face is evident. This clinical picture is called Trigeminal neuralgia and the pain it causes is some of the strongest pain a person can feel.
It comes to Sudden, violent attacks of pain in the facewhich usually only last a few minutes, but recur frequently (up to 100 times a day). Those affected usually have no pain between the individual pain attacks. Also a Facial muscles twitching can occur as a result of trigeminal neuralgia. Due to the severe pain and the helplessness and limitations it causes, trigeminal neuralgia often goes along with it depressions hand in hand.
Also certain Fragrancesthat activate the pain receptors (e.g. acetic acid) can irritate a branch of the trigeminal nerve. This type of trigeminal irritation plays an important role in establishing a complete Loss of smell (Anosmia) The trigeminal nerve is involved in the masseter and corneal reflexes and reacts in the reflex pattern when stimulated accordingly. A decreased or increased reflex reaction can indicate damage. An increased masseter reflex, possibly up to a masseter clonus, can occur on many Infarcts in the brain stem (Status lacunaris) Clues. A diminished or extinguished masseter reflex can affect a peripheral bilateral Trigeminal paralysis based. If the corneal reflex is weakened, this may be due to damage to the trigeminal nerve (afferent leg of the reflex arch) or to damage to the spinal trigeminal nucleus or to damage to the facial nerve (efferent leg of the reflex arch).
To the causes of neuralgia count Brain tumors and aneurysmswhich put increased pressure on the nerve Strokes and diseases like multiple sclerosiswhich damages the insulating layer that surrounds the nerve. Often, however, no cause can be identified; one then speaks of classic trigeminal neuralgia.
At Space claimsthat press on the nerve, it is often necessary to have a surgery perform to alleviate the discomfort. If it doesn't, the neuralgia will with Medication treated.
Various diagnostic options can provide information about the cause of trigeminal neuralgia. These include the Magnetic resonance imaging (MRI), Computed Tomography (CT), one Lumbar puncture to recognize or exclude multiple sclerosis and the Angiography, during which the blood vessels in the skull are examined and any malformations can be detected.
The normal pain medication (such as ibuprofen) is used for the severe pain of trigeminal neuralgia mostly ineffective. The permanent administration of stronger painkillers is then necessary. Usually that will Anti-epileptic drug carbamazepine used for therapy to prevent further pain attacks. In addition is Phenytoin another drug alternative. Helps with trigeminal neuralgia caused by multiple sclerosis Misoprostol. The dose of medication is gradually increased until pain relief is achieved.
If by giving medication no improvement can be reached, or if there is a known cause, a surgery to be necessary. There are three different methods of doing this. In which classic surgical procedure become Sponge inserted between the trigeminal nerve and the vesselto counteract permanent irritation. The percutaneous thermocoagulation consists in that under X-ray control with the help of a probe Pain fibers of the nerve destroyed by exposure to heat become. In which radiosurgical procedures become Pain fibers of the nerve through a so-called Gamma knife destroyed by a high dose of radiation. Each of these surgical procedures has its advantages and disadvantages, so it must be decided individually which method is used.
Inflammation of the trigeminal nerve
Is the Trigeminal nerve inflamed, so it comes to the Symptoms of trigeminal neuralgia. The inflammation can be caused by multiple sclerosis. Read more about this in the Irritation section.
Pain (trigeminal neuralgia)
The pain caused by a Trigeminal neuralgia caused are among the strongest known pain. Typically the pain occurring suddenly and stabbing. The pain can also be triggered by applying pressure to the trigeminal pressure points.
Read a lot more information on this topic at: Trigeminal neuralgia
Pressure points
As Trigeminal pressure points will the Exit points of the individual trigeminal branches from the skull designated. In total, there are three pressure points on each side of the face. These are roughly in line above the eye (Supraorbital foramen), below the eye (Infraorbital foramen) and on chin (Mental foramen). Normally no pain should be felt when applying slight pressure on these areas.
At certain clinical pictures however, such as the Trigeminal neuralgia, the patients complain about strong pain at certain pressure points. Even with increased intracranial pressure, meningitis and sinusitis, there is strong pain sensation when checking the pressure points.
MRI
The Magnetic resonance imaging (MRI) is an important tool in Diagnosis a trigeminal neuralgia. Possible causes can be recognized as for example a Brain tumor, Malformations of the vessels or a previous one stroke. Indications of multiple sclerosis can also be seen on the recordings.
