Neuropathic pain

The symptoms of neuropathic pain mostly start appearing after a long period of injury, which may take several months to years. Initially, a person may experience pain in their digits, which can progress to the limbs.

The pain may be mild or severe but is often worse at night. The symptoms may persist even beyond the healing period.

• Spontaneous pain: This refers to shooting, burning, stabbing, or electric shock-like pain, usually in the arms and legs. It feels like someone has pricked the skin with a needle.
• Evoked pain (allodynia): Defined as pain due to a stimulus that does not normally provoke pain. Pain is experienced during normal activities such as gentle touch on the skin, buttoning a shirt, touching a cold surface, and brushing teeth.
• Hyperalgesia: This refers to increased sensitivity to pain, where the brain of individuals with hyperalgesia overreacts to normal painful triggers such as pinpricks and heat.
• Hypoalgesia: In some cases, a person may have decreased sensitivity to pain for normal painful triggers.
• Loss of sensations: This can occur in a part of the body.

Other symptoms include:

• Trouble sleeping
• Emotional problems
• Changes in sensation
• Weakness
• Muscle wasting (decrease in size of a body part or tissue)

Neuropathic pain interferes with normal activities such as sleep, exercise, and sex. It can lead to emotional problems such as:

• Mood swings
• Anxiety
• Depression

Here are 8 natural ways to fight depression.

Before understanding the cause of neuropathic pain, it is important to know the concept of neurons and the mechanism of pain.

What are neurons?

• Neurons are nerve cells that send messages all over the body.
• They receive sensory input from the external world and send motor commands to our muscles after processing in the brain.
• There are approximately 86 billion neurons present in the human brain.
• Neurons play a significant role in the perception of pain.

Mechanism of pain

• Any painful stimulus such as pressure, pinch, heat, chemicals, or burns activates pain receptors (nociceptive receptors) that are widely distributed in the skin and deep tissues.
• These pain receptors send signals to the brainstem (the lower part of the brain) via first-order neurons.
• A release of calcium in the brainstem leads to the release of a chemical called glutamate.
• The released glutamate binds to specific receptors on the second-order neurons.
• These neurons then cross over in the spinal cord and reach the cerebral cortex (the part of the brain involved in the sensation of pain).

Note: An inhibitory pathway is also present in the brainstem, which travels down the spinal cord. This pathway contains several connecting neurons that release chemicals such as serotonin, noradrenaline, and gamma-aminobutyric acid (GABA) to mitigate the feeling of pain. Pain cessation results from the dominance of inhibitory pathways, whereas pain enhancement occurs due to the stimulatory pathways activated by painful stimuli.

How does neuropathic pain originate?

There are multiple theories behind neuropathic pain. Although the exact mechanism is not clear, neuropathic pain may arise due to:

• Increased activity of first-order neurons if they are partially damaged.
• Impairment of the inhibitory pathway.
• Development of a memory of pain in the second and third-order neurons due to alterations in the central processing of pain.
• Increased sensitivity of neurons.
• Reduced activation threshold of neurons.

Several risk factors contribute to the development of neuropathic pain. These factors can increase the likelihood of experiencing neuropathic pain or exacerbating existing pain. Some common risk factors include:

1. Brain injury
   • Stroke
   • Spinal cord injuries
   • Trigeminal neuralgia
2. Nutritional deficiencies

   Various vitamins play a crucial role in maintaining the overall health of neurons. Deficiencies in Vitamin B1, B6, B12, and E can increase the risk of neuropathic pain.

3. Inflammatory conditions

   People with inflammatory conditions such as vasculitis (inflammation of the blood vessels) are more prone to developing neuropathic pain.

4. Autoimmune conditions

   Autoimmune diseases refer to a group of diseases in which the immune system attacks the body. Some autoimmune diseases, such as Guillain-Barré syndrome, Sjögren’s syndrome, lupus, and rheumatoid arthritis, increase the risk of neuropathic pain.

5. Diabetes

   Diabetes increases the risk of neuropathic pain several fold. Approximately 50% of patients with diabetes develop neuropathic pain.

6. Infections

   Some infections, such as Lyme disease, Epstein-Barr virus, Hepatitis C, shingles, leprosy, and HIV, are associated with neuropathic pain.

7. Toxins

   Exposure to certain chemicals, such as lead, mercury, arsenic, and thallium, can predispose individuals to neuropathic pain.

8. Amputation

   Amputation, which refers to the removal of any body part, is associated with an increased risk of pain within the first week after the procedure.

9. Alcoholism

   Chronic alcoholism increases the risk of neuropathy either through a direct toxic effect on neurons or through malnutrition.

10. Certain medications

    Long-term use of the following medications may be associated with neuropathic pain:

    • Amiodarone
    • Hydralazine
    • Cisplatin
    • Docetaxel
    • Paclitaxel
    • Vincristine
    • Chloroquine
    • Dapsone
    • Isoniazid (INH)
    • Metronidazole
11. Tumors

    Some tumors can press on the peripheral nerves in the body, increasing the risk of peripheral neuropathy.

There can be multiple causes of neuropathic pain. It is very important to uncover the primary cause. The diagnosis involves understanding the medical history. The doctor may also inquire about:

• Exposure to toxins
• Medications
• Trauma
• Nutritional deficiencies
• Consumption of alcohol

There are no standard tests to diagnose neuropathy. However, the following tests may aid in diagnosis:

1. Quantitative sensory testing (QST)

   In this test, individuals are given stimuli to induce pain. The stimuli are provided in ascending and descending orders of magnitude. QST measures the perception of mechanical, thermal, and painful stimuli. It is useful for assessing allodynia and hyperalgesia. This technique does not diagnose other conditions with similar sensory abnormalities as neuropathic pain.

2. Nerve conduction study (NCS)

   In this test, two electrodes are placed on the skin. One electrode stimulates the nerve while the other records the time taken by the muscle to contract in response to the electrical pulse.

3. Skin biopsy

   This involves the examination of a small sample of skin tissue under a microscope. It helps detect nerve degeneration or the presence of lesions under the skin as a possible cause of neuropathic pain.

4. Other tests

   Some other tests are performed to determine other disorders with similar symptoms or to diagnose the exact cause of neuropathic pain. These include:

   • Complete blood count
   • Glycosylated hemoglobin (HbA1c)
   • Vitamin and mineral levels (copper, thiamine, pyridoxine, folate, Vitamin B12, and Vitamin E)
   • Metal levels (mercury, lead, and arsenic)
   • Infectious disease tests (Lyme disease, Epstein-Barr virus, HIV, and syphilis)
   • Antibody testing for specific autoimmune diseases known to cause peripheral neuropathies such as Sjögren syndrome, lupus, and rheumatoid arthritis
   • MRI or CT scans in cases where nerve compression is a concern
   • Nerve biopsy
   • Genetic testing (for inherited neuropathies)
   • Urine test

1. Manage underlying conditions

Almost all cases of neuropathic pain are associated with some disease. The best way to prevent neuropathic pain is to manage any underlying conditions.

2. Keep a check on your diet

A wholesome, well-balanced diet that includes carbohydrates, good fats, protein, vitamins, and minerals is essential for preventing any disease. Vitamin B12 is a key component of neurons. Ensure to consume rich sources of Vitamin B12 such as meats, fish, eggs, low-fat dairy products, and fortified cereals.

3. Exercise regularly

Engage in at least 30 minutes to one hour of exercise at least three times a week.

4. Avoid triggers

Avoid risk factors such as exposure to toxic chemicals, smoking, and alcohol consumption, as these can trigger nerve damage that may lead to neuropathic pain.

Tips to prevent or delay neuropathic pain in diabetes

Neuropathic pain is a prominent complication of diabetes, with nearly half of the diabetic population developing neuropathic pain over time. The best way to prevent or delay this complication is to keep blood sugar levels in check. This can be achieved by:

• Indulging in regular physical activity
• Losing weight if you’re overweight
• Limiting or avoiding alcohol
• Quitting smoking
• Following a well-guided healthy diet plan
• Avoiding late-night meals
• Adhering to the medications as prescribed by your doctor

Drug and non-drug therapies are usually used in combination for the management of neuropathic pain.

I. Treatment considerations

1. The treatment usually focuses on the underlying disease such as:
   • Glucose control in diabetic neuropathy
   • Cessation of alcohol in alcoholic neuropathy
   • Supplementation in vitamin and mineral deficiencies
2. Chronic neuropathic pain is usually treated using corticosteroids.
3. Neuropathic pain that develops due to small-fiber neuropathies does not typically respond to pain relief medications. Such severe pain requires the use of certain anti-epileptics and tricyclic antidepressants.

II. Pharmacological (drug) therapy

It includes the following classes of drugs:

1. Antidepressants: They are effective against steady burning and aching pain. Common examples include:
   • Tricyclic antidepressants (TCAs): Amitriptyline, imipramine, nortriptyline, and doxepin
   • Selective serotonin reuptake inhibitors (SSRIs): Fluoxetine, paroxetine, sertraline, and citalopram
   • Serotonin-norepinephrine reuptake inhibitors (SNRIs): Venlafaxine
2. Anti-epileptic drugs: These drugs enhance the effect of inhibitory chemicals such as GABA. Common examples are carbamazepine and gabapentin.
3. Opioid analgesics: These drugs decrease pain impulses from the brain. Oxycodone is the most commonly used opioid for relieving neuropathic pain.
4. Local anesthetics: They work by desensitizing the affected area. The 5% lidocaine patch is used for post-herpetic neuralgia.

III. Other treatment modalities

In cases of chronic neuropathic pain that have failed to respond to conservative medical management, the following approaches are considered:

• Epidural injections (injections into the space around the spinal nerves in your lower back) of local anesthetics and corticosteroids
• Implantation of epidural and intrathecal drug delivery systems
• Insertion of spinal cord stimulators
• Local nerve blocks

Here are some general tips that might help manage neuropathic pain at home:

1. Consume a diet rich in Vitamin B
   It is essential to add vitamin B rich foods to your diet, including eggs, milk, and other dairy products.
2. Use hot and cold compresses
   Hot and cold compresses are an effective therapy for neuropathic pain. A warm compress over the painful area helps relieve pain by increasing blood flow. It also reduces muscle stiffness and spasms. A cold compress is helpful in subsiding the pain by reducing swelling.
3. Soak in warm water and Epsom salt
   Severe neuropathic pain, especially in the feet, can be managed to a great extent by soaking the feet in Epsom salt and warm water. This can help ease pain and discomfort. The magnesium sulfate in the salt helps reduce inflammation and promote healing. One can also try a few home remedies that can act as adjuncts to conventional treatment. However, if the nerve pain is severe, one shouldn't rely solely on home remedies and should consult a doctor. It is also advisable to seek advice from a healthcare provider before initiating any of these remedies.
4. Turmeric (haldi)
   The anti-inflammatory properties of turmeric help ease nerve pain. You can consume it raw, cooked, with milk, or as a supplement.
5. Apple cider vinegar
   Apple cider vinegar is loaded with magnesium, phosphorus, calcium, potassium, and anti-inflammatory properties that can augment relief from nerve pain. It can be consumed by adding 1-2 tablespoons of apple cider vinegar to a glass of warm water.

The chronic ongoing neuropathic pain can lead to serious complications:

• Injuries: The loss of sensations increases the chances of injuries and wounds due to a lack of pain perception.
• Gangrene: Untreated infected wounds can lead to gangrene, which is the death of tissue due to reduced blood supply. In rare cases, this may necessitate amputation to prevent the infection from spreading.
• Loss of bladder control: Neuropathy can cause involuntary urination due to loss of sensation in the bladder. Diabetic neuropathy is the most common cause, but it is also observed in individuals with Guillain-Barré syndrome and HIV infection.
• Disturbed sleep: The constant pain hampers the quality of sleep in most individuals with neuropathic pain.
• Anxiety and depression: Many people with neuropathic pain experience mood swings, anxiety, and depression due to the chronic nature of the condition.

Many patients with neuropathic pain pursue complementary and alternative treatments that include:

• Acupuncture: Acupuncture is the practice of penetrating the skin with thin needles. These needles are then activated through gentle and specific movements of the practitioner's hands or with electrical stimulation. The technique might release chemicals that numb pain or block the pain signals sent from the nerves.
• Percutaneous electrical nerve stimulation: In this method, nerves are stimulated through electrodes placed under the skin, causing muscle contractions that help relieve pain. Another technique called transcutaneous electrical nerve stimulation involves placing electrodes on the skin.
• Physical therapy (physiotherapy): Nerve damage can lead to muscle weakness and wasting. Physiotherapy helps improve muscle tone, balance, and coordination. It includes guided movements, massages, and the application of stimuli such as heat, cold, and electrical currents.
• Occupational therapy: This therapy is recommended for individuals who have trouble coordinating normal physical movements, such as walking up or down stairs, kicking balls, or jumping.
• Massage: Massage provides symptomatic relief by increasing blood flow and releasing knots of muscle tension, which helps reduce overall pain.
• Graded motor imagery: This involves various innovative exercises and movements to target neuropathic pain.
• Cognitive behavioral therapy: Cognitive behavioral therapy (CBT) is a talking therapy that helps individuals cope better with the emotional symptoms of severe neuropathic pain.

The following measures help in managing the pain:

1. Indulge in exercise: Individuals with neuropathic pain should engage in regular exercise. Stretching and yoga are effective in increasing muscle flexibility and reducing pain severity.
2. Use compression socks: Individuals with neuropathic pain in the feet should wear compression socks. They help reduce swelling, inflammation, and overall pain.
3. Take adequate rest: People should take regular breaks from activities such as walking and standing. Adequate rest aids in faster nerve repair.
4. Avoid alcohol: Individuals with neuropathic pain should avoid alcohol, as it may hinder recovery. Alcohol negatively affects the absorption of vital vitamins and minerals necessary for normal nerve function.
5. Managing emotional stress: Living with neuropathic pain can lead to feelings of hopelessness, anger, or depression. People may withdraw from social interactions and stop engaging in enjoyable activities. The following measures may help manage emotional distress:
   • Surround yourself with supportive friends and family.
   • Engage in activities you love that bring you happiness.
   • Explore mentally stimulating activities, such as reading or puzzles.
   • Communicate openly with those around you.