Overview on pathophysiology and newer approaches to treatment of peripheral neuropathies.

Peripheral neuropathies are extremely heterogeneous nosological entities. One of the most common symptoms is pain, the underlying mechanisms of which are numerous and complex. Inflammation, reparative processes, and anatomical and gene expression alterations lead to chronic pain, the persistence of which is sustained by peripheral and central sensitisation mechanisms. Treatment of peripheral neuropathies is targeted to its symptomatic and aetiological features. For pain relief, several types of drugs may be used, notably antidepressants (e.g. tricyclic antidepressants, selective serotonin reuptake inhibitors, and both serotonin and noradrenaline [norepinephrine] reuptake inhibitors), antiepileptic drugs (e.g. carbamazepine, phenytoin, lamotrigine, valproic acid, gabapentin, topiramate and pregabalin), NSAIDs and opioid analgesics. Aetiological therapy is aimed at modifying the pathophysiological mechanisms underlying the neuropathy, some of which are common in different neuropathic conditions. Certain drugs are known to exert more than one action on different pathophysiological mechanisms. This is the case with acetyl-L-carnitine (ALC), which can be considered both a symptomatic therapy that can be used in any kind of painful neuropathy, and an aetiological therapy, at least in diabetic neuropathy and neuropathies induced by nucleoside reverse transcriptase inhibitors and cancer chemotherapeutic agents. ALC acts via several mechanisms, inducing regeneration of injured nerve fibres, reducing oxidative stress, supporting DNA synthesis in mitochondria, and enhancing nerve growth factor concentrations in neurons.