Search Results

You are looking at 1 - 10 of 12 items for

  • Author or Editor: Hiroaki Sakamoto x
  • Refine by Access: all x
Clear All Modify Search
Restricted access

Hiroaki Sakamoto, Akira Hakuba, Ken Fujitani, and Shuro Nishimura

✓ In a series of 75 patients with surgically treated lipomyelomeningoceles, the neurological condition of six patients deteriorated 6 months to 14 years after the operation due to repeat tethering of the spinal cord. The tethering resulted from postoperative dense adhesion between the cord and the overlying dura mater. Two of the six patients underwent conventional repeat untethering procedures, and the remaining four were successfully treated with a new surgical technique developed by the authors to prevent such dural adhesion. For this procedure, after complete untethering of the spinal cord, the lumbosacral cord is retained in the center of the dural sac by fine stay sutures between the pia mater of the conus medullaris and the ventral dura mater. In addition, the dura mater is tacked to the posterior arch which is reconstructed with bone grafts at one or two bifid vertebral levels. During a postoperative follow-up period of 1 to 3 years, no further deterioration has been observed and magnetic resonance studies have demonstrated a space filled with cerebrospinal fluid (CSF) around the lumbosacral cord. The authors conclude that long-term observation, both neurological and radiological, is essential even after successful repair of a lipomyelomeningocele. This new surgical procedure can maintain a CSF bath around the lumbosacral cord, thus preventing dural adhesion. Application of this technique will hopefully be beneficial in lipomyelomeningocele patients with a high risk of cord retethering after initial repair.

Restricted access

Misao Nishikawa, Hiroaki Sakamoto, Akira Hakuba, Naruhiko Nakanishi, and Yuichi Inoue

✓ To investigate overcrowding in the posterior cranial fossa as the pathogenesis of adult-type Chiari malformation, the authors studied the morphology of the brainstem and cerebellum within the posterior cranial fossa (neural structures consisting of the midbrain, pons, cerebellum, and medulla oblongata) as well as the base of the skull while taking into consideration their embryological development. Thirty patients with Chiari malformation and 50 normal control subjects were prospectively studied using neuroimaging. To estimate overcrowding, the authors used a “volume ratio” in which volume of the posterior fossa brain (consisting of the midbrain, pons, cerebellum, and medulla oblongata within the posterior cranial fossa) was placed in a ratio with the volume of the posterior fossa cranium encircled by bony and tentorial structures. Compared to the control group, in the Chiari group there was a significantly larger volume ratio, the two occipital enchondral parts (the exocciput and supraocciput) were significantly smaller, and the tentorium was pronouncedly steeper. There was no significant difference in the posterior fossa brain volume or in the axial lengths of the hindbrain (the brainstem and cerebellum). In six patients with basilar invagination the medulla oblongata was herniated, all three occipital enchondral parts (the basiocciput, exocciput, and supraocciput) were significantly smaller than in the control group, and the volume ratio was significantly larger than that in the Chiari group without basilar invagination.

These results suggest that in adult-type Chiari malformation an underdeveloped occipital bone, possibly due to underdevelopment of the occipital somite originating from the paraxial mesoderm, induces overcrowding in the posterior cranial fossa, which contains the normally developed hindbrain. Basilar invagination is associated with a more severe downward herniation of the hindbrain due to the more severely underdeveloped occipital enchondrium, which further exacerbates overcrowding of the posterior cranial fossa.

Full access

Misao Nishikawa, Hiroaki Sakamoto, Junsuke Katsuyama, Akira Hakuba, and Shuro Nishimura

The authors present the case of a patient with ischemic episodes and recurrent intracerebral hemorrhages probably caused by primary angiitis of the central nervous system (CNS). An initial angiogram revealed multiple cerebral artery aneurysms as well as vascular wall irregularity; a second angiogram obtained 2 years later, however, did not demonstrate the previous aneurysms but instead showed new ones together with stenosis. Based on the histopathological findings and clinical course in this case, the multiple aneurysms appear to have been induced by vascular wall fragility and subsequent self-repair resulting from primary angiitis of the CNS. The authors present the histological and clinical characteristics of this unusual case of granulomatous, necrotizing CNS vasculitis.

Full access

Misao Nishikawa, Hiroaki Sakamoto, Akira Hakuba, Naruhiko Nakanishi, and Yuichi Inoue

To investigate overcrowding in the posterior cranial fossa as the pathogenesis of adult-type Chiari malformation, the authors studied the morphology of the brainstem and cerebellum within the posterior cranial fossa (neural structures consisting of the midbrain, pons, cerebellum, and medulla oblongata) as well as the base of the skull while taking into consideration their embryological development. Thirty patients with Chiari malformation and 50 normal control subjects were prospectively studied using neuroimaging. To estimate overcrowding, the authors used a "volume ratio" in which volume of the posterior fossa brain (consisting of the midbrain, pons, cerebellum, and medulla oblongata within the posterior cranial fossa) was placed in a ratio with the volume of the posterior fossa cranium encircled by bony and tentorial structures. Compared to the control group, in the Chiari group there was a significantly larger volume ratio, the two occipital enchondral parts (the exocciput and supraocciput) were significantly smaller, and the tentorium was pronouncedly steeper. There was no significant difference in the posterior fossa brain volume or in the axial lengths of the hindbrain (the brainstem and cerebellum). In six patients with basilar invagination the medulla oblongata was herniated, all three occipital enchondral parts (the basiocciput, exocciput, and supraocciput) were significantly smaller than in the control group, and the volume ratio was significantly larger than that in the Chiari group without basilar invagination.

These results suggest that in adult-type Chiari malformation an underdeveloped occipital bone, possibly due to underdevelopment of the occipital somite originating from the paraxial mesoderm, induces overcrowding in the posterior cranial fossa, which contains the normally developed hindbrain. Basilar invagination is associated with a more severe downward herniation of the hindbrain due to the more severely underdeveloped occipital enchondrium, which further exacerbates overcrowding of the posterior cranial fossa.

Restricted access

Misao Nishikawa, Hiroaki Sakamoto, Junsuke Katsuyama, Akira Hakuba, and Shuro Nishimura

✓ The authors present the case of a patient with ischemic episodes and recurrent intracerebral hemorrhages probably caused by primary angiitis of the central nervous system (CNS). An initial angiogram revealed multiple cerebral artery aneurysms as well as vascular wall irregularity; a second angiogram obtained 2 years later, however, did not demonstrate the previous aneurysms but instead showed new ones together with stenosis. Based on the histopathological findings and clinical course in this case, the multiple aneurysms appear to have been induced by vascular wall fragility and subsequent self-repair resulting from primary angiitis of the CNS. The authors present the histological and clinical characteristics of this unusual case of granulomatous, necrotizing CNS vasculitis.

Restricted access

Hiroaki Sakamoto, Ken Fujitani, Shouhei Kitano, Keiji Murata, and Akira Hakuba

✓ The authors report four hydrocephalic children with cerebrospinal fluid (CSF) edema extending along the ventricular catheter of an obstructed CSF shunt. Three of the patients exhibited massive CSF edema along the ventricular catheter, yet they manifested neither ventricular enlargement nor apparent periventricular CSF edema despite increased intraventricular pressure. These findings suggested ventricular tautness. The remaining patient, who had dilated ventricles with periventricular CSF edema, displayed CSF edema in a limited area along the ventricular catheter. Replacement of the obstructed peritoneal catheter of the shunt resulted in rapid improvement of the edema in all patients. In the three patients with massive CSF edema, however, a small lesion remained in the subcortical white matter along the ventricular catheter as demonstrated by computerized tomography and/or magnetic resonance imaging 3 to 5 years after shunt revision. It is concluded that shunt obstruction may result in massive CSF edema along the ventricular catheter in hydrocephalic children who have ventricular tautness after installation of the shunt causing irreversible although usually asymptomatic damage to the affected area of the brain.

Restricted access

Masaki Komiyama, Misao Nishikawa, Shouhei Kitano, Hiroaki Sakamoto, Nobuhiro Miyagi, Satoshi Kusuda, and Hisakazu Sugimoto

✓ A neonate, in whom a congenital cerebral vascular anomaly had been diagnosed prenatally, exhibited progressive high-output congestive heart failure soon after birth. Cerebral angiography revealed a congenital dural arteriovenous fistula (AVF) with a huge dural lake located at the torcular herophili. In addition to the meningeal blood supply, an unusual pial blood supply from all cerebellar arteries was observed to feed the fistula. The patient was treated by repeated transarterial and transvenous embolization through the umbilical venous route. To the authors' knowledge, neither the existence of a congenital dural AVF at the torcular herophili presenting with an enormous pial blood supply or the technique of transumbilical venous intervention has been reported in the literature.

Restricted access

Keisuke Imai, Hiroyuki Komune, Chiaya Toda, Takeru Nomachi, Eiji Enoki, Hiroaki Sakamoto, Shohei Kitano, Mitsuo Hatoko, and Takuya Fujimoto

Object. The authors describe their experience in remodeling the shape of the cranium in children with craniosynostosis by using gradual distraction. In half of the cases, a new distraction device developed by the authors was used.

Methods. Twenty children with craniosynostosis underwent frontoorbital advancement and cranial remodeling assisted by gradual distraction. There were five children with brachycephaly, two with oxycephaly, five with scaphocephaly, two with plagiocephaly, one with combined scaphocephaly and plagiocephaly, and five with trigonocephaly. Four cases were syndromic and 16 were nonsyndromic. The patients ranged in age from 3 to 50 months (mean 14.5 months) at the first surgery. Simulated surgery was first performed on a three-dimensional solid model made of polyurethane, which accurately represented cranial flexibility, to determine the most favorable osteotomy line. Distraction was initiated 1 week postoperatively. The speed and extent of advancement (maximum extension 45 mm) were predetermined on the basis of previously reported criteria and the results of simulated surgery. Postoperatively, the cranial configuration was favorable in all cases. Spontaneous remodeling of irregularities and/or gaps apparent after distraction was found to occur 2 to 5 months after removal of the distraction devices, especially in patients with trigonocephaly or scaphocephaly. No major perioperative complication was observed in any patient. There were minor complications in six of the first 10 cases, including exposure of the device, shaft slippage, and fluid discharge. A new device was developed and used on the last 10 patients treated; it successfully eliminated device exposure and shaft slippage. A 3-year follow-up review confirmed that there was no relapse of advanced bones.

Conclusions. Highly satisfactory results were achieved in cases of both syndromic and nonsyndromic craniosynostosis when gradual distraction was performed.

Restricted access

Yonehiro Kanemura, Nobuhiko Okamoto, Hiroaki Sakamoto, Tomoko Shofuda, Hiroyuki Kamiguchi, and Mami Yamasaki

Object

Mutations in the gene that codes for the human neural cell adhesion molecule L1 (L1CAM), are known to cause a wide variety of anomalies, now understood as phenotypic expressions of L1 syndrome. The correlations between genotype and phenotype, however, are not fully established. The authors report the results of a nationwide investigation of L1CAM gene mutations that was performed to improve the understanding of L1-mediated molecular mechanisms of X-linked hydrocephalus and to establish neurorimaging criteria for this severe form of L1 syndrome.

Methods

Ninety-six genomic DNA samples from members of 57 families were obtained from the Congenital Hydrocephalus Research Committee. By using polymerase chain reaction and direct DNA sequencing, the authors identified 25 different L1CAM gene mutations, 20 of them novel, in 26 families with X-linked hydrocephalus. All the mutations were L1CAM loss-of-function mutations, and all the patients had severe hydrocephalus and severe mental retardation. In all cases, specific abnormalities were visible on neuroimaging: a rippled ventricular wall after shunt placement, an enlarged quadrigeminal plate, a large massa intermedia, and hypoplasia of the cerebellar vermis (anterior or total). The patients also had adducted thumbs, spastic paraplegia, and hypoplasia of the corpus callosum, which are characteristic of L1 syndrome.

Conclusions

The L1CAM loss-of-function mutations cause a severe form of L1 syndrome, unlike the milder form produced by mutations in the L1CAM cytoplasmic domain. We also identified neurorimaging criteria for this severe form of L1 syndrome. These criteria can be used to predict loss-of-function mutations in patients with X-linked hydrocephalus and to help in diagnosing this syndrome.