A precise understanding of the anatomy is essential to perform vagus nerve stimulation VNS therapy for refractory epilepsy. We evaluated the anatomical relationships of the cervical vagus nerve with the carotid artery and jugular vein on the basis of findings during VNS surgery. We investigated the anatomical relationships among the vagus nerve VN , common carotid artery CCA , and internal jugular vein IJV in 73 patients who underwent VNS surgery at our hospital from December 2010 to January 2015, classified the position of the VN into 5 categories, and studied the frequency of each category. The position of the VN was medial to the IJV and ventral to the CCA type 1 in 8 patients 10.9 , medial to the IJV and lateral to the CCA type 2 in 4 5.5 , dorsomedial to the IJV and ventral to the CCA type 3 in 51 70 , dorsomedial to the IJV and lateral to the CCA type 4 in 7 9.5 , and dorsal to the CCA type 5 in 3 4.1. This report is the first to propose a classification of the anatomical relationships of the VN with the CCA and IJV based on intraoperative findings. According to this classification, the difficulty of VNS surgery increases with advances of the type. Type 3 was the most frequent, and types 2 and 5 were rare. Understanding the variation in the position of the cervical vagus nerve is considered to contribute to safer surgical manipulations in VNS surgery.

C orpus callosotomy is accepted as a palliative procedure for patients with, in particular, medically intractable generalized epilepsy and drop attack seizures. Although a 1-stage total corpus callosotomy can be performed in patients younger than 16 years, a 2-stage corpus callosotomy is preferred for patients older than 16 years given its lower risk for disconnection syndrome.14 At some institutions, posterior corpus callosotomy has been performed when the efficacy of anterior corpus callosotomy was insufficient. 1,[8][9][10]13 We have performed a second surgery for total callosotomy in cases that showed little or no clinical improvement in the 6-month follow-up after anterior partial callosotomy. The previous skin incision and craniotomy were generally reopened in the second surgery; 6 however, difficulties have been associated with this dissection because of intracranial adhesion, which is often observed following surgical intervention, and because of the long distance to the splenium of the corpus callosum, especially in adult cases. On the other hand, the shorter distance to the splenium in a posterior corpus callosotomy with a parietooccipital interhemispheric approach permits a safer, more precise dissection. Here, we present, as a second surgery, a technique for posterior callosotomy using a parietooccipital interhemispheric approach with a semiprone park-bench position. MethodsIn this retrospective study, we searched our institutional database for patients with epilepsy and drop attack seizures who had undergone anterior corpus callosotomy and an additional posterior corpus callosotomy for residual seizures in the period from 1999 to 2013. Patients with follow-up periods shorter than 3 months were excluded from our analysis. Magnetic resonance imaging was performed after surgery to evaluate the complete division. Surgical techniquesMagnetic resonance venography was performed in all cases preoperatively to determine which side was favorable for approach. The nondominant venous side was selected as the approach side; for example, when bridging veins were dominant in the right side, the left side was regarded as the approach side. A 2-stage corpus callosotomy is accepted as a palliative procedure for patients older than 16 years with, in particular, medically intractable generalized epilepsy and drop attack seizures and is preferable for a lower risk of disconnection syndrome. Although the methods by which a previously performed craniotomy can be reopened for posterior callosotomy have already been reported, posterior corpus callosotomy using a parietooccipital interhemispheric approach with the patient in a semi-prone park-bench position has not been described in the literature. Here, the authors present a surgical technique for posterior callosotomy using a parietooccipital interhemispheric approach with a semi-prone parkbench position as a second surgery. Although this procedure requires an additional skin incision in the parietooccipital region, it makes the 2-stage callosotomy safer and easier to perf...

Coronal sections obtained by MR cisternography are able to demonstrate the severity of vessel invagination into the brainstem as well as revealing the presence of the offending vessel. This information is helpful for planning a suitable approach to the root exit zone.

BackgroundPerineural cysts are sometimes found incidentally with magnetic resonance imaging, and clinical symptoms requiring treatment are rare. Perineural cysts typically exhibit delayed filling with contrast medium on myelography, which is one of the criteria used by Tarlov to distinguish perineural cysts from meningeal diverticula. We present a case of multiple thoracolumbar perineural cysts, one of which was considered the cause of intermittent intercostal neuralgia with atypical findings on postmyelographic computed tomography seen as selective filling of contrast medium.Case presentationA 61-year-old woman presented with intermittent pain on her left chest wall with distribution of the pain corresponding to the T10 dermatome. Magnetic resonance imaging showed multiple thoracolumbar perineural cysts with the largest located at the left T10 nerve root. On postmyelographic computed tomography immediately after contrast medium injection, the largest cyst and another at left T9 showed selective filling of contrast medium, suggesting that inflow of cerebrospinal fluid to the cyst exceeded outflow. Three hours after the injection, the intensity of the cysts was similar to the intensity of the thecal sac, and by the next day, contrast enhancement was undetectable. The patient was treated with an intercostal nerve block at T10, and the pain subsided. However, after 9 months of observation, the neuralgia recurred, and the nerve block was repeated with good effect. There was no recurrence 22 months after the last nerve block.ConclusionsWe concluded that intermittent elevation of cerebrospinal fluid pressure in the cyst caused the neuralgia because of an imbalance between cerebrospinal fluid inflow and outflow, and repeated intercostal nerve blocks resolved the neuralgia. Our case demonstrates the mechanism of cyst expansion.