Trigeminal Neuralgia

Trigeminal Neuralgia

Trigeminal Neuralgia is also known as Tic Douloureux, Hunt's Neuralgia, and Suicide Disease.

Why is Trigeminal Neuralgia also known as Suicide Disease?

🌬 What is Trigeminal Neuralgia?

Trigeminal Neuralgia (TN) is a chronic facial pain syndrome characterized by recurrent episodes of sudden onset, intense, stabbing, electric shock-like pain in the distribution of one or more branches of the Trigeminal Nerve (Cranial Nerve V).

What is the distribution of Trigeminal Nerve?

Which divisions of Trigeminal nerve is most commonly affected in Trigeminal Neuralgia?

🌍 Epidemiology of Trigeminal Neuralgia:

• Affects approximately 4-5 per 100,000 people per year.

• Age: Typically begins in the 5th to 7th decade of life.

Rare before 30 years old, except in cases associated with Multiple Sclerosis (MS), where onset can be earlier.

• Sex: More commonly affects females than males.

✨ Causes (Etiology) of Trigeminal Neuralgia

The causes of Trigeminal Neuralgia are classified into three types:

1- Classical Trigeminal Neuralgia (75%):

The cause is typically compression of the trigeminal nerve root (near where it exits the brainstem) by an aberrant blood vessel (often a loop of the superior cerebellar artery). This neurovascular compression is the most frequent finding.

What is the most common aberrant blood vessel causing Classical Trigeminal Neuralgia?

2- Secondary Trigeminal Neuralgia (15%):

The pain is caused by an underlying structural pathology affecting the trigeminal nerve or ganglion.

What are some secondary causes of Trigeminal Neuralgia?

3- Ididopathic (10%)

Cause is unknown.

🚶 Clinical Features of Trigeminal Neuralgia

The hallmark of Trigeminal Neuralgia is the severe pain:

• Pain Character: Described as sharp, lancinating, stabbing, electrical shock-like. Very severe and intense.

• Duration: Brief episodes, lasting only a fraction of a second up to 2 minutes.

• Frequency: Can occur multiple times a day.

• Distribution: Strictly localized to the territory of one or more branches of the Trigeminal Nerve (V1, V2, or V3).

What are the 2 patterns of pain distribution in Trigeminal Neuralgia?

• Side: Usually unilateral. Rare (~3%) cases can be bilateral (more common in MS).

• Course: Pain occurs in periods (days to months) separated by pain-free remissions (months to years).

• Trigger Factors: A defining feature is that pain is precipitated by innocuous stimuli (things that normally wouldn't cause pain).

What are the triggers for pain in Trigeminal Neuralgia?

• Sensory Deficits: Patients may report a transient sensory deficit immediately following a pain spasm.

However, any persistent objective sensory loss, impaired corneal reflex, or trigeminal motor weakness (difficulty chewing) should raise suspicion for a secondary cause and generally invalidate a diagnosis of classical/idiopathic TN.

🩺 Diagnosis of Trigeminal Neuralgia

Trigeminal Neuralgia is primarily a clinical diagnosis based on the patient's history and the characteristic pain presentation.

What is the Diagnostic Criteria (ICHD-3) of Trigeminal Neuralgia?

• Investigations: Usually not needed for diagnosis of classical/idiopathic TN. Performed to rule out secondary causes or assess treatment side effects.

  • MRI Brain (with dedicated trigeminal nerve sequences)
  • MR Angiography

What is the indication of Imaging in Trigeminal Neuralgia?

🤔 Differential Diagnosis of Trigeminal Neuralgia

Other conditions can cause facial pain. It's important to differentiate TN from:

• Dental causes
• Temporomandibular Joint (TMJ) disorders
• Temporal Myositis
• Migraine or Cluster Headache
• Mandibular Osteomyelitis
• Temporal Arteritis
• Postherpetic Neuralgia
• Other Cranial Neuralgias (e.g., Glossopharyngeal Neuralgia)
• Sinusitis

🏥 Treatment of Trigeminal Neuralgia

The primary aim of treatment is pain relief. Management can be medical or surgical.

Medical Treatment:

• Patient Education and Reassurance: Crucial given the severity of the pain.

• First-line Drug: Carbamazepine.

  • Highly effective for acute symptomatic relief in many patients (~90%).

What is the dose of Carbamazepine in Trigeminal Neuralgia?

What are the possible side effects of Carbamazepine and what monitoring should be done in these patients?

• Other Medical Alternatives:

  • Oxcarbazepine
  • Baclofen
  • Lamotrigine, Gabapentin, Topiramate (antiepileptics)
  • Phenytoin
  • Clonazepam, Valproic Acid

• Note: Standard painkillers (Paracetamol, NSAIDs, Opioids) are generally ineffective for the sharp, shooting pain of TN.

Surgical Treatment:

Considered when medical treatment fails to provide adequate pain control or side effects are intolerable.

Aims to reduce nerve irritation or block pain signals.

• Microvascular Decompression (MVD):

  • Often considered the preferred first-line surgical option for classical TN where neurovascular compression is identified on MRI.

• Less Invasive/Ablative Procedures (for patients not suitable for MVD or who prefer less invasive options): These procedures damage the nerve or ganglion to block pain signals, often resulting in facial numbness/hypoesthesia as a trade-off for pain relief.

  • Percutaneous Rhizotomy (Gangliolysis)

  • Stereotactic Radiosurgery (Gamma Knife or CyberKnife)

  • Peripheral Neurectomy

  • Intracranial Trigeminal Root Section