Tinnitus Intensity Dependent Gamma Oscillations of the Contralateral Auditory Cortex

Non-pulsatile tinnitus is considered a subjective auditory phantom phenomenon present in 10 to 15% of the population. Tinnitus as a phantom phenomenon is related to hyperactivity and reorganization of the auditory cortex. Magnetoencephalography studies demonstrate a correlation between gamma band activity in the contralateral auditory cortex and the presence of tinnitus. The present study aims to investigate the relation between objective gamma-band activity in the contralateral auditory cortex and subjective tinnitus loudness scores. In unilateral tinnitus patients (N = 15; 10 right, 5 left) source analysis of resting state electroencephalographic gamma band oscillations shows a strong positive correlation with Visual Analogue Scale loudness scores in the contralateral auditory cortex (max r = 0.73, p<0.05). Auditory phantom percepts thus show similar sound level dependent activation of the contralateral auditory cortex as observed in normal audition. In view of recent consciousness models and tinnitus network models these results suggest tinnitus loudness is coded by gamma band activity in the contralateral auditory cortex but might not, by itself, be responsible for tinnitus perception

Does transcranial direct current stimulation to prefrontal cortex affect mood and emotional memory retrieval in healthy individuals?

Studies using transcranial direct current stimulation (tDCS) of prefrontal cortex to improve symptoms of depression have had mixed results. We examined whether using tDCS to change the balance of activity between left and right dorsolateral prefrontal cortex (DLPFC) can alter mood and memory retrieval of emotional material in healthy volunteers. Participants memorised emotional images, then tDCS was applied bilaterally to DLPFC while they performed a stimulus-response compatibility task. Participants were then presented with a set of images for memory retrieval. Questionnaires to examine mood and motivational state were administered at the beginning and end of each session. Exploratory data analyses showed that the polarity of tDCS to DLPFC influenced performance on a stimulus-response compatibility task and this effect was dependent on participants' prior motivational state. However, tDCS polarity had no effect on the speed or accuracy of memory retrieval of emotional images and did not influence positive or negative affect. These findings suggest that the balance of activity between left and right DLPFC does not play a critical role in the mood state of healthy individuals. We suggest that the efficacy of prefrontal tDCS depends on the initial activation state of neurons and future work should take this into account. © 2014 Morgan et al

Cerebral dural arteriovenous fistulae presenting with acute hemorrhage : a systematic review

Abstract: Background: Cerebral dural arteriovenous fistulae (dAVFs) are rare connections between arteries and veins or sinuses in the brain. dAVFs have a higher risk of intracranial hemorrhages due to increased venous pressure. Endovascular treatment is considered the first line treatment. However, it is unknown if surgery improves outcomes for patients presenting with an acute hemorrhage. Therefore, this systematic review assesses complete obliterations and recurrences of surgery and endovascular treatment in hemorrhagic dAVFs patients.Methods: A literature search in the PubMed and Web of Sciences database was conducted up till October 2021. Studies of surgical and endovascular treatments with hemorrhagic dAVFs were included. The Quality Assessment Tool for Before-After (Pre-Post) Studies with No Control Group and the JBI critical appraisal checklist for case reports were used for risk of bias assessment.Results: Eleven articles were included. 681 dAVFs patients with 686 fistulae were reported. 245 (36 %) patients presented with an intracranial hemorrhage. Most fistulae were found in the transverse or sigmoid sinuses (n = 220; 32.1 %) and the majority were classified as Borden III. 571 endovascular treatments resulted in 390 (68.3 %) complete dAVF obliterations and there was a recurrence of 66 dAVFs (16.9 %). 183 surgeries resulted in the complete obliteration of 166 fistulae (91.8 %) with a recurrence of 2 dAVFs (1.2 %).Conclusions: Due to the lack of literature on hemorrhagic dAVFs exclusively, we cannot make a statement on the effectiveness of surgical interventions compared to endovascular treatments. Future studies should report out-comes based on location, previous treatments, and patient presentation

Surgical management of anterior cranial fossa dural arteriovenous fistulas: Illustrative case series and review of surgical approaches

Background: Dural arteriovenous fistulas (DAVF) within the anterior cranial fossa (ACF) are of particular concern due to their higher hemorrhage rates. Surgical intervention is typically the most effective treatment for ACF DAVFs, although recent advancements suggest increasing use of endovascular techniques. It has consistently shown effectiveness, with minimal thromboembolic risks. Case description: We present two cases of ACF DAVF graded Cognard type IV. A successful pterional and frontotemporal approach was performed, respectively. Postoperative angiography confirmed complete DAVF occlusions, and the patients had an uneventful recovery. Conclusion: ACF DAVFs can be exposed through direct or indirect approaches, with advantages and drawbacks for each method. The anterior interhemispheric approach is widely recognized for its safety and efficacy. Limited studies have advocated for the use of the pterional approach, showing feasibility and potential benefits such as avoiding frontal sinus reconstruction and providing an excellent view of the fistula. Furthermore, pterional approach offers sufficient exposure and favorable cosmetic outcomes, making it a viable option for ACF DAVFs. The presented cases exemplify the efficacious surgical management of ACVF DAVFs through distinct approaches, underscoring the significance of personalized treatment strategies and the effectiveness of surgical interventions in accomplishing total obliteration of the fistulas

Surgical management of anterior cranial fossa dural arteriovenous fistulas : illustrative case series and review of surgical approaches

Abstract: Background: Dural arteriovenous fistulas (DAVF) within the anterior cranial fossa (ACF) are of particular concern due to their higher hemorrhage rates. Surgical intervention is typically the most effective treatment for ACF DAVFs, although recent advancements suggest increasing use of endovascular techniques. It has consistently shown effectiveness, with minimal thromboembolic risks. Case description: We present two cases of ACF DAVF graded Cognard type IV. A successful pterional and frontotemporal approach was performed, respectively. Postoperative angiography confirmed complete DAVF occlusions, and the patients had an uneventful recovery. Conclusion: ACF DAVFs can be exposed through direct or indirect approaches, with advantages and drawbacks for each method. The anterior interhemispheric approach is widely recognized for its safety and efficacy. Limited studies have advocated for the use of the pterional approach, showing feasibility and potential benefits such as avoiding frontal sinus reconstruction and providing an excellent view of the fistula. Furthermore, pterional approach offers sufficient exposure and favorable cosmetic outcomes, making it a viable option for ACF DAVFs. The presented cases exemplify the efficacious surgical management of ACVF DAVFs through distinct approaches, underscoring the significance of personalized treatment strategies and the effectiveness of surgical interventions in accomplishing total obliteration of the fistulas