Faculty Bibliography

Dorsal root ganglion (DRG) stimulation has recently emerged as a treatment for persistent neuropathic pain, but the permanent implantation of stimulator leads and the pulse generator can be difficult and is sometimes associated with complications. We used a single-incision approach to tunnel and implant the leads and pulse generator for DRG stimulation treatment in a patient suffering from intractable foot pain. At long-term follow-up, the patient experienced a decrease in pain intensity and improvement in function, without any complications. A single-incision implantation technique for DRG stimulator implantation may simplify implantation and decrease the risk of complications.

Coccydynia can be difficult to resolve with conventional treatment options. Dorsal root ganglion (DRG) stimulation has recently emerged as a treatment for chronic pain, but its application has not been described in the context of coccydynia. We used DRG stimulation treatment in a patient suffering from intractable coccyx pain. At long-term follow-up, the patient experienced a decrease in pain intensity and improvement in function, without any complications. DRG stimulation may be a treatment modality for coccydynia refractory to other approaches.

BACKGROUND: The current American Society of Regional Anesthesia (ASRA) guidelines recommend discontinuing anti-thrombotic therapy prior to any interventional spine procedures to decrease the incidence of bleeding complications. However, discontinuing anti-thrombotics may pose considerable danger in terms of cerebrovascular and cardiovascular events. Recent evidence suggests that some spinal interventions may still be performed safely with anti-thrombotics on board and some practitioners thus elect to continue certain anti-thrombotics for these procedures. OBJECTIVE: To assess the rate of adverse events in patients undergoing spine procedures that are currently classified by the ASRA guidelines as "low-to-intermediate bleeding risk," while being on continued anti-thrombotic therapy. STUDY DESIGN: Retrospective cohort study. SETTING: Interventional pain management practice. METHODS: A retrospective chart review was performed on patients who underwent low-to-intermediate risk spine procedures with variable anti-thrombotic medications continued throughout the course of treatment. RESULTS: Between October 2015 and May 2016, out of 2,204 patients who underwent low-to-intermediate risk spine procedures, we identified 490 patients on anti-thrombotic medications. These included aspirin (N = 275), P2Y12 inhibitors (N = 129), warfarin (N = 62), heparin (N = 10), factor Xa inhibitors (N = 55), and dipyridamole (N = 1). Forty-two patients were on multiple anti-thrombotics. Anti-thrombotics were continued throughout the procedure for 467 of 490 patients (88%). One bleeding complication (injection site bleeding) occurred in a patient that continued clopidogrel and aspirin during a lumbar radiofrequency ablation. We encountered no bleeding complications attributable to anti-thrombotics in the other 466 procedures in which anti-thrombotics were continued during lumbar (N = 260), thoracic (N = 18), and cervical (N = 40) medial branch injections, sacroiliac injections (N = 47), and during lumbar (N = 87) thoracic (N = 2), and cervical (N = 12) medial branch radiofrequency ablations. LIMITATIONS: The retrospective nature of the study and its reliance on electronic medical records are potential limitations. CONCLUSIONS: Continuing anti-thrombotic medication during medial branch and sacroiliac injections may be possible. KEY WORDS: Interventional pain management, thrombotic complications, hemostasis, anti-coagulation, bleeding complications.

Spinal cord stimulation is an effective treatment modality for refractory neuropathic pain conditions, but the placement of leads can be challenging due to unforeseen anatomical variations. We used a retrograde C7-T1 approach to place a lead at the bottom of T8 in a patient suffering from failed back surgery syndrome. We were able to achieve adequate stimulation in her lower back and legs, which resulted in significant reduction in pain intensity during the spinal cord stimulation trial. Cervical retrograde placement of leads may represent an alternative method for successful placement of percutaneous leads in patients with abnormal anatomy due to thoracic postsurgical changes.

BACKGROUND AND PURPOSE/OBJECTIVE:Changes in extracellular fluid osmolarity, which occur after tissue damage and disease, cause inflammation and maintain chronic inflammatory states by unknown mechanisms. Here, we investigated whether the osmosensitive channel, transient receptor potential vanilloid 4 (TRPV4), mediates inflammation to hypotonic stimuli by a neurogenic mechanism. EXPERIMENTAL APPROACH/METHODS:TRPV4 was localized in dorsal root ganglia (DRG) by immunofluorescence. The effects of TRPV4 agonists on release of pro-inflammatory neuropeptides from peripheral tissues and on inflammation were examined. KEY RESULTS/RESULTS:Immunoreactive TRPV4 was detected in DRG neurones innervating the mouse hindpaw, where it was co-expressed in some neurones with CGRP and substance P, mediators of neurogenic inflammation. Hypotonic solutions and 4alpha-phorbol 12,13-didecanoate, which activate TRPV4, stimulated neuropeptide release in urinary bladder and airways, sites of neurogenic inflammation. Intraplantar injection of hypotonic solutions and 4alpha-phorbol 12,13-didecanoate caused oedema and granulocyte recruitment. These effects were inhibited by a desensitizing dose of the neurotoxin capsaicin, antagonists of CGRP and substance P receptors, and TRPV4 gene knockdown or deletion. In contrast, antagonism of neuropeptide receptors and disruption of TRPV4 did not prevent this oedema. TRPV4 gene knockdown or deletion also markedly reduced oedema and granulocyte infiltration induced by intraplantar injection of formalin. CONCLUSIONS AND IMPLICATIONS/CONCLUSIONS:Activation of TRPV4 stimulates neuropeptide release from afferent nerves and induces neurogenic inflammation. This mechanism may mediate the generation and maintenance of inflammation after injury and during diseases, in which there are changes in extracellular osmolarity. Antagonism of TRPV4 may offer a therapeutic approach for inflammatory hyperalgesia and chronic inflammation.