by What is it?
Neuropathic pain is an umbrella term used to describe various painful conditions caused by damage or disease of the somatosensory nervous system. This includes the peripheral sensory neurons that transmit signals from all over the body to the spinal cord and brain. Nerve pain arises due to abnormal signals being sent from injured or malfunctioning sensory nerves in the peripheral and central nervous systems. Some common examples of nerve pain include postherpetic neuralgia, diabetic neuropathy, trigeminal neuralgia, and pain from traumatic nerve injury or nerve compression.
Causes of Nerve Pain
There are several underlying causes that can lead to nerve pain:
– Nerve damage from physical injury or trauma to the limbs, back or other parts of the body. This includes injuries from accidents, surgery, pressure damage of nerves.
– Metabolic and infectious diseases that can damage peripheral nerves like diabetes, shingles, HIV/AIDS, leprosy and vitamin deficiencies.
– Compression of nerves due to tumors, bones, or herniated disks putting pressure on nerve roots in the spine.
– Toxic neuropathies caused by chemotherapeutic agents, alcohol abuse or exposure to toxins like heavy metals.
– Genetic conditions like Friedreich’s ataxia that mainly affect the peripheral nervous system.
– Central neuropathies due to strokes that damage pain-processing areas of the brain and spinal cord.
– Idiopathic causes where the underlying reason for pain is unknown.
Pathophysiology of Neuropathic Pain
The pathophysiology of nerve pain involves changes that take place at molecular, cellular and neural circuit levels in both the peripheral and central nervous systems due to the original nerve injury or other causes. Some key things that occur include:
– Spontaneous nerve fiber activity – Neuropathic Pain Damaged nerves may fire impulses independent of stimulation leading to persistent pain even without stimulation.
– Ectopic nerve sprouting – Nerves grow new branches in locations like the dorsal root ganglia where they shouldn’t, forming new connections that allow stimuli to trigger pain.
– Changes in ion channels – Expression levels of sodium and other ions channels are altered at the site of nerve injury, reducing excitation threshold and making them more easily stimulated.
– Glial cell activation – Microglia and astrocytes in the spinal cord and brain are activated, contributing to central sensitization by releasing pro-inflammatory cytokines.
– Loss of inhibitory control – The balance between excitatory and inhibitory control of pain signaling in the spinal cord and brain is disrupted after nerve damage, reducing the ability to modulate pain.
Symptoms of Neuropathic Pain
Nerve pain tends to have some distinct symptoms that help distinguish it from other pain types:
– Spontaneous ongoing pain – Occurring without any apparent stimulus or cause. Commonly described as burning, shooting electrical-like sensations.
– Hyperalgesia – Non-painful stimulation like brushing of skin causes a pain response that is exaggerated and disproportionate to the stimulus.
– Allodynia – Pain that results from a stimulus which would not normally provoke pain like light touch. Things like bedsheets can cause burning pain.
– Pain in unusual or non-dermatomal patterns – Affected areas may not necessarily follow patterns of specific nerve distributions.
– Paroxysmal pain – Brief, episodic shooting or electric shock-like pains that can occur spontaneously or be triggered.
– Pains evoked by stimuli such as brushing, pressure or cold – Normally innocuous actions elicit pain.
Diagnosis and Treatment of Nerve Pain
There is no single test to definitively diagnose nerve pain, so doctors employ a set of diagnostic tools to evaluate potential causes and mechanisms:
– Physical examination focusing on neurological function and areas of sensitivity or allodynia/hyperalgesia.
– Imaging tests like MRI, CT and sometimes nerve conduction studies to look for structural problems pressing on nerves.
– Sensory testing using methods like pinprick, vibration and temperature sensation evaluation.
– Blood tests for causes like diabetes, vitamin deficiencies, infectious diseases.
– Skin biopsy in some cases to directly examine small nerve fibers.
Treatment involves addressing the underlying cause if possible, along with medications, nerve blockade techniques, transcutaneous electric nerve stimulation, cognitive behavioral therapy and other approaches. Drugs commonly used include anticonvulsants, antidepressants and topical lidocaine. Multidisciplinary care is often needed for difficult nerve pain.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
