Adverse Events Associated With 10-kHz Dorsal Column Spinal Cord Stimulation: A 5-Year Analysis of the Manufacturer and User Facility Device Experience (MAUDE) Database.

BACKGROUND: High-frequency (10-kHz) spinal cord stimulation (SCS) continues to be an emerging therapy in chronic pain management. The same complications that plagued earlier SCS systems may affect newer stimulation technologies, although there is limited data on the type of complications and surgical management of these complications. OBJECTIVE: The aim of this study was to systematically examine real-world complications associated with 10-kHz SCS reported on the Manufacturer and User Facility Device Experience (MAUDE) database. MATERIALS AND METHODS: The MAUDE database was queried for entries reported between January 1, 2016 and December 31, 2020. Entries were classified into procedural complications, device-related complications, patient complaints, surgically managed complications, serious adverse events, and/or other complications. Primary outcomes included type and frequency of complications, and surgical management of complications. RESULTS: A total of 1651 entries were analyzed. Most entries were categorized as procedural complications (72.6%), followed by serious adverse events (10.5%), device-related complications (10.5%), and patient complaints (9.9%). Most complications were managed surgically with explant (50.9%) rather than revision (5.0%) or incision/drainage (6.6%). Of procedural complications, the most common entries included non-neuraxial infection (52.9%), new neurological symptoms (14.7%), and dural puncture (9.5%). Of device-related complications, the most common entries included lead damage (41.6%), erosion (18.5%), and difficult insertion (11.5%). CONCLUSION: This retrospective 5-year analysis of complications from10-kHz SCS provides a real-world assessment of safety data unique for this stimulation modality. This analysis may help inform future clinical decisions, lead to device enhancement and optimization, and improve mitigation of risks to provide safe and efficacious use of 10-kHz SCS.

Comparative Effectiveness of Landmark-guided Greater Occipital Nerve (GON) Block at the Superior Nuchal Line Versus Ultrasound-guided GON Block at the Level of C2: A Randomized Clinical Trial (RCT).

OBJECTIVES: The purpose of this single center, prospective randomized controlled trial was to compare clinical outcomes between an ultrasound-guided greater occipital nerve block (GONB) at the C2 vertebral level versus landmark-based GONB at the superior nuchal line. METHODS: Patients with occipital neuralgia or cervicogenic headache were randomized to receive either a landmark-based GONB with sham ultrasound at the superior nuchal line or ultrasound-guided GONB at the C2 vertebral level with blinding of patients and data analysis investigators. Clinical outcomes were assessed at 30 minutes, 2 weeks, and 4 weeks postinjection. RESULTS: Thirty-two patients were recruited with 16 participants in each group. Despite randomization, the ultrasound-guided GONB group reported higher numeric rating scale (NRS) scores at baseline. Those in the ultrasound-guided GONB group had a significant decrease in NRS from baseline compared with the landmark-based GONB group at 30 minutes (change of NRS of 4.0 vs. 2.0) and 4-week time points (change of NRS of 2.5 vs. -0.5). Both groups were found to have significant decreases in Headache Impact Test-6. The ultrasound-guided GONB had significant improvements in NRS, severe headache days, and analgesic use at 4 weeks when compared with baseline. No serious adverse events occurred in either group. CONCLUSIONS: Ultrasound-guided GONBs may provide superior pain reduction at 4 weeks when compared with landmark-based GONBs for patients with occipital neuralgia or cervicogenic headache.

Perioperative Opioid Consumption and Clinical Outcomes in Surgical Patients With a Pre-existing Opioid-Based Intrathecal Drug Delivery System.

BACKGROUND: Intrathecal drug delivery systems (IDDS) have been utilized for over 3 decades for management of chronic pain and spasticity. Patients with IDDS may present for surgical procedures unrelated to the IDDS device, although data are limited regarding perioperative outcomes. METHODS: This is a historical matched cohort study conducted between January 1, 2007 and December 31, 2016 of patients with an opioid-based IDDS versus matched control patients undergoing surgery excluding interventional pain procedures. Patients in the IDDS group were matched with up to 2 patients without an IDDS. Multivariable regression analyses were utilized to assess differences in the primary outcome of cumulative perioperative opioid consumption (ie, intraoperative and postanesthesia care unit [PACU] opioid consumption), and opioid consumption during the first 24 and 72 postoperative hours. Postoperative clinical outcomes were also assessed including escalating oxygen requirements, naloxone administration, pain-sedation mismatch, and perioperative pain service consultation. RESULTS: A total of 321 surgeries were included, 112 with IDDS and 209 controls, with median (interquartile range [IQR]) age of 57 (49-64) years. Compared to matched controls, patients with an IDDS had greater perioperative opioid consumption (median [IQR] oral morphine milligram equivalents [OME] of 110 [60-163] vs 93 [IQR, 53-142]; adjusted multiplicative increase 1.28 [95% confidence interval {CI}, 1.03-1.59]; P = .026). IDDS patients also had greater opioid consumption in the first 24 and 72 postoperative hours (multiplicative increases of 2.23 [95% CI, 1.36-3.63], P = .001, and 2.46 [95% CI, 1.41-4.32], P = .002, respectively). There were no significant differences in postoperative oxygen requirements, naloxone administration, or pain-sedation mismatch. Inpatient pain medicine consultation was more frequent in IDDS patients compared to controls (51.8% vs 6.2%; P < .001). CONCLUSIONS: Patients with opioid-based IDDS received more perioperative opioids and were more likely to receive postoperative pain service consultation compared to matched controls. There were no significant differences in clinical safety outcomes, suggesting tolerance for higher opioid doses. Further research is warranted to optimize perioperative outcomes in those with IDDS.

Peripheral Nerve Stimulation for Occipital Neuralgia.

BACKGROUND: Chronic headaches are the second most prevalent disease and second most common cause for years lived with disability worldwide. Occipital neuralgia can cause headaches or be present in addition to other more prevalent causes of headache. If these headaches fail to respond to conservative and pharmacological therapy, physicians proceed to more invasive treatments, starting with infiltration of the greater occipital nerve with local anesthetic with or without corticosteroids, followed by nerve ablation or stimulation. Occipital nerve stimulation gained more popularity as the technology improved and more pain physicians received training on interventional procedures. METHODS: In this manuscript, we are presenting our experience with ultrasound-guided implant of occipital nerve stimulators using peripheral nerve stimulator systems. After confirming appropriateness of treatment by a successful occipital nerve block (i.e., resulting in >50% relief in patients' pain intensity), we implanted five stimulator systems in three patients (two bilateral). RESULTS: We followed these patients for an average of eight months, and the average pain reduction was ∼50%. We did not observe any adverse events during or immediately after surgery. One patient developed an adverse reaction to the adhesive of the battery transmitter, but it was not severe enough to stop her from using the stimulator. CONCLUSIONS: Considering the ease of implant and minimal side effects, implant of peripheral nerve stimulators to stimulate the occipital nerve is a promising treatment modality for patients with chronic headache who present with features of occipital neuralgia. However, wider use of this treatment modality is subject to further studies.

Serotonin Syndrome in the Perioperative Setting.

BACKGROUND Serotonin syndrome is a life-threatening condition that can lead to neurologic complications and is associated with the use of serotonergic medications. As the use of antidepressant medications has increased, the incidence of perioperative serotonin syndrome has transitioned from a rare diagnosis to one that should be considered as a differential diagnosis for any patient displaying signs of neuroexcitation. CASE REPORT A 70-year-old man (ASA 2) with a history of vestibular migraines (treated with venlafaxine), gastroesophageal reflux disease, and benign prostatic hyperplasia presented to our institution for photoselective vaporization of the prostate. Upon review of prior anesthetic records, his medical chart was found to list a propofol allergy. In discussion with the patient, he stated the reaction was rigidity. The anesthesiologist and patient agreed this was not an allergy. Thus, the patient was induced with propofol and given ketamine and fentanyl boluses throughout the procedure. During emergence, the patient exhibited myoclonic jerks in the upper and lower extremities. He was given intravenous meperidine for postoperative shivering; minutes after administration, the myoclonic jerks and rigidity worsened. The anesthesia team raised concern about serotonin syndrome. Intravenous midazolam improved the patient's myoclonic jerks and rigidity. CONCLUSIONS Patients with a history of rigidity/movement disorders during the perioperative period may have experienced serotonin toxicity. It is possible, as in our case, for this history to have been labelled as an allergy to a perioperative medication. Clinicians should remain vigilant for patients at risk of developing serotonin syndrome, such as those taking outpatient medications that increase neuronal serotonin.

Role of mutations in the cellular internalization of amyloidogenic light chains into cardiomyocytes.

Light chain (AL) amyloidosis is characterized by the misfolding of immunoglobulin light chains, accumulating as amyloid fibrils in vital organs. Multiple reports have indicated that amyloidogenic light chains internalize into a variety of cell types, but these studies used urine-derived proteins without indicating any protein sequence information. As a result, the role of somatic mutations in amyloidogenic protein internalization has not been yet studied. We characterized the internalization of AL-09, an AL amyloidosis protein into mouse cardiomyocytes. We also characterized the internalization of the germline protein κI O18/O8, devoid of somatic mutations, and three AL-09 restorative mutations (I34N, Q42K, and H87Y) previously characterized for their role in protein structure, stability, and amyloid formation kinetics. All proteins shared a common internalization pathway into lysosomal compartments. The proteins caused different degrees of lysosomal expansion. Oregon green (OG) labeled AL-09 showed the most rapid internalization, while OG-Q42K presented the slowest rate of internalization.