ADVANCE NEUROSURGERY

Trigeminal Neuralgia (Tic Douloureux)

---

Introduction

Trigeminal neuralgia is caused due to the involvement of the trigeminal nerve, which carries sensation from the face to the brain.It is one of the most unbearably painful human condition. It causes abrupt, severe lancinating, electric-shock-like facial pain. Most commonly the pain involves the lower face and jaw, but symptoms may appear near the nose, ears, eyes or lips.

What are the casues for Trigeminal Neuralgia ?

Most commonly it is caused secondary to a blood vessel in contact with the fifth cranial nerve (trigeminal nerve) and its pulsations leading to episodes of severe pain. The other causes which are uncommon are multiple sclerosis and brain tumors compressing on the trigeminal nerve like epidermoid or acoustic schwannoma (secondary trigeminal neuralgia). Secondary trigeminal neuralgia may have accompanying sensory loss over face or weakness of chewing musculature (masticatory muscles).

In a few cases the cause maybe unknown. What are the triggers for pain ?

A variety of triggers may set off the pain of trigeminal neuralgia, including:

• 1. Washing your face
• 2. Shaving
• 3. Touching your face
• 4. Eating or drinking
• 5. Brushing your teeth
• 6. Talking
• 7. Encountering a breeze
• 8. Smiling

What are the Investigations required for diagnosis ?

Trigeminal neuralgia is usually a clinical diagnosis presenting with a typical history. However an MRI scan is recommended in case of the following:

• * If there are atypical symptoms.
• * An underlying cause like tumor or multiple sclerosis is suspected
• * Patients younger than 40.
• * The condition does not improve with drug treatment.
• * Surgery is being considered.

What are the possible treatment options?

Treatment can be subdivided into pharmacologic therapy, percutaneous procedures, surgery, and radiation therapy depending upon the age of the patient, cause for neuralgia and comorbid conditions.

Drug Therapy

Carbamazepine which is an antiepileptic drug is the best studied drug for this disorder and the only one with US Food and Drug Administration (FDA) approval for trigeminal neuralgia. First-line therapy should be carbamazepine (CBZ; 200 - 1200 mg/day) and oxcarbazepine (OXC; 600 - 1800 mg/day) according to current evidence-based treatment guidelines. Oxcarbazepine has a better safety profile. About 75% patients would respond to this therapy.

Second line medications

Include baclofen, lamotrigine,phenytoin,gabapentin,pregabalin and sodium valproate . Second-line treatment is based on very little evidence.

Surgical Treatment

Surgical treatments are generally reserved for patients with debilitating pain refractory to an adequate trial of at least three drugs including CBZ in sufficient dosage. Side effects of medication may also lead patients to think about surgical intervention.

Microvascular Decompression (Janetta Procedure)

Microvascular decompression (MVD) achieves the most sustained pain relief with 90% of patients reporting initial pain relief.. At 10 year follow-up, 68% had excellent or good relief. 32% had recurrent symptoms. It is, however, a major surgical procedure that entails craniotomy to reach the trigeminal nerve in the posterior fossa.

Key hole minimally invasive craniotomy for MVD provides excellent results with minimal stay in the hospital and least morbidity.

When compared to the other procedures, MVD carries the highest long-term success rate but it also carries the highest risk.

Gamma knife surgery

A focused beam of radiation is aimed at the trigeminal root in the posterior fossa. One year after gamma knife surgery, 69% of patients are pain free without additional medication. At 3 years, 52% are pain free.

Percutaneous Procedures

They are usually employed in debilitated or patients over 65 years of age. Three types of procedures: percutaneous radiofrequency trigeminal gangliolysis (PRTG), percutaneous retrogasserian glycerol rhizotomy (PRGR), and percutaneous balloon microcompression (PBM) are available.