drug delivery Intrathecal pumps deliver medication to the fluid filled (subarachnoid) space surrounding the spinal cord. Opioids alone or opioids with adjunctive medication (either a local anesthetic or clonidine). Rarely there are complications such as serious infection (meningitis), urinary retention, hormonal disturbance and intrathecal granuloma formation have been noted with intrathecal infusion, associated with the delivery method. Conotoxins Ziconotide is a voltage-gated calcium channel blocker which may be used in severe cases of ongoing neuropathic pain it is delivered intrathecally. Ambroxol Ambroxol is a drug that reduces mucus. Preclinical research suggests it may produce analgesic effects by blocking sodium channels in sensory neurons. Gene therapy The use of gene therapy is a potential treatment for chronic neuropathic pain. In animals a gene therapy for local transgenes encoding for GABA synthesizing-releasing inhibitory machinery has been demonstrated and was effective for months at a time. It increases synaptically GABA-mediated neuronal inhibition in the spinal cord (or in the brain) via the induced expression of genes GAD65 and VGAT without any detected systemic or segmental side effects. Topical agents In some forms of neuropathy the topical application of local anesthetics such as lidocaine may provide relief. A transdermal patch containing lidocaine is available commercially in some countries. Repeated topical applications of capsaicin are followed by a prolonged period of reduced skin sensibility referred to as desensitization, or nociceptor inactivation. Capsaicin causes reversible degeneration of epidermal nerve fibers. Notably the capsaicin used for the relief of neuropathic pain is a substantially higher concentration than capsaicin creams available over the counter, there is no evidence that over the counter capsaicin cream can improve neuropathic pain and topical capsaicin can itself induce pain. Surgical Interventions Orthopaedic interventions are frequently used to correct underlying pathology which may contribute to neuropathic pain. Many orthopaedic procedures have more limited evidence. Historically, neurosurgeons have attempted lesions of regions of the brain, spinal cord and peripheral nervous system. Whilst they cause some short term analgesia, these are considered to be universally ineffective. Alternative therapies Herbal products There is no good evidence that herbal products (nutmeg or St John's wort) are useful for treating neuropathic pain. Dietary supplements A 2007 review of studies found that injected (parenteral) administration of alpha lipoic acid (ALA) was found to reduce the various symptoms of peripheral diabetic neuropathy. While some studies on orally administered ALA had suggested a reduction in both the positive symptoms of diabetic