Neuralgia : Symptoms, Causes, Diagnosis and Management

Neuralgia : Symptoms, Causes, Diagnosis and Management

Neuralgia is pain in one or more nerves caused by a change in neurological structure or function of the nerves rather than by excitation of healthy pain receptors.

Types of trigeminal neuralgia

Trigeminal neuralgia can be divided into different categories depending on the type of pain. These are described below.

Trigeminal neuralgia type 1 (TN1) is the classic form of trigeminal neuralgia. The piercing and stabbing pain can occur at any time and is not constant. This type of neuralgia is known as idiopathic (when no cause can be identified)
Trigeminal neuralgia type 2 (TN2) can be referred to as atypical (not typical) trigeminal neuralgia. Pain is more constant and involves aching, throbbing and burning sensations
Symptomatic trigeminal neuralgia (STN) is when pain results from an underlying cause, such as multiple sclerosis

Symptoms :

The main symptom of neuralgia is a sudden severe stabbing or piercing pain in the area of distribution of concerned nerve. It can be due to irritation or damage to the nerve.

Increased sensitivity of the skin in area of distribution of the damaged nerve, so that any touch or pressure is felt as pain
Numbness along the path of the nerve
Weakness or complete paralysis of muscles supplied by the same nerve

Causes:

Causes of neuralgia include:

Chemical irritation
Chronic renal insufficiency
Diabetes
Infections, such as herpes zoster ( shingles), HIV, Lyme disease, and syphilis
Pressure on nerves by nearby bones, ligaments, blood vessels, or tumours
Trauma (including surgery)

Diagnosis:

Diagnosis of neuralgia can be difficult at times. It can be diagnosed with the help of tests like:

Laser evoked potentials
Laser evoked potentials (LEPs) are used to measure cortical responses to selectively stimulate thermonociceptors in the skin. Lasers can emit a radiant-heat pulse stimulus to selectively activate A-delta and C free nerve endings. It specifically targets the pain and temperature pathways and measuring cortical responses, doctors can identify even minute lesions in the spinothalamic pathways. LEP abnormalities are strongly indicative of neuropathic pain, while a normal LEP is often more ambiguous. LEPs have high sensitivity and are very reliable in assessing damage to both central and peripheral nervous systems.

Punch skin biopsy
Recently, skin biopsy has also been used to investigate mechanoreceptors and their myelinated afferents. Though available in only a few research centers, skin punch biopsy is an easy procedure and is minimally invasive. Punch skin biopsy is used to quantify nerve fibers C fibers and A-delta nerve fibers through measurement of the density of intra-epidermal nerve fibers (IENF). Loss of IENF has been observed in several cases of neuropathic pain.

Management:

Treatment include both medicines and surgery,
Anticonvulsant medicines: They are used to block nerve pathways and tricyclic antidepressants are generally effective in treating neuralgia.

Surgery: Neural augmentative surgery is used to stimulate the affected nerve. Electrodes are carefully placed in the dorsal root and subcutaneous nerve stimulation is used to stimulate the targeted nerve pathway.

References:
www.ncbi.nlm.nih.gov
www.ninds.nih.gov
www.nlm.nih.gov
www.nhs.uk