Pain Relief and Functional Recovery in Patients with Complex Regional Pain Syndrome after Motor Cortex Stimulation

Abstract

In addition to pain and neurovegetative symptoms, patients with severe forms of complex regional pain syndrome (CRPS) develop a broad range of symptoms, including sensory disturbances, motor impairment and dystonic posturing. While most patients respond to medical therapy, some are considered refractory and become surgical candidates. To date, the most commonly used surgical procedure for CRPS has been spinal cord stimulation. This therapy often leads to important analgesic effects, but no sensory or motor improvements. We report on 2 patients with pain related to CRPS and severe functional deficits treated with motor cortex stimulation (MCS) who not only had significant analgesic effects, but also improvements in sensory and motor symptoms. In the long term (27 and 36 months after surgery), visual analog scale pain scores were improved by 60–70% as compared to baseline. There was also a significant increase in the range of motion in the joints of the affected limbs and an improvement in allodynia, hyperpathia and hypoesthesia. Positron emission tomography scan in both subjects revealed that MCS influenced regions involved in the circuitry of pain.

Motor Cortex Stimulation Therapy for Relief of Central Post-Stroke Pain: A Retrospective Study with Neuropathic Pain Symptom Inventory

“…We observed a significant association between burning (superficial) spontaneous pain relief and effective results (based on the VAS score) in our study; thus, we believe that the pain relief mediated by MCS is the result of orthodromic activation of the corticofugal pathways and antidromic activation of thalamocortical pathways, and the substantia gelatinosa, which participates in the modulation of the whole pain and the burning pain, plays an important role in these procedures. This is consistent with Fonoff’s research in animal models [26-28]. There are some limitations in our study.…”

“…According to a study by Goto et al [25] using diffusion tensor imaging to examine the effectiveness of M1 rTMS for CPSP, preservation of thalamocortical and corticofugal motor tracts predicts treatment efficacy. In an animal model of neuropathic pain, Pagano et al [26] and Fonoff et al [27, 28] found that animals treated with MCS had a decrease in Fos and zif expression in the dorsal horn of the spinal cord (DHSC), and an increase in Fos and zif expression in the periaqueductal gray matter. The periaqueductal gray matter is a part of a descending pain suppressor pathway that projects to the DHSC via the rostral ventromedial medulla.…”

Motor cortex stimulation for facial chronic neuropathic pain: A review of the literature

“…[118119120] In the worldwide literature, there is a growing interest on stimulation of the motor cortex for treatment of FCNP [Figure 1]. [96] Initially tried for thalamic pain, it has been tried for many treatment-resistant pain syndromes [54] such as phantom limb pain, [95101106] postherpetic neuralgia, brachial plexus avulsion, [57] poststroke pain, [324648505176106111] Wallenberg syndrome,[3349] complex regional pain syndrome, [2770108] pain secondary to multiple sclerosis, [112] spinal cord injury pain, [88113] and posttraumatic brain injury pain. [107] Recently, MCS has also been tried in other nonpainful conditions.…”

Invasive treatment to control neuropathic pain

“…Motor cortex stimulation (MCS) is considered promising, especially to treat trigeminal NP and post-stroke central pain syndromes, such as thalamic pain and brachial plexus avulsion, among others 21,[61][62][63] . Most studies involving MCS focuses on post-stroke and atypical trigeminal neuropathy, for which there are few effective treatments.…”

“…MCS results for trigeminal NP are very interesting, because they show that 75% to 100% of patients have obtained good to excellent pain relief. Other groups have also shown pain improvement in less studied syndromes, such as complex regional pain syndrome, with encouraging results in very severely ill patients with therapeutic failure to spinal cord stimulation [61][62][63] . Motor cortex stimulation effect depends on electrodes implant target, which apparently should be implanted in motor cortex region corresponding to body segment affected by pain.…”