Details of a Researcher - AKIYAMA Yukinori

Papers - AKIYAMA Yukinori

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Hearing preservation surgery for vestibular schwannomas via the retrosigmoid transmeatal approach: surgical tips.

Masahiko Wanibuchi, Takanori Fukushima, Allan H Friedman, Kentaro Watanabe, Yukinori Akiyama, Takeshi Mikami, Satoshi Iihoshi, Tomohiro Murakami, Toshiya Sugino, Nobuhiro Mikuni

Neurosurgical review 37 ( 3 ) 431 - 44 2014.07 [International journal]

Maximum tumor extirpation with preservation of the facial and cochlear nerve function is the goal of surgery for vestibular schwannoma. To preserve cochlear nerve function, the surgeon must employ a detailed knowledge of microanatomy, precise microsurgical techniques, and persistence. This paper describes the "pearls" of surgical techniques based on the anatomical study inside the mastoid from the view of the retrosigmoid transmeatal approach. A total of 592 consecutive patients underwent surgical removal of unilateral vestibular schwannoma (VS) between January 1994 and December 2009. The hearing preservation rate was 53.7 % for large vestibular schwannomas (>20 mm in diameter) and 74.1 % for tumors of all sizes. The key procedures for hearing preservation surgery are as follows: bloodless microdissection, sufficient coring-debulking, capsular elevation to locate the facial and cochlear nerves both electrophysiologically and by visual observation, sharp dissection of the facial and cochlear nerves, and avoidance of heat and mechanical injury to the nerves, the internal auditory artery, and the brain stem. Besides these techniques, appropriate instruments are essential to preserve hearing. The function of the facial and cochlear nerves should be the foremost concern. Meticulous techniques and the knowledge of microsurgical anatomy lead to hearing preservation with maximum tumor removal.

DOI PubMed

The lateral suboccipital retrosigmoid approach and its variations

Masahiko Wanibuchi, Yukinori Akiyama, Nobuhiro Mikuni

Japanese Journal of Neurosurgery ( Japanese Congress of Neurological Surgeons ) 23 ( 10 ) 802 - 811 2014 [Refereed]

The lateral suboccipital retrosigmoid approach, one of the common procedures used in neurosurgical operations, is indicated for lesions at the cerebellopontine angle (CPA). The location of the craniotomy varies according to the main location of the pathology in the superior, middle, or inferior CPA. Here we introduce the basic procedure of the technique and its variations. First, the diagnosis of the pathology, and the relationship between the sutures and sinuses should be confirmed by preoperative magnetic resonance imaging (MRI)and computed tomography (CT). Three-dimensional MRI-CT fusion images are a great help in performing secure operative planning. Neuromonitoring techniques using cranial nerve stimulators or auditory evoked potentials, are also essential for CPA surgery. The lateral positioning obtained, with suitable head fixation, is especially important. Two different skin incisions, either a lazy “S” or “V” shaped, are used in consideration of the hair pattern of the patient. The bulk of the posterior nuchal muscles are caudally reflected, to avoid damaging them, which prevents postoperative shoulder stiffness and muscle contraction headaches. Performing the appropriate craniotomy is also key for a successful outcome. A superior CPA approach is taken for lesions around the trigeminal nerve, a middle CPA approach is used for pathological conditions around the auditory and facial nerves, and an inferior CPA approach is best for lesions around the lower cranial nerves and the pontomedullary junction. A high-speed drill and kerrison rongeurs are used for the craniotomy in order to obtain secure exposure of the posterior margin of the sigmoid sinus and to maximally preserve the autologous bone. The opening of the foramen magnum and removal of the posterior arch of the C1 are not necessary however, a transcondylar or extreme lateral approach should be considered when a more ventrocaudal visual axis is required. For intradural procedures, careful attention should be paid to the preservation of the veins, direction of the optic axis of the microscope, and circulation of the cerebrospinal fluid. In conclusion, there are three basic craniotomies of the lateral suboccipital retrosigmoid approach, which broadly correspond to addressing pathological conditions in the superior, middle, and inferior CPA.

DOI

Microvascular decompression for hemifacial spasm associated with the vertebral artery.

Takeshi Mikami, Yoshihiro Minamida, Yukinori Akiyama, Masahiko Wanibuchi, Toshiya Sugino, Kiyohiro Houkin, Nobuhiro Mikuni

Neurosurgical review 36 ( 2 ) 303 - 8 2013.04 [International journal]

In patients with vascular compression syndromes, the preoperative recognition of the cranial nerves and compressed vessels will contribute to improved surgical results. The aim of this study was to clarify the pathophysiology of hemifacial spasm (HFS) associated with the vertebral artery (VA) and to assess the value of preoperative imaging. Fifty-three consecutive patients with HFS underwent microvascular decompression (MVD). Of these, 18 cases of HFS were associated with the VA; this case series was compared with the remaining non-VA-associated HFS. For preoperative assessment, magnetic resonance imaging (MRI) was performed. Since January 2006, fusion imaging has been performed by combining MRI and computed tomography angiography. Of the 18 cases of VA-associated HFS, 17 (94.4 %) were on the left side; this was significantly higher than in the non-VA-associated HFS cases (p < 0.0001). The VA was attached to the root exit zone (REZ) directly in three cases. In the other 15 cases, the VA was compressing the REZ indirectly as a result of other intervening vessels. In all cases, preoperative imaging fully simulated the status of the REZ. The symptom disappeared in 17 cases (94.4 %) after MVD, and there was no significant difference in the surgical results between the VA-associated group and the non-VA-associated group (p = 0.9925). HFS associated with VA is not a rare condition. Preoperative recognition is thus important to the improvement of surgical results. Fusion imaging is useful to determine the status of the REZ, especially in indirect VA-associated HFS.

DOI PubMed

Primary central nervous system anaplastic large-cell lymphoma mimicking lymphomatosis cerebri.

Toshiya Sugino, Takeshi Mikami, Yukinori Akiyama, Masahiko Wanibuchi, Tadashi Hasegawa, Nobuhiro Mikuni

Brain tumor pathology 30 ( 1 ) 61 - 5 2013.01 [Domestic journal]

Primary central nervous system lymphoma (PCNSL) is usually diffuse large B-cell lymphoma. Anaplastic large-cell lymphoma (ALCL) rarely occurs in the central nervous system. PCNSL always presents as single or multiple nodular contrast-enhancing mass lesions within T2-hyperintense areas on magnetic resonance imaging (MRI). Infrequently, diffuse infiltrating change with little contrast enhancement called lymphomatosis cerebri can be seen in PCNSL. In this report, we describe a 75-year-old immunocompetent man who had progressive dementia. On MRI, diffuse white matter lesions with little contrast enhancement were observed to gradually progress, which was clinically consistent with his worsening condition. A biopsy specimen revealed non-destructive, diffusely infiltrating, anaplastic large CD30-positive lymphoma, indicating a diagnosis of ALCL. After the biopsy, he was treated by whole brain irradiation (total 46 Gy) and focal boost irradiation (total 14 Gy). However, his performance status worsened and there was no symptom improvement. The patient died 8 months after symptom onset. The clinical course, diagnostic workup, pathologic correlates, and treatment outcomes are described herein.

DOI PubMed

Practical decision-making in the treatment of unruptured cerebral aneurysm in Japan: the U-CARE study.

Yukinori Akiyama, Kiyohiro Houkin, Kazuhiko Nozaki, Nobuo Hashimoto

Cerebrovascular diseases (Basel, Switzerland) 30 ( 5 ) 491 - 9 2010 [International journal]

BACKGROUND: Decision-making during the management of unruptured cerebral aneurysms is a delicate process for both neurosurgeons and patients. Guidelines are evidence-based references that can aid in making decisions. However, neurosurgeons do not always follow guidelines in clinical practice. The purpose of this study is to verify the hypothesis that there is substantial dissociation between treatment guidelines and practical decision-making due to a bias in treatment selection for unruptured cerebral aneurysms. This bias is dependent upon clinician-driven factors such as experience and specialty, and patient-driven factors such as patient preference. METHODS: This study was performed using internet questionnaires. A total of 282 randomly selected, qualified Japanese neurosurgeons (out of approx. 6,000 registered neurosurgeons), including 45 endovascular specialists, participated in this study. Radiological and demographic data from 88 cases of unruptured cerebral aneurysm were opened on the Web. Participating neurosurgeons decided on the treatment for each case (clipping, coiling or observation). RESULTS: Variations in treatment selection were not significant between neurosurgeons and endovascular specialists, except for aneurysms such as anterior choroidal artery aneurysm. However, contrary to the guidelines, aneurysms larger than 10 mm tended to be treated conservatively because the risk of treatment is high, while aneurysms smaller than 5 mm in diameter were often selected for intervention (clipping or coiling). CONCLUSIONS: This study revealed that in real-world clinical practice, physicians are not always faithful to the current guidelines. In making practical treatment decisions for unruptured cerebral aneurysms, the patient's will and the recognition of unavoidable, treatment-related risks seriously influence neurosurgeons' decisions.

DOI PubMed

Susceptibility-weighted magnetic resonance imaging for the detection of cerebral microhemorrhage in patients with traumatic brain injury.

Yukinori Akiyama, Kei Miyata, Kuniaki Harada, Yoshihiro Minamida, Tadashi Nonaka, Izumi Koyanagi, Yasufumi Asai, Kiyohiro Houkin

Neurologia medico-chirurgica 49 ( 3 ) 97 - 9 2009.03 [Domestic journal]

The sensitivity of susceptibility-weighted magnetic resonance (MR) imaging was compared with conventional MR sequences, including T(2)*-weighted imaging, and computed tomography for the detection of cerebral hemorrhages in 15 patients with head injury. Susceptibility-weighted imaging detected a mean of 76+/-52 (total 1132) hypointense spotty lesions, compared to a mean of 21+/-19 (total 316) detected by T(2)*-weighted imaging (p<0.0001, paired t-test). Susceptibility-weighted imaging is extremely sensitive for the visualization and detection of microhemorrhages.

PubMed

Suprasellar Hemangioblastoma

Shiro Miyata, Takeshi Mikami, Yoshihiro Minamida, Yukinori Akiyama, Kiyohiro Houkin

JOURNAL OF NEURO-OPHTHALMOLOGY ( LIPPINCOTT WILLIAMS & WILKINS ) 28 ( 4 ) 325 - 326 2008.12 [Refereed] [International journal]

DOI PubMed

Interstitial spinal-cord oedema in syringomyelia associated with Chiari type 1 malformations

Y. Akiyama, I. Koyanagi, K. Yoshifuji, T. Murakami, T. Baba, Y. Minamida, T. Nonaka, K. Houkin

JOURNAL OF NEUROLOGY NEUROSURGERY AND PSYCHIATRY ( B M J PUBLISHING GROUP ) 79 ( 10 ) 1153 - 1158 2008.10 [Refereed]

Object: The pathophysiology of syringomyelia in Chiari type 1 malformations has not been clarified. Oedema-like spinal-cord swelling was recently reported in several pathological conditions, including Chiari type 1 malformations as a pre-syrinx state. However, the role of the pre-syrinx state in the development of syringomyelia is unknown. The purpose of this study is to investigate the parenchymal changes of the spinal cord in syringomyelia associated with Chiari type 1 malformations. Methods: Pre- and postoperative MRI findings in 14 patients who underwent foramen magnum decompression in our institute were reviewed. The analysis was focused on differences in visualisation of the syrinx between T1- and T2-weighted images and abnormal parenchymal signal changes. There were 6 men and 8 women, aged from 6 to 79 years. No patients showed hydrocephalus. Results: Twelve patients had large and expansive syrinx, whereas 2 patients showed small syrinx confined to the centre of the spinal cord. T2-weighted images displayed significantly larger intramedullary abnormal signal areas. Nine patients showed parenchymal hyperintensity areas around the enlarged central canal or base of the posterior white columns adjacent to the syringomyelic cavity. Such parenchymal hyperintensity areas markedly diminished with reduction of the syrinx after surgery and were considered to be interstitial oedema. Conclusions: From this study, the interstitial oedema of the spinal cord commonly accompanies syringomyelia with Chiari type 1 malformations. Accumulation of the extracellular fluid due to disturbed absorption mechanisms may play an important role in the pathophysiology of syringomyelia associated with Chiari type 1 malformations.

DOI

Alveolar soft part sarcoma in brain with cardiac metastasis. A case report

Yukinori Akiyama, Takeo Baba, Yukihiro Ibayashi, Yasufumi Asai, Kiyohiro Houkin

International Journal of Cardiology ( 3 ) 114 ( 3 ) E93 - E95 2007.01 [Refereed] [International journal]

Alveolar soft part sarcoma (ASPS) is a rare soft tissue neoplasm. The coexistence of ASPS with cardiac metastasis is quite rare, in particular. In general, the sarcoma is a malignant disease and grows very fast. However, the mean survival time of patients with ASPS is relatively long. Patients who are diagnosed with localized disease usually have a favorable prognosis, while those who present with widespread metastases usually have a poor prognosis and ultimately, succumb to their disease. The use of modern treatment modalities, such as combination of surgery, and radiotherapy, may significantly prolong the survival time in many patients. Because of the long-term period with symptomatic brain tumors in this disease, the patients should be treated even in the presence of multiple metastases in other organs. © 2006 Elsevier Ireland Ltd. All rights reserved.

DOI PubMed

False-negative cerebral infarction on diffusion magnetic resonance imaging.

Yukinori Akiyama, Yasufumi Asai, Kiyohiro Houkin

The American journal of emergency medicine 24 ( 6 ) 746 - 8 2006.10 [International journal]

PubMed

Lhermitte-Duclos disease with cervical paraspinal arteriovenous fistula.

Yukinori Akiyama, Jun Ikeda, Yukihiro Ibayashi, Tadashi Nonaka, Yasufumi Asai, Kiyohiro Houkin

Neurologia medico-chirurgica 46 ( 9 ) 446 - 9 2006.09 [Domestic journal]

A 38-year-old man presented with a dysplastic cerebellar gangliocytoma associated with a paraspinal arteriovenous fistula (AVF) at the upper cervical portion. Neuroimaging examination indicated the diagnosis of Lhermitte-Duclos disease. The patient was treated by embolization of the AVF followed by partial resection of the cerebellar tumor. Genetic examination showed a mutation of the phosphatase and tensin homolog deleted on chromosome ten (PTEN) gene. Histological examination confirmed the diagnosis. Lhermitte-Duclos disease is a rare dysplastic gangliocytoma manifesting as a slowly growing mass in the cerebellum and is usually asymptomatic. This case of Lhermitte-Duclos disease associated with paraspinal AVF and mutation of the PTEN gene suggests a relationship between Lhermitte-Duclos disease and Cowden disease.

PubMed

Remyelination of spinal cord axons by olfactory ensheathing cells and Schwann cells derived from a transgenic rat expressing alkaline phosphatase marker gene.

Yukinori Akiyama, Karen Lankford, Christine Radtke, Charles A Greer, Jeffery D Kocsis

Neuron glia biology 1 ( 1 ) 47 - 55 2004.02 [International journal]

Transplantation of cell suspensions containing olfactory ensheathing cells (OECs) has been reported to remyelinate demyelinated axons in the spinal cord with a Schwann cell (SC)-like pattern of myelination. However, questions have been raised recently as to whether OECs can form SC-like myelin. To address this issue we prepared SCs and OECs from transgenic rats in which a marker gene, human placental alkaline phosphatase (hPAP), is linked to the ubiquitously active promoter of the R26 gene. SCs were prepared from the sciatic nerve and OECs from the outer nerve-fiber layer of the olfactory bulb. Positive S100 and p75 immunostaining indicated that >95% of cells in culture displayed either SC or OEC phenotypes. Suspensions of either SCs or OECs were transplanted into an X-irradiation/ethidium bromide demyelinating lesion in the spinal cord. We observed extensive SC-like remyelination following either SC or OEC transplantation 3 weeks after injection of the cells. Alkaline phosphatase (ALP) chromagen reaction product was associated clearly with the myelin-forming cells. Thus, cell suspensions that are enriched in either SCs or OECs result in peripheral-like myelin when transplanted in vivo.

PubMed

Cell transplantation of peripheral-myelin-forming cells to repair the injured spinal cord

JD Kocsis, Y Akiyama, KL Lankford, C Radtke

JOURNAL OF REHABILITATION RESEARCH AND DEVELOPMENT ( JOURNAL REHAB RES & DEV ) 39 ( 2 ) 287 - 298 2002.03 [Refereed]

Much excitement has been generated by recent work showing that a variety of myelin-forming cell types can elicit remyelination and facilitate axonal regeneration in animal models of demyelination and axonal transection. These cells include peripheral-myelin-forming cells, such as Schwarm cells and olfactory ensheathing cells. In addition, progenitor cells derived from the subventricular zone of the brain and from bone marrow (BM) can form myelin when transplanted into demyelinated lesions in rodents. Here, we discuss recent findings that examine the remyelination potential of transplantation of peripheral-myelin-forming cells and progenitor cells derived from brain and bone marrow. Better understanding of the repair potential of these cells in animal models may offer exciting opportunities to develop cells that may be used in future clinical studies.

Transplantation of an acutely isolated bone marrow fraction repairs demyelinated adult rat spinal cord axons

M Sasaki, O Honmou, Y Akiyama, T Uede, K Hashi, JD Kocsis

GLIA ( WILEY-LISS ) 35 ( 1 ) 26 - 34 2001.07 [Refereed]

The potential of bone marrow cells to differentiate into myelin-forming cells and to repair the demyelinated rat spinal cord in vivo was studied using cell transplantation techniques. The dorsal funiculus of the spinal cord was demyelinated by x-irradiation treatment, followed by microinjection of ethidium bromide. Suspensions of a bone marrow cell fraction acutely isolated from femoral bones in LacZ transgenic mice were prepared by centrifugation on a density gradient (Ficoll-Paque) to remove erythrocytes, platelets, and debris. The isolated cell fraction contained hematopoietic and nonhematopoietic stem and precursor cells and lymphocytes. The cells were transplanted into the demyelinated dorsal column lesions of immunosuppressed rats. An intense blue beta -galactosidase reaction was observed in the transplantation zone. The genetically labeled bone marrow cells remyelinated the spinal cord with predominately a peripheral pattern of myelination reminiscent of Schwann cell myelination. Transplantation of CD34(+) hematopoietic stem cells survived in the lesion, but did not form myelin. These results indicate that bone marrow cells can differentiate in vivo into myelin-forming cells and repair demyelinated CNS. GLIA 35:26-34, 2001. (C) 2001 Wiley-Liss, Inc.

Transplantation of clonal neural precursor cells derived from adult human brain establishes functional peripheral myelin in the rat spinal cord

Y Akiyama, O Honmou, T Kato, T Uede, K Hashi, JD Kocsis

EXPERIMENTAL NEUROLOGY ( ACADEMIC PRESS INC ) 167 ( 1 ) 27 - 39 2001.01 [Refereed]

We examined the myelin repair potential of transplanted neural precursor cells derived from the adult human brain from tissue removed during surgery. Sections of removed brain indicated that nestin-positive cells were found predominately in the subventricular zone around the anterior horns of the lateral ventricle and in the dentate nucleus. Neurospheres were established and the nestin-positive cells were clonally expanded in EGF and bFGF. Upon mitogen withdrawal in vitro, the cells differentiated into neuron- and glia-like cells as distinguished by antigenic profiles; the majority of cells in culture showed neuronal and astrocytic properties with a small number of cells showing properties of oligodendrocytes and Schwann cells. When transplanted into the demyelinated adult rat spinal cord immediately upon mitogen withdrawal, the cells elicited extensive remyelination with a peripheral myelin pattern similar to Schwann cell myelination characterized by large cytoplasmic and nuclear regions, a basement membrane, and PO immunoreactivity. The remyelinated axons conducted impulses at near normal conduction velocities. This suggests that a common neural progenitor cell for CNS and PNS previously described for embryonic neuroepithelial cells may be present in the adult human brain and that transplantation of these cells into the demyelinated spinal cord results in functional remyelination. (C) 2001 Academic Press.

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Papers - AKIYAMA Yukinori