[Posterior Fossa Anatomy for Microvascular Decompression Surgery].

In most microvascular decompression surgeries, surgical maneuvers are performed within normal anatomical structures without any neoplasms. Thus, detailed anatomical knowledge is essential to perform safe and efficient procedures. "Rule of 3" by Rhoton AL Jr. is helpful for understanding not only the anatomy of the posterior fossa but also the three neurovascular compression syndromes. The cerebellar arteries and posterior fossa veins have substantial variability, but a basic understanding of their typical patterns is useful to explore individual cases. To use adequate surgical approaches through the cerebellar tentorial or petrosal surface in individual trigeminal neuralgia surgeries, anatomical knowledge of the bridging veins on the tentorial(the bridging veins into the tentorial sinus)and petrosal surfaces(the superior petrosal vein)is crucial. Fissure openings help to minimize cerebellar retraction, similarly to the sylvian fissure dissection in supratentorial surgeries.

Evolution of microneurosurgical anatomy with special reference to the history of anatomy, surgical anatomy, and microsurgery: historical overview.

This article reviews the evolution of microneurosurgical anatomy (MNA) with special reference to the development of anatomy, surgical anatomy, and microsurgery. Anatomy can be said to have started in the ancient Greek era with the work of Hippocrates, Galen, and others as part of the pursuit of natural science. In the sixteenth century, Vesalius made a great contribution in reviving Galenian knowledge while adding new knowledge of human anatomy. Also in the sixteenth century, Ambroise Paré can be said to have started modern surgery. As surgery developed, more detailed anatomical knowledge became necessary for treating complicated diseases. Many noted surgeons at the time were also anatomists eager to spread anatomical knowledge in order to enhance surgical practice. Thus, surgery and anatomy developed together, with advances in each benefiting the other. The concept of surgical anatomy evolved in the eighteenth century and became especially popular in the nineteenth century. In the twentieth century, microsurgery was introduced in various surgical fields, starting with Carl O. Nylen in otology. It flourished and became popularized in the second half of the century, especially in the field of neurosurgery, following Jacobson and Suarez's success in microvascular anastomosis in animals and subsequent clinical application as developed by M.G. Yasargil and others. Knowledge of surgical anatomy as seen under the operating microscope became important for surgeons to perform microneurosurgical procedures accurately and safely, which led to the fuller development of MNA as conducted by many neurosurgeons, among whom A.L. Rhoton, Jr. might be mentioned as representative.

Evolution of cerebellomedullary fissure opening: its effects on posterior fossa surgeries from the fourth ventricle to the brainstem.

Surgical approaches to the fourth ventricle and its surrounding brainstem regions have changed significantly in the previous 30 years, after the establishment of cerebellomedullary fissure (CMF) opening. With the development of CMF opening techniques, CMF opening surgeries have become widely used for the treatment of various pathologies and have contributed to the improvement of surgical results in posterior fossa surgeries. We here review the historical progress of CMF opening surgeries to help the future progression of neurosurgical treatments. The authors studied the available literature to clarify how CMF opening surgeries have developed and progressed, and how much the idea and development of CMF opening techniques have affected the advancement of posterior fossa surgeries. With the establishment of angiography, anatomical studies on CMF in the 1960s were performed mainly to clarify vascular anatomy on radiological images. After reporting the microsurgical anatomy of CMF in a cadaveric study in 1982, one of the authors (T.M.) first proposed the clinical usefulness of CMF opening in 1992. This new method enabled wide exposure of the fourth ventricle without causing vermian splitting syndrome, and it took the place of the standard approach instead of the conventional transvermian approach. Several authors reported their experiences using this method from the end of the twentieth century to the early twenty-first century, and the naming of the approach, "telovelar approach" by Mussi and Rhoton in 2000 contributed to the global spread of CMF opening surgeries. The approach has become widely applied not only for tumors but also for vascular and brainstem lesions, and has assisted in the development of their surgical treatments, and brought up the idea of various fissure dissection in the posterior fossa. Studies of microsurgical anatomy of the fourth ventricle, including the CMF, has led to new surgical approaches represented by the transCMF/telovelar approach. The CMF opening method caused a revolution in posterior fossa surgeries. The idea was developed based on the experience gained while dissecting the CMF (the roof of the fourth ventricle) in the laboratory. Anatomical studies using cadaveric specimens, particularly their dissection by surgeons themselves, together with a deep understanding of brain anatomy are essential for further advancements in neurosurgical treatments.

The history of Rhoton's Lab.

The work performed in Dr. Rhoton's Lab, represented by over 500 publications on microneurosurgical anatomy, greatly contributed to improving the level of neurosurgical treatment throughout the world. The authors reviewed the development and activities of the Lab over 40 years. Dr. Albert L. Rhoton Jr., the founder of, and leader in, this field, displayed great creativity and ingenuity during his life. He devoted himself to perfecting his study methodology, employing high-definition photos and slides to enhance the quality of his published papers. He dedicated his life to the education of neurosurgeons. His "lab team," which included microneuroanatomy research fellows, medical illustrators, lab directors, and secretaries, worked together under his leadership to develop the methods and techniques of anatomical study to complete over 160 microneurosurgical anatomy projects. The medical illustrators adapted computer technologies and integrated art and science in the field of microneurosurgical anatomy. Dr. Rhoton's fellows established methods of injecting colors and pursued a series of projects to innovate surgical approaches and instruments over a 40-year period. They also continued to help Dr. Rhoton to conduct international educational activities after returning to their home countries. Rhoton's Lab became a world-renowned anatomical lab as well as a microsurgical training center and generated the knowledge necessary to perform accurate, gentle, and safe surgery for the sake of patients.

Outcome of microvascular decompression for hemifacial spasm associated with the vertebral artery.

We retrospectively compared the outcome of microvascular decompression (MVD) for hemifacial spasm (HFS) associated with the vertebral artery (VA) with that of MVD for HFS unrelated to the VA. Between April 2008 and April 2015, 22 patients with VA-associated HFS underwent MVD at our institution. The median follow-up period was 28 months (range, 12-90 months). Results were classified as excellent in 19 patients (86 %), good in one (5 %), fair in one (5 %), and poor in one (5 %). Immediate complications developed in five patients (23 %), and one of these complications (5 %) was permanent. The surgical outcome of MVD for VA-associated HFS was similar to that of MVD for HFS unrelated to the VA; however, the incidence of complications was significantly more frequent in patients whose VA compressed the more proximal portion of the facial nerve root exit zone from the caudal side at the pontomedullary sulcus. We conclude that preoperative evaluation of VA compression patterns is important to predict the difficulty of the planned MVD procedure.

[A Rare Case of Cerebellar Hemangioblastoma Causing Taste Disorder].

Taste(gustation)is one of the five senses, and comprises the types: sweet, bitter, salty, sour, and umami. Taste disorders, such as dysgeusia and parageusia, are classified into 2 types: those with peripheral origin and those with central origin. The peripheral origin-type taste disorder is caused by zinc deficiency, mouth dryness, a side effect of radiotherapy or complication of systemic diseases such as, diabetes, hepatopathy, and nephropathy. The central origin-type taste disorder is reported to be caused due to demyelinating disease, pontine hemorrhage, pontine infarction, and thalamic infarction; it is very rarely caused by a brain tumor. We surgically treated a 69-year-old man with cerebellar hemangioblastoma who had developed taste disorder. The tumor compressed the solitary nucleus, which includes the taste tract in the central nervous system. On removal of the tumor, the taste disorder gradually improved.

Outcome of microvascular decompression for trigeminal neuralgia treated with the stitched sling retraction technique.

The purpose of this retrospective study was to describe and evaluate the long-term outcome of microvascular decompression (MVD) with the stitched sling retraction technique for treating trigeminal neuralgia (TN). Between January 2007 and December 2012, 50 patients with idiopathic TN underwent MVD using the stitched sling retraction technique at our institution. The median follow-up period was 5.2 years (range, 1.8-6.8 years). Using Kaplan-Meier analysis, the rates of complete pain relief without medications were 88% at 1 year and 83% at 5 years. Recurrence was noted in two patients, and one patient was re-treated using a complementary procedure for pain relief. Although transient complications were observed in seven patients, no permanent neurological deficit was observed. We conclude that the stitched sling retraction technique is a safe and effective treatment for TN and maintains substantial pain relief and low recurrence rates over a long period of time.

Anatomy of the superior petrosal veins and their exposure and management during petrous apex meningioma surgery using the lateral suboccipital retrosigmoid approach.

During surgeries in the upper cerebellopontine angle (CPA), the superior petrosal veins (SPVs) often act as obstacles; and their sectioning sometimes causes serious complications. In this study, we introduced a classification system for the SPVs wherein their tributaries were classified into four groups on the basis of their courses and draining areas. We furthermore explained the detailed anatomy of the vein of the cerebellopontine fissure, which is the largest tributary. In surgeries of petrous apex meningioma, the knowledge of the displacement pattern of the vein is very helpful for avoiding major venous complications. Therefore, we elucidated its anatomical situation in relation to the original portion of the meningioma and the natural draining point of the vein into the superior petrosal sinus (SPS) in each patient. In addition, we described the methods and techniques used to expose and manage the vein of the cerebellopontine fissure during surgery using the lateral suboccipital retrosigmoid approach. Presenting two illustrative cases, we recommend that the initial exposure of the tumor should be performed through the infratentorial lateral supracerebellar route and that the suprafloccular cistern is the best area to find the vein of the cerebellopontine fissure. We emphasized the importance of the preservation of the vein of the cerebellopontine fissure and also proposed the order for exposure of SPV tributaries during upper CPA surgery using the retrosigmoid approach.

Posterior condylar canals and posterior condylar emissary veins-a microsurgical and CT anatomical study.

The posterior condylar canals (PCCs) and posterior condylar emissary veins (PCEVs) are potential anatomical landmarks for surgical approaches through the lateral foramen magnum. We conducted computed tomography (CT) and microsurgical investigation of how PCCs and PCEVs can aid in planning and performing these approaches. We analyzed the microanatomy of PCCs and PCEVs using cadaveric specimens, dry skulls, and CT images. The recognition frequency and geometry of PCCs and PCEVs and their relationships with surrounding structures were evaluated. PCCs were identified in 36 of 50 sides in dry bones and 82 of 100 sides by CT. PCCs had a 3.5-mm mean diameter and a 6.8-mm mean canal length. We classified their courses into four types according to intracranial openings: the sigmoid sinus (SS) type, the jugular bulb (JB) type, the occipital sinus type, and the anterior condylar emissary vein type. In most cases, PCEV originated near the boundary between the SS and JB. PCCs and PCEVs can be useful anatomical landmarks to differentiate the transcondylar fossa approach from the transcondylar approach, thus preventing unnecessary injury of the atlantooccipital joint. They can also be used as landmarks when the jugular foramen (JF) and hypoglossal canal (HGC) are being exposed. The area anterior to the brain stem and the medial part of HGC can be accessed by removal of the lateral foramen magnum medial to PCC. JF and the lateral part of HGC can be accessed by removal of the skull base lateral to PCC without damaging the lateral rim of the foramen magnum.

Technical strategies for en bloc resection and immediate reconstruction in hemangioma of the frontal bone.

Hemangioma of the skull is a benign solitary tumor, often found in the frontal or parietal area. A hemangioma lesion typically involves the outer table rather than the inner, but its complete removal at the diploe level is difficult. Full-thickness resection at the calvaria is often needed to ensure a free margin, but it will leave a bony defect that requires reconstruction. Although curettage and covering of the lesion with alloplastic material are a simple treatment option for hemangioma of the skull, it does not always prevent recurrence. Hence, complete resection is needed. As our technical strategies for reconstruction, we organize a split calvarial bone graft if a defect is near the frontal sinus and calcium phosphate cement if it is somewhat far from the sinus.

Executive function and diffusion in frontal white matter of adults with moyamoya disease.

BACKGROUND: Cognitive impairment is a frequent complication of moyamoya disease (MMD) in adults. Chronic hypoperfusion in frontal lobes can lead to subtle brain injury, resulting in cognitive dysfunctions. Apparent diffusion coefficient (ADC) in normal-appearing white matter on conventional magnetic resonance imaging correlates with cerebral hemodynamics in the frontal lobe. OBJECTIVE: The purpose of this study was to examine the relationship of ADC with executive function in patients with MMD. METHODS: Thirty-one patients (25 women and 6 men; mean age, 32.6 ± 10.4 years) were included in this study. Executive function was evaluated by the Frontal Assessment Battery (FAB) at 21.5 ± 7.5 years after disease onset. ADC was measured in the normal-appearing frontal white matter. RESULTS: ADC was statistically related to the occurrence of executive dysfunction in multivariate analysis (P = .0179). Total FAB score and ADC were negatively correlated (r(2) = .22; P = .0072; Spearman correlation coefficient, -.41; P = .024). Elevated ADC predicted executive dysfunction (area under the receiver operating characteristic curve, .73; 95% confidence interval, .55-.91; P = .029). CONCLUSIONS: The association of ADC with executive function might suggest that ADC is useful in screening for executive dysfunction during follow-up in the outpatient setting.

Does childhood maltreatment affect hikikomori via traits of modern-type depression?

BACKGROUND: In the 1990s, the concepts of hikikomori and modern-type depression (MTD) emerged in Japan. Hikikomori is a condition of social avoidance or isolation, characterized by staying at home and being physically isolated for at least six months. MTD is characterized by depressive symptoms-mainly in stressful work or school situations during adolescence and early adulthood-which tend to rapidly reduce or disappear after leaving the stressful situation. We hypothesized that childhood maltreatment can form MTD traits that lead to hikikomori. METHODS: As a first step, we conducted a multigroup path analysis between childhood maltreatment, MTD traits, and physical isolation in the hikikomori group. This study utilized the nine-item Patient Health Questionnaire (PHQ-9), Home Environment Questionnaire (HEQ), 22-item Tarumi Modern-Type Depressive Trait Scale (TACS-22), 25-item Hikikomori Questionnaire (HQ-25), and Hamilton Depression Rating Scale (HDRS). The HQ-25 contains three factors: physical isolation, lack of socialization, and lack of emotional support. RESULTS: The hikikomori group included 92 patients and the control group comprised 137 healthy individuals. All total and subscale scores of PHQ-9, HEQ, TACS-22, HQ-25, and HDRS were significantly higher in the hikikomori group than in the control group. The risk model of childhood maltreatment for physical isolation via MTD traits obtained good fit with a goodness-of-fit index of.982. LIMITATIONS: The study's limitations were its sample selection bias, cross-sectional design, and use of self-report scales. CONCLUSIONS: Our findings support the hypothesis that childhood maltreatment is an important risk factor for hikikomori via MTD traits.

Development of depression assessment tools using humanoid robots -Can tele-operated robots talk with depressive persons like humans?

BACKGROUND: Depression is a common mental disorder and causes significant social loss. Early intervention for depression is important. Nonetheless, depressed patients tend to conceal their symptoms from others based on shame and stigma, thus hesitate to visit psychiatrists especially during early phase. We hypothesize that application of humanoid robots would be a novel solution. Depressed patients may feel more comfortable talking with such robots than humans. METHODS: We recruited 13 patients with major depressive disorder (MDD) and 27 healthy volunteers as controls. Participants took both tele-operated humanoid robot and human interviews to evaluate severity of depression using the Hamilton Depression Rating Scale (HDRS). In addition, participants completed a self-administered questionnaire asking about their impressions of the robot interview. RESULTS: Confidence interval and t-test analysis have revealed that the HDRS scores are equally reliable between robot and human interviews. No significant differences were observed between the two interviews regarding "nervousness about the interview" and "hesitancy to talk about depressed moods and suicidal ideation." Compared to human interviews, robot interviews yielded significantly lower scores on shame-related factors especially among patients with MDD. LIMITATION: Small sample size, and the evaluator is male only. CONCLUSIONS: This is the first report to show the reliability of tele-operated humanoid robot interviews for assessment of depression. Robot interviews are potentially equally reliable as human interviews. Robot interviews are suggested to be more appropriate in assessing shame-related suppressed emotions and hidden thoughts of depressed patients in clinical practice, which may reduce the stigma associated with depression.

Obstructive hydrocephalus following aqueductal stenosis caused by supra- and infratentorial developmental venous anomaly: case report.

OBJECTIVE: We report a rare case of hydrocephalus following aqueductal stenosis caused by developmental venous anomaly (DVA). METHODS: Four years after the incidental discovery of asymptomatic DVA, the 10-year-old boy presented with symptoms of hydrocephalus. Enhanced computed tomographic scans and magnetic resonance images showed supra- and infratentorial DVAs with caput medusae appearances in the right basal ganglia and cerebellum. Three dilated collector veins in the right basal ganglia, floor of the third ventricle, and floor of the fourth ventricle gathered together to drain into the great vein of Galen. Three-dimensional fusion images showed that the serpentine dilated vein from the posterior fossa coursed in the aqueduct and caused the aqueductal stenosis, which was confirmed by operative endoscopy. RESULTS: Endoscopic third ventriculostomy was performed and the hydrocephalus was relieved. CONCLUSIONS: Although aqueductal stenosis caused by DVA is rare, it is important to be considered in the differential diagnosis of hydrocephalus. Three-dimensional reconstruction and fusion images are very useful.

3D Computer graphics simulation to obtain optimal surgical exposure during microvascular decompression of the glossopharyngeal nerve.

The affected artery in glossopharyngeal neuralgia (GPN) is most often the posterior inferior cerebellar artery (PICA) from the caudal side or the anterior inferior cerebellar artery (AICA) from the rostral side. This technical report describes two representative cases of GPN, one with PICA as the affected artery and the other with AICA, and demonstrates the optimal approach for each affected artery. We used 3D computer graphics (3D CG) simulation to consider the ideal transposition of the affected artery in any position and approach. Subsequently, we performed microvascular decompression (MVD) surgery based on this simulation. For PICA, we used the transcondylar fossa approach in the lateral recumbent position, very close to the prone position, with the patient's head tilted anteriorly for caudal transposition of PICA. In contrast, for AICA, we adopted a lateral suboccipital approach with opening of the lateral cerebellomedullary fissure, to visualize better the root entry zone of the glossopharyngeal nerve and to obtain a wide working space in the cerebellomedullary cistern, for rostral transposition of AICA. Both procedures were performed successfully. The best surgical approach for MVD in patients with GPN is contingent on the affected artery--PICA or AICA. 3D CG simulation provides tailored approach for MVD of the glossopharyngeal nerve, thereby ensuring optimal surgical exposure.

[A case of cerebellar variant of posterior reversible encephalopathy syndrome in puerperium].

A 29-year-old woman complained of headache and nausea several hours after delivery, followed by mild disturbance of consciousness. Physical examination revealed hypertension, systemic edema, nystagmus, dysarthria, and cerebellar ataxia. Computed tomography showed low attenuation areas in the cerebellum, and MR imaging revealed vasogenic edema in the cerebellum. MR angiography and MR venography demonstrated no significant abnormalities. We diagnosed a cerebellar variant of posterior reversible encephalopathy syndrome(PRES), and treated the patient immediately with antihypertensive drug and diuretic. The symptoms dramatically improved and MR imaging ten days after admission revealed disappearance of the vasogenic edema in the cerebellum. She was discharged without any sequelae. Though a cerebellar variant of PRES is very rare, rapid diagnosis and treatment is important for good prognosis when the disease is encountered.

[Blood blister-like aneurysm on the posterior wall of the internal carotid artery causing subarachnoid hemorrhage: a case report].

We report a case of blood blister-like aneurysm(BBA)on the posterior wall of the internal carotid artery(ICA)causing subarachnoid hemorrhage(SAH). A 45-year-old man suffering from SAH(WFNS grade 5)was referred to our hospital. 3D-CT angiography showed a BBA on the posterior wall of the ICA. The aneurysm had been enlarged for a few days. Therefore we performed coil embolization. Four weeks after the operation, the aneurysm was found to have regrown. In the second operation the aneurysm was successfully treated by the ICA proximal occlusion with extracranial-intracranial bypass. Postoperative follow-up cerebral angiography detected no aneurysm. To our knowledge, BBA on the posterior wall of the ICA is rare. Radical surgery with bypass should be performed as soon as possible when the BBA is found to regrow. We discuss the clinical characteristics with a review of the literature.

Telovelar/Transcerebellomedullary Fissure Approach: Giant Distal Posterior Inferior Cerebellar Artery Aneurysm, Epidermoid Cyst, and Brainstem Cavernoma: 2-Dimensional Operative Video.

INDICATIONS CORRIDOR AND LIMITS OF EXPOSURE: The telovelar or transcerebellomedullary fissure approach can provide wide exposure of the cerebellomedullary fissure and fourth ventricle by separating the natural plane between the medulla and cerebellum. 1-5. ANATOMIC ESSENTIALS NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT: The cerebellar tonsil is attached to the adjacent cerebellum only by the tonsillar peduncle at its superolateral edge. 2 The posterior inferior cerebellar artery (PICA) runs in the cerebellomedullary fissure, usually making its caudal and cranial loops. 6,7. ESSENTIALS STEPS OF THE PROCEDURE: After widely opening the foramen magnum, the tonsil is gently elevated by shearing the tela choroidea up to the lateral recess from the taenia, where the vein of the inferior cerebellar peduncle courses. 8,9. PITFALLS/AVOIDANCE OF COMPLICATIONS: The developed occipital sinus, posterior condylar vein, and anomalies of the vertebral artery and PICA origin can obstruct the exposure. Detailed neuromonitoring is essential for accomplishing the procedure safely. 10,11. VARIANTS AND INDICATIONS FOR THEIR USE: This exposure can be extended to the lower cerebellopontine angle and can also be applied to the dorsal brainstem surgery. 2,12 The patients consented to the procedure and to the publication of their images.Image Credits: Department of Neurosurgery, Tokyo Medical University logo used by permission. Image at 0:10, 1:02, 2:46, 6:22, and 7:10 from Matsushima and Kohno, 1 used by permission from Medical View Co., Ltd.Right image at 0:14 and also upper image at 0:46, image at 1:26, and for left and lower right images at 1:54 from Matsushima et al, 2 by permission from Journal of Neurosurgery Publishing Group (JNSPG). Left image at 0:14, from Matsushima et al, 4 used by permission from the Congress of Neurological Surgeons. Lower image at 0:46 reprinted from Matsushima et al, 9 by permission from Elsevier. Left image at 1:06 from Matsushima et al, 8 used by permission from the Congress of Neurological Surgeons.Image at top right at 1:54 from Lister et al, 6 used by permission from the Congress of Neurological Surgeons. Image in center at 6:56 from Matsushima et al, 11 used by permission from Springer Nature. Image at right at 6:56 from Matsushima et al, 10 used by permission from JNSPG. Images at 9:48, by year: 1982 article screenshot and figure from Matsushima et al, 4 by permission from the Congress of Neurological Surgeons; 1992: article title screenshot from Matsushima et al, 3 by permission from the Congress of Neurological Surgeons; 1996: used with permission of McGraw-Hill Health Professions Division, from Microsurgical Anatomy of the Fourth Ventrical, Matshushiam T and Rhoton AL Jr, in Neurosurgery , eds Wilkins and Rengachary, vol 1, 1996, permission conveyed through Copyright Clearance Center, Inc.; 2000: article title screenshot from Mussi et al, 5 reused with permission from JNSPG; 2001: article title screenshot from Matsushima, Transcerebellomedullary fissure approach with special reference to methods of dissecting the fissure, J Neurosurg , vol 91, 2001, p. 257-264, by permission from JNSPG; 2021: article title screenshot from Matsushima et al, 12 by permission from Springer Nature. Images at 11:05 from Inoue T et al, "Surgical approach to the mesencephalic vascular malformation" [in Japanese], Surg Cereb Stroke , vol 26, 1998, p 288-289, by permission from the Japanese Society on Surgery for Cerebral Stroke. Cadaveric image at 11:56 from Matsushima T et al, "Exposure of the wide interior of the fourth ventricle without splitting the vermis: importance of cutting procedures for the tela choroidea" Neurosurg Rev , vol 35, 2012, p 563-571, used with permission from Springer Nature.