The role of periradicular infiltration in dorsal root ganglion stimulation for chronic neuropathic pain

Background Targeting the correct spinal level is essential in dorsal root ganglion (DRG) stimulation. Anatomical selection of the DRG alone is not ideal since the pain area is not necessarily confined to the borders of the dermatomes. This study aims to establish the role of periradicular infiltration therapy (PRT) in the preoperative assessment of the correct level for DRG stimulation performed under general anesthesia. Method We report a prospective study of 20 patients selected for DRG stimulation and submitted to a PRT for identification of the spinal level. Lead implantation for the stimulation trial occurred under general anesthesia: 19 patients experienced positive results and underwent implantation of the pulse generator. All patients suffered from chronic neuropathic pain unresponsive to best medical treatment. PRT levels were compared with the levels targeted with DRG leads. Patients were followed for up to 12 months; pain intensity and coverage of the painful area were assessed. Results In 12 patients, the trial leads were placed on the same level as previously tested positive by PRT. In 6 patients, leads were placed in the PRT target and additionally in adjacent spinal levels. In one case, the selected target for the trial diverged from the PRT target because of intense fibrosis in the chosen level. Coverage of the target area of at least 50% was achieved by two-thirds of the patients. For the six subjects with additional implanted leads as a consequence of the PRT results, 80% achieved a coverage of at least 50%. A total of 47.4% of the patients achieved sustained significant pain relief in the last follow-up. None of the patients needed a repeated surgery for implantation of additional leads. Conclusions PRT is a helpful tool to confirm the stimulation targets. A PRT preceding the stimulation trial is an additional opportunity to optimize the coverage of the target area with stimulation-induced paresthesia for patients operated under general anesthesia.

Lessons of a multicenter noninvasive brain stimulation trial in patients with unilateral spatial neglect after stroke: barriers to trial participation from a developing country

Background: There is a high demand for stroke rehabilitation in the Brazilian public health system, however most studies that addressed rehabilitation for unilateral spatial neglect (USN) after stroke have been performed in highincome countries. Objectives: Analyze the USN patient recruitment in a multicenter non-invasive brain stimulation clinical trial performed in Brazil. Design and setting: Observation study of reasons for exclusion of patients in a multicenter, randomized, double-blinded clinical trial performed at Botucatu Medical School. Methods: We evaluated reasons for exclusion of patients in a multicenter, randomized, double-blinded clinical trial of rehabilitation of USN patients after stroke. Results: 173 of 1956 potential neglect patients (8.8%) passed initial screening. After screening evaluation, 87/173 patients (50.3%) were excluded for clinical reasons. Cognitive impairment led to exclusion of 21/87 patients (24.1%). Low socioeconomic status led to exclusion of 37/173 patients (21.4%). Difficulty in transportation to access treatment was the most common reason (16/37 patients, 43.3%). Conclusions: The analyzed Brazilian institutions have potential for conducting studies in USN. Recruitment of stroke survivors with USN was restricted by the study design and limited financial support. Cognitive impairment, presence of stent or craniectomy and lack of transportation was the most common barriers to participate in a multicenter non-invasive brain stimulation trial in patients with unilateral spatial neglect after stroke.

A Deep Brain Stimulation Trial Period for Treating Chronic Pain

Early studies of deep brain stimulation (DBS) for various neurological disorders involved a temporary trial period where implanted electrodes were externalized, in which the electrical contacts exiting the patient’s brain are connected to external stimulation equipment, so that stimulation efficacy could be determined before permanent implant. As the optimal brain target sites for various diseases (i.e., Parkinson’s disease, essential tremor) became better established, such trial periods have fallen out of favor. However, deep brain stimulation trial periods are experiencing a modern resurgence for at least two reasons: (1) studies of newer indications such as depression or chronic pain aim to identify new targets and (2) a growing interest in adaptive DBS tools necessitates neurophysiological recordings, which are often done in the peri-surgical period. In this review, we consider the possible approaches, benefits, and risks of such inpatient trial periods with a specific focus on developing new DBS therapies for chronic pain.