European journal of pain : EJP
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Case Reports
Spinal cord stimulation in adolescents with complex regional pain syndrome type I (CRPS-I).
Complex regional pain syndrome type I (CRPS-I) is not uncommon in children, particularly in adolescent girls. Most often, the condition involves a foot and is characterized by spontaneous pain, tactile allodynia and dysautonomic signs. There is usually a history of a minor, local trauma but sometimes no reasonable cause can be identified, and there are no signs of persistent tissue injury giving rise to ongoing nociception. ⋯ In one case, a local infection necessitated the removal of the electrode; nevertheless a few days of trial stimulation produced substantial pain relief that still persists. In four patients, the SCS use was gradually diminished and eventually the device could be removed. The favourable outcome in all seven cases with no or minor remaining symptoms and without severe recurrences illustrates that SCS may also be an efficient treatment in paediatric cases with exceptionally therapy resistant forms of CRPS I.
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Randomized Controlled Trial
Antihyperalgesic and analgesic properties of the N-methyl-D-aspartate (NMDA) receptor antagonist neramexane in a human surrogate model of neurogenic hyperalgesia.
NMDA-receptors are a major target in the prevention and treatment of hyperalgesic pain states in neuropathic pain. However, previous studies revealed equivocal results depending on study design and efficacy parameters. We tested the analgesic (generalized reduction of generation and processing of nociceptive signalling) and anti-hyperalgesic (prevention of central sensitization) properties of the NMDA-receptor antagonist neramexane and the potassium channel opener flupirtine in the intradermal capsaicin injection model. ⋯ The results suggests that in a human surrogate model of neurogenic hyperalgesia a single low-dose of neramexane had a marked analgesic effect in the sensitized and in the non-sensitized state and thus may be a useful drug to treat the enhanced pain sensitivity in neuropathic pain patients. Its efficacy may be based on analgesia rather than anti-hyperalgesia or anti-windup. In contrast, flupirtine showed neither an analgesic nor an anti-hyperalgesic effect at a dose used for the treatment of postoperative pain.
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Patients with chronic neuropathic pain (non-CRPS) and brush-evoked allodynia watched a reflected image of their corresponding but opposite skin region being brushed in a mirror. Unlike complex regional pain syndrome Type 1, this process did not evoke any sensation at the affected area ('dysynchiria'). We conclude that central nociceptive sensitisation alone is not sufficient to cause dysynchiria in neuropathic pain. The results imply a difference in cortical pain processing between complex regional pain syndrome and other chronic neuropathic pain.
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Surgical removal of third molars may carry a risk of developing persistent orofacial pain, and central sensitization appears to play an important role in the transition from acute to chronic pain. ⋯ We found clear signs of sensitization of the trigeminal nociceptive system for at least one week after the surgery. Our results indicate that even a minor orofacial surgical procedure may be sufficient to evoke signs of both central and peripheral sensitization, which may play a role in the transition from acute to chronic pain in susceptible individuals.
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In a previously published pilot study, we addressed the possibility to increase the effectiveness of spinal cord stimulation (SCS) applied for neuropathic pain by using adjunct pharmacological therapy. This combined treatment approach was a direct spin-off from animal experiments aiming at the exploration of transmitter and receptor mechanisms involved in the pain relieving effect of SCS. Out of 48 patients with neuropathic pain of peripheral origin responding poorly to SCS, seven received pumps for intrathecal baclofen (GABA-B receptor agonist) delivery together with SCS, and four had pumps alone. ⋯ At the follow-up the remaining nine patients still enjoy about the same pain relief as initially, but with a mean, further dose increase of about 30%. This study demonstrates that a deficient SCS effect in neuropathic pain may be considerably improved by intrathecal baclofen administration, and that this enhanced effect persists for a long-time. On-going and future animal studies may provide new and even more efficient pharmaceutical candidates for such combined therapy.