From the Guidelines
Trigeminal neuralgia is primarily caused by neurovascular compression of the trigeminal nerve in or around the root entry zone, which is the most common cause of this condition. This compression damages the protective myelin sheath around the nerve, leading to abnormal transmission of pain signals 1. The clinical features of trigeminal neuralgia are characterized by sudden, usually unilateral, severe, brief, stabbing, recurrent episodes of pain in the distribution of one or more branches of the trigeminal nerve 1.
Causes of Trigeminal Neuralgia
- Neurovascular compression of the trigeminal nerve is the most common cause, resulting from a blood vessel pressing against the nerve near its connection to the brainstem 1
- Other less common causes include:
- Multiple sclerosis, which can damage the myelin sheath
- Tumors that compress the trigeminal nerve
- Arteriovenous malformations
- Physical trauma to the nerve from injury or surgery
- Structural abnormalities at the base of the skull
- In some cases, the cause remains unknown, termed idiopathic trigeminal neuralgia
Pathophysiology
The compression or damage to the trigeminal nerve creates a hypersensitive nerve that overreacts to normal stimuli, resulting in the characteristic sudden, severe, shock-like pain typically triggered by routine activities like eating, talking, or touching the face 1. The pain usually affects one side of the face along the distribution of one or more branches of the trigeminal nerve, which supplies sensation to the face, teeth, and mouth.
Clinical Implications
Understanding the cause of trigeminal neuralgia is crucial for effective management, as it can significantly impact the quality of life of affected individuals 1. Accurate diagnosis and appropriate treatment, including pharmacological and surgical interventions, can help alleviate symptoms and improve patient outcomes.
From the Research
Causes of Trigeminal Neuralgia
- Trigeminal neuralgia can be caused by vascular compression of the trigeminal nerve or a tumor process 2, 3, 4, 5
- The compression of the nerve itself causes nerve demyelination, which is the cause of abnormal depolarization, resulting in the development of ectopic impulses 2, 4
- Other causes of trigeminal neuralgia include multiple sclerosis and compressive space-occupying masses in the posterior fossa 3, 4, 5
- The etiology of idiopathic trigeminal neuralgia is unknown 5
Types of Trigeminal Neuralgia
- Classical trigeminal neuralgia is typically characterized by a stimulus-evoked, recurrent and intense short-lasting stabbing pain in the innervation area of the trigeminal nerve 5
- Secondary trigeminal neuralgia is related to an underlying neurological disease, such as multiple sclerosis or compression by a brain tumor 3, 5
- Idiopathic trigeminal neuralgia has an unknown etiology 5
Pathogenesis of Trigeminal Neuralgia
- Demyelination of trigeminal sensory fibres within either the nerve root or the brainstem is a key factor in the pathogenesis of trigeminal neuralgia 4
- Focal demyelination in the region of compression, with close apposition of demyelinated axons and an absence of intervening glial processes, can lead to ectopic generation of spontaneous nerve impulses and their ephaptic conduction to adjacent fibres 4