Mangaluru : Neuralgia is literally pain in the nerves. It is not a disease by itself but be a symptom of an underlying illness. It can affect people of any age group. There are several sites in the body where neuralgia is common. Neuralgic pain can be experienced as short lasting bouts of shock like pain.
Trigeminal Neuralgia (Tic doloureux)-This is the commonest type of neuralgia. Pain in the trigeminal nerve (nerve which carries sensation from the face) is termed as trigeminal neuralgia. It affects one sided of the face, usually affects the forehead, cheek or lower part of the face. Pain may be triggered by brushing teeth, shaving, washing face, speaking, chewing. Pain lasts for few seconds or minutes. It is usually described as shock like sensation in the face. It is sometimes accompanied by twitching or tics during the attacks hence the name. It is usually due to an abnormal blood vessel compressing on the trigeminal nerve inside the brain. It may also be due to trauma. MRI is required to look for any abnormal blood vessel compressing on the trigeminal nerve.
There are multiple options to treat trigeminal neuralgia. Medical options include anticonvulsants like Carbamazepine, Oxcarbazepine. Pain which is resistant to medicines may be offered surgical options or Botox injection. Surgical options include microvascular decompression (Decompressing the nerve from the aberrant blood vessel), percutaneous glycerol rhizotomy (glycerol is injected into trigeminal cistern effectively reducing the function of the nerve thereby also pain, radiofrequency themocoagulation. Botox injection is a neurotoxin which paralyses the muscles. It relieves pain in trigeminal neuralgia by resolving muscle trigger points.
Post Herpetic neuralgia-Post herpetic neuralgia is a complication of Chicken pox virus (Herpes). Reactivation of Varicella Zoster virus because of aging or immunosuppression leads to Herpes Zoster. In this condition blisters appear in one dermatome (skin supplied by a specific nerve root). After the blisters disappear patients experience pain in the dermatome which is shock like. Common sites are the chest and the face. It is usually limited to a dermatome and doesn’t cross the midline. It can be mistaken for insect bites, fungal infection or drug eruptions. Virus can be isolated from a smear taken from the blisters.
Treatment includes antivirals, topical agents, anticonvulsants, opioids. Antivirals are given during the acute stage when the patient develops blisters or vesicles. Antivirals used are Acyclovir, Gancyclovir, Famcyclovir Pain is treated with anticonvulsants like Carbamazepine, Oxcarbazepine, Gabapentin, Pregabalin. Topical agents (Medicines which are applied on the skin directly) like Lidocaine, Capsaicin are also used. Opioids are used in pain which is resistant.
Glossophayngeal neuralgia- This is a relatively rare condition where the episodic pain is felt in the tongue, throat, ear, tonsils. Pain is paroxysmal lasting from a fraction of a second to 2 minutes. It is one sided affecting the back of the tongue, throat, jaw or ear. It is sharp, stabbing and severe and precipitated by swallowing, talking, chewing, coughing. Most are idiopathic (with no known cause). It may be associated with tumors in the base of the brain (cerebellopontine angle tumors), oropharyngeal tumors, vascular malformations. Treatment includes medications used in other neuralgias. Glossopharyngeal nerve blocks can be used in the treatment of glossopharyngeal neuralgia especially those caused by pharyngeal cancer. Surgical treatment like rhizotomy, direct section of the trigeminal nerve.
Neuralgia due to peripheral neuropathy -Neuropathy is a condition caused by damage of the peripheral nerves. It can be due to various reasons like diabetes, kidney disease, chemotherapy. Neuropathy can present with weakness of the extremities, loss of sensation or numbness, cramps. Neuralgic pain can be seen in a subset of patients. Small fibre neuropathy is a neuropathy affecting small nerve fibres which sub serve pain. It can be seen in various medical conditions common being Amyloidosis and Diabetes. Alcohol itself can produce small fibre neuropathy which presents with burning sensation in the feet. Neuropathy affecting plexus (branching network of nerves) can present with weakness and pain in the upper or lower limbs depending on site of affection. Neuralgic amyotrophy also known as Parsonage Turner Syndrome affects the brachial or upper limb plexus. It presents with pain and weakness around the shoulders. Treatment includes steroids, anticonvulsants and antidepressants.
To summarize neuralgia is a symptom of an underlying disease rather than a disease by itself. Timely diagnosis and appropriate treatment can alleviate the pain and helps to lead a normal life.