Complex regional pain syndrome of the knee after conventional radiofrequency ablation of the genicular nerves treated successfully with dorsal root ganglion stimulation: A case report.

BACKGROUND: Radiofrequency (RF) treatment of the genicular nerves offers pain relief in patients suffering from chronic knee pain including persistent post-surgical knee pain (PPSP). We present the first case report of the development of complex regional pain syndrome (CRPS) in a chronic knee pain patient after an RF ablation of the genicular nerves that was successfully treated with dorsal root ganglion (DRG) stimulation. CASE PRESENTATION: The patient developed increased pain, sympathetic and dysmorphic changes of the index knee 10 weeks after RF treatment for PPSP. Diagnosis of CRPS type II was made using positive clinical findings and the Budapest diagnostic tool. Laboratory workup and PET-CT were negative. The patient was refractory to usual care and she was treated successfully with dorsal ganglion root stimulation. CONCLUSIONS: Complex regional pain syndrome is a possible complication of RF ablation of the genicular nerves in patients with chronic knee pain, and DRG stimulation may be a treatment option. Physicians should be aware of this complication, especially when patients have a medical history of CRPS.

Detoxification of Neuromodulation-Eligible Patients by a Standardized Protocol: A Retrospective Pilot Study.

OBJECTIVES: Patients eligible for spinal cord stimulation (SCS) generally experience excruciating pain, requiring more opioid consumption, which is usually an indication for SCS implantation. After final implantation, SCS has the ability to stabilize or decrease opioid usage in half of the patients. In this study, opioids were actively eliminated prior to implantation of any neuromodulation device with a standardized detoxification protocol. This pilot study aims to explore the feasibility, effectiveness, and safety of this opioid detoxification protocol prior to neuromodulation techniques. MATERIALS AND METHODS: In this retrospective pilot study, 70 patients who were taking opioids and who were eligible for neuromodulation techniques underwent the detoxification program. A combined in- and out-patient clinic protocol was applied, whereby clonidine was the main component of both parts of the program. A multidisciplinary team with pain physicians and psychologists was responsible for performing this detoxification program. Safety and feasibility were systematically recorded during the hospitalization. RESULTS: No serious safety issues were reported. At the start of the program, patients reported a mild sedative effect of clonidine. Additionally, most patients presented mild symptoms of opioid withdrawal, which were partially countered by the sedative effect of clonidine. Both patients and the medical staff found this protocol feasible in clinical practice. Concerning the effectiveness, a statistically significant decrease in median morphine milligram equivalents (MMEs) was found with an MME of 175 (Q1-Q3: 118.1-240) at baseline, and at the last available follow-up visit the MME was 0 (Q1-Q3: 0-16.88). CONCLUSIONS: This standardized detoxification program has proven its effectiveness, safety, and feasibility in this single-center experience pilot study in patients eligible for neuromodulation techniques.

Dorsal root ganglion stimulation for patients with refractory pain due to anterior cutaneous nerve entrapment syndrome: A case series.

BACKGROUND: Anterior cutaneous nerve entrapment syndrome (ACNES) is a painful condition that can be refractory in a small percentage of patients. Abdominal pain caused by thoracic nerve entrapment in the abdominal wall characterizes ACNES. In the small number of refractory patients to all standard treatments, medication overuse and abuse are serious problems. Dorsal root ganglion (DRG) stimulation might be a good treatment to improve pain scores and to lower medication use. METHODS: We describe the retrospective analysis of nine cases of patients who underwent DRG stimulation for refractory ACNES using a treatment algorithm. We focused on reported pain intensity scores, medication use, and adverse events. RESULTS: All nine patients experienced a decrease in pain intensity during the trial period and received a permanent pulse generator implantation. Three months after permanent implantation, eight of nine patients showed a pain reduction of more than 50%. Medication use was substantially lower. DISCUSSION AND CONCLUSION: This case series shows that DRG stimulation might be a very good treatment for refractory ACNES.

Trigeminal neuropathy: Two case reports of gasserian ganglion stimulation.

This report describes the successful treatment of two patients with trigeminal neuropathy by using gasserian ganglion stimulation. Case reports: The first case report deals with a 53-year-old woman suffering from right-sided facial pain after a gamma knife lesion for schwannoma of the right inner ear. For 9 years, several interventions with the aim of relieving the pain were unsuccessful; in fact, they had aggravated the symptoms. A trial with a neurostimulator at the level of the Gasser ganglion had an immediately positive effect on her score for facial pain, which decreased from 7.3 to 0 on a visual analog scale, assessed during a period of 2 months. Additionally, the patient had weaned off all her medication by the end of the period. The second case report describes a 64-year-old man suffering from trigeminal neuropathy, which mainly manifested itself as an itch. For a period of 15 years, neither medication nor several interventions were effective. A trial with an electrode at the level of the Gasser ganglion reduced his pain score from 7.0 to 1.5 on a visual analog scale, assessed during a period of three months. His medication could be limited to pregabalin 150 mg bidaily. In contrast, prior to the implantation, his oral medication consisted of pregabalin 75 mg up to five times a day. Conclusion: These case reports show that stimulation of the gasserian ganglion is a successful, minimally invasive, and non-destructive treatment in refractory trigeminal neuropathy and should be considered earlier in the treatment algorithm of trigeminal neuropathy.

Real-World Analysis: Long-Term Effect of Spinal Cord Stimulation With Different Waveforms for Patients With Failed Back Surgery Syndrome.

INTRODUCTION: Spinal cord stimulation (SCS) is effective for patients with failed back surgery syndrome (FBSS). SCS improves their pain, as well as their functionality and health-related quality of life. Different waveforms for SCS have emerged that show improvement in small prospective studies. Analysis of real-world data shows the clinical implementation and the effect of different waveforms in SCS. METHODS: A real-world analysis was performed of 208 patients with FBSS who were treated over 3 years. Stimulators with tonic, burst, high-density, and 10-kHz high-frequency (HF10) waveforms were implanted in patients with FBSS who had predominant pain in the back, legs, or both back and legs. Pain as measured by the VAS, functional disability as measured by the Oswestry Disability Index (ODI), and health-related quality of life as measured by the 3-level EuroQol 5-Dimension (EQ5D-3L) questionnaire were determined at baseline and for outcome assessment. RESULTS: SCS is effective for patients with FBSS. This analysis showed a change in baseline VAS score from 8.0 to 4.7 (P < 0.0001) at 24 months. The EQ5D-3L score improved from 0.29 to 0.49 (P < 0.0001) at 24 months. The ODI score improved from 54% to 42% (P < 0.0001) at 24 months. The unanticipated explantation rate was only 1.6%. CONCLUSION: This study of SCS showed significant long-term improvement in pain, disability, and quality of life in a large dataset of patients with FBSS. Strict selection procedures and a strong opioid policy contributed to the high success rate and low unanticipated explantation rate. There was no difference in pain reduction between tonic and HF10 stimulation. Further investigation is necessary to detect any difference between other waveforms of SCS.

Predicting the Response of High Frequency Spinal Cord Stimulation in Patients with Failed Back Surgery Syndrome: A Retrospective Study with Machine Learning Techniques.

Despite the proven clinical value of spinal cord stimulation (SCS) for patients with failed back surgery syndrome (FBSS), factors related to a successful SCS outcome are not yet clearly understood. This study aimed to predict responders for high frequency SCS at 10 kHz (HF-10). Data before implantation and the last available data was extracted for 119 FBSS patients treated with HF-10 SCS. Correlations, logistic regression, linear discriminant analysis, classification and regression trees, random forest, bagging, and boosting were applied. Based on feature selection, trial pain relief, predominant pain location, and the number of previous surgeries were relevant factors for predicting pain relief. To predict responders with 50% pain relief, 58.33% accuracy was obtained with boosting, random forest and bagging. For predicting responders with 30% pain relief, 70.83% accuracy was obtained using logistic regression, linear discriminant analysis, boosting, and classification trees. For predicting pain medication decrease, accuracies above 80% were obtained using logistic regression and linear discriminant analysis. Several machine learning techniques were able to predict responders to HF-10 SCS with an acceptable accuracy. However, none of the techniques revealed a high accuracy. The inconsistent results regarding predictive factors in literature, combined with acceptable accuracy of the currently obtained models, might suggest that routinely collected baseline parameters from clinical practice are not sufficient to consistently predict the SCS response with a high accuracy in the long-term.