Last Updated on October 29, 2023
Trigeminal neuralgia, also known as tic douloureux, is a common pain syndrome that leads to by unilateral facial pain in the sensory distribution of fifth cranial nerve or trigeminal nerve and often accompanied by a brief facial spasm or tic. Mandibular and maxillary branches are more commonly involved than ophthalmic.
Anatomy and Pathophysiology
The trigeminal nerve is the largest of all the cranial nerves. It exits laterally at the mid-pons level and gives a smaller motor root and a larger sensory root. The motor root supplies the temporalis, pterygoid, tensor tympani, tensor palati, mylohyoid, and anterior belly of the digastrics muscle. The motor root also contains sensory pain nerve fibers.
The gasserian ganglion is located in the trigeminal fossa (Meckel cave) of the petrous bone in the middle cranial fossa. It contains first order sensory fibers that carry pain, temperature, and touch. The peripheral processes of neurons in the ganglion form the 3 divisions of the trigeminal nerve – ophthalmic, maxillary, and mandibular. The ophthalmic division exits the cranium via the superior orbital fissure whereas the maxillary and mandibular divisions exit via the foramen rotundum and foramen ovale, respectively.
Causes of Trigeminal Neuralgia
Exact causation of trigeminal neuralgia is not established but it could be central, peripheral, or both.
Primary or Idiopathic
No structural lesion is found in 85% of the cases. Vascular compression leading to focal trigeminal nerve demyelination is suggested for idiopathic or classic trigeminal neuralgia.
Symptomatic or Secondary
Other type of trigeminal neuralgia is called symptomatic trigeminal neuralgia which can have multiple causes as below.
Tumors
- Acoustic neurinoma
- Chordoma at the level of the clivus
- pontine glioma
- Glioblastoma
- Epidermoid
- Metastases
- Lymphoma
- Paraneoplastic etiologies.
Vascular
- Pontine infarct
- Arteriovenous malformation
- Aneurysm in the vicinity.
Inflammatory
- Multiple sclerosis
- Sarcoidosis
- Lyme disease neuropathy
Clinical Presentation
Trigeminal neuralgia presents as a stabbing unilateral facial pain which could be triggered by variety of triggers. The major known triggers are chewing, touching affected part, talking, smilingor drinking cold or hot fluids, brushing teeth, blowing nose etc.
The right side of the face is affected 5 times more frequently than the left.
60% of patients complain pain shooting from the corner of the mouth to the angle of the jaw; 30% experience from the upper lip or canine teeth to the eye and eyebrow.
The pain quality is severe, paroxysmal, and lancinating. It starts as electrical sensation and quickly progresses to an excruciating discomfort. It then starts fading which is followed by burning ache lasting seconds to minutes. Patient may grimace and make an aversive head movement [Hence the name tic douloureux.]
The number of attacks may vary from less than 1 per day, to a 12 or more per hour.
Patients with multiple sclerosis present at a much younger age (often < 40 y).
Patient may appear unkempt because facial care triggers pain. Some patients may be tense while examination for fear of pain attack.
Sensorimotor examination of the face is normal including corneal reflexes. Any abnormality of neural examination like numbness or muscle weakness goes against the diagnosis of primary neuralgia or suggests another etiology.
Sensory loss can often be seen in patients of multiple sclerosis.
Differential Diagnoses
- Cavernous Sinus Syndromes
- Cerebral Aneurysms
- Cluster Headache
- Hemifacial Spasm
- Hydrocephalus
- Intracranial Hemorrhage
- Migraine Headache
- Multiple Sclerosis
- Postherpetic Neuralgia
- Subarachnoid Hemorrhage
Diagnosis of Trigeminal Neuralgia
Diagnosis is clinical and no laboratory, electrophysiologic, or radiologic testing is routinely indicated.
A therapeutic trial of medication may be considered . Relief of pain with carbamazepine or another anticonvulsant confirms the diagnosis of idiopathic trigeminal neuralgia.
Investigations may be needed in following situations
- To rule out rheumatic diseases, such as scleroderma or SLE (trigeminal neuropathy may be associated). – ESR, antinuclear antibody titer, double-stranded DNA, anti-Sm antibody, lupus erythematosus cell preparation, and complete blood cell count, creatinine kinase and aldolase levels.
- In cases with suspected metastatic carcinomatosis, cerebrospinal fluid analysis may confirm the diagnosis..
- Approximately 15% of patients with trigeminal neuralgia have abnormalities on neuroimaging. The most common findings are cerebello-pontine angle tumors and multiple sclerosis.
Diagnostic Criteria
International Headache Society criteria
Primary
- A – Paroxysmal attacks of pain lasting from a fraction of a second to 2 minutes, affecting 1 or more divisions of the trigeminal nerve and fulfilling criteria B and C
- B – Pain has at least 1 of the following characteristics
- Intense, sharp, superficial or stabbing
- Precipitated from trigger areas or by trigger factors
- C – Attacks stereotyped in the individual patient
- D – No clinically evident neurologic deficit
- E – Not attributed to another disorder
Symptomatic
- A – Paroxysmal attacks of pain lasting from a fraction of a second to 2 minutes, with or without persistence of aching between paroxysms, affecting 1 or more divisions of the trigeminal nerve and fulfilling criteria B and C
- B – Pain has at least 1 of the following characteristics
- Iintense, sharp, superficial or stabbing
- Precipitated from trigger areas or by trigger factors
- C – Attacks stereotyped in the individual patient
- D – A causative lesion, other than vascular compression, demonstrated by special investigations and/or posterior fossa exploration
Treatment of Trigeminal Neuralgia
Medical Treatment
Treatment of trigeminal neuralgia must be individualized.
Medical therapy alone is adequate treatment for 75% of patients.
Patient generally gets immediate and relief with medication. Over the period patient might need to add more drugs.
Carbamazepine and oxcarbazepine are considered first-line therapy in trigeminal neuralgia. Lamotrigine and baclofen are second-line therapy.
Carbamazepine acts by inhibiting the neuronal sodium channel activity, thereby reducing the excitability of neurons.
If the patient does not respond at least partially to carbamazepine, reconsider the diagnosis of idiopathic trigeminal neuralgia.
Many adverse central nervous system effects like vertigo, sedation, ataxia, diplopia are associated with carbamazepine. The dose may be tapered once pain is controlled, since remission may occur.
Gabapentin has demonstrated effectiveness in trigeminal neuralgia in patients with multiple sclerosis.
Phenytoin may benefit when patient fails to have relief with carbamazepine alone.
Baclofen may also be effective in patients with trigeminal neuralgia.
Misoprostol, an NSAID has shown modest efficacy.
Surgery
Surgical treatment should be considered in patients in whom medical therapy has failed.
Surgery is generally more helpful in those patients with paroxysmal rather than constant pain and in patients whose pain is localized than diffuse.
Ninety percent of patients are pain-free immediately or soon after any of the operations. Pain may recur aftera period of initial relief and repeat procedure may be needed. Still some patients eventually restart pain medication after surgery.
Surgery is less effective for trigeminal neuralgia secondary to multiple sclerosis
Microvascular Decompression
This procedure is commonly performed in younger, healthier patients. It is now the most common surgery performed for trigeminal neuralgia.
It requires general anesthesia.
Microvascular decompression consists of opening a keyhole in the mastoid area and freeing the trigeminal nerve from the compression/pulsating artery. A piece of Teflon is placed between them.
Percutaneous Procedures
Percutaneous procedures usually can be performed on an outpatient basis under local or brief general anesthesia at acceptable or minimal risk of morbidity. They commonly are performed in debilitated persons or those older than 65 years.
Percutaneous retrogasserian glycerol rhizotomy
A needle similar to spinal needle penetrates the face, this time to the trigeminal cistern, at which point a cisternogram is obtained with water-soluble contrast material. After removing this material, the surgeon instills anhydrous glycerol, asking the patient to remain seated for an additional 2 hours to fully ablate the nerve.
Percutaneous balloon microcompression
A balloon catheter is inserted through the foramen ovale into the region of the ganglion and inflated it for 1-10 minutes.
Gamma Knife Surgery
Multiple rays high-energy photons concentrated with high accuracy destroy the specific components of nerve.
Prognosis of Trigeminal Neuralgia
After an initial attack, trigeminal neuralgia may remit for months or even years. It may recur with increased frequency, easily triggered and more disabling, requiring long-term medication. It waxes and wanes in frequency.
The morbidity associated with the chronic and recurrent facial pain can be considerable. The condition may evolve into a chronic pain syndrome, and patients may suffer from depression and related loss of daily functioning.
Activities of the patients may become limited due to pain precipitation. Severity of the pain may lead to suicide.