Motor cortex stimulation for post-stroke pain: comparison of spinal cord and thalamic stimulation

We analyzed the effects of spinal cord stimulation (SCS), deep brain stimulation (DBS) of the thalamic nucleus ventralis caudalis (VC) and motor cortex stimulation (MCS) in 45 patients with post-stroke pain. Satisfactory pain control was obtained more frequently as the stimulation site was moved to higher levels (7% by SCS, 25% by DBS and 48% by MCS). A painful sensation was sometimes produced by stimulation of the VC as well as the post-central, pre-central and pre-frontal cortices. Such a sensation occurred less frequently as the stimulation site was moved to higher levels (50% at the VC, 39% at the post-central cortex, 6% at the pre-central cortex and 3% at the pre-frontal cortex). These findings imply that abnormal processing of nociceptive information develops at the level of deafferentation and spreads to higher levels to a varying extent. This may be one of the reasons why satisfactory pain control was obtained more frequently as the stimulation site was moved to higher levels.     

Spinal epidural stimulation for central pain caused by spinal cord lesion]

Epidural spinal cord stimulation was carried out in 4 patients with denervation caused by spinal cord lesion, and we reviewed previously reported cases. Initial result showed at 1 week in 100% of our cases, but about 1/3 of the cases, even those with the same denervation caused by spinal cord lesion, had no pain relief at this stage in previously reported cases. In our cases, excellent pain relief was gained temporarily, even though the painful area and the spinal cord lesion were separated somatotopically in 2 cases (case 3, 4). Temporary success bore no relationship to quality and duration of pain. In all cases except case 1, a rapidly decreasing effectiveness was noted, and finally no pain relief was gained at all after 4, 3 and 5 months, respectively. In case 1 there was persistent pain relief estimated at 70-80% after 19 months, only when the spinal cord was stimulated. Epidural stimulation also produced sensations in the painful area. Spinal cord stimulation would suppress at least the dorsal horn neurons which were destroyed by various kinds of diseases. A decline in effectiveness with time would occur due to essential causes of the deafferentation pain, such as anatomical and regeneration factors.     

Efficacy of motor cortex stimulation for intractable central neuropathic pain: comparison of stimulation parameters between post-stroke pain and other central pain

Motor cortex stimulation (MCS) has now become the preferred option for neurosurgical management of intractable central neuropathic pain such as post-stroke pain and trigeminal neuropathic pain. However, the efficacy of MCS for other central neuropathic pain such as pain resulting from spinal cord or brainstem lesions is unclear. We retrospectively reviewed 11 consecutive patients with intractable central neuropathic pain who underwent MCS in our institution. Eight patients had poststroke pain caused by thalamic hemorrhage (n = 5) or infarction (n = 3) (thalamic group). Two patients had postoperative neuropathic pain caused by spinal cord lesions, and one patient had facial pain caused by a brainstem lesion associated with multiple sclerosis (brainstem-spinal group). Visual analog scale and stimulation parameters were evaluated at 1 and 6 months postoperatively. MCS was effective for six of eight patients in the thalamic group, and all three patients in the brainstem-spinal group. These efficacies continued for 6 months after surgery without significant change in the stimulation parameters compared with the parameters at 1 month in both groups. The mean amplitude at 1 month and frequency at 6 months after surgery were significantly higher in the brainstem-spinal group than the thalamic group, although the patient number was small. MCS is effective for other central neuropathic pain, but higher intensity stimulation parameters may be necessary to gain adequate pain reduction.     

脊髓电刺激术治疗内脏痛的研究进展

背景 脊髓电刺激术(spinal cord stimulation,SCS)可以缓解多种原因导致的疼痛,改善器官功能,尤其对于神经病理性疼痛和周围血管病变引起的缺血性疼痛的治疗作用明显.最近研究发现,其对内脏痛性疾病也有艮好的缓解作用.目的 通过综述SCS在内脏痛中的应用及其作用机制,为内脏痛的治疗提供参考. 内容 SCS的发展及其对内脏痛的镇痛机制,对各种内脏痛相关疾病的治疗效应和进展. 趋向 SCS可以治疗药物治疗效果欠佳的内脏痛疾病,为内脏痛的治疗提供新的工具.     

脊髓损伤后中枢性疼痛的实验模型和机制研究进展

中枢性疼痛(central pain,CP)是脊髓损伤(spi-nal cord injury,SCI)的顽固性合并症,为患者主观上感到损伤平面以下皮肤痛觉消失区一种以自发痛为主的疼痛,发生率为11%~94%,严重者为5%~30%。近年来其发生率逐年增高,使很多患者陷于抑郁、药物成瘾、甚至自杀的悲惨境地。许多疼痛     

序贯法药物治疗脊髓损伤后中枢性疼痛

目的：研究应用序贯法药物治疗脊髓损伤后中枢性疼痛及临床效果。方法：自1994年至2008年共收治脊髓损伤后中枢性疼痛28例,其中男23例,女5例;年龄25—59岁,平均42岁。应用三级序贯法药物治疗,根据患者对药物治疗的反应,逐步调整药物治疗级别,直至疼痛缓解。根据治疗前后的VAS评分情况,评估药物镇痛效果。第一级：应用COX-2抑制剂。第二级：应用三环类抗抑郁药物阿米替林＋COX-2抑制剂＋卡马西平。第三级：应用阿米替林三环类抗抑郁药物＋加巴喷丁＋神经妥乐平或COX-2抑制剂。结果：28例均有不同程度的疼痛缓解。第一级药物治疗VAS评分降低（23．3±1．2）分,第二级药物治疗VAS评分降低（54．5±3．8）分,第三级药物治疗VAS评分降低（65．8±5．1）分。结论：应用三级序贯法药物治疗脊髓损伤后中枢性疼痛,具有疗效优良、不良反应少的优点。     

Spinal cord anatomy,pain, and spinal cord stimulation mechanisms

The effectiveness and mechanisms of spinal cord stimulation described in literature rely on a proper understanding of spinal cord anatomy and pain theory. In this article we provide an overview of relevant spinal cord anatomy, pain mechanisms, and theories of pain perception. This includes the gate control theory that is the foundation for spinal cord stimulation as a treatment for chronic pain. Thereafter, we describe the different mechanisms of spinal cord stimulation. Specifically, there are considerations in anatomy, electrophysiology, neurochemistry, and neurophysiology of the central nervous system that play a role in how spinal cord stimulation modulates the pain “gate” system.     

Treatment of recurrent chest pain in a heart transplant recipient using spinal cord stimulation

A patient presented with chest pain refractory to conventional medical therapy eight years after heart and renal transplantation. High-dose opioids provided limited relief and repeated hospitalisation was required. Angiography demonstrated severe cardiac allograft vasculopathy, unsuitable for percutaneous or surgical intervention. Reports of sympathetic re-innervation of the transplanted heart encouraged us to undertake a trial of spinal cord stimulation. This was successful so we proceeded to permanent implantation. The patient was weaned from opioids and after six months had needed no further hospital admissions. We recommend consideration of spinal cord stimulation in patients with features of angina pectoris following heart transplantation.     

Equipment for spinal cord stimulation

Spinal cord stimulation has gained widespread popularity for the treatment of pain. This literature discribed our equipments, methods, patient selection, and operative procedures for spinal cord stimulation.     

Implantable devices for pain control: spinal cord stimulation and intrathecal therapies

Untreated chronic pain is costly to society and to the individual suffering from it. The treatment of chronic pain, a multidimensional disease, should rely on the expertise of varying health care providers and should focus not only on the neurobiological mechanisms of the process but also on the psychosocial aspects of the disease. Implantable devices are costly and invasive, and such efficacious therapies should be used only when more conservative and less costly therapies have failed to provide relief of pain and suffering. Spinal cord stimulation provides neuromodulation of neuropathic, but not nociceptive, pain signals and when used for appropriate indications in the right individuals provides approximately 60–80% long-term pain relief in 60–80% of patients trialled for efficacy. Intrathecal therapies with opioids such as morphine, fentanyl, sufentanil or meperidine – or non-opioids such as clonidine or bupivacaine – provide analgesia in patients with nociceptive or neuropathic pain syndromes. Baclofen, intrathecally, provides profound relief of muscle spasticity due to multiple sclerosis, spinal cord injuries, brain injuries or cerebral palsy.     

Transcutaneous electrical nerve stimulation and spinal cord stimulation for pain relief in reflex sympathetic dystrophy

35 patients with the diagnosis of reflex sympathetic dystrophy in a late stage have been treated with transcutaneous electrical nerve stimulation (TENS). 6 out of the 35 were also submitted to spinal cord stimulation (SCS). The follow-up was from 10 to 36 months. The results obtained were TENS group: 25% excellent, 45% good, 10% fair, 20% poor; in the SCS group: 16.6% excellent; 66.6% good and 16.6% fair. In the long run these results are better than those obtained with sympathetic blocks and sympathectomy. TENS and SCS have no effect on osteoporosis or ankylosis.     

Bilateral cortical stimulation for deafferentation pain after spinal cord injury. Case report

The relief of intractable pain after spinal cord injury (SCI) is very difficult to obtain, even with dorsal root entry zone lesioning, spinal cord stimulation, and thalamic stimulation. Using bilateral motor cortex stimulation (MCS) the authors successfully treated a woman who experienced deafferentation pain 4 years after sustaining an SCI. To the authors' knowledge, this is the first report of bilateral MCS for pain relief after SCI. The success they achieved using this method indicates that MCS could be a new treatment option for deafferentation pain following SCI.     

Clinical indications for spinal cord stimulation

As a form of neuromodulation, spinal cord stimulation can be used with great efficacy in treating chronic pain symptoms. However, careful consideration in choosing the correct patient is important in ensuring maximal pain relief, and ultimate success of the spinal cord stimulator. The most common indication for spinal cord stimulation in the United States is failed back surgery syndrome. Other indications for spinal cord stimulator placement include complex regional pain syndrome, peripheral vascular disease, refractory angina, and painful diabetic neuropathy.     

Evidence for a central pathway in the cerebrovascular effects of spinal cord stimulation

OBJECTIVE: Cervical spinal cord stimulation (SCS) augments cerebral blood flow (CBF) in a number of animal models. The mechanisms underlying the cerebrovascular effects of SCS are not yet well delineated. In this study, we analyzed two alternative pathways in CBF alterations induced by SCS in rats, one involving direct modulation of sympathetic outflow and the other through central vasomotor influence. METHODS: Resection of the superior cervical ganglion (SCG), SCS alone, or SCS after SCG removal was performed in adult male Sprague-Dawley rats. CBF was measured with (14)C-inosine monophosphate radiotracer studies. In another set of experiments, SCS was performed after spinalization at the cervicomedullary junction or after laminectomy alone. RESULTS: Baseline CBF in the SCG removal group was 71 +/- 8 ml/100 g/min, similar to controls. SCS alone significantly increased blood flow to 100 +/- 10 ml/100 g/min (P < 0.05). Animals that underwent SCS after SCG removal demonstrated a similar robust augmentation in CBF. SCS-induced changes in CBF were completely attenuated by spinalization. CONCLUSION: The profound effects of spinal cord transection on SCS-induced CBF augmentation, together with the lack of effect of surgical sympathectomy, suggest that the mechanisms underlying the effects of SCS involve central influences rather than cervical sympathetic outflow. These findings suggest a possible role for brainstem vasomotor centers in the cerebrovascular effects of SCS.