Effects of Spinal Cord Stimulation in Patients with Chronic Nausea, Vomiting, and Refractory Abdominal Pain.

BACKGROUND: Patients with chronic nausea and vomiting often also have chronic abdominal pain. Spinal cord stimulation (SCS) may provide pain control, but scarce data are available regarding the effect of SCS on chronic nausea and vomiting. AIMS: We aimed to determine the effect of SCS in patients with chronic nausea, vomiting, and refractory abdominal pain. METHODS: Retrospective chart review of 26 consecutive patients who underwent SCS trial for a primary diagnosis of nausea, vomiting and refractory abdominal pain. RESULTS: 26 patients underwent SCS trial, with an average age of 48 years. Twenty-three patients (88.5%) reported > 50% pain relief during the temporary SCS trial and then underwent permanent implantation. Patients were then followed for 41 (22-62) months. At baseline, 20 of the 23 patients (87.0%) reported daily nausea, but at 6 months and the most recent follow-up, only 8 (34.8%) and 7 (30.4%) patients, respectively, had daily nausea (p < 0.001). Days of nausea decreased from 26.3 days/month at baseline to 12.8 and 11.7 days/month at 6 months and at the most recent visit, respectively. Vomiting episodes decreased by 50%. Abdominal pain scores improved from 8.7 to 3.0 and 3.2 at 6 months and the most recent visit, respectively (both p < 0.001). Opioid use decreased from 57.7 mg MSO4 equivalents to 24.3 mg at 6 months and to 28.0 mg at the latest patient visit (both p < 0.05). CONCLUSIONS: SCS may be an effective therapy for long-term treatment of symptoms for those patients afflicted with chronic nausea, vomiting, and refractory abdominal pain.

Magnesium Implants: Prospects and Challenges.

Owing to their suitable mechanical property and biocompatibility as well as the technological possibility of controlling their high corrosion rates, magnesium and its alloys have attracted significant attention as temporary bio-implants. Though the ability of magnesium to harmlessly biodegrade and its inherent biocompatibility make magnesium alloys a suitable choice for a temporary implant, their high corrosion rates limit their practical application, as the implants can potentially corrode away even before the healing process has completed. Different approaches, such as alloying, surface modification, and conversion coatings, have been explored to improve the corrosion resistance of various magnesium alloys. However, the corrosion behavior of magnesium implants with and without a surface modification has been generally investigated under in-vitro conditions, and studies under in-vivo conditions are limited, which has contributed to the lack of translation of magnesium implants in practical applications. This paper comprehensively reviews the prospects of magnesium alloy implants and the current challenges due to their rapid degradation in a physiological environment. This paper also provides a comprehensive review of the corrosion mitigation measures for these temporary implants.

Long-term efficacy of 1-1.2 kHz subthreshold spinal cord stimulation following failed traditional spinal cord stimulation: a retrospective case series.

BACKGROUND AND OBJECTIVE: We investigated whether an effective long-term pain relief could be achieved using subthreshold 1-1.2 kHz spinal cord stimulation (SCS) among patients who were initially implanted with traditional paresthesia-based SCS but who failed to maintain an adequate pain relief. METHODS: Retrospective chart review was conducted of patients' electronic records who underwent a trial of subthreshold 1-1.2 kHz SCS. One hundred and nine patients implanted and programmed at traditional paresthesia-based frequencies 40-90 Hz (low-frequency SCS) with unsatisfactory pain relief or unpleasant paresthesias were identified. Patients' settings were switched to 1-1.2 kHz and 60-210 µs, and variable amplitude adjusted to subthreshold. Pain scores and medication usage were collected. Complete data are presented on 95 patients. RESULTS: Data were collected from 36 men and 59 women who were converted from above-threshold 40-90 Hz SCS to 1-1.2 kHz SCS, with a minimum follow-up of 12 months. Nearly a third (63/95 or 66.3%) of the subjects deemed 1-1.2 kHz SCS ineffective and returned to low-frequency SCS within 1 week after switch, and one-sixth (16/95 or 16.8%) of the subjects returned to low-frequency SCS within 1 month. Only 13 (13.7%) subjects continued using 1-1.2 kHz subthreshold SCS for 3 months or longer and 2.1% (2/95) of subjects continued using it at 12 months. A comparison of their pain scores and opioid use before and during the time we used 1-1.2 kHz SCS revealed no significant difference. CONCLUSION: The results from our single center failed to show additional long-term clinical benefit of 1-1.2 kHz subthreshold SCS in patients with chronic pain failing traditional low-frequency SCS.

Four-Extremity Neurostimulation Using Two Cervical Octapolar Leads and High Frequency of 10 kHz.

OBJECTIVES AND METHODS: A few published reports describe successful clinical use of low-frequency spinal cord stimulation (SCS) in the cervical spine resulting in bilateral upper and lower extremity pain relief. A major side-effect when using this modality of SCS is the uneven intensity of paresthesias, which are frequently excessive in upper extremities while attempting to achieve optimal paresthesia coverage in all 4 extremities. RESULTS AND CONCLUSIONS: Here we describe a successful case of high-frequency SCS at 10 kHz where profound control of neuropathic pain of all 4 extremities was achieved without the complication of paresthesias. Discussed are future implications of such therapy.

Resistance of Magnesium Alloys to Corrosion Fatigue for Biodegradable Implant Applications: Current Status and Challenges.

Magnesium (Mg) alloys are attracting increasing interest as the most suitable metallic materials for construction of biodegradable and bio-absorbable temporary implants. However, Mg-alloys can suffer premature and catastrophic fracture under the synergy of cyclic loading and corrosion (i.e., corrosion fatigue (CF)). Though Mg alloys are reported to be susceptible to CF also in the corrosive human body fluid, there are very limited studies on this topic. Furthermore, the in vitro test parameters employed in these investigations have not properly simulated the actual conditions in the human body. This article presents an overview of the findings of available studies on the CF of Mg alloys in pseudo-physiological solutions and the employed testing procedures, as well as identifying the knowledge gap.

Influence of bovine serum albumin in Hanks' solution on the corrosion and stress corrosion cracking of a magnesium alloy.

It is essential for any temporary implant to possess adequate strength to maintain their mechanical integrity under the synergistic effects of mechanical loading characteristics of human body and the corrosive physiological environment. Such synergistic effects can cause stress corrosion cracking (SCC). The aim of the present study is to investigate the effect of the addition of bovine serum albumin (BSA) to Hanks' solution in corrosion and SCC susceptibility of AZ91D magnesium alloy. The electrochemical impedance spectroscopy (EIS) results indicated that the addition of BSA increased corrosion resistance of the alloy during the first 48h of immersion and then decreased it rapidly. The energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses indicated adsorption of BSA on the alloy surface during initial hours of immersion. However, with the increasing immersion time, BSA chelated with the corrosion products causing disruption of the protective film; thus, it accelerated the corrosion of the alloy. Both the mechanical data and fractographic evidence have confirmed susceptibility of the alloy to SCC. However, in the presence of BSA, the alloy suffered greater SCC which was attributed to its increased susceptibility towards localized corrosion.