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Biomedical subjects

M Samii

Publications and source records attributed to M Samii.

At least 19 recordsLinked to original sources
PubMed2002

Regeneration of auditory nerve following complete sectioning and intrathecal application of the IN-1 antibody.

The cochlear nerve of adult Lewis rats was following microsurgical exposure in the cerebellopontine angle (CPA). The lesions completely interrupted the auditory nerve axons at the lesion site producing ipsilateral deafness in all animals. The rats were then treated with a recombinant Fab fragment of the antibody IN-1 against nerve growth inhibitory proteins for one to two weeks. An age-matched control group of rats was treated with unspecific mouse IgG antibody. Because the cochlear nerve lesions resulted in significant neuronal apoptosis of spiral ganglion cells, neurotrophin-3 (NT-3) was applied to the lesion site immediately post-injury in some rats. Electrophysiological studies were carried out by recording the brainstem auditory evoked potentials (BAEP) before and immediately after the lesion, and at regular intervals up to 2 months after injury. Cochlear nerve fibres were anterogradely traced by horseradish peroxidase (HRP) or biotinylated dextran amine (BDA) injected into the spiral ganglion. The results achieved in this study were consistent with the following conclusions: 1) transection of the adult rat cochlear nerve at the CPA results in functional deafness, disappearance of BAEP, apoptosis of parent axotomized neurons of the spiral ganglion, and interruption of labelled axons close to the lesion site; 2) NT-3 is able to partially rescue axotomized neurons of the spiral ganglion; 3) injured cochlear nerve fibres show a limited spontaneous sprouting and regrowth response which does not lead to BAEP recovery; 4) intrathecal treatment with IN-1 directed against myelin-associated neurite growth inhibitory proteins promotes significant elongation of the injured fibres; and 5) the regenerating fibres seem to navigate to correct targets, and be able to establish synaptic connections for functional recovery as depicted by BAEP examinations.

Animals↗
PubMed2002

Single cerebral metastasis 3 and 19 years after primary renal cell carcinoma: case report and review of the literature.

Cerebral metastasis in general is associated with a relatively short survival time. However, brain deposits may occur rather late during follow up. Nine cases of solitary brain metastasis of renal cell carcinoma with a latency period of more than 10 years after nephrectomy have been reported in the literature so far. This is the first report of a case describing a second solitary brain metastasis which occurred 16 years after a first metastatic brain lesion. Complete microsurgical resection alone led to an excellent outcome in this particular case as the patient refused any adjuvant therapy at the same time. Regular nuclear morphology, a low mitotic index, and the absence of chromosomal abnormalities in tumour cells may be indicative for a relative benign clinical course.

Brain Neoplasms↗
PubMed2001

Evidence of recurrent atypical meningioma with rhabdoid transformation and expression of pyrogenic cytokines in a child presenting with a marked acute-phase response: case report and review of the literature.

Children presenting with acute systemic illnesses that lack specific clinical or serological defining features may be diagnosed as having a chronic infection, an atypical systemic vasculitis or a connective tissue disease, but often turn out to have occult neoplasias. Cytokines have been implicated in causing many of the systemic effects in such cases. In this study, we describe the case of a 9-year-old boy presenting at an interval of 18 months with a marked acute-phase response due to a recurrent atypical meningioma with rhabdoid transformation of the tentorium cerebelli. Resection of the recurrent tumor was curative. We evaluated in detail the local and systemic production of cytokines released by the primary and the recurrent tumor. Blood and CSF samples were taken pre-, intra-, and postoperatively, and the production of IL-6, IL-1beta, and TNF-alpha was measured by enzyme-linked immunosorbent assays (ELISA). The level of IL-6 in CSF was about 150-fold increased before tumor resection, normalizing postoperatively. On the contrary, the levels of IL-1beta and TNF-alpha in CSF and of IL-6, IL-1beta, and TNF-alpha in serum were pre-, intra-, and postoperatively within normal limits. Cytokine production was also evaluated immunohistochemically, and confirmed strong IL-6 and TNF-alpha expression in the primary and the recurrent tumor, while expression of IL-1beta was lacking. The scattered MHC class II- and leukocyte common antigen (LCA)-expressing inflammatory cells, which were infiltrating exclusively the tumoral stroma, had no detectable cytokine immunoreactivity. We conclude that chronic IL-6 and TNF-alpha production by the tumor cells in this patient was responsible for the severe systemic illness with which he presented.

Acute Disease↗
PubMed2001

Regeneration of a transected peripheral nerve by transplantation of spinal cord encapsulated in a vein.

The objective was to investigate the regeneration of a transected peripheral nerve after transplantation of fragmented embryonic (E14-15) spinal cord cells which were encapsulated within a vein cavity. After 3 months transplantation, axonal regeneration was observed by staining with HE and antibody to neurofilament subtypes in six of 10 rats. In all six animals compound muscle action potentials to electrical stimulation could be recorded and indicated incomplete reinnervation of the fibular and tibial nerve, respectively. A chronic inflammation process around the transplant and a negative result of staining neurofilaments within the vein cavity and the transected nerve were found in animals lacking electrophysiological response to stimulation.

Action Potentials↗
PubMed2001

Comparison of unilateral and bilateral intrastriatal 6-hydroxydopamine-induced axon terminal lesions: evidence for interhemispheric functional coupling of the two nigrostriatal pathways.

Partial lesions of the nigrostriatal dopamine system can be induced reliably by the intrastriatal injection of 6-hydroxydopamine (6-OHDA) and are considered to be analogous to the early stages of human Parkinson's disease. Previous studies have established a clear correlation between different doses and placements of the 6-OHDA toxin and the degree of neurodegenerative changes and behavioral impairments. In the present study, the influence of the interdependence between the two nigrostriatal systems in both hemispheres on the effects on sensorimotor behavioral performances after terminal 6-OHDA lesions was investigated. The behavioral effects were correlated to the extent of nigral dopamine neuron cell and striatal tyrosine-hydroxylase (TH)-positive fiber loss. Sprague-Dawley rats receiving unilateral intrastriatal 6-OHDA injections (4 x 5 microg) exhibited a 30-70% reduction in striatal TH-positive fiber density along an anterior-posterior gradient, an 80% loss of nigral dopamine neurons and a mild degree of behavioral impairments as revealed by amphetamine-induced rotational asymmetry, and a reduced performance in the stepping and postural balance tests. When the same amount of toxin was injected twice into both hemispheres (2 x 4 x 5 microg), additional behavioral deficits were observed, consisting of a significant, but temporary, weight loss, a stable reduction in general locomotor activity and explorational behavior, and a long-term deficit in skilled forelimb use. This is interesting in light of the morphological findings, in which uni- and bilaterally lesioned animals did not differ significantly in the extent of TH-immunoreactive fiber and dopamine neuron loss within the nigrostriatal system in each lesioned hemisphere. These results indicate that the interdependent regulation of the two nigrostriatal systems may provide some compensatory support for the function and behavioral performance of the lesioned side via the normal unlesioned side, which is lost in animals with bilateral lesions of the nigrostriatal system. Therefore, this model of uni- and bilateral partial lesions of the nigrostriatal system, as characterized in the present study, may foster further exploration of compensatory functional mechanisms active in the early stages of Parkinson's disease and promote development of novel neuroprotective and restorative strategies.

Adrenergic Agents↗
PubMed2001

Resting regional cerebral glucose metabolism in advanced Parkinson's disease studied in the off and on conditions with [(18)F]FDG-PET.

Studies of resting regional cerebral glucose consumption (rCMRGlc) in nondemented patients with Parkinson's disease (PD) have produced conflicting results, reporting both reduced and normal metabolism in advanced disease and reduced or normal metabolism after dopaminergic therapy. To investigate these issues, [(18)F]fluorodeoxyglucose (FDG) positron emission tomography (PET) was performed in 11 nondemented PD patients with advanced disease and 10 age-matched controls. PD patients were studied after withdrawal of all dopaminergic medication to produce a practically defined off condition, and a second time 1 hour after levodopa, resulting in a clinical on state. Dynamic PET scans and simultaneous arterialised venous blood samples of [(18)F] activity were obtained. A graphical approach was used to generate parametric images of rCMRGlc and statistical parametric mapping to localise significant metabolic changes in PD. Compared with controls, global rCMRGlc was reduced in the on but not in the off condition in PD. In both states, significant regional reductions of glucose uptake were found in the parietal, frontal, temporal cortex, and caudate nucleus. Reductions correlated with the severity of disability in frontal and temporal cortex. Direct comparison between on and off conditions revealed relatively greater reductions of uptake in the ventral/orbital frontal cortex and the thalamus during on. Results suggest that cortical and caudate hypometabolism are common in advanced PD and that caution is mandatory if [(18)F]FDG PET is being used to differentiate advanced PD from dementia and progressive supranuclear palsy where similar reductions are seen. Furthermore, in PD, administration of levodopa is associated with further hypometabolism in orbitofrontal cortex; an area known to be relevant for reversal learning where performance is typically impaired after dopaminergic treatment.

Adult↗
PubMed2001

Dermoid cyst in the posterior fossa accompanied by Klippel-Feil syndrome.

OBJECTS: Dermoid cysts accompanied by Klippel-Feil syndrome are uncommon, and the coincidence of these two rare diseases suggests an interesting idea about the pathogenesis of a dermoid cyst, which the authors consider with reference to an actual case. A posterior fossa dermoid cyst with dermal sinus and Klippel-Feil syndrome are reported in the same patient. A 23-year-old woman was admitted to hospital with progressive headaches. METHODS: Cervical radiography demonstrated C4-5 vertebral fusion, and magnetic resonance imaging revealed a large cystic mass in the midline of the posterior fossa. The cystic lesion was totally removed along with the accompanying dermal sinus. It was histopathologically diagnosed as a dermoid cyst. CONCLUSION: The rare coincidence of a dermoid cyst and Klippel-Feil syndrome suggests the possibility that a disturbance in the mesoderm before the fourth week of gestation might play an important part in the causation of dermoid cyst.

Adult↗
PubMed2001

Trigeminal root recording in normal trigeminal function.

Despite many investigations on the detection of trigeminal evoked potentials (TEP), there is still no consensus on a technique or interpretation of its components. In order to obtain clear TEP waveforms and analyze the origin of early components, we recorded TEP by the conventional far-field technique at the ipsilateral auricula as well as by near-field technique with a bipolar electrode at the trigeminal root just distal to the entry zone of its root. Trigeminal recordings were performed in nine patients with intrameatal vestibular schwannomas and in three with trigeminal neuralgia without trigeminal nerve deficits. In near-field recording at the trigeminal root, a triphasic response was recorded, with the first component occurring at 3.16 ms, 2.98 ms, and 4.16 ms following supraorbital, infraorbital, and mandibular nerve stimulation, respectively. Using conventional farfield TEP, the first component recorded at the trigeminal root occurred later than the first component in all other recordings. This suggests that the N2.0 component of far-field TEP is of extra-axial origin and the N5 component is of brainstem origin. The N13.0 component may be of cortical origin. We conclude that the N5.0 component and N5.0-N13.0 interpeak latency may be used as electrophysiological parameters of brainstem function during posterior fossa surgery.

Electric Stimulation↗
PubMed2001

Arterial supply of the temporo-medial region of the brain: significance for preoperative vascular occlusion testing.

The mesiobasal limbic system is of particular significance in the surgical treatment of temporo-medial tumors and epilepsy. It consists of the uncus, amygdaloid body, hippocampus, dentate gyrus, subiculum, fasciolar gyrus and the parahippocampal gyrus. Knowledge of the vascular microanatomy is a key to the surgical treatment of pathologies in the region. The anterior choroidal artery was selectively injected in fresh brain specimens: 50 specimens with a gelatinous ink mixture to demonstrate vascular territories in stereotactic brain slices, and 50 with a Biodur resin to obtain casts for microanatomical evaluation. The cast technique was also applied to 35 specimens injected into the posterior cerebral artery. The rostral third of the temporomedial region is mainly supplied by branches of the anterior choroidal artery. The occipital two thirds are supplied by hippocampal branches, the posteromedial choroidal artery and the inferior temporal branches of the posterior cerebral artery. Important vessel variations with significant implications for the preoperative Wada-test are presented.

Anterior Cerebral Artery↗
PubMed2001

Thoracic intradural extramedullary lipomas. Report of three cases and review of the literature.

BACKGROUND: Indication for surgery and the surgical strategy for treatment of spinal intradural lipomas are still discussed controversially. Among spinal lipomas the cervicothoracic region is rarely affected. We report on our experience with spinal decompression for the treatment of three intradural thoracic lipomas. FINDINGS: Three adult patients with extramedullary intradural lipomas of the thoracic spinal cord demonstrated progressive neurological symptoms and signs without evidence of growth of the lipoma. All patients underwent surgery with decompression of the affected spinal levels. No attempt was made to reduce the size of the lipomas. Postoperatively, each patient demonstrated significant clinical improvement. Interpretation. Attempts to remove lipomas are associated with significant risks of surgical morbidity. Lipomas are hamartomas which change their size according to alterations of body fat. Therefore, decompression of the affected spinal levels is sufficient to achieve significant neurological improvement.

Adult↗
PubMed2001

Intracerebral epidermoid tumor: a case report and review of the literature.

BACKGROUND: Intracerebral epidermoid cysts are rare lesions and may account for only 1.5% of intracranial epidermoid tumors. Cell entrapment from the mesectodermal origin of the neural crest within the primitive cerebral hemisphere may lead to the formation of such rare intracerebral lesions. METHODS: An intracerebral epidermoid cyst located in the right temporal lobe that was surgically treated is presented. The origin, clinical course, radiological features, and surgical treatment of such uncommon lesions are discussed based on a review of the literature. RESULTS: Intraoperative findings revealed an epidermoid tumor. The postoperative course was uneventful and the patient was discharged with no neurological deficits. On long-term follow-up (2 years), there were no signs of recurrence. CONCLUSIONS: Truly intracerebral epidermoid tumors are rarely found. Cells originating from mesectodermal lines may migrate and remain trapped within the primitive cerebral hemisphere while the neural tube is closing, leading to the formation of such intraparenchymal epidermoid tumors. Accurate preoperative diagnosis can be very difficult due to the radiological similarities to other common intracerebral cysts (e.g., astrocytomas or gliomas). Magnetic resonance imaging (MRI) studies, especially with diffusion-weighted images, allow greater accuracy in the preoperative differential diagnosis. Radical surgical removal should be attempted, but a less aggressive surgical strategy should be considered if there is strong adherence between the tumor capsule and the brain tissue, particularly in eloquent areas.

Adult↗
PubMed2001

Immunohistochemical characterization of axonal sprouting and reactive tissue changes after long-term implantation of a polyimide sieve electrode to the transected adult rat sciatic nerve.

The development of artificial microstructures suited for interfacing of peripheral nerves is not only relevant for basic neurophysiological research but also for future prosthetic approaches. Aim of the present study was to provide a detailed analysis of axonal sprouting and reactive tissue changes after implantation of a flexible sieve electrode to the proximal stump of the adult rat sciatic nerve. We report here that massive neurite growth after implantation, steadily increasing over a period of 11 months, was observed. Parallel to this increase was the expression of myelin markers like Po, whereas non-myelin-forming Schwann cells did not change. Compared to five weeks post-implantation. where both Schwann-cell phenotypes were intermingled with each other, non-myelin-forming Schwann cells occupied a peripheral position in each microfascicle after 11 months. After an initial increase, hematogenous macrophages were down-regulated in number but maintained close contact with the implant. However, at no time were signs of its degradation observed. It is concluded that the introduced flexible polyimide electrode is suitable for contacting peripheral nerves since it permits substantial neurite growth and offers excellent long-term stability.

Animals↗
PubMed2001

[Computer assisted plastic closure of calvarial defects].

Large bony skull defects sometimes face problems of some pathophysiological effects, protection of the underlying brain, the impaired appearance, and from a psychological point of view. A computer-assisted method is presented, which has been successfully used in 44 patients. From 3-D-CT data a phantom was built in which Refobacin-Palacos was modeled for individual requirements. The plastic can be implanted after sterilization and leads to excellent cosmetical results. The use of a negative model reveals the possibility of an extended field of application without the necessity of highly specialized computersystems.

Adolescent↗
PubMed2001

Disturbances of cerebrospinal fluid flow attributable to arachnoid scarring cause interstitial edema of the cat spinal cord.

OBJECTIVE: Spinal arachnoid scarring may be caused by trauma, inflammation, surgery, spinal instability, degenerative diseases, or malformations and may lead to progressive neurological deficits and syringomyelia. We wanted to investigate the effects of focal arachnoid scarring in the cervical spinal canal of cats on pressures in the subarachnoid space and spinal cord tissue, as well as on spinal cord histological features. METHODS: Twenty-nine adult cats were used for this study. Nine animals served as control animals, whereas 20 animals received a focal arachnoid scar at C1-C2, which was produced by placement of a kaolin-soaked fibrin sponge on the posterior surface of the spinal cord. After 4 months, pressure recordings above and below the scar, in the subarachnoid space and spinal cord, were performed. Elasticity measurements were performed with small bolus injections. Morphometric analyses of brain and ventricle volumes, sizes of the central canal, and sizes of the perivascular spaces in gray and white matter were also performed. RESULTS: No animal developed clinical or neurophysiological evidence of neurological symptoms at any time. In the kaolin-treated group, pressure recordings revealed a significant increase in the subarachnoid pressure at C1, because of the cerebrospinal fluid flow obstruction. Pressure gradients tended to increase at all measuring points. A significant difference was detected between the spinal cord and subarachnoid space at C2, where the intramedullary pressure exceeded the subarachnoid pressure. Elasticity was significantly increased in the spinal cord at C2. Intracranially, no evidence of hydrocephalus was observed. In the spinal cord, perivascular spaces were significantly enlarged in the posterior white matter above the arachnoid scar and in the central gray matter below the area of scarring in the cervical cord. CONCLUSION: Arachnoid scarring at C1-C2 produces an interstitial type of edema in the central gray matter below the area of scarring in the cat cervical cord, because of altered cerebrospinal fluid and extracellular fluid flow dynamics. These changes may be interpreted as the initial stage in the development of syringomyelic cavities.

Animals↗
PubMed2001

Spontaneous resolution of Chiari I malformation and syringomyelia: case report and review of the literature.

OBJECTIVE AND IMPORTANCE: Indications for surgery and the surgical technique of foramen magnum decompression for patients with Chiari I malformation and syringomyelia are controversial issues. This case report supports the view that observation may be adequate for patients without progressive symptoms or with mild clinical symptoms. CLINICAL PRESENTATION: A 37-year-old woman presented with a 3-month history of burning dysesthesias and hypesthesia in her right arm. A neurological examination revealed hypesthesia in the right trigeminal distribution. A magnetic resonance imaging scan revealed a Chiari I malformation with syringomyelia between C2 and T2. No hydrocephalus was observed. CLINICAL COURSE: Because the patient's symptoms regressed spontaneously, surgery was not performed. Thirty-two months after her initial examination, the patient was asymptomatic. A second magnetic resonance imaging scan was obtained, which demonstrated complete spontaneous resolution of the Chiari I malformation and syringomyelia. CONCLUSION: We attribute the regression of the patient's symptoms to spontaneous recanalization of cerebrospinal fluid pathways at the foramen magnum, which most likely was due to rupture of the arachnoid membranes that had obstructed cerebrospinal fluid flow.

Adult↗
PubMed2001

Microsurgical removal of a petrous apex meningioma after stereotactic radiation: technical case report.

OBJECTIVE AND IMPORTANCE: Stereotactic radiation is increasingly advocated as a primary treatment option for benign cranial base lesions. The clinical course of the patient reported herein raises questions regarding the rationale for initiation of radiotherapy to a petrous apex meningioma before microsurgery. CLINICAL PRESENTATION: We report a 50-year-old woman who experienced medically refractory trigeminal pain. She was diagnosed with a meningioma around the petrous apex and treated by fractionated stereotactic radiation. After a short period of alleviation accompanied by hypesthesia, the pain returned in a previously unknown and violent fashion. INTERVENTION: Complete tumor removal through a retrosigmoid intradural suprameatal approach resulted in immediate and permanent pain cessation. CONCLUSION: Radiotherapy should be withheld for benign and accessible tumors of the cranial base until the option of radical microsurgical treatment has been explored.

Combined Modality Therapy↗