Spinal cord stimulation with sympathetically independent pain and sympathetically maintained pain

BACKGROUND: Complex regional pain syndrome (CRPS) is categorized into sympathetically maintained pain (SMP) and sympathetically independent pain (SIP). Spinal cord stimulation (SCS) is a promising approach in the treatment of severely disabling CRPS. Patients with good responses to sympathetic block before SCS are more likely to have positive responses to SCS than those with negative responses. This study compared the effects of SCS in patients with CRPS, of SMP and SIP categories. METHODS: This was a retrospective study of 16 patients (SMP 8, SIP 8) with CRPS who had undergone trials of SCS. Eleven of the patients had permanent SCS device implants, and the pain relief levels at 1 and 6 months were recorded. RESULTS: Sixteen patients with severe, incapacitating, and therapy-resistant CRPS underwent SCS trials. Five patients (SMP 3, SIP 2) had poor pain relief during the trial despite adequate coverage. The remaining 11 patients (SMP 5, SIP 6) had permanent electrode implantation performed under local anesthesia and experienced good pain relief. The difference in VAS reduction was not significant between the two groups at the 1-month follow-up (P = 0.325) and the 6-month follow-up (P = 0.779). CONCLUSIONS: There were no statistically significant differences in VAS pain scores between the two groups. The favorable outcome in all 11 patients with only minor remaining symptoms or without remaining symptoms or severe recurrences suggests that SCS is an efficient treatment in SMP and SIP.

Does the Tibial and Sural Nerve Transection Model Represent Sympathetically Independent Pain?

Neuropathic pain can be divided into sympathetically maintained pain (SMP) and sympathetically independent pain (SIP). Rats with tibial and sural nerve transection (TST) produce neuropathic pain behaviors, including spontaneous pain, tactile allodynia, and cold allodynia. The present study was undertaken to examine whether rats with TST would represent SMP- or SIP-dominant neuropathic pain by lumbar surgical sympathectomy. The TST model was generated by transecting the tibial and sural nerves, leaving the common peroneal nerve intact. Animals were divided into the sympathectomy group and the sham group. For the sympathectomy group, the sympathetic chain was removed bilaterally from L2 to L6 one week after nerve transection. The success of the sympathectomy was verified by measuring skin temperature on the hind paw and by infra red thermography. Tactile allodynia was assessed using von Frey filaments, and cold allodynia was assessed using acetone drops. A majority of the rats exhibited withdrawal behaviors in response to tactile and cold stimulations after nerve stimulation. Neither tactile allodynia nor cold allodynia improved after successful sympathectomy, and there were no differences in the threshold of tactile and cold allodynia between the sympathectomy and sham groups. Tactile allodynia and cold allodynia in the neuropathic pain model of TST are not dependent on the sympathetic nervous system, and this model can be used to investigate SIP syndromes.

Does the Tibial and Sural Nerve Transection Model Represent Sympathetically Independent Pain?

Neuropathic pain can be divided into sympathetically maintained pain (SMP) and sympathetically independent pain (SIP). Rats with tibial and sural nerve transection (TST) produce neuropathic pain behaviors, including spontaneous pain, tactile allodynia, and cold allodynia. The present study was undertaken to examine whether rats with TST would represent SMP- or SIP-dominant neuropathic pain by lumbar surgical sympathectomy. The TST model was generated by transecting the tibial and sural nerves, leaving the common peroneal nerve intact. Animals were divided into the sympathectomy group and the sham group. For the sympathectomy group, the sympathetic chain was removed bilaterally from L2 to L6 one week after nerve transection. The success of the sympathectomy was verified by measuring skin temperature on the hind paw and by infra red thermography. Tactile allodynia was assessed using von Frey filaments, and cold allodynia was assessed using acetone drops. A majority of the rats exhibited withdrawal behaviors in response to tactile and cold stimulations after nerve stimulation. Neither tactile allodynia nor cold allodynia improved after successful sympathectomy, and there were no differences in the threshold of tactile and cold allodynia between the sympathectomy and sham groups. Tactile allodynia and cold allodynia in the neuropathic pain model of TST are not dependent on the sympathetic nervous system, and this model can be used to investigate SIP syndromes.

Bloqueos terapéuticos en dolor mantenido por el simpático / Therapeutic blockades in maintained pain for the simpathic nervous system

Se realiza una revisión de los estados dolorosos en que tienen participación las vías simpáticas el sistema nervioso autónomo: en la mediación del dolor (dolor mediado por el simpático) o en la mantención de éste (dolor mantenido por el simpático), considerando la evidencia clínica y experimental con los bloqueos de las vías autonómicas en el control de este tipo de dolor. Se analiza la utilidad de estas técnicas en síndrome de dolor regional complejo tipo 1, herpes zoster y neuralgia post herpética, dolor de miembro fantasma y dolor visceral de origen oncológico.

It is carried out a revision of the painful states with participation of the sympathetic pathways of the autonomic nervous system: in the mediation of the pain (sympathetically mediated pain) or in the maintention of this (simpathetically maintained pain), considering the clinical and experimental evidence that indicate the beneficial effects with the interruption of autonomic pathways in the control of this type of pain. were analyzed this techniques in complex regional pain syndrome type 1, herpes zoster and post-herpetic neuralgia, phantom limb pain and visceral pain of oncology origin.

Minimal Concentration of Lidocaine for a Diagnostic Stellate Ganglion Block / 대한마취과학회지

BACKGROUND: The aim of this study was to determine an adequate minimal concentration of lidocaine in a stellate ganglion block for decreasing a false positive response to a diagnostic sympathetic blockade determining whether the patient's pain is SMP or SIP. METHODS: This crossover study was performed in twenty patients with sudden sensory neural hearing loss. All patients received three times SGB using three different concentrations (1%, 0.5% and 0.25%) of 8 ml lidocaine at the sixth cervical vertebral level via an anterior paratracheal approach. The blocks were separately done at one week intervals in random order. The occurrence, onset time and action duration of Horner's syndrome were observed after each SGB. RESULTS: Positive cranial sympathetic blockade (Horner' syndrome) was present in all patients using 1% and 0.5% lidocaine. It was present in 60% of the patients using 0.25% lidocaine. Onset time was not significantly different among the three groups. Action duration of 1% and 0.5% lidocaine groups was significantly longer than the 0.25% lidocaine group. There was no critical side effects, and temporary foreign body sensation was the most common side effect. CONCLUSIONS: The results of this study suggest that 0.5% lidocaine is an adequate minimal concentration for diagnostic SGB. Therefore, we recommend that 0.5% lidocaine instead 1% should be used in diagnostic SGB to decrease a false positive response to a sympathetic blockade.

Effects of Clonidine and Epinephrine on Neuropathic Pain in an Experimental Animal Model for Peripheral Neuropathy

OBJECTIVE: To evaluate the effect of clonidine on the experimental neuropathic pain model and to observe whether neuropathic pain is related to the sympathetic nervous system in this model by reversal of allodynia with administration of epinephrine. METHOD: The neuropathic pain was produced by unilateral transection of the superior caudal trunk innervating the rat's tail. Tail withdrawal responses based on mechanical (withdrawal frequency to bending force of von Frey hair 2.0 g) and the thermal (withdrawal latency to tail immersion in a 4degrees C or 40degrees C water with a cut-off time of 15 seconds) stimuli were used. Experiments were performed two weeks after surgery when neuropathic pain had fully been developed. Experimental group by administration of clonidine was examined by tail withdrawal responses at Day 1, Day 3 and Day 5. After one week of wash-out period, reversal of allodynia by administration of epinephrine was examined by the same test. RESULTS: Clonidine significantly decreased the frequency of withdrawal with the mechanical stimuli compared with control (P<0.01), but did not significantly decrease with the cold or warm stimuli. Epinephrine tended to aggravate the mechanical allodynia, but it was not significant compared with the control. CONCLUSION: Clonidine may relieve mechanical allodynia in neuropathic pain, but the mechanism of neuropathic pain that is related to the sympathetic nervous system in this experimental model may be unreliable.