Synergistic neuromodulation therapy for persistent spinal pain: a proof-of-concept trial on the use of spinal cord and dorsal root ganglion stimulation.

PURPOSE: Persistent Spinal Pain Syndrome type 2 (PSPS-T2) poses a significant clinical challenge, demanding innovative therapeutic interventions. The integration of Spinal Cord Stimulation (SCS) and Dorsal Root Ganglion Stimulation (DRG-S) is emerging as a potent synergistic strategy for comprehensive pain management. This single patient-blind proof of concept (POC) trial explores the efficacy and synergistic potential of combined SCS and DRG-S in a patient with refractory PSPS-T2. METHODS: A 45-year-old male with intractable PSPS-T2 underwent a unique, methodically structured study, involving three treatment phases: Phase A with SCS alone, Phase B with DRG-S alone, and Phase C The patient, blinded to the treatment modalities, provided pain assessments using the Visual Analogue Scale (VAS) and Douleur Neuropathique 4 Questions (DN4) conducted by clinical investigators at each phase. Baseline pain scores were ten and nine, respectively. RESULTS: Distinct responses were noted across the phases. Phase A demonstrated moderate pain relief, while Phase B offered further pain intensity reduction. However, Phase C, combining both strategies, yielded the most significant improvement, remarkably enhancing the patient's quality of life and functional capacity. CONCLUSION: This POC trial underscores the synergistic potential of SCS and DRG-S in managing complex cases of PSPS-T2, suggesting a paradigm shift towards integrated neuromodulation strategies for enhanced pain control. The development of dual intent implantable pulse generators (IPGs) capable of offering combination therapy simultaneously might be effective for pain management in select cases. The significant pain reduction and functional improvement observed advocate for further research in dual neuromodulation therapies. TRIAL REGISTRATION NUMBER: IRB 20190536.

Retrograde thoracic spinal cord stimulation paddle placement for complex persistent spinal pain syndrome type 2.

BACKGROUND: Spinal cord stimulation (SCS) is a cost-effective option for treating refractory persistent spinal pain syndrome type-2 (PSPS-2). For patients with extensive spine instrumentation including the thoraco-lumbar junction, percutaneous placement of SCS leads is usually not an option being paddle leads typically implanted anterograde. Paddle lead placement will be particularly challenging in more complex cases when the instrumentation covers the targeted level. To overcome this barrier, we studied using a retrograde approach to reach the sweet spot, facilitate the placement, and reduce associated risks. OBJECTIVES: To study the use of retrograde SCS paddle as a placement method to optimize the spinal cord target and reduce the risks of conventional placement in complex cases. STUDY DESIGN: Case series and technical note. METHODS: We present three cases of thoracic retrograde SCS paddle lead placement cases, detailing patient selection, operative technique, and outcome. All the cases had extensive instrumentation to the thoraco-lumbar spine, and one had additional spinal canal stenosis. The surgical procedure entailed a retrograde midthoracic inter-laminar approach, flavectomy, and caudal placement of the paddle lead with intraoperative neurophysiologic monitoring (IONM) guidance for functional midline determination. RESULTS: All the cases had a successful lead placement over the sweet spot without complications. The same approach was used to decompress a focal spinal stenosis in one case. One case had significantly improved pain and hence underwent a pulse generator implant. The other cases had non-satisfactory pain control and were explanted. LIMITATIONS: These case description could guide technical procedural steps, however, a larger number of such cases would be needed to describe further technical nuances. CONCLUSIONS: We demonstrated that placing SCS paddle leads via retrograde midthoracic approach with IONM guidance is safe. This procedure should be an option for SCS paddle implants in patients with posterior spinal fusion encompassing the intended targeted spinal stimulation level.

Review of spinal cord stimulation for disorders of consciousness.

PURPOSE OF REVIEW: High-cervical spinal cord stimulation can alter cortical activity and cerebral metabolism. These effects are potentially beneficial for disorders of consciousness. A better understanding of the effects of clinical application of stimulation is needed. We aimed to evaluate the existing literature to determine the state of available knowledge. We performed a literature review of clinical studies assessing cervical spinal cord epidural stimulation for disorders of consciousness. Only peer-reviewed articles reporting preoperative and postoperative clinical status were included. RECENT FINDINGS: Nineteen studies were included. A total of 532 cases were reported, and 255 patients were considered responsive (47.9%). Considering only studies published after the definition of minimally conscious state (MCS) as an entity, 402 individuals in unresponsive wakefulness syndrome (UWS) and 113 in MCS were reported. Responsiveness to SCS was reported in 170 UWS patients (42.3%) and in 78 MCS cases (69.0%), although the criteria for responsiveness and outcome measures varied among publications. SUMMARY: Cervical SCS yielded encouraging results in patients with disorders of consciousness and seems to be more effective in MCS. More extensive investigation is needed to understand its potential role in clinical practice.

Asymmetry of P1 and vertebral arteries is not related to basilar tip aneurysm development or rupture.

OBJECTIVE: Lately, morphological parameters of the surrounding vasculature aside from aneurysm size, specific for the aneurysm location, e.g., posterior cerebral artery angle for basilar artery tip aneurysms, could be identified to correlate with the risk of rupture. We examined further image-based morphological parameters of the aneurysm surrounding vasculature that could correlate with the growth or the risk of rupture of basilar artery tip aneurysms. METHODS: Data from 83 patients with basilar tip aneurysms (27 not ruptured; 56 ruptured) and 100 control patients were assessed (50 without aneurysms and 50 with aneurysms of the anterior circle of Willis). Anatomical parameters of the aneurysms were assessed and analyzed, as well as of the surrounding vasculature, namely the asymmetry of P1 and the vertebral arteries. RESULTS: Patients with basilar tip aneurysm showed no significant increase in P1 or vertebral artery asymmetry compared with the control patients or patients with aneurysms of the anterior circulation, neither was there a significant difference in asymmetry between cases with ruptured and unruptured aneurysms. Furthermore, we observed no significant correlations between P1 asymmetry and the aneurysm size or number of lobuli in the aneurysms. CONCLUSION: We observed no significant difference in aneurysm size, rupture, or lobulation associated with P1 or vertebral artery (surrounding vasculature) asymmetry. Therefore, the asymmetry of the surrounding vessels does not seem to be a promising morphological parameter for the evaluation of probability of rupture and growth in basilar tip aneurysms in future studies.

Morphometric Study of the Internal Globus Pallidus Using the Robert, Barnard, and Brown Staining Method.

BACKGROUND: The globus pallidus internus (Gpi) is a major target in functional neurosurgery. Anatomical studies are crucial for correct planning and good surgical outcomes in this region. The present study described the anatomical coordinates of the Gpi and its relationship with other brain structures and compared the findings with those from previous anatomical studies. METHODS: We obtained 35 coronal and 5 horizontal brain specimens from the Department of Anatomy and stained them using the Robert, Barnard, and Brown technique. After excluding defective samples, 60 nuclei were analyzed by assessing their distances to the anatomical references and the trajectories to these nuclei. RESULTS: The barycenter of the Gpi was identified at the level of the mammillary bodies and 1 cm above the intercommissural plane. Thereafter, the distances to other structures were found. The mean ± standard deviation distance was 15.62 ± 2.66 mm to the wall of the third ventricle and 17.02 ± 2.69 mm to its midline, 4.74 ± 1.12 mm to the optic tract, 2.51 ± 0.8 mm and 13.56 ± 2 mm to the internal and external capsule, and 21.3 ± 2.44 mm to the insular cortex. The cortical point of entry should be located 22.03 ± 4.34 mm to 48.74 ± 4.44 mm from the midline. CONCLUSION: The Gpi has less variability in distance to closer anatomical references, such as the optic tract and internal capsule. Distant locations showed a more inhomogeneous pattern. Anatomical studies such as ours are important for the development of new therapeutic approaches and can be used as a basis for new research involving volumetric and specific group analyses.

Cervical and High-Thoracic Dorsal Root Ganglion Stimulation in Chronic Neuropathic Pain.

INTRODUCTION: Dorsal root ganglion stimulation is a meanwhile established but rather new technique of neuromodulation to treat chronic pain states of different origin. While being primarily used in the lumbar region, dorsal root ganglion (DRG) stimulation also can be used in the upper thoracic and cervical region with slight alterations of the surgical approach. This offers new therapeutic options especially in the treatment of neuropathic pain states of the upper extremities. Data on surgical technique, outcome and complications rates of DRG in this region are limited. MATERIALS AND METHODS: We report a consecutive series of 20 patients treated with DRG stimulation in the upper thoracic and cervical region. All patients suffered from chronic neuropathic pain unresponsive to best medical treatment. Main pain etiologies were trauma, spine surgery, postherpetic neuralgia, and peripheral nerve surgery. All patients were trialed with externalized electrodes prior to permanent pulse generator implantation. Routine clinical follow-up was performed during reprogramming sessions. RESULTS: Out of all 20 patients trialed, 18 were successfully trialed and implanted with a permanent stimulation system. The average pain relief after three months compared to the baseline was of 60.9% (mean VAS 8.5 to VAS 3.2). 77.8% of the patients reported a pain relief of at least 50% after three months. One patient developed a transient paresis of the arm caused by the procedure. She completely recovered within three months. CONCLUSION: Cervical and upper thoracic DRG stimulation resulted in good overall response rates to trialing and similar pain relief when compared to DRG stimulation for groin and lower limb pain. A modified surgical approach has to be used when compared with lumbar DRG electrode placement. Surgery itself in this region is more complication prone and challenging.

Cerebral Collateral Circulation: A Review in the Context of Ischemic Stroke and Mechanical Thrombectomy.

The pial (leptomenigeal) collateral circulation is a key determinant of functional outcome after mechanical thrombectomy after large-vessel ischemic stroke. Patients with good collateral blood flow benefit up to 24 hours after stroke onset, whereas those with poor collateral flow evidence less or no benefit. However, clues to why collateral flow varies so widely among patients have remained elusive. Recent findings in animal studies, which are currently being tested for confirmation in humans, have found that naturally occurring variants of a novel "collateral gene," Rabep2, result in large differences in the extent of anatomic collaterals and thus blood flow and infarct size in mice after stroke. The comprehension of collagerogenesis in humans and the evaluation of collateral status could aid in identifying patients who will benefit not only from mechanical thrombectomy in the extended time window but also from any reperfusion strategy. We performed a literature review focused on radiographic, clinical, and genetic aspects of the collateral circulation.

Morphometric Analysis of the Nucleus Accumbens Using the Mulligan Staining Method.

BACKGROUND: There is a need to further anatomically describe the nucleus accumbens (NA), as there is a growing neurosurgical interest in this locus but a limited understanding of its structure. In this study, we evaluated quantitative NA parameters and spatial relationships with adjacent structures found in the telencephalon. METHODS: A total of 155 NA specimens from coronal sections and 3 NA specimens from transverse sections were stained using the Mulligan technique as modified by Barnard et al. The distance from the NA to other structures was then measured. RESULTS: The mean radius of the 155 NAs in the coronal sections was 6.23 ± 0.964 mm, averaging 8.99 ± 2.02 mm from midline (coordinate x), 27.09 ± 3.15 mm from the insula, 12.95 ± 3.21 mm from the outer border of the putamen, 10.52 ± 2.66 mm from the upper border of the caudate, and 8.84 ± 2.93 mm from the midline of the lateral ventricle. The mean distance from the NA center of gravity to the middle of the intercommissural line parallel to the midline (coordinate y) was 17.08 ±3.61 mm, and the mean vertical distance from the intercommissural line to the NA was 8.12 ± 1.265 mm. CONCLUSIONS: We obtained the stereotactic coordinates of (x, y, z) = (8, 17, -8) for the NA. From this and other delineations of the described position of the NA, it is possible to contribute to stereotactic surgical atlases, improving neurosurgical interventions in this structure.