Neuropathic Pain

Introduction

There is absolutely no doubt that one of the miracles of the modern science is the ability to identify study and combat diseases that would have left scientists and doctors of the past century completely baffled. Such is the beauty of modern medical science.

If the human body were to be categorized as Organ systems, there would be about 11 main systems including circulatory, immune, muscle, respiratory etc. And while all these are vital for the normal function of our bodies, the nervous system is undisputedly the most complex and crucial component. From head to toe and right to left, we have nerves of all sizes running around the body, carrying "messages" to and from the brain to all organs. The slightest damage to any part of this system can have devastating impact on the individual, both physically and mentally. One such medical condition is neuropathic pain, which as the name suggests, is a disorder caused by a malfunctioning or damaged nervous system.

Pain - what, when and how?

What we perceive as pain is actually a series of "messages" sent from the pain receptors in our skin. For example, when you fall off your bike and bruise your arm; the sensory receptors in your skin at the location of injury send signals using the nerve fibers as channels to the brainstem and all the way to the thalamus, a part of the brain which directs it further to different areas of the brain for interpretation. After the brain decodes the signal as something that is hurting you, the signal is moved to the limbic system, the emotional system of the brain, and finally you feel the pain and irritation. All of this in a fraction of a second - talk about miracles.

Neuropathic pain - The Definition

What if this absolutely breath-taking sequence of events described above was to malfunction? In some cases you wouldn't feel the pain, that is, when the pain receptors are dead. And in other cases you feel pain when there is no apparent reason for the pain. The latter is generally referred to as neuropathic pain - Pain caused by damaged or oversensitive nerve endings, where the sensory receptors get triggered without an input, and the brain gets tricked into believing that you are experiencing pain.

Discovery

Although, modern sciences has been able to dissect this disorder using resources available today and study it to the depth as never done before, neuropathic pain has been recorded and studied by scholars as old as the medieval period. The medical experts of the time such as Rhazes, Ibn-e-Seena and Ali Abbas named it as "vaja al asab", which literally translates to nerve originating pain. Decades later, in the 18th century, another scientist by the name John Fothergill also studied this condition. However, the term 'neuropathy' was first published in a medical article called "Clinical Lecture on Neuropathy" by a medical scholar named Gordon in 1924.

Causes:

While no obvious cause can be associated with neuropathic pain, there are several medical conditions and habits that can contribute greatly towards initiating this disorder or worsening an existing case of neuropathic pain. Some of the most common causes are mentioned below:

• Alcoholism: Who says alcohol isn't good, a little every now and then can lighten up the mood and relax you. But as too much of everything is harmful, excessive alcohol consumption can result in alcoholic neuropathy. This is a condition where the nerves responsible for the communication between the brain and the rest of the body, limbs in particular, get damaged due to the unbalance of nutrients such as thiamine, niacin, and several other vitamins. Severe excess of alcohol in the system is responsible for these alterations, so the next time anyone says, "Alcohol is toxic for your nerves", please take it seriously! The nerve damage in this case can result in tingling feeling in the body, or numbness in the limbs. And even though some of the nerve damage is permanent in alcoholic neuropathic patients, reforms in the lifestyle such as quitting drinking and healthy eating can restore most of the nutritional health and reduce the symptoms.
• Drug abuse: Most of the younger generation now-a-days is familiar with several drugs. The experiences they relate to the drug use such as relaxation, feeling happy, out-of-the-world experiences and so on, are usually interesting to hear. What is more interesting is that the users seldom think about the mechanism in which these drugs drag them away from reality into a realm where they can escape their problems, worries and stress. Putting it in simplest terms, drugs either activate certain areas of the brain responsible for pleasure, such as THC in marijuana, or they simply trick the brain by altering the chemical composition, which can also lead to the brain into confusing signals from all over the body with signals from the pain receptors.
• Amputation: is one of the oldest surgical methods employed by doctors in extreme cases. Despite the medical advancements, this is a very painful procedure and can result in nociceptive pain due to bone and tissue damage and neuropathic pain due to severe neural trauma. The nerve cells and pain receptors at the point of amputation can get so traumatized that even after the procedure is complete they keep sending signals to the brain which interprets the incoming signals as pain from the limb that is actually not present. This phenomenon is referred to as the Phantom limb.
• Chemotherapy: Chemotherapy-induced-peripheral-neuropathy (CIPN) is another common cause of neuropathic pain in cancer survivors. The anti-cancer drugs used during chemo can affect the sensory, motor and other parts of the nervous systems. The symptoms can be observed at any stage and can become severe as CIPN progresses. It usually is misdiagnosed due to lack of study and research on the topic. The patients can have a tingling feeling across the body and it could become as severe as highly intense burning sensation. This has been observed to originate at feet first and then up the body in most cases.
• Diabetes: Diabetic patients are often diagnosed with a more aggressive form of neuropathic condition, referred to as polyneuropathy, where the nervous system at multiple locations in the body malfunctions simultaneously. It is well-known that diabetic patients can suffer from numb limbs and in some cases it results in amputation. Excess sugar in the body can easily damage nerves. However, controlling the sugar levels and strict diets can help reduce the symptoms and the associated pain.
• Nerve compression: Nerves can become compressed due to several reasons such as a herniated disc etc and can lead to neuropathic pain. If the affected nerves are confined to a small area, a decompression surgery can help relieve the pressure; however, this is not possible if the affected nerves cover a wider area.
• Injury to a nerve: is also a common cause for neuropathic pain. Injury here relates to the damage caused by a sudden impact. In such cases, the nerve usually heals itself and begins normal function after it heals.

Other common causes may include facial nerve issues, infections such as HIV or AIDS, spine surgery, hormonal imbalance, exposure to toxic material, brain strokes, immune system disorders and vitamin deficiencies.

Symptoms:

The most common symptoms associated with neuropathic pain are:

1. Numbness in the limbs, especially the extremities.
2. Unexplained tingling feeling over the body usually in patches
3. Rapid movement of pain from one location to another, usually referred to as shooting pain
4. Burning sensation of different intensities.
5. Persistent and ongoing pain without obvious reason

Diagnosis:

Since patients suffering from neuropathic pain usually refer to primary healthcare professionals, it is not immediately diagnosed.

The initial and most basic diagnosis is done during an interview where the doctor focuses on the terminology used by patients to describe the symptoms. If patients describe their pain as unexplained, or if the doctor cannot identify a cause, he or she reviews the patient's medical history to identify a cause. This includes everything from medical records to lifestyles to family history. To understand more about the case neurological exams may be used to examine reflexes, posture, muscle strength and coordination.

Other tests used to diagnose neuropathic pain include:

• Blood tests to examine levels of nutrients, sugar, vitamins, red blood cells (RBCs) and white blood cells (WBCs) in the body
• CT and MRT can be used to look for abnormalities such as herniated discs etc.
• Nerve conduction studies where an electrical probe is used to send a signal to the nerve and a receiver is used to study the nerve response along the pathway
• Nerve function tests - These tests will examine the response from the pain receptors under different conditions such as varying pressure and temperature, vibrations and basic touch inputs.
• Nerve and skin biopsy - where a small portion of either the skin or the nerve is removed for analysis and the purpose is to identify any physical abnormalities.

These precise sensory tests are usually enough to reach a diagnosis. For further study, techniques like quantitative sensory testing and laser evoked potentials are also employed in the assessments.

Treatment:

Pain Management is a vast topic, both in practice and research. It is beyond doubt, that neuropathic pain can have adverse effects on the patient's standard of living, and can cause severe stress and anxiety making everyday tasks very difficult. Several anti-depressants are prescribed to the patients. In cases where the cause of neuropathic pain cannot be identified or reversed, medical treatments and pain killers are used to allow the gradual and usually slow healing of the damaged nerves. If the pain is not addressed adequately and timely, the pain management is more tedious and requires equally aggressive treatment.

Since, there is no particular and definite treatment for neuropathic pain, the doctors target the symptoms and work their way into relieving the symptoms and also aim at restoring the patient's daily life. It is important to note that like several other medical conditions, if the treatment is received at an earlier stage, the results are more promising than if it is delayed. Nerve damage is difficult to reverse completely and hence the process of rehabilitation is a slow and steady one.

Some medical drugs are prescribed for such patients to help them cope with the symptoms. These include:

1. Pain relievers: Anti-inflammatory creams and medications can be prescribed by the doctor to ease the pain, however if the pain persists, stronger pain-killers may also be used.
2. Anti-seizure medications: Medications used to treat nerve related problems may be used to relieve nerve pain.
3. Topical treatments: Specialized creams can be used to soothe the pain. The side effects may include burning sensations which can disappear over time.
4. Antidepressants: have proven to be useful when dealing with neuropathic pain just like they work in anxiety and stress related cases. These medicines chemically treat the brain to reduce the pain signals being sent.
5. Besides medication, therapies can also be employed to deliver results in some cases.

Conclusion:

Neural damage and the accompanying neuropathic pain can be very testing for the patients and their families. While scientists, researchers and doctors do their best to stay ahead of diseases and medical conditions, there is a lot to be done in this field. Several institutions around the world are working endlessly towards understanding this condition. Till a definite treatment is developed, patients can do more for themselves than they know. Improving their diets, refraining from alcohol or drug abuse, getting adequate sleep, exercising etc have proven to be very useful when combating neuropathic pain. Moreover, as mentioned earlier, these conditions only worsen with time if not treated properly, so anyone who has the slightest of symptoms should consult with a doctor. It is always better to be safe than sorry.