Prospective, Multicenter Feasibility Study to Evaluate Differential Target Multiplexed Spinal Cord Stimulation Programming in Subjects With Chronic Intractable Back Pain With or Without Leg Pain.

OBJECTIVE: This prospective, open-label, multicenter study evaluated the feasibility of spinal cord stimulation (SCS) therapy programming for chronic low back pain that uses multiple electrical pulsed signals (Differential Target Multiplexed). METHODS: Twenty-five SCS candidates with low back pain equal to or greater than lower limb pain were enrolled at 7 sites in the United States. The subjects evaluated standard and Differential Target Multiplexed programs, each for 4 ± 1 days. A commercially available SCS trial system was used for standard SCS therapy programming. During the trialing of the multiplexed programs, implanted temporary leads were connected to an investigational external trial stimulator system. RESULTS: Twenty subjects concluded the study. The mean baseline numeric pain rating scale (NPRS) score for low back pain was 7.4, with a mean age of 62.4 years and mean pain duration of 18.0 years. Significant relief in back pain was observed for both treatments, with significantly better response with multiplexed programming. At the end of the trial period, subjects reported a reduction in their mean NPRS score from baseline to 4.2 after standard programming and to 2.4 after Differential Target Multiplexed programming. The difference between standard and multiplexed programming was significant. The responder rate for low back pain relief was 50% for standard programming and 80% for Differential Target Multiplexed programming. Eighty-five percent of subjects who evaluated both programming approaches preferred Differential Target Multiplexed SCS. CONCLUSION: In this difficult-to-treat patient population, subjects reported significant reduction in chronic back pain when using multiplexed programming. A randomized clinical trial is needed to confirm the results from this feasibility study.

Cervical plexus as anatomical target for the treatment of postoperative cervical neuropathic pain.

Objective: The incidence of chronic neuropathic pain following neck dissections is approximately 40%. Standard drug therapy in these patients include pharmacologic treatments due to the neuropathic pain (gabapentinoids, tricyclic antidepressants…). In this case, standard options were limited. The addition of ultrasound guidance to invasive pain management techniques has enabled us to successfully treat pathologies in which previous treatments options had been limited. Pulsed radiofrequency (PRF) ablation permits treatment over nerve structures that, due to either their morphological or functional characteristics, could not be approached using the conventional variant. Case report: A 45-year-old man with severe postoperative pain after undergoing partial glossectomy and functional neck dissection for squamous cell carcinoma of the tongue. The patient had been treated pharmacologically for several years with minimal results, baseline VAS of 90. After a successful superficial cervical plexus block under ultrasound guidance, he underwent PRF for a possible long-lasting effect. VAS post PRF improved in subsequent visits: VAS at 1 month was 0; at 3 months was 10 and at 6 months was 60. Conclusion: Postoperative changes to include alterations in nerve structures are a frequent source of chronic pain. The incidence of this type of pain in the cervical region is quite variable. Noninvasive treatment options are limited and oftentimes ineffective. Due to its location, superficial cervical plexus is an anatomical site with the potential risk of undergoing structural alterations (fibrosis, radiotherapy-associated retraction phenomena or neuroma formation). Interventional treatments performed under ultrasound guidance allow the dynamic application of therapies such as radiofrequency ablation. PRF could potentially cause an additive effect between neuromodulation and the hydrodissection caused by the infiltration of substances within a fibrotic area.

Anatomic and Ultrasonographic Evaluation of the Knee Sensory Innervation: A Cadaveric Study to Determine Anatomic Targets in the Treatment of Chronic Knee Pain.

BACKGROUND AND OBJECTIVES: Osteoarthrosis is a main cause of knee pain in the elderly. Pain associated with this condition is often refractory to conservative treatment. Total knee replacement may be the best option for severe pathologies; however, the occurrence of a chronic pain state after knee replacement has been well documented in the literature. The previous descriptions of the genicular nerves have been considered somewhat inaccurate. This innervation is complex and exhibits significant interindividual variability. A precise description of these nerves will increase our knowledge on different patterns and targets, to guide treatment and improve outcomes. The objective of this study was to determine sensory innervation patterns of the knee joint and correlate them with dynamic visualization via ultrasound imaging. METHODS: Systematic cadaveric dissections were performed to determine different patterns of sensory innervation of the knee followed by ultrasonographic correlation. A short-axis ultrasound view of the nerves was used to inject India ink at several points along their course to facilitate the anatomic dissection and confirm their location among adjacent structures. RESULTS: The visualized structures were the following: infrapatellar branch of the saphenous nerve, the branches to vastus medialis, intermedius, and lateralis muscles; obturator nerve; and lateral retinacular and recurrent peroneal nerves. CONCLUSIONS: We conclude that reproducible correlations showing the sensory innervations for the knee are linked to muscular structures. However, high variability among individuals makes it difficult to predict their paths. Our systematic approach, using direct visualization via ultrasound, allows a more accurate placement of the needle for therapeutic purposes.

Transient thermal sympathectomy as a possible mechanism for hypotension after kyphoplasty: a case report.

BACKGROUND: Vertebroplasty and kyphoplasty are minimally invasive treatments for vertebral compression fractures. Although infrequent, both transitory and persistent adverse effects have been reported. They range from asymptomatic to severe neurological deficits that are caused directly by polymethylmethacrylate (PMMA) leakage or may be related to local or general reactions not due to PMMA leakage. Transitory hypotension after the procedure has been observed, but the characteristics and etiology of this phenomenon are not defined. OBJECTIVE: To describe a case of prolonged hypotension after kyphoplasty and suggest a possible mechanism. METHODS: Six months after L2 kyphoplasty, a 63-year-old woman with severe osteoporosis developed a new back pain due to compression fracture of L1 and compression deformity of the superior L3 endplate. The patient underwent bilateral kyphoplasty at the L1 and L3 levels. She developed persistent hypotension for approximately 46 hours immediately after the procedure. Common causes of hypotension were ruled out and the event resolved spontaneously. RESULTS: On the basis of needle placement, the temporal relationship between the procedure and blood pressure change, and the lack of other identifiable causes, thermal sympathectomy from heating of the PMMA adjacent to the paravertebral sympathetic chain is proposed as a potential mechanism. LIMITATIONS: Single case report based on clinical observation. DISCUSSION: Prolonged hypotension can complicate kyphoplasty at upper lumbar levels. Two days of severe hypotension has not been described as a complication of kyphoplasty. Although the mechanism is unknown, a transient thermal sympathectomy may be the cause.

Using Transcranial Direct Current Stimulation to Treat Depression in HIV-Infected Persons: The Outcomes of a Feasibility Study.

UNLABELLED: Transcranial direct current stimulation (tDCS) is a novel non-invasive neuromodulatory method that influences neuronal firing rates and excitability of neuronal circuits in the brain. tDCS has been shown to relieve Major Depressive Disorder (MDD) in the general population, suggesting its potential for other vulnerable populations with high MDD prevalence. AIMS: This study evaluated the feasibility, safety, acceptability, and clinical outcomes of a 2-week tDCS antidepressant treatment in HIV-MDD co-diagnosed patients, and the feasibility of collecting serum and saliva for analysis of immunity biomarkers. METHODS: Ten enrolled patients underwent baseline evaluation and started the tDCS treatment (Monday-Friday for 2 weeks) delivered with Phoresor II 850 PM for 20 min at 2 mA at each visit, using two saline-soaked sponge electrodes placed over the F3 position of EEG 10-20 system and the contralateral supraorbital region. Outcome measures were collected at baseline, after the last tDCS and 2 weeks later. A quantitative microarray (Ray Bio Tech Inc.) for TH1/TH2 cytokines was used for saliva and plasma analysis. RESULTS: Analyzable outcome-data were obtained from eight subjects. Depression scores significantly decreased (p < 0.0005) after the treatment. No serious adverse events occurred. Several transient minor AEs and occasional changes of blood pressure and heart rate were noted. Mini-mental state examination scores remained unchanged or increased after the treatment. All subjects were highly satisfied with the protocol and treatment results and described the desire to find new treatments for HIV-MDD as motivating participation. CONCLUSION: Findings support feasibility and clinical potential of tDCS for HIV-MDD patients, and justify larger-sample, sham-controlled trials.

Oral ketamine in the palliative care setting: a review of the literature and case report of a patient with neurofibromatosis type 1 and glomus tumor-associated complex regional pain syndrome.

Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has been shown to be effective not only for its anesthetic properties but also for the analgesic and opiate-sparing effects. However, data on efficacy and safety of oral ketamine for the treatment of neuropathic or cancer pain syndromes is limited with most of the evidence based on small clinical trials and anecdotal experiences. In this review, we will analyze the clinical data on oral ketamine in the palliative care setting. After an extensive search using five major databases, a total of 19 relevant articles were included. No official clinical guidelines for the use of oral ketamine in this patient population were found. Studies on oral ketamine for cancer and neuropathic pain have shown mixed results which could be partially due to significant differences in hepatic metabolism. In addition, we will include a case report of a 38-year-old female with neurofibromatosis type 1 (NF1) with history of chronic, severe pain in her fingertips secondary to multiple glomus tumors which evolved into CRPS resistant to multiple therapies but responsive to oral ketamine. Based on our experience with oral ketamine, this drug should be administered after an intravenous trial to monitor response and side effects in patients with an adequate functional status. However, patients in the palliative care and hospice setting, especially the one at the end of their lives, may also benefit from oral ketamine even if an intravenous trial is not feasible.