Biomedical subjects

M Samii

Publications and source records attributed to M Samii.

At least 37 records · Page 2Linked to original sources

PubMed2002

Neuropsychological testing to improve surgical management of patients with chronic hydrocephalus after shunt treatment.

AIM: To find out a practical neuropsychological tool for early and reliable outcome assessment in chronic hydrocephalus. In 30 patients (65 +/- 13 yrs.) 11 neuropsychological tests providing a wide range of psychomotor functions (visual and verbal attention, verbal memory and learning and visuomotor skills) were applied before (pre), one week (early) and 7 months (late) after shunting. After 7 months, clinical outcome was classified according to Stein and Langfitt. Statistics included factor analysis, logistic regression and non-parametric tests. Visual attention ("Digit-symbol"), verbal recall ("10-words-list") and motor precision ("line-tracing") were the most representative (and practical) tests (orthogonal loads > 0.9). These tests, in contrast to others, revealed significant differences between outcome groups concerning early postoperative changes: responder showed marked improvement in visual attention t-scores (47 +/- 8 vs. 41 +/- 8 (pre); p = 0.005) and motor precision scores (109 +/- 26 vs. 149 +/- 47 (pre); p = 0.03). Non-responder even decreased in verbal recall t-scores early after shunting (35 +/- 7 vs. 41 +/- 11 (pre); p = 0.007). By logistic regression, visual attention was most sensitive indicating shunt-response by early psychometric changes (p = 0.04). Psychomotor deficits in hydrocephalic patients can be represented by a few neuropsychological skills: visual attention, verbal recall and line tracing. Since they showed early post-operative differences regarding long-term response to shunting they may offer a practical and standardised method for reliable follow-up.

Aged↗

PubMed2002

Neuropsychological sequels to changes in global cerebral blood flow and cerebrovascular reserve capacity after shunt treatment in chronic hydrocephalus--a quantitative PET-study.

AIM: To study relationship of neuropsychological deficits in chronic hydrocephalus before and after shunting with dynamics in cerebral blood flow. In 27 patients (65 +/- 13 yrs) with idiopathic chronic hydrocephalus 11 selected neuropsychological tests, providing a wide range of psychomotor functions, were performed before, one week (early) and 7 months (late) after shunting. Parallel global cortical blood flow (CBF) and cerebrovascular reserve capacity (CVR) were determined by dynamic 15-O-water PET studies (Siemens ECAT 951/31) before and after application of acetazolamide (1 g). Test raw data and changes after treatment were compared with global and regional blood flow values by polynomial regression. No relationship of test profiles with hemodynamics before surgery was found. After one week, improvement of gait was related to an increase in cerebrovascular reserve capacity (p = 0.05). After 7 months changes in mental tests were related to changes in hemodynamics: again increases in CVR were significantly related to improvements in visual attention and verbal memory (p < 0.01). Early improvement of hemodynamic reserve was related to improvement in gait, whereas mental improvement was particularly related to increases in global CVR at later periods after shunting. These results indicate that neurological sequels in idiopathic chronic hydrocephalus after shunting may actually depend on consecutive improvement of cerebral hemodynamics.

Aged↗

PubMed2002

Dynamic shunt testing applying short lasting pressure waves--inertia of shunt systems.

Laboratory shunt testing often comprises only static pressure flow and flow pressure tests. We applied shorter acting pressure waves using a computerised shunt testing rig to investigate shunt behaviour under conditions that might occur in the clinical situation, e.g. during nocturnal vasogenic pressure waves or shorter rises in ICP at movements or exercise. Additionally the influence of a human-like compliance situation compared to a fixed pressure/volume relationship was investigated. Shunts behaved very differently than seen in static tests and demonstrated a marked inertia the shorter pressure waves acted. Although some valves opened at higher pressure, all valves showed marked hysteresis and none did close--if at all--at the specified pressure level. This behaviour might be a cause of shunt overdrainage not related to siphoning. The simulation of a human-like variable pressure-volume relationship with higher compliance at lower pressures had a positive effect on shunt function by decreasing the amount of drained volume. We therefore suggest to include dynamic pressure wave testing if hydrodynamic properties of shunts are to be evaluated.

Cerebrospinal Fluid↗

PubMed2002

Long-time in-vivo metabolic monitoring following experimental brain contusion using proton magnetic resonance spectroscopy.

In a Sham-controlled study we applied proton magnetic resonance spectroscopy (1H-MRS) at 4.7 T to a model of experimental traumatic brain contusion. The time course of cerebral metabolite changes was monitored in serial investigation in 14 Sprague Dawley rats up to 4 weeks after trauma. 6 animals served as controls. 1H-MRS spectra were acquired from a voxel covering the hippocampus/basal ganglia ipsi and contralateral to the lesion. Metabolites ratios of the injured hemisphere were compared to those ipsilateral in Sham animals and to those of the contralateral side in the trauma animals. NAA/Cr ratio and Glu/Cr ratio, possible markers of neuronal loss, persistently decreased after trauma to a minimum of -40% and -20% versus controls, respectively. One week after trauma Cho/Cr ratio was strongly increased by 73%. This might indicate a high inflammatory activity at that time. Lac/Cr ratio showed long-lasting and continuing increases up to 2000% versus controls as a sign of permanently shifted posttraumatic energy metabolism. 1H-MRS proved to be a useful non-invasive method for in-vivo monitoring of posttraumatic metabolism also in models of brain contusion. In single cases however, accompanying haemorrhage can potentially prevent useful data acquisition.

Animals↗

PubMed2002

Determination of contusion and oedema volume by MRI corresponds to changes of brain water content following controlled cortical impact injury.

The time-course of brain contusion/oedema development as visualised by high-resolution MRI was compared to brain water content following experimental brain contusion. 36 Sprague-Dawley rats underwent Controlled Cortical Impact Injury (CCII), 24 served as controls. In 16 animals serial T2 weighted MRI investigations at 1 h, 4 h, 24 h and 7 d after CCII were performed, in 44 rats hemispheric brain water content was determined at the same time points by wet dry weight method. MRI lesion volume (mm3) and brain water content of injured hemisphere (%) showed for absolute and relative values a strictly parallel course. Significant posttraumatic increases had a maximum at 24 hours. Values on day 7 were below those of 1st h in both methods. The simple non-invasive MRI method quantifies contusion and surrounding penumbra according to elevated tissue water signal. The invasive wet dry weight method quantifies changes of hemispheric brain water content that are likely to take place in contusion core and surrounding penumbra. Therefore, from a theoretical aspect both methods seem comparable. Following experimental brain contusion, the simple MRI method might be an equally sufficient way to describe post-traumatic or post-therapeutic changes of lesion size and brain oedema.

Animals↗

PubMed2002

Traumatic subarachnoidal hemorrhage in the developing rat.

The aim of the present study was to utilize an experimental traumatic subarachnoidal hemorrhage model in the developing rat. Diffuse brain injury was produced in intubated and ventilated 21 to 25 days old Sprague-Dawley rats (N = 10) using a modification (1 m/100 g) of the Marmarou-model. Before induction of the injury heparin was administered i.v. and antagonised after injury by protamine. Mean arterial blood pressure and intracranial pressure was measured continuously. Histopathological investigations were performed. The results were compared to readings in adult animals (N = 12) subjected to a 1.5 m/500 g injury. In the developing rat ICP increased immediately following injury from 11.4 +/- 2.1 mm Hg to 55.9 +/- 20.3 mm Hg. It remained elevated till the end of the experiment 1 h after injury. MABP increased from 79.8 +/- 8.7 mm Hg to 100.2 +/- 21.7 mm Hg immediately following injury, returning to 61.3 +/- 28.7 mm Hg at the end of the experiment resulting in a marked decrease of CPP. The mortality rate was 60%. All brains showed a severe subarachnoidal hemorrhage in the basal cisterns. The increase of ICP following injury is attributable to the bleeding similar as in adult animals. The high mortality is due to the marked decrease of CPP. Rat pups are more vulnerable to t-SAH compared to adult rats.

Aging↗

PubMed2002

Temporal and regional profile of neuronal and glial cellular injury after induction of kaolin hydrocephalus.

AIM: To study regional and temporal pattern of glial and neuronal reaction to induction of kaolin hydrocephalus in adult rats. Enzyme- and immunohistochemistry was performed in 20 adult rats with kaolin-hydrocephalus after 2, 4, 6 and 8 weeks to glial glutamatergic transmission activity (GLDH) and neuronal nitrous oxide synthetic activity (nNOS). Also, glial fibrillary acidic protein (GFAP), 68 kd neurofilament protein (NF68) and synaptophysin (SYN38) and basic fibroblastic growth-factor (bFGF) were stained. Results were quantified by imaging analysis (SCION IMAGE) and expressed as relative immunopositive area. After 2 weeks, nNos-activity increased in cortical and hippocampal neurones (CA1 and CA3) and GLDH-activity also showed increases, most significant in periventricular white matter (25.7 +/- 3.8 vs. 15.5 +/- 4.9; p < 0.001) and hippocampus (p < 0.01). After 4 or 6 weeks, global cortical GLDH-activity showed further marked increases (25.7 +/- 3.9 vs. 11.3 +/- 1.5; p < 0.05), while sustained structural changes have occurred: GFAP decreased in periventricular (3.3 +/- 0.5 vs. 6.3 +/- 1.2; p < 0.01), hippocampal and cortical astrocytes (0.9 +/- 0.34 vs. 5.0 +/- 0.7%; p < 0.01), whereas NF68 in cortical efferent neurones increased (6.5 +/- 1.5% vs. 4.7 +/- 0.1; p < 0.01) followed by a decrease in cortical and hippocampal (CA1) SYN 38 (p < 0.05). Acute glial and neuronal reactions were almost functional and in chronic stages sustained structural changes predominated. Since neuronal reactions were pronounced in selective vulnerable areas glial reaction was not restricted to periventricular astrocytes.

Animals↗

PubMed2002

Natural history of chondroid skull base lesions--case report and review.

Long-term follow-up reports on chondroid lesions of the skull base are rarely presented in the literature. There are virtually no data on natural growth rates of these tumors based on MRI obtained over a period of 10 years or longer. We followed a patient who has had such a lesion for more than 12 years. A non-progressive, slight abducens palsy has been the only associated symptom so far. Even though the patient was operated on for an additional intracranial arterio-venous malformation, clinical features and chromosomal testing excluded Maffucci's syndrome. The MRI follow-up in this case provides an extraordinary perspective on the natural history of chondroid skull base tumors.

Adult↗

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

Lumbar ependymoma presenting with paraplegia following attempted spinal anaesthesia.

Neurological deterioration from intraspinal haematoma following insertion of a spinal needle is extremely rare. We present the case of a 28-yr-old female, who presented with complete paraplegia following attempted spinal anaesthesia for delivery of her third child. Space-occupying iatrogenic spinal haemorrhage from a previously undiagnosed lumbar ependymoma was found to be the precipitating cause. Following laminotomy with blood clot and tumour removal her neurological function improved.

Adult↗

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↗

PubMed2002

Vestibular schwannomas and auditory function: options in large T3 and T4 tumors?

OBJECTIVE: While hearing preservation has become an accepted treatment goal, there are still major doubts whether and to what extent this aim is feasible in large tumors that cover the auditory nerve and involve the brainstem. METHODS: One thousand eight hundred (1,800) vestibular schwannomas (VS) were operated on at Nordstadt Neurosurgical Department from 1978 to 1999 by the senior surgeon (MS). There were 1,800 tumors in 1,750 patients, 1,605 patients had unilateral tumors, 145 patients had neurofibromatosis type 2 with bilateral tumors, 195 of which were treated surgically in our unit. Preservation of the cochlear nerve was attempted when ever possible. The audiometric data are analyzed by Hannover Classification System graded in steps of 20 dB by audiometry and in steps of 10% to 30% by speech discrimination. Those data were set into relation with the Hannover tumor extension grading T1 to T4. RESULTS: Overall preservation rate was 40% with considerable differences, though, depending on the preoperative hearing quality and the tumor extension. Best results were obtained for intrameatal tumors (T1) with 56% and small intra-extrameatal tumors (T2) with 57% preservation rate. While preservation rate was at 44% in medium-sized tumors (T3), it was at 20% for T4 tumors with brainstem compression or even dislocation. However, satisfactory chances were encountered in cases with normal or good preoperative hearing, on average 54%, specifically 71% in T1, 69% in T2, 58% in T3 and 29% in T4. Regarding the quality of the preserved hearing, up to one third of cases in T1 and T2 may retain their preoperative hearing level, while this ranges around 20% for T3 and 10% to 14% in T4 tumors. DISCUSSION: For long, hearing preservation in medium sized or large tumors has not received any attention because of the presumed lack of realistic chances and the expected bad quality. Obviously, hearing preservation may be achieved in relevant numbers and at satisfactory quality levels. This aspects appears important to be addressed further in view of the fact that over 70% of tumors are presented for surgery at T3 or T4 extensions. CONCLUSION: The summit of hearing preservation has not been reached as improvements are still achieved even in most difficult conditions.

Cerebellopontine Angle↗

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↗