Predictors of Skip Laminotomy for Placement of Paddle Leads for Spinal Cord Stimulation.

OBJECTIVES: Placement of a standard paddle lead for spinal cord stimulation (SCS) requires a laminotomy for positioning of the lead within the epidural space. During initial placement, an additional laminotomy or laminectomy, termed a "skip" laminotomy, may be necessary at a higher level to pass the lead to the appropriate midline position. Patient and radiographic factors that predict the need for a skip laminotomy have yet to be identified. MATERIALS AND METHODS: Participants who underwent SCS paddle placement at Albany Medical Center between 2016 and 2017 were identified. Operative reports were reviewed to identify the paddle type, level of initial laminotomy, target level, and skip laminotomy level. Preoperative thoracic magnetic resonance images (MRIs) were reviewed, and spinal canal diameter, interpedicular distance, and dorsal cerebral spinal fluid thickness were measured for each participant when available. RESULTS: A total of 106 participants underwent thoracic SCS placement. Of these, 97 had thoracic MRIs available for review. Thirty-eight participants required a skip laminotomy for placement of the paddle compared with 68 participants who did not. There was no significant difference in demographic features including age, sex, body mass index, and surgical history. Univariate analyses that suggested trends were selected for further analysis using binary logistic regression. Level of initial laminotomy (odds ratio [OR] = 1.51, p = 0.028), spinal canal diameter (OR = 0.71, p = 0.015), and dorsal cerebrospinal fluid thickness (OR = 0.61, p = 0.011) were correlated with skip laminotomy. Target level (OR = 1.27, p = 0.138) and time from trial (1.01, p = 0.117) suggested potential association. The multivariate regression was statistically significant, X2(10) = 28.02, p = 0.002. The model explained 38.3% of the variance (Nagelkerke R2) and predicted skip laminectomy correctly in 73.3% of cases. However, for the multivariate regression, only a decrease in spinal canal diameter (OR = 0.59, p = 0.041) was associated with a greater odds of skip laminotomy. CONCLUSIONS: This study aims to characterize the patient and radiographic factors that may predict the need to perform a skip laminotomy during the initial placement of SCS paddles. Here, we show that radiographic and anatomic variables, primarily spinal canal diameter, play an important role in predicting the need for a skip laminotomy. Furthermore, we suggest that target level for placement and level of initial laminotomy also may contribute. Further investigation of the predictive factors for performing a skip laminotomy would help optimize surgical planning and preoperative patient selection and counseling.

Comparison of Characteristics, Inpatient Outcomes, and Trends in Percutaneous Versus Open Placement of Spinal Cord Stimulators.

OBJECTIVES: Spinal cord stimulation (SCS) is an effective treatment modality for chronic pain conditions for which other treatment modalities have failed to provide relief. Ample prospective studies exist supporting its indications for use and overall efficacy. However, less is known about how SCS is used at the population level. Our objective is to understand the demographics, clinical characteristics, and utilization patterns of open and percutaneous SCS procedures. MATERIALS AND METHODS: The Nationwide Inpatient Sample data base of 2016-2019 was queried for cases of percutaneous or open placement (through laminotomy/laminectomy) of SCS (excluding SCS trials) using International Classification of Disease (ICD), 10th revision, procedure coding system. Baseline demographic characteristics, complications, ICD-Clinical Modification, Diagnosis Related Group, length of stay (LOS), and yearly implementation data were collected. Complications and outcomes were evaluated in total and between the open and percutaneous SCS groups. RESULTS: A total of 2455 inpatients had an SCS placed, of whom 1970 (80.2%) received SCS through open placement. Placement of open SCS was associated with Caucasian race (odds ratio [OR] = 1.671, p < 0.001), private insurance (OR = 1.332, p = 0.02), and age more than 65 years (OR = 1.25, p = 0.034). The most common diagnosis was failed back surgery syndrome (23.8%). Patients with percutaneous SCS were more likely to have a hospital stay of < 1 day (OR = 2.318; 95% CI, 1.586-3.387; p < 0.001). Implant complications during the inpatient stay were positively associated with open SCS placement and reported in 9.4% of these cases (OR = 3.247, p < 0.001). CONCLUSIONS: Patients who underwent open SCS placement were more likely to be older, Caucasian, and privately insured. Open SCS placement showed greater LOS and implant-related complications during their hospital stay. These findings highlight both potential socioeconomic disparities in health care access for chronic pain relief and the importance of increasing age and medical comorbidities as important factors that can influence SCS implants in the inpatient setting.

Treatment Strategies for Generator Pocket Pain.

OBJECTIVE: Generator site pain is a relatively common phenomenon in patients undergoing spinal cord stimulation (SCS) that complicates management and effective pain relief. This pain may be managed conservatively, with repositioning of the battery and, in some cases, with explant. Here we explore our experience with management of generator site pain ("pocket pain") in a large single-center study. METHODS: All SCS permanent implants and implantable pulse generator (IPG) placements over 9 years were reviewed. Of 785 cases, we identified 43 patients with pocket pain (5.5%). Demographics and treatments of the pocket pain cohort were analyzed. RESULTS: The mean age (± SEM) of the pocket pain cohort was 46.86 ± 1.06, and there were 10/33 males/females. Females were overrepresented in pocket pain cohort (76.7%) when compared with the total SCS cohort (59.0%) (X2 = 5.93, P = 0.015). Diagnosis included failed back surgery syndrome (51.2%), complex regional pain syndrome (23.3%), and chronic neuropathic pain (25.5%). No patients improved with conservative therapy. All patients either went on to revision (n = 23) or explant (n = 20). Time from initial surgery to development of pocket pain was 7.5 months (range: 0.3-88) and from pocket pain to revision surgery was 4.5 months (range: 0.4-26). In addition, significantly more pocket pain patients (65.1%) had workers' compensation (WC) insurance compared with patients without pocket pain (24.9%) (X2 = 33.3, P < 0.001). CONCLUSION: In our institutional experience, pocket pain was inadequately managed with conservative treatments. Being female and having SCS filed under WC increased risk of pocket pain. Future work will explore the nuances in device placement based on body shape and manual activity responsibilities.

Deep brain and motor cortex stimulation.

Deep brain stimulation (DBS) and motor cortex stimulation (MCS) are established surgical modalities that have been successfully used over the last several decades for treatment of numerous chronic pain disorders. Most often, these approaches are reserved for severe, disabling, and medically refractory syndromes after less invasive approaches have been tried and have failed. Although the exact mechanism of action for DBS and MCS remains unknown, it appears that these central neuromodulation processes have multifactorial effects on central pain processing and descending pain inhibition. Clinical studies and laboratory reports have shed some light on stimulation details and optimal parameters, as well as the choice of stimulation targets, best surgical indications, and expected long-term outcomes. Based on the worldwide published experience, it appears that additional data is needed to obtain regulatory approval for both MCS and DBS for the treatment of pain. Following approval, further clinical research will shape the ability to initiate, implement, and update comprehensive patient and procedure selection paradigms.

Responsive Neurostimulation Targeting the Anterior, Centromedian and Pulvinar Thalamic Nuclei and the Detection of Electrographic Seizures in Pediatric and Young Adult Patients.

Background: Responsive neurostimulation (RNS System) has been utilized as a treatment for intractable epilepsy. The RNS System delivers stimulation in response to detected abnormal activity, via leads covering the seizure foci, in response to detections of predefined epileptiform activity with the goal of decreasing seizure frequency and severity. While thalamic leads are often implanted in combination with cortical strip leads, implantation and stimulation with bilateral thalamic leads alone is less common, and the ability to detect electrographic seizures using RNS System thalamic leads is uncertain. Objective: The present study retrospectively evaluated fourteen patients with RNS System depth leads implanted in the thalamus, with or without concomitant implantation of cortical strip leads, to determine the ability to detect electrographic seizures in the thalamus. Detailed patient presentations and lead trajectories were reviewed alongside electroencephalographic (ECoG) analyses. Results: Anterior nucleus thalamic (ANT) leads, whether bilateral or unilateral and combined with a cortical strip lead, successfully detected and terminated epileptiform activity, as demonstrated by Cases 2 and 3. Similarly, bilateral centromedian thalamic (CMT) leads or a combination of one centromedian thalamic alongside a cortical strip lead also demonstrated the ability to detect electrographic seizures as seen in Cases 6 and 9. Bilateral pulvinar leads likewise produced reliable seizure detection in Patient 14. Detections of electrographic seizures in thalamic nuclei did not appear to be affected by whether the patient was pediatric or adult at the time of RNS System implantation. Sole thalamic leads paralleled the combination of thalamic and cortical strip leads in terms of preventing the propagation of electrographic seizures. Conclusion: Thalamic nuclei present a promising target for detection and stimulation via the RNS System for seizures with multifocal or generalized onsets. These areas provide a modifiable, reversible therapeutic option for patients who are not candidates for surgical resection or ablation.

Intraoperative navigation in surgical management of traumatic spine injury: a propensity score matching analysis.

BACKGROUND: Traumatic spinal injury (TSI) can lead to severe morbidity and significant health care resource utilization. Intraoperative navigation (ION) systems have been shown to improve outcomes in some populations. However, controversy about the benefit of ION remains. To our knowledge, there is no large database analysis studying the outcomes of ION on TSI patients. Here we hope to compare complications and outcomes in patients with TSI undergoing spinal fusion of 3 or more levels with or without the use of ION. METHODS: The 2015-2019 National Surgical Quality Improvement Program (NSQIP) database was queried for cases of posterior spinal instrumentation of 3 or more levels. This population was then selected for postoperative diagnosis consistent with TSI. The effect of prolonged operative time was analyzed for all patients. Propensity score matching analysis was performed to create ION case and non-ION control groups. Baseline demographic characteristics, complications, and outcome data were collected and compared between ION and non-ION groups. RESULTS: A total of 1,034 patients were included in the propensity matched analysis. Among comorbidities, only obesity was significantly more likely in the non-ION group. There was no difference in case complexity between the two groups. ION was associated with higher incidence of prolonged operative time but was a negative independent predictor for sepsis. Prolonged operative time was a significant independent predictor for pulmonary embolism and requirement of transfusion in all patients. Discharge to home, readmission, and reoperation rates did not differ between TSI patients with or without ION. CONCLUSIONS: Use of ION during posterior spinal fusion of 3 or more levels in TSI patients is not associated with worse outcomes. Prolonged operative time, rather than ION, appears to have a higher influence on the rate of complications in this population. Evaluation of ION in the context of specific populations and pathology is warranted to optimize its use.

Efficacy of Simultaneous Usage of Spinal Cord Stimulation and Intrathecal Therapy for Nonmalignant Chronic Neuropathic Pain.

BACKGROUND: Some patients with chronic pain and implanted spinal cord stimulators or intrathecal (IT) pumps fail to obtain significant pain relief. The use of dual modality treatment with both therapies is understudied. This study evaluated comprehensive outcomes in this patient population and reported outcomes primarily using IT ziconotide. METHODS: We retrospectively analyzed 11 patients with chronic pain treated with both spinal cord stimulation and IT therapy. When a primary treatment failed to achieve significant pain relief, a secondary device was trialed and implanted. Pain severity (measured by a numeric rating scale) was assessed by the change from baseline to after the first and second intervention. In a subset of patients (n = 6), quality-of-life metrics were also assessed. Outcome measures were analyzed closest to the 1-year follow-up date after implantation of the first modality and then at the most recent follow-up after implantation of the second modality. RESULTS: Spinal cord stimulation leads were percutaneous (n = 2) or paddles (n = 9) and commonly covered T8-10. IT medication included ziconotide (n = 8), baclofen (n = 1), hydromorphone (n = 1), and morphine/clonidine (n = 1). There was a mean of 19.64 ± 3.17 months between primary and secondary intervention. There was a significant improvement in pain severity from baseline to implantation of the second modality (P = 0.032) at a mean follow-up of 50.18 ± 11.83 months. CONCLUSIONS: Dual modality therapy is a potential treatment option in patients who have lost efficacy with a single neuromodulation modality. Further study is required to identify potential responders and nonresponders.

Sex-specific effects of subthalamic nucleus stimulation on pain in Parkinson's disease.

OBJECTIVE: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is known to reduce motor symptoms of Parkinson's disease (PD). The effects of DBS on various nonmotor symptoms often differ from patient to patient. The factors that determine whether or not a patient will respond to treatment have not been elucidated. Here, the authors evaluated sex differences in pain relief after DBS for PD. METHODS: The authors prospectively evaluated 20 patients preoperatively and postoperatively after bilateral STN DBS with the validated numeric rating scale (NRS), Revised Oswestry Disability Index for low-back pain (RODI), and King's Parkinson's Disease Pain Scale (KPDPS) and assessed the impact of sex as a biological variable. RESULTS: The cohort consisted of 6 female and 14 male patients with a mean duration of 11.8 ± 2.0 months since DBS surgery. Females were significantly older (p = 0.02). Covariate analysis, however, showed no effect of age, stimulation settings, or other confounding variables. KPDPS total scores statistically significantly improved only among males (p < 0.001). Males improved more than females in musculoskeletal and chronic subsets of the KPDPS (p = 0.03 and p = 0.01, respectively). RODI scores significantly improved in males but not in females (p = 0.03 and p = 0.30, respectively). Regarding the NRS score, the improvements seen in both sexes in NRS were not significant. CONCLUSIONS: Although it is well recognized that pain complaints in PD are different between men and women, this study is unique in that it examines the sex-specific DBS effects on this symptom. Considering sex as a biological variable may have important implications for DBS pain outcome studies moving forward.

Intrathecal Pain Therapy for the Management of Chronic Noncancer Pain.

Intrathecal drug delivery has been well established an effective and safe method for the treatment of pain, including palliative cancer-related and chronic nonmalignant pain. In this article, we discuss the role of intrathecal pain therapy in the management of chronic, refractory nonmalignant pain. Common indications, patient selection criteria, medication options, complications, and adverse events are discussed within the context of results from randomized controlled trials, clinical consensus guidelines, and best available literature to date.

Deep brain stimulation of the globus pallidus suppresses post-traumatic dystonic tremor.

Dystonic tremor is an unusual movement disorder that is highly disabling and difficult to treat medically. We describe an 18-year-old patient with dystonic tremor whose medical treatment failed, and was considered for surgery. The patient had a long-standing dystonic tremor and was recommended for globus pallidus (GP) deep brain stimulation. At 2 year follow-up, we observed substantial tremor suppression and best clinical effect with contact three, which, radiographically, is located in the internal globus pallidus/external globus pallidus transition area. The stimulation was more rostral than expected. We conclude that the GP is a potentially useful therapeutic target for dystonic tremor.