by Sanjay Trivedi, M.D.
The term “neuropathic pain” is most often reserved for patients who have had the chronic pain for at least three months; pain characterized by sharp, knife-like, electric, jolting, burning, shooting and tingling sensations.
In reality, these sensations are reported by patients who have experienced tissue injury, as with acute herniated disc or severance of a peripheral nerve in an injury or accident.
If the tissue injury is fresh, the inflammatory cascade leads to an increase of neuronal channels and receptors, and causes increased excitability of the neurons. If the inflammation leads to proper healing of the nerve and surrounding tissue, then the pain gradually resolves. But if the inflammatory changes do not decrease, but instead continue to irritate the surrounding tissue, and if the receptors and neuronal channels do not heal, the nerves spontaneously maintain level of excitability and firing threshold. Physicians would then see hyperalgesia, allodynia, and typical neuropathic pain.
While treating the acute injury, the physician needs to recognize the presence of nerve injury. Physicians often use non-steroidal anti-inflammatory (NSAIDS) for treatment of acute tissue injuries to reduce the negative impact of inflammatory cascade. This is a logical choice for treatment as it will provide some control over the inflammation and in return give some pain relief.
The other option chosen for treatment of acute pain is Opioids, which can be effective in reducing pain arising from acute nerve injury. This is some what because the opioid receptors are sensitized at tissue injury to a lower response threshold. Opioids are commonly not thought to be effective in chronic neuropathic pain, but can be effective in acute nerve-related injury pain due to hyper responsiveness of the opioids receptor in an acutely injured state.
Other medications employed for neuropathic pain are Gabapentin and Pregabalin, which affect the Sodium channels. They have been used with varying degrees of response in acute and chronic neuropathic pain.
Lidocaine is an amide of local anesthetic class. The local anesthetic is a Sodium channel blocker and, for decades, has shown to have pain–relieving properties. Lidocaine can be used locally (topically or injectable) or systemically. The literature supports the use of Lidocaine as a local and systemic agent for pain reduction and relief. There is some literature to support Lidocaine’s effectiveness as an anti-inflammatory agent.
Lidocaine has been proven to reduce the neuronal transmission of pain signal by blocking sodium channel in at least the acute but also possibly chronic pain states. It is also believed to serve as an anti-inflammatory agent, which effectively helps in reducing pain transmission.
See related article: Myofascial Pain (Muscular) Explained
Don H. Bivins MD. “Neuropathic Pain, Inflamation and our Friend Lidocaine.”
Cassuto J. Sinclair, et al. “Anti–Inflamatory properties of local anesthetics and their potential clinical implications.”