In the field of functional neurosurgery, intervention using implantable devices has contributed greatly to the development of clinical applications. Electrodes for deep brain stimulation (DBS), pulse generators producing stimulus currents, and extension leads connecting them are applied as implantable devices. In addition to them, percutaneous programming devices are used to identify the optimal stimulation parameters. Rechargeable pulse generators and charging devices have already been launched. Technological improvement and evolution of these devices has contributed to better QOL for patients with DBS. They will improve DBS therapy and further develop functional neurosurgery in the future.

  One of the greatest concerns for neurosurgical oncologists is pathological findings of the surgical margin. Learning the pathology of the brain-tumor interface (BTI) in detail has many clinical implications, such as determining of surgical strategies, recognition of the surgical resection limit, selection of post-operative adjuvant treatment, and prognosis prediction.

  In this article, the author provides pathological findings of the BTI of normal brain reactions and the representative brain tumors. In most of the intra-parenchymal tumors, the pathology of the BTI demonstrates infiltrative tumor cells with some differences. On the contrary, most of the extra-parenchymal tumors, except for the atypical/anaplastic meningiomas, demonstrate clear tumor margins. The atypical/anaplastic meningiomas demonstrate a specific invasion pattern.

  These studies suggest the many clinical implications for achieving maximum safety in brain tumors resections.

  Neurosurgeons still find it challenging to preserve brain functions during surgeries for lesions around the eloquent areas. In awake craniotomy, high-frequency electrical stimulation has been established to monitor and map intraoperative brain functions and preserve the eloquent areas. However, awake craniotomy cannot be performed in patients with preoperative language or cognitive dysfunction. Therefore, intraoperative electrophysiological monitoring is needed to preserve the integrity of the functional motor or language network.

  Motor evoked potentials have been used in intraoperative methods to monitor motor function even under general anesthesia. We recently developed an in vivo electrical tract tracing method using cortico-cortical evoked potentials (CCEPs). In the intraoperative setting, we could map the supplementary motor area and dorsal language white matter pathway using the CCEP connectivity pattern. CCEPs potentially enable monitoring of brain function during surgery, even when general anesthesia is used. An intraoperative CCEP study also suggested that each subdivision of the inferior frontal gyrus had different connectivities to the temporal lobe with an anterior-posterior gradient, that is, the frontal lobe is newly connected to the temporal lobe through the limen insulae.

  The development of an intraoperative electrophysiological monitoring system that can be used in parallel with general anesthesia during surgery is clinically useful for preserving brain function in patients who cannot undergo awake craniotomy.

  Objective : Craniosynostosis (CS) has recently been diagnosed at an earlier age because Japanese parents are more conscious of their infant skull shape. Endoscopy-assisted suturectomy (EAS) is a potential primary surgical treatment for CS in combination with postoperative helmet cranial remodeling. We report our preliminary experience with EAS for the treatment of CS.

  Methods : We retrospectively reviewed 7 infants with CS who underwent EAS and were fitted with custom-made cranial helmets postoperatively.

  Results : Synostosis of the bilateral coronal sutures was noted in three patients ; unilateral coronal suture synostosis in two patients ; sagittal suture synostosis in one patient ; and metopic suture synostosis in one patient. All fused sutures in these patients were removed under endoscopic support, via small scalp incisions of a few centimeters. The cranial bones were soft and cut with scissors. The average operation time was 168 (range 117-228) minutes ; the average blood loss was 33.4 (range 5-87) ml. Four patients received blood transfusion. All patients were fitted with custom-made cranial molding helmets postoperatively. All patients experienced favorable improvements in skull shape with no mobility impairment, mortality, or complications, except for one patient with Pfeiffer syndrome, who did not receive helmet therapy because of a decubitus on the valve of the ventriculo-peritoneal shunt that required additional surgery.

  Conclusion : EAS is minimally invasive and has yielded good results when performed in combination with helmet therapy. We will further develop the bone resection technique and hemostasis methods.

  Rotational vertical artery occlusion syndrome (RVAOS) is a rare cause of vertebrobasilar insufficiency. We report a case of RVAOS caused by an unusual mechanism. A 52-year-old man presented with gait disturbance and impaired finger dexterity of the right hand with onset 2 days before his visit. Brain magnetic resonance imaging (MRI) demonstrated cerebral infarction in the left cerebellum and brain stem. No stenosis or occlusion of the major intracranial arteries was observed in MR angiography (MRA). Cervical ultrasonography showed occlusion of the left vertebral artery (VA) in the neutral head position, but blood flow was observed when the head was rotated to the right. Cerebral angiography showed occlusion of the left vertebral artery origin in the neutral head position, but blood flow was observed on rightward head rotation despite the stenosis remaining at the level of the sixth cervical vertebra (C6). Computed tomography (CT) angiography on rightward head rotation detected the existence of soft tissues having an isodensity shadow equivalent to the intervertebral disc near the entrance of C6 foramen transversarium, which was found to be the cause of VA mechanical occlusion. Decompression was chosen for treatment, and the occlusion of VA was relieved through the anterior approach, which is unroofing the left C6 foramen transversarium and removing fibrous tissue involved in direct compression. The blood flow of the left VA has been maintained for 6 months after surgery.

  Juvenile xanthogranuloma (JXG) is a benign cutaneous tumor with a predilection for the head and neck region, that usually appears in children, and central nervous system involvement is rare. Here we present a case of an isolated intracranial JXG. A 14-year-old female suffered from transient headache and right visual disorder after intense exercise, and magnetic resonance imaging demonstrated a solid mass with edema at the base of the left occipital lobe. She underwent total removal of the tumor with left occipital craniotomy. The pathological findings were non-Langerhans cell histiocytic proliferation, and finally diagnosed as JXG based on clinical features. Patients diagnosed with intracranial JXG have a favorable outcome if it is totally removed. However, long-term prognosis of this disease is still unknown. Moreover, there are some cases of multiple lesions that show more aggressive progression and need adjuvant therapies. Therefore, careful follow up is needed for patients with JXG.