[Pathophysiologic basis of the treatment of neurogenic pain].
According to the International Association for the Study of Pain (IASP) neuropathic pain is "pain initiated or caused by a primary lesion or dysfunction or transitory perturbation in the peripheral or central nervous system". Neuropathic pain is usually classified according to the etiology, location of the lesion, and pain characteristics--individual symptoms and signs, but also according to the possible mechanisms involved. Identifying the underlying pain mechanisms during the diagnosis becomes essential for treatment strategies. The clinical picture of neuropathic pain is similar in many cases, and clinical features include: ongoing spontaneous or evoked pain in an area with sensory loss, positive sensory symptoms such as allodynia and hyperalgesia, wind-up pain following repetitive stimulation, referred pain and abnormal sympathetic activity. The understanding of the mechanisms underlying neuropathic pain has increased over the last decade. The primary pathophysiologic mechanisms that produce pain are: nociceptor sensitization, nerve trunk inflammation, sympathetic nervous system involvement, ectopic neuronal discharges, pathologic synaptic reorganization--neuroplasticity and central sensitization. In most clinical features, there is a complex interaction that involves peripheral and central nervous system rather than a single mechanism. Because numerous mechanisms are implicated, the traditional approach to pain control using single drug therapy may not be most effective, and therapeutic combinations are a better choice. Neuropathic pain is poorly responsive to conventional analgesics. In spite of a variety of drug classes used to treat neuropathic pain including antidepressants, anticonvulsants, antiarrhythmics, opioids, local anesthetic blockers, neuropathic pain remains difficult to treat. The possibility to select specific drugs and treatments for the individual patient lies in elucidating the relationships between clinical neuropathic states and underlying pathophysiologic changes. Progress in defining the mechanisms involved in neuropathic pain, based on further clinical studies and fundamental investigations, will improve therapeutic management of neuropathic pain.
Planjar-Prvan
Miljenka
M
Zavod za neurologiju, Opća boblica Sveti Duh, Zagreb, Hrvatska. miljenka-planjar@net.hr
Bielen
Ivan
I
Baraba
Ranka
R
Buljan
Radmila
R
D000818:Animals; D006801:Humans; D010146:Pain / Q000209:etiology / Q000503:physiopathology*; D059408:Pain Management; D010523:Peripheral Nervous System Diseases / Q000150:complications* / Q000503:physiopathology