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A technology that simultaneously records membrane potential from multiple neurons in behaving animals will have a transformative effect on neuroscience research.sup.1,2. Genetically encoded voltage indicators are a promising tool for these purposes; however, these have so far been limited to single-cell recordings with a marginal signal-to-noise ratio in vivo.sup.3-5. Here we developed improved near-infrared voltage indicators, high-speed microscopes and targeted gene expression schemes that enabled simultaneous in vivo recordings of supra- and subthreshold voltage dynamics in multiple neurons in the hippocampus of behaving mice. The reporters revealed subcellular details of back-propagating action potentials and correlations in subthreshold voltage between multiple cells. In combination with stimulation using optogenetics, the reporters revealed changes in neuronal excitability that were dependent on the behavioural state, reflecting the interplay of excitatory and inhibitory synaptic inputs. These tools open the possibility for detailed explorations of network dynamics in the context of behaviour. A combination of improved near-infrared voltage indicators, high-speed microscopes and targeted gene expression schemes enabled simultaneous in vivo optogenetic control and recording of voltage dynamics in multiple neurons in the hippocampus of behaving mice., Author(s): Yoav Adam [sup.1] , Jeong J. Kim [sup.1] , Shan Lou [sup.1] , Yongxin Zhao [sup.2] , Michael E. Xie [sup.1] , Daan Brinks [sup.1] , Hao Wu [sup.1] [...]

Objective: Microvascular decompression (MVD) is an effective intervention in patients with trigeminal neuralgia (TN). How prior rhizotomy can impact long-term pain outcomes following MVD is not well understood. In this study, the authors sought to compare pain outcomes in patients who had undergone primary MVD versus those who had undergone secondary MVD after a single or multiple rhizotomies., Methods: The authors retrospectively reviewed the data on all patients who had undergone MVD at their institution from 2007 to 2020. Patients were included in the study if they had undergone primary MVD or if their surgical history was notable for past rhizotomy. Barrow Neurological Institute (BNI) pain scores were assigned at preoperative and final follow-up appointments. Perioperative complications were noted for each patient, and evidence of pain recurrence was recorded as well. A history of rhizotomy as well as other variables that might influence TN pain recurrence were evaluated using a Cox proportional hazards model. The impact of prior rhizotomy on TN pain recurrence following MVD was further assessed using Kaplan-Meier survival analysis., Results: Of 1044 patients reviewed, 947 met the study inclusion criteria. Of these, 796 patients had undergone primary MVD, 84 had a history of a single rhizotomy before MVD, and 67 had a history of ≥ 2 rhizotomies prior to MVD. Patients in the single rhizotomy and multiple rhizotomies cohorts exhibited a greater frequency of preoperative numbness (p < 0.001), higher preoperative BNI pain scores (p < 0.005), and higher rates of postoperative numbness (p = 0.04). However, final follow-up BNI pain scores were not significantly different between the primary MVD and prior rhizotomy groups (p = 0.34). Cox proportional hazards analysis revealed that younger age, multiple sclerosis, and female sex independently predicted an increased risk of pain recurrence following MVD. Neither a history of a single prior rhizotomy nor a history of multiple prior rhizotomies independently increased the risk of pain recurrence. Furthermore, Kaplan-Meier analysis of pain-free survival among the 3 groups revealed no relationship between a history of prior rhizotomy and pain recurrence following MVD (p = 0.57)., Conclusions: Percutaneous rhizotomy does not complicate outcomes following subsequent MVD for TN pain. However, patients undergoing rhizotomy before MVD may have an increased risk of postoperative facial numbness compared to that in patients undergoing primary MVD.

Objective: Pediatric intracranial aneurysms are rare. Most large series in the last 15 years reported on an average of only 39 patients. The authors sought to report their institutional experience with pediatric intracranial aneurysms from 1991 to 2021 and to compare pediatric patient and aneurysm characteristics with those of a contemporaneous adult cohort., Methods: Pediatric (≤ 18 years of age) and adult patients with one or more intracranial aneurysms were identified in a prospective database. Standard epidemiological features and outcomes of each pediatric patient were retrospectively recorded. These results were compared with those of adult aneurysm patients managed at a single institution over the same time period., Results: From a total of 4500 patients with 5150 intracranial aneurysms admitted over 30 years, there were 47 children with 53 aneurysms and 4453 adults with 5097 aneurysms; 53.2% of children and 36.4% of adults presented with a subarachnoid hemorrhage (SAH). Pediatric aneurysms were significantly more common in males, more likely giant (≥ 25 mm), and most frequently located in the middle cerebral artery. Overall, 85.1% of the pediatric patients had a modified Rankin Scale score ≤ 2 at the last follow-up (with a mean follow-up of 65.9 months), and the pediatric mortality rate was 10.6%; all 5 patients who died had an SAH. The recurrence rate of treated aneurysms was 6.7% (1/15) in the endovascular group but 0% (0/31) in the microsurgical group. No de novo aneurysms occurred in children (mean follow-up 5.5 years)., Conclusions: Pediatric intracranial aneurysms are significantly different from adult aneurysms in terms of sex, presentation, location, size, and outcomes. Future prospective studies will better characterize long-term aneurysm recurrence, rebleeds, and de novo aneurysm occurrences. The authors currently favor microsurgical over endovascular treatment for pediatric aneurysms.