Ultrasound-Guided Percutaneous Peripheral Nerve Stimulation of C2 Dorsal Root Ganglion for the Treatment of Refractory Atypical Facial Pain: A Technical Report and Case Series.

BACKGROUND: Chronic craniofacial pain can be difficult to manage clinically. This technical report documents the peripheral nerve stimulation of the C2 dorsal root ganglion as an effective modality to treat refractory atypical facial pain. MATERIALS AND METHODS: In this case series, three patients with chronic refractory atypical facial pain and p >50% pain relief following diagnostic C2 dorsal root ganglion blockade underwent ultrasound-guided percutaneous placement of a peripheral nerve stimulator adjacent to the C2 dorsal root ganglion. Patients were then observed clinically and monitored for improvement in symptoms and adverse events. RESULTS: Three patients underwent peripheral nerve stimulator placement. At follow-up, there were no reported adverse events, and all patients reported satisfactory improvement in pain. CONCLUSION: The neuromodulation of C2 dorsal root ganglion via ultrasound-guided percutaneously implanted peripheral nerve stimulator is a novel and potentially effective approach for the management of chronic refractory craniofacial pain.

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.

Transforaminal Epidural Injection of Local Anesthetic and Dorsal Root Ganglion Pulsed Radiofrequency Treatment in Lumbar Radicular Pain: A Randomized, Triple-Blind, Active-Control Trial.

BACKGROUND: Lumbar radicular pain (LRP) results from inflammation and irritation of lumbar spinal nerves and the dorsal root ganglion (DRG). METHODS: Our study is a prospective, triple-blind, randomized, activecontrol trial (CTRI/2016/02/006666) comparing transforaminal epidural local anesthetic (LA) injection and pulsed radiofrequency treatment of DRG in patients with chronic LRP. Patients with LRP after failed conservative management for >3 months received selective diagnostic nerve root block with 1 mL 2% lidocaine. Fifty patients showing positive responses were divided into groups of 25 each. The LA group received transforaminal epidural injection of 1 mL 0.5% bupivacaine. The lumbar pulsed radiofrequency (LPRF) group received transforaminal epidural injection of 1 mL 0.5% bupivacaine with 3 cycles of pulsed radiofrequency of the DRG for 180 seconds RESULTS: Both groups were compared by observing pain intensity on a 0- to 100-point VAS and improvement in functional status by the Oswestry Disability Index (ODI version 2.0) at 2 weeks and 1, 2, 3, and 6 months. All baseline variables were comparable between the 2 groups. Statistically significant reduction in both outcomes was seen in the LPRF group compared to the LA group from 2 weeks to 6 months. One hundred percent of patients in the LPRF group had a ≥20- point decrease in VAS and significant percentage reduction in ODI at all time intervals up to 6 months, whereas it was seen in 80% and 28% of patients in the LA group at 3 and 6 months, respectively. No complications were seen in any patients CONCLUSION: Pulsed radiofrequency of the DRG applied for longer duration results in long-term pain relief and improvement in the functional quality of life in patients with chronic LRP.

Location and Volume of MRI Artifacts in Patients With Implanted Sphenopalatine Ganglion Neurostimulators for Treatment of Chronic Cluster Headache.

INTRODUCTION: Sphenopalatine ganglion stimulation (SPG-S) is an invasive form of neuromodulation by which a neurostimulator is implanted into the pterygopalatine fossa to treat refractory chronic cluster headache. The implant is MRI conditional, up to 3 T, however there is no clinical data on the shape, size, and location of the artifact produced by the implant. MATERIALS AND METHODS: Records of patients with SPG-S were analyzed for postoperative cranial MRI scans. MRI and intraoperative CT scans for visualization of the implant were fused and volumetry was performed for both the implant and the MRI artifact in different MRI sequences. RESULTS: In total, n = 3 patients with postoperative MRI scans were identified. The mean CT artifact volume was 0.73 cm3 (±0.15 cm3 ). MRI artifact volume differed between sequences (range: 25.2-220.7 cm3 ). The intracranial space was largely unaffected besides the pole of the ipsilateral temporal lobe and the basal frontal gyrus. MRI artifacts affected the extracranial space (orbit, maxillary and ethmoid sinuses, and parts of the parotid gland). No adverse events occurred during or after MRI scans. CONCLUSIONS: Cranial MRI scans with SPG-S implants were safely performed in three patients following the manufacturer's MRI conditions. MRI artifacts were mostly located in the extracranial space. Brain MRI imaging is largely unaffected. CONFLICT OF INTEREST: The authors declare no potential conflicts of interest with respect to research, authorship, and/or publication of this article.

Open Microsurgical Dorsal Root Ganglion Lead Placement.

INTRODUCTION: Dorsal root ganglion stimulation (DRG) is a new but well-established neuromodulation technique allowing new indications and superiority to pre-existing stimulation techniques such as spinal cord stimulation in selected pain etiologies. Previous surgical procedures in the implantation area pose a challenge for the percutaneous technique and are therefore considered contraindications for DRG stimulation surgery. We describe the successful open DRG electrode placement in two patients with previous surgeries suffering from severe radiculopathy due to foraminal stenosis. METHODS: Percutaneous implantation attempts failed and an open laminotomy/foraminotomy followed by open lead placement was performed. Leads and loops were placed under the microscope, lead location was verified by x-ray during surgery. Leads and loops were kept in position with fibrin glue and fibrin sealant patches. No special tool was required for open lead placement. RESULTS: In both patients, surgery resulted in lead and loop placement resembling the results seen in percutaneous technique. Programming and stimulation results are similar to observations made following percutaneous techniques in one patient significantly lower stimulation amplitudes were necessary. In 18 and 12 months follow-up, respectively, lead location and paresthesia coverage were stable. CONCLUSION: The option of open electrode placement should be taken into account following unsuccessful percutaneous lead placement. A combination of fibrin sealant patch and fibrin glue may be a good option for stabilization of the lead and specially of the strain relief loops in open placement. Knowledge of basic spinal surgery techniques and experience in percutaneous DRG stimulation is necessary to perform this procedure.

The mechanistic basis for photobiomodulation therapy of neuropathic pain by near infrared laser light.

BACKGROUND AND OBJECTIVE: Various irradiances have been reported to be beneficial for the treatment of neuropathic pain with near infrared light. However, the mechanistic basis for the beneficial outcomes may vary based on the level of irradiance or fluence rate used. Using in vivo and in vitro experimental models, this study determined the mechanistic basis of photobiomodulation therapy (PBMT) for the treatment of neuropathic pain using a high irradiance. STUDY DESIGN/MATERIALS AND METHODS: In vitro experiments: Cultured, rat DRG were randomly assigned to control or laser treatment (LT) groups with different irradiation times (2, 5, 30, 60, or 120 seconds). The laser parameters were: output power = 960 mW, irradiance = 300 mW/cm2 , 808 nm wavelength, and spot size = 3 cm diameter/area = 7.07cm2 , with different fluences according to irradiation times. Mitochondrial metabolic activity was measured with the MTS assay. The DRG neurons were immunostained using a primary antibody to ß-Tubulin III. In vivo experiments: spared nerve injury surgery (SNI), an animal model of persistent peripheral neuropathic pain, was used. The injured rats were randomly divided into three groups (n = 5). (i) Control: SNI without LT; (ii) Short term: SNI with LT on day 7 and euthanized on day 7; (iii) Long term: SNI with LT on day 7 and euthanized on day 22. An 808 nm wavelength laser was used for all treatment groups. Treatment was performed once on day 7 post-surgery. The transcutaneous treatment parameters were: output power: 10 W, fluence rate: 270 mW/cm2 , treatment time: 120 seconds. The laser probe was moved along the course of the sciatic/sural nerve during the treatment. Within 1 hour of irradiation, behavior tests were performed to assess its immediate effect on sensory allodynia and hyperalgesia caused by SNI. RESULTS: In vitro experiments: Mitochondrial metabolism was significantly lower compared to controls for all LT groups. Varicosities and undulations formed in neurites of DRG neurons with a cell body diameter 30 µm or less. In neurites of DRG neurons with a cell body diameter of greater than 30 µm, varicosities formed only in the 120 seconds group. In vivo experiments: For heat hyperalgesia, there was a statistically significant reduction in sensitivity to the heat stimulus compared to the measurements done on day 7 prior to LT. A decrease in the sensitivity to the heat stimulus was found in the LT groups compared to the control group on days 15 and 21. For cold allodynia and mechanical hyperalgesia, a significant decrease in sensitivity to cold and pin prick was found within 1 hour after LT. Sensitivity to these stimuli returned to the control levels after 5 days post-LT. No significant difference was found in mechanical allodynia between control and LT groups for all time points examined. CONCLUSION: These in vitro and in vivo studies indicate that treatment with an irradiance/fluence rate at 270 mW/cm2 or higher at the level of the nerve can rapidly block pain transmission. A combination therapy is proposed to treat neuropathic pain with initial high irradiance/fluence rates for fast pain relief, followed by low irradiance/fluence rates for prolonged pain relief by altering chronic inflammation. Lasers Surg. Med. 49:516-524, 2017. © 2017 Wiley Periodicals, Inc.

Effect of low level laser therapy on chronic compression of the dorsal root ganglion.

Dorsal root ganglia (DRG) are vulnerable to physical injury of the intervertebral foramen, and chronic compression of the DRG (CCD) an result in nerve root damage with persistent morbidity. The purpose of this study was to evaluate the effects of low level laser therapy (LLLT) on the DRG in a CCD model and to determine the mechanisms underlying these effects. CCD rats had L-shaped stainless-steel rods inserted into the fourth and fifth lumbar intervertebral foramen, and the rats were then subjected to 0 or 8 J/cm2 LLLT for 8 consecutive days following CCD surgery. Pain and heat stimuli were applied to test for hyperalgesia following CCD. The levels of TNF-α, IL-1ß and growth-associated protein-43 (GAP-43) messenger RNA (mRNA) expression were measured via real-time PCR, and protein expression levels were analyzed through immunohistochemical analyses. Our data indicate that LLLT significantly decreased the tolerable sensitivity to pain and heat stimuli in the CCD groups. The expression levels of the pro-inflammatory cytokines TNF-α and IL-1ß were increased following CCD, and we found that these increases could be reduced by the application of LLLT. Furthermore, the expression of GAP-43 was enhanced by LLLT. In conclusion, LLLT was able to enhance neural regeneration in rats following CCD and improve rat ambulatory behavior. The therapeutic effects of LLLT on the DRG during CCD may be exerted through suppression of the inflammatory response and induction of neuronal repair genes. These results suggest potential clinical applications for LLLT in the treatment of compression-induced neuronal disorders.

A patient-mount navigated intervention system for spinal diseases and its clinical trial on percutaneous pulsed radiofrequency stimulation of dorsal root ganglion.

STUDY DESIGN: Development of a patient-mount navigated intervention (PaMNI) system for spinal diseases. An in vivo clinical human trial was conducted to validate this system. OBJECTIVE: To verify the feasibility of the PaMNI system with the clinical trial on percutaneous pulsed radiofrequency stimulation of dorsal root ganglion (PRF-DRG). SUMMARY OF BACKGROUND DATA: Two major image guiding techniques, i.e., computed tomography (CT)-guided and fluoro-guided, were used for spinal intervention. The CT-guided technique provides high spatial resolution, and is claimed to be more accurate than the fluoro-guided technique. Nevertheless, the CT-guided intervention usually reaches higher radiograph exposure than the fluoro-guided counterpart. Some navigated intervention systems were developed to reduce the radiation of CT-guided intervention. Nevertheless, these systems were not popularly used due to the longer operation time, a new protocol for surgeons, and the availability of such a system. METHODS: The PaMNI system includes 3 components, i.e., a patient-mount miniature tracking unit, an auto-registered reference frame unit, and a user-friendly image processing unit. The PRF-DRG treatment was conducted to find the clinical feasibility of this system. RESULTS: The in vivo clinical trial showed that the accuracy, visual analog scale evaluation after surgery, and radiograph exposure of the PaMNI-guided technique are comparable to the one of conventional fluoro-guided technique, while the operation time is increased by 5 minutes. CONCLUSION: Combining the virtues of fluoroscopy and CT-guided techniques, our navigation system is operated like a virtual fluoroscopy with augmented CT images. This system elevates the performance of CT-guided intervention and reduces surgeons' radiation exposure risk to a minimum, while keeping low radiation dose to patients like its fluoro-guided counterpart. The clinical trial of PRF-DRG treatment showed the clinical feasibility and efficacy of this system.