Hirofumi Nagatomi

Aneurysm of the posterior cerebral artery: report of eleven cases--surgical approaches and procedures.

Eleven cases of an aneurysm of the posterior cerebral artery are reported. All 11 aneurysms were saccular, and 3 were either giant or large. The aneurysms arose from the P1 segment in three patients, the P1-P2 junction in three patients, the P2 segment in three patients, and from the P3 segment in two patients. In all, 10 patients underwent surgery. All P1 and P1-P2 junction aneurysms were treated with the pterional approach. Three P2 and two P3 aneurysms were managed by the subtemporal approach. Two small aneurysms in the series were treated by coating the aneurysmal dome, two by clipping the afferent artery, and all other saccular type aneurysms were treated by clipping the aneurysmal neck. Seven patients had either an excellent or good outcome; two had poor results; and one patient died. The operative approaches and procedures are also discussed in relation to the anatomy of posterior cerebral artery aneurysms.

Aneurysm of the Posterior Cerebral Artery

Eleven cases of an aneurysm of the posterior cerebral artery are reported. All 11 aneurysms were saccular, and 3 were either giant or large. The aneurysms arose from the P1 segment in three patients, the P1-P2 junction in three patients, the P2 segment in three patients, and from the P3 segment in two patients. In all, 10 patients underwent surgery. All P1 and P1-P2 junction aneurysms were treated with the pterional approach. Three P2 and two P3 aneurysms were managed by the subtemporal approach. Two small aneurysms in the series were treated by coating the aneurysmal dome, two by clipping the afferent artery, and all other saccular type aneurysms were treated by clipping the aneurysmal neck. Seven patients had either an excellent or good outcome; two had poor results; and one patient died. The operative approaches and procedures are also discussed in relation to the anatomy of posterior cerebral artery aneurysms.

The anterior medullary-anterior pontomesencephalic venous system and its bridging veins communicating to the dural sinuses: normal anatomy and drainage routes from dural arteriovenous fistulas

IntroductionWe evaluated the normal venous anatomy of the anterior medullary/anterior pontomesencephalic venous (AMV/APMV) system and bridging veins connected to the dural sinuses using magnetic resonance (MR) imaging and demonstrated cases of dural arteriovenous fistulas (DAVFs) with bridging venous drainage.Materials and methodsMR images obtained using a 3D gradient echo sequence in 70 patients without lesions affecting the deep or posterior venous channels were reviewed to evaluate the normal anatomy of the AMV/APMV system and bridging veins. MR images and digital subtraction angiography in 80 cases with intracranial or craniocervical junction DAVFs were reviewed to evaluate the bridging venous drainage from DAVFs.ResultsMR images clearly revealed AMV/APMV in 35 cases. Fifteen cases showed a direct connection between AMV and APMV, while 15 cases showed an indirect communication via the transverse pontine vein or the bridging vein. In the five remaining cases, the AMV and APMV end separately to the bridging vein or the transverse pontine vein. Bridging veins were identified in 34 cases, connecting to the cavernous sinus in 33, to the suboccipital cavernous sinus in 11, and the inferior petrosal sinus in five cases. In 80 DAVF cases, seven of 40 cavernous sinus DAVFs, two craniocervical junction DAVFs, and one inferior petrosal sinus DAVF drained via bridging veins to the brain stem.ConclusionThe AMV/APMV and bridging veins showed various anatomies and frequently showed a connection to the cavernous sinus. Knowledge of the venous anatomy is helpful for the diagnosis and intravascular treatment of DAVFs.

Postoperative adjuvant treatment for pineal parenchymal tumour of intermediate differentiation

Pineal parenchymal tumour of intermediate differentiation (PPTID) in adults is rare and a treatment strategy for this condition has not yet been established. We present a case of an elderly patient treated with postoperative adjuvant therapy using radio- and chemotherapy. This 60-year-old man presented with a 3-month history of memory disturbance, gait instability and double vision. Computed tomography and magnetic resonance imaging demonstrated a mass in the pineal region that suggested a malignant tumour. Partial removal of the tumour was undertaken via the right occipital transtentorial approach. The histological diagnosis was PPTID. Postoperative radio- and chemotherapy were administered, with a good response. Little is known about the clinical behaviour of PPTID in adults. Our treatment plan indicates one effective option for the management of such tumours.

Tolerance dose in gamma knife surgery of lesions extending to the anterior visual pathway

OBJECT The authors performed a retrospective analysis of the radiation dose to the anterior visual pathway (AVP) to assess its tolerance to gamma knife surgery. METHODS They examined five cases followed for more than 3 years. The AVP was treated with 10-Gy doses or higher. The mean maximum delivered dose to the AVP was 14 Gy. Ten gray or more was delivered to 25.5% of the ipsilateral AVP, 12 Gy or more to 12.5% of the ipsilateral AVP, and 14 Gy or more to 5.7% of the ipsilateral AVP. Although the mean follow-up period was 40.8 months (36-51 months), no cases of visual function deterioration developed. CONCLUSIONS The tolerance dose of the AVP is considered to be less than 8 to 10 Gy; however, although the delivered dose to the AVP definitely exceeded the tolerance dose in all five cases, no visual disturbance has been identified. Longer follow up is required before any final conclusions may be drawn. Nonetheless, it is suggested that a visual disturbance may be avoided by using careful accurate dose planning even if the dose delivered to the AVP is higher than currently believed to be acceptable.

Detection of the residual lumen of intracranial aneurysms immediately after coil embolization by three-dimensional digital subtraction angiographic virtual endoscopic imaging.

OBJECTIVE Detection of a small residual lumen after coil embolization is often difficult because of the coil mass and the overlap of the cerebral arteries. The purpose of this study was to assess the usefulness of virtual endoscopic (VE) analysis of three-dimensional digital subtraction angiographic (DSA) images for evaluation of aneurysmal occlusion immediately after the procedure. METHODS Twenty-seven intracranial aneurysms were treated with coil embolization using a three-dimensional DSA system. Biplane and rotational DSA scanning was performed before and immediately after the procedures. VE images were obtained at a separate workstation, after transfer of the rotational images. Two-dimensional (2D) DSA images and VE images obtained after the procedure were assessed with respect to aneurysmal occlusion. Morphological outcomes and other factors, including location, size, volumetric ratio (coil volume/aneurysm volume), and residual sites, were also evaluated. RESULTS Seven aneurysms were evaluated as complete occlusion (CO) on both 2D DSA images and VE images. Twelve aneurysms exhibited residual lumina on both 2D DSA images and VE images. Five aneurysms were evaluated as CO on 2D DSA images and as incomplete occlusion on VE images. There were no recurrences among the aneurysms that were evaluated as CO on VE images. Two of five aneurysms that were evaluated as CO on 2D DSA images and as incomplete occlusion on VE images demonstrated regrowth in follow-up examinations. Residual sites and volumetric ratios were correlated with aneurysmal regrowth. CONCLUSION VE imaging can demonstrate a residual lumen more frequently than can 2D DSA imaging and is useful for evaluating aneurysmal occlusion after coil embolization.

Third nerve palsy caused by compression of the posterior communicating artery aneurysm does not depend on the size of the aneurysm, but on the distance between the ICA and the anterior–posterior clinoid process

OBJECTIVE Third nerve palsy (TNP) caused by a posterior communicating artery (PCoA) aneurysm is a well-known symptom of the condition, but the characteristics of unruptured PCoA aneurysm-associated third nerve palsy have not been fully evaluated. The aim of this study was to analyze the anatomical features of PCoA aneurysms that caused TNP from the viewpoint of the relationship between the ICA and the skull base. METHODS Forty-eight unruptured PCoA aneurysms were treated surgically between January 2008 and September 2013. The characteristics of the aneurysms were evaluated. RESULTS Thirteen of the 48 patients (27%) had a history of TNP. The distance between the ICA and the anterior-posterior clinoid process (ICA-APC distance) was significantly shorter in the TNP group (p<0.01), but the maximum size of the aneurysms was not (p=0.534). CONCLUSION Relatively small unruptured PCoA aneurysms can cause third nerve palsy if the ICA runs close to the skull base.

Dedifferentiated chordoid meningioma with rhabdomyosarcomatous differentiation on the middle cranial fossa

A 46‐year‐old woman presented with headache and right hemiparesis. MRI demonstrated a mass in the left middle fossa. Total resection was performed. A histological examination of the tumor specimen showed several characteristic morphological features. A chordoid meningioma showing an epithelial‐like palisade arrangement was observed. An anaplastic short spindle cell tumor exhibiting a fascicular pattern was considered to be a rhabdomyosarcoma. After conventional radiotherapy, the tumor was well controlled without any neurological deficit for 20 months. When subsequent recurrences were observed, the patient was treated by surgery, stereotactic radiosurgery and chemotherapy. Thirty‐two months after the initial treatment, the patient died due to intracranial dissemination and an autopsy was performed. The histological examination of the recurrent and autopsy specimens showed a prominent sarcoma component. This case appears to be the first reported intracranial tumor diagnosed as a dedifferentiated chordoid meningioma with rhabdomyosarcomatous differentiation.

Recurrent Arteriovenous Malformation after Gamma Knife Radiosurgery: Recurrence or New Nidus Formation after Complete Obliteration

Gamma Knife radiosurgery (GKRS) for arteriovenous malformation (AVM) is a well-established procedure, and there have been few reports of recurrence or new nidus formation after complete obliteration. To date, we have had to treat three pediatric patients again because of recurrence of radiosurgically treated nidus or formation of a new nidus at a different site. Here, we reviewed these cases and report their pathological features. The three of our AVM patients are 8, 11, and 13 years-old respectively. Each patients’ AVM are found due to either intracerebral or intraventricular hemorrhage. For their first GKRS, 20-25 Gy was delivered to the margin of a nidus 0.08-2.33 ml in volume. The post GKRS course was uneventful in all cases. In cases 1 and 2, complete obliteration was observed several years after GKRS. However, approximately 1 year later from the complete obliteration, the patients had bleeding because of nidus formation at the same or an adjacent site, and this necessitated a second GKRS. Subsequently, the patients have been followed-up closely, and complete obliteration has been achieved. In case 3, angiography performed approximately 3 years after the first GKRS revealed a residual subtle shunt but verified the disappearance of the nidus. However, angiography also revealed the formation of a new nidus adjacent to the site of the previous one. The patient underwent a second GKRS and complete obliteration was achieved 3 years later. Obliteration progresses gradually after GKRS for AVM. Our cases suggest that along with obliteration, gradual hemodynamic or other changes also occur simultaneously in the surrounding area, which may result in recurrence or new nidus formation at the same or a different site. Therefore, even after complete obliteration is observed, magnetic resonance imaging should be performed for careful follow-up of patients. Any changes observed should necessarily be evaluated by angiography to exclude the possibility of a new nidus formation.

Utility and Efficacy of a Rigid Endoscope for Recurrent Huge Chronic Subdural Hematoma: Case Report

An 83-year-old male patient was admitted to our hospital due to consciousness disturbance. Computed tomography demonstrated a huge chronic subdural hematoma on the left side. The thickness was 4 cm, and the cingulate gyrus was herniated to the right side. Blood examination showed that prothrombin time and activated partial thromboplastin time were normal. Bleeding time was slightly prolonged at 3 minutes 30 seconds. Emergency surgery was performed on admission. Three weeks after the first surgery, the patient became progressively drowsy and feeding was slow. Repeated computed tomographic scans demonstrated recurrence. At the second surgery, we used the 70-degree rigid endoscope (Storz, Germany) to obtain a direct view of the clot and bleeding site. We removed the clot and washed out the cavity with saline. Six months after the second surgery, there has not been any recurrence of the chronic subdural hematoma. In Japan, many aged patients with ischemic heart disease or cerebral infarction have been treated with anticoagulative agent and/or antithrombotic agent. We need to carefully monitor patients receiving antithrombotic therapy or anticoagulation therapy. Special training in the care of such patients is needed for support staff to prevent falls. For aged patients, minimally invasive surgery such as endoscope-assisted surgery may be effective for thick or intractable chronic subdural hematoma.