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Burning Sensation and Needle-Like Pain of Trigeminal Neuralgia

Hong Kong records approximately 800 new cases of trigeminal neuralgia annually, but due to a lack of awareness among the populace, a majority of cases remain undiagnosed. What exactly is trigeminal neuralgia?


Sudden Onset Pain Without Warning

The trigeminal nerve is a mixed nerve, being the fifth pair of cranial nerves and the largest in the face, comprising both general somatic sensory and motor fibres. It governs the sensation of the face, mouth, and nose, as well as the movement of masticatory muscles, conveying sensory information from the head to the brain. The trigeminal nerve emerges from the ophthalmic (first branch), maxillary (second branch), and mandibular (third branch), responsible for sensation above the eyelid, between the eyelid and upper jaw, and below the upper jaw, respectively, alongside contracting the chewing muscles. The first branch includes the forehead, upper face, eyeball, and nose; the second branch encompasses the upper lip, lower face, beside the nose, upper dental arch and its gums; the third branch covers the lower lip, area in front of the ear, forehead, lower dental arch and its gums, and tongue.

This condition is categorised into primary (vascular compression) and secondary (multiple sclerosis, brainstem tumours) types. High-risk groups for primary trigeminal neuralgia include genetics, those over 50 years old, females, individuals with hypertension, diabetes, high cholesterol, and smokers. Patients often experience unilateral sudden pain without any precursor, described as burning, needle-like, electric shock, or knife-like pain, frequently accompanied by facial muscle spasms, tearing, drooling, facial flushing, conjunctival injection, etc. With disease progression, the frequency of attacks may increase. Approximately 60% of cases have pain extending from the corner of the mouth to the jawbone, about 30% have pain spreading from the upper lip or canine to the eye or eyebrow area, and less than 5% affect the ophthalmic nerve. Pain is easily triggered by certain actions or environmental factors like airflow, chewing, temperature changes, etc.

Easily Confused with Other Conditions, Misdiagnosis Occurs

Trigeminal neuralgia is often confused with dental pain and temporomandibular joint dysfunction, making diagnosis straightforward yet misdiagnoses frequent. Besides clinical diagnosis, doctors may use X-rays, brain scans, and magnetic resonance imaging (MRI) to assist in diagnosis. Additionally, it's crucial to exclude the possibility of tumours, such as vestibular schwannomas, cholesteatomas, angiomas, meningiomas, or dermoid cysts.

Initially, medication treatment may be considered for one to two months, but medications treat symptoms rather than the cause. They are generally considered for patients who respond well to medication treatment, wish to avoid surgery, are too old, or have other diseases making surgery unsuitable. Injection treatments include trigeminal nerve peripheral injection therapy, gasserian ganglion intramuscular alcohol injection therapy, gasserian ganglion radiofrequency thermocoagulation therapy, or separating the compressed nerve ganglion through a balloon inserted via a needle into the nerve foramen. Surgery often involves microvascular decompression of the trigeminal nerve root, aimed at separating the compressed trigeminal nerve from the blood vessel through a microscope to eliminate nerve short-circuiting. For those unsuitable for surgery, radiosurgery techniques like Gamma Knife can be employed. Consultation with dental and neurosurgical specialists is advised before any invasive procedures or surgery. Delaying treatment can result in irreversible nerve damage, reducing the success rate of surgery, potentially affecting daily activities, and prolonged pain can lead to depression.

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