Overview:
Trigeminal neuralgia, also known as Tic douloureux, is a painful condition that is mainly due to a nerve disturbance either in the branches or the root of the trigeminal nerve (cranial nerve V). The trigeminal nerve is both sensory and motor in function (mixed nerve), and hence this has an acute and compromising effect on the patient's orofacial regions.
What Is Cranial Nerve V or Trigeminal Nerve?
Sensory information in the cranial system is established by the trigeminal sensory system, composed of peripheral structures, such as the trigeminal nerve or cranial nerve V and trigeminal ganglia. The trigeminal nerve, that is, the cranial nerve V is divided mainly into three branches:
-
Ophthalmic (V1) Branch - The superior region of the head, like the layers of meninges and cornea, is innervated by the V1 or ophthalmic branch.
-
Maxillary (V2) Branch - The maxillary branch innervates the upper lip, maxillary teeth, and mucosa.
-
Mandibular (V3) Branch - This innervates mainly the mandible, lower lip, mucosa, and mandibular teeth.
The V1 and V2 branches are sensory, whereas V3 has motor functions responsible for the innervation of the jaw muscles. The fibers that form the trigeminal nerve have both nociceptors and mechanoreceptors.
What Is Trigeminal Neuralgia?
Trigeminal neuralgia is an excruciatingly painful condition (neuropathic and facial pain) due to the disturbance in the nerve branches (one or more) of the trigeminal nerve or the ganglion. The international association for pain study describes or defines trigeminal neuralgia mainly as a sudden unilateral stabbing and recurrent episodes of pain in the distribution of one or more branches of the cranial nerve V (trigeminal nerve).
As per traditional research and evidence, in almost 60 % of the cases, only one branch of the trigeminal nerve is affected: the maxillary or the mandibular branch. However, in nearly 30 % of the affected instances experiencing this severe pain, both the maxillary and the mandibular branches of the nerve may be involved. The clinical fact in this disorder to be observed is that even though the ophthalmic branch is also a branch of the trigeminal nerve, rarely is it affected, causing symptoms of trigeminal pain in nearly less than 4 % of the documented cases.
Patients over the age of 50 years are the most affected, and increasing age, especially in females, is a risk factor with a female to male prevalence ratio of 3:1.
How Does Trigeminal Neuralgia Pain Feel Like?
There are certain trigger points in the territory of the face supplied by the trigeminal nerve, which can be triggered or activated before every episode of pain. These excruciating or severe episodes are paroxysmal or limited to a specific area that may seem like an electric shock kind of sensation or even felt as a burning sensation in that part in some individuals.
Psychosocial life is frequently affected by these painful attacks as daily activities become a hindrance to perform with the recurrence of these episodes. The patient may often be disturbed to perform even routine tooth brushing, chewing, or eating and talking to people, which can greatly impair the quality of life. Hence this medical condition requires immediate attention from the physician and also possibly management by the dental surgeon for the jaw pain and poor masticatory control due to pain.
How Is Trigeminal Neuralgia Diagnosed?
The location of trigeminal pain is variable from the trigger zone at times and can be felt as a radiating stretch of pain from the sensation of light touch and breeze to tooth brushing and shaving, even light mechanical stimuli within the orofacial cavity can provoke a painful episode. Trigeminal neuralgia patients also mistakenly feel they suffer from a dental abscess due to radiating jaw pain. After no relief, even after root canal treatment, they may recognize the symptoms are not tooth-related.
Hence it is essential to recognize the source and period of pain. For the accurate diagnosis of trigeminal neuralgia, it is essential to assess clinical symptoms by the physician before suggesting the diagnostic modality to adopt. For example, classic trigeminal neuralgia requires MRI (magnetic resonance imaging) scans to thoroughly examine the trigeminal root (as morphologic changes are seen in the trigeminal nerve root due to vascular compression).
MRI can be a useful tool to map and visualize 3-dimensional reconstruction and examinations of arteries, veins, and nerve segments. However, it is pivotal for the physician to assess clinically before suggesting an MRI for confirming the symptoms of classic trigeminal neuralgia.
Quantitative sensory testing advised by many physicians is a method in which sensory deficit is clearly observed on bedside examination of the patient. Trigeminal neuralgia caused due to underlying systemic disease or secondary trigeminal neuralgia is often suspected and followed up if the sensory abnormalities are evident through the test. In a rare but relatively smaller number of cases, it may be possible for the cause of trigeminal neuralgia to be undetermined by the advanced diagnostic criterion like MRI, sensory testing. Hence, in such cases, it may be deemed idiopathic trigeminal neuralgia (when the investigation cannot detect the cause).
How Is Trigeminal Neuralgia Treated?
-
Management of trigeminal neuralgia is by an interprofessional approach between the physician, neurologist, otolaryngologist, and the dentist.
-
In severe cases of trigeminal neuralgia pain, microvascular decompression remains the most effective surgical procedure.
-
Anticonvulsant medications Carbamazepine, Oxcarbazepine, and frequency-dependent sodium channel blockers are the first line of efficacious drugs used in managing and providing symptomatic relief of neuropathic pain. The pain paroxysms can be controlled from partial to total suppression, depending on the patient's recovery.
-
The dental examination also plays a crucial role in differentiating tooth pain from neuropathic pain. In patients already suffering from trigeminal neuralgia, the dentist can prescribe appropriate prophylactic and oral hygiene measures to avoid the dental sources of infections.
Conclusion:
Trigeminal neuralgia is a condition with acute psychosocial impact. A multicentric approach from the specialists and preventive diagnosis can alleviate and manage the otherwise severe pain experienced by these patients.
