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Biomedical subjects

M Samii

Publications and source records attributed to M Samii.

At least 73 records · Page 4Linked to original sources
PubMed2000

Epidermoid cyst of the cavernous sinus: clinical features, pathogenesis and treatment.

Epidermoid cyst may rarely arise within the lateral wall of the cavernous sinus (CS) and produce clinical symptoms mimicking the Tolosa-Hunt syndrome. Pathogenically, it is suggested that some of the subpopulation of cells arising from the neural crest which give rise to skin, may remain entrapped in the meninges around the nerves in the lateral wall in an uncompleted stage of maturation and may develop epidermoid cysts. A case is presented of a 68-year-old man with a 4-week history previously diagnosed as Tolosa-Hunt syndrome. MRI is the investigation of choice. Surgical resection can result in excellent recovery of preoperative deficits of cranial nerves (CN) III through VI.

Aged↗
PubMed2000

Cerebral metabolic response to traumatic brain injury sustained early in development: a 2-deoxy-D-glucose autoradiographic study.

Following fluid percussion (FP) traumatic brain injury (TBI), adult rats exhibit dynamic regional changes in cerebral glucose metabolism characterized by an acute (hours) increase and subsequent chronic (weeks) decrease in metabolic rates. The injury-induced hyperglycolysis is the result of ionic fluxes across cell membranes and the degree and extent of metabolic depression is predictive of neurobehavioral deficits. Given that younger animals appear to exhibit similar physiological responses to injury yet show an improved rate of recovery compared to adults, we wanted to determine if this injury-induced dynamic metabolic response to TBI is different if the injury is sustained early in life. Local cerebral metabolic rates for glucose (ICMRglc: micromol/100 g/min) using [14C]2-deoxy-D-glucose were measured immediately, 30 min, 1 day, and 3 days following a mild to moderate level of lateral FP injury in postnatal day 17 (P17) rats. Even though gross morphological damage was not evident, injured pups exhibited ipsilateral hyperglycolysis immediately after injury, predominantly in cortical regions (ranging from 59.2% to 116.5% above controls). This hyperglycolytic state subsided within 30 min, and by 1 day all cerebral structures, except the ipsilateral cerebellar cortex, showed lower rates of glucose metabolism (ranging from 5.7% to 63.0% below controls). This period of posttraumatic metabolic depression resolved within 3 days for all structures measured. Compared to previous adult studies these results suggest that the young rat pup, although exhibiting acute hyperglycolysis, is not subjected to a prolonged period of metabolic depression, which supports the findings that at this level of injury severity, these young animals show remarkable neurological sparing following TBI.

Age Factors↗
PubMed2000

Cystic schwannomas of the jugular foramen: clinical and surgical remarks.

OBJECTIVE: The goals of this report were to outline the clinical presentation, radiological characteristics, surgical techniques, postoperative morbidity, and long-term follow-up results for cystic jugular foramen (JF) schwannomas and to describe their differences, compared with solid schwannomas involving the JF. METHODS: A retrospective analysis of radiological studies and surgical records identified five primarily cystic tumors among 21 cases of JF schwannomas that had been surgically treated at our institution. RESULTS: Two types of cystic JF schwannomas were observed, i.e., Type 1 lesions, which are single large cysts with thin ring-like enhancement of the tumor wall, and Type 2 lesions, which are multiple cysts with very irregular, thick enhancement of the cyst wall. The most common symptoms were hearing loss, ataxia, and headaches. Total surgical removal could be performed in all cases. The immediate postoperative findings indicated hearing improvement in three cases. No deterioration of lower cranial nerve function was observed. All patients were independent in the immediate postoperative period and in the long-term follow-up period (Karnofsky Performance Scale score, 90). CONCLUSION: Surgical treatment of cystic JF schwannomas can be very demanding because of generally stronger adhesion of the tumor capsule to the surrounding structures, fragile tumor capsules, and difficulty in identification of the arachnoidal planes in some cases. Early identification of the arachnoidal planes without opening of the cyst and sharp dissection may be useful. Careful intradural opening of the JF should be performed to achieve total removal of the last tumor portion within the JF. A comparison of these lesions with solid schwannomas involving the JF indicated that cystic tumors affected a younger population, with less preoperative swallowing impairment (P < 0.05). The immediate postoperative course in both types of cystic JF schwannomas was usually better than for solid lesions, because of minor postoperative cranial nerve morbidity, especially involving lower cranial nerve function, in the latter cases. Long-term follow-up data failed to demonstrate any significant differences in final patient outcomes, however.

Adult↗
PubMed2000

Navigation-guided opening of the internal auditory canal via the retrosigmoid route for acoustic neuroma surgery: cadaveric, radiological, and preliminary clinical study.

OBJECTIVE: We investigated the usefulness of a microscope-based navigational system (Multi Koordinaten Manipulator; Zeiss, Oberkochen, Germany) for removal of the posterior wall of the internal auditory canal (IAC) via the retrosigmoid route. METHODS: A cadaveric study was performed to assess the navigational localization error for the retrosigmoid approach to the IAC. Computed tomographic findings for 47 acoustic neuroma cases were divided into three groups, on the basis of the relationship between the labyrinth and the sigmoid-fundus line (medial, on the line, or lateral). Furthermore, the shortest distances between the most medial labyrinthine extension and the resection line were measured. In 20 acoustic neuroma operations, the different features and the practicality of the microscope-based navigational system for opening of the IAC were evaluated. RESULTS: The mean anatomic localization errors were 0.67 +/- 0.2 mm (95th percentile, 1.32 mm) for navigation to the IAC and 0.71 +/- 0.37 mm (95th percentile, 1.68 mm) for navigation to the posterior semicircular canal. The average distances between the most medial labyrinthine extension and the resection line were 3.65, 3.36, and 2.0 mm for the lateral, on-the-line, and medial groups, respectively. Direct contouring of structures at risk does not take into account the localization error, nor does it provide reliable navigational information. A novel indirect contouring concept that takes into account the localization error (the safety corridor method) was therefore introduced. CONCLUSION: The value of navigational assistance for opening of the IAC is promising but still limited. Further development is required before the clinical effects of this navigational approach can be evaluated.

Cadaver↗
PubMed2000

Sporadic unilateral vestibular schwannoma with islets of meningioma: case report.

OBJECTIVE AND IMPORTANCE: Vestibular schwannomas with meningioma islets have been rarely reported in the literature; they have been observed only among patients with neurofibromatosis Type II. We present a case of a sporadic mixed tumor in a patient without neurofibromatosis Type II that was not suspected before surgery. CLINICAL PRESENTATION: A 59-year-old female patient presented with clinical signs of progressive loss of hearing. Her family history did not include evidence of neurological diseases. Magnetic resonance imaging scans revealed a typical unilateral vestibular schwannoma. INTERVENTION: The tumor presented with invasion of the surrounding arachnoid membrane, as well as Cranial Nerves VII and VIII. Preservation of the facial nerve with complete removal of the tumor was not possible. Therefore, Cranial Nerve VII reconstruction was performed. CONCLUSION: The concomitant occurrence of schwannomas and meningiomas infiltrating the arachnoid membrane might be related to poor clinical outcomes for patients with neurofibromatosis Type II, with respect to preservation of facial and acoustic nerves. Among sporadic schwannomas, this phenomenon is extremely rare.

Female↗
PubMed2000

Subarachnoid fat dissemination after resection of a cerebellopontine angle dysontogenic cyst: case report and review of the literature.

OBJECTIVE AND IMPORTANCE: This case report illustrates the clinical and radiological relevance of extensive intracranial subarachnoid and ventricular dissemination in dysontogenic (dermoid) tumors. CLINICAL PRESENTATION: We describe a patient with a cerebellopontine angle dysontogenic tumor. Postoperatively, the cyst disseminated fat particles extensively into the subarachnoid space. Magnetic resonance imaging (MRI) studies revealed continuous dispersion of the fat particles into the cerebral cisterns, subarachnoid space, and ventricles. INTERVENTION: Eight years of clinical and MRI follow-up demonstrated neither neurological deterioration in the patient nor growth of the multiple lesions. CONCLUSION: Intracranial subarachnoid dissemination of fat material may occur during the preoperative or postoperative course of dermoid and epidermoid cysts. Aseptic meningitis or other complications such as hydrocephalus, seizures, or cranial nerve deficits also may occur owing to spillage of intracranial cyst contents into the subarachnoid space. MRI can detect the presence of fat drops that may adhere to the surrounding structures or migrate with the cerebrospinal fluid flow. Intracranial disseminated fat particles can remain silent without radiological or neurological change, justifying a wait-and-see approach. During long-term postoperative follow-up, however, regular MRI studies and clinical examinations are necessary to avoid potential complications.

Adult↗
PubMed2000

Remission of superior oblique myokymia after microvascular decompression.

Superior oblique myokymia (SOM) is an ocular motility disorder characterized by oscillopsia, vertical or torsional diplopia, sometimes combined with pressure sensation. Although the pathophysiological basis is unclear, isolated case reports have documented its association with intracranial pathological processes. We present a case of SOM associated with a vascular compression of the fourth nerve at the root exit zone. Following microneurosurgical decompression, SOM completely resolved and paralysis of the fourth nerve occurred. This was less disturbing.

Decompression, Surgical↗
PubMed2000

Ectopic choroid plexus within a juvenile arachnoid cyst of the cerebellopontine angle: cause of cyst formation or reason of cyst growth.

The unusual and rare case of a 6-year-old boy is reported who presented with an arachnoid cyst located in the cerebellopontine angle incorporating an ectopic piece of choroid plexus tissue. A microneurosurgical cyst wall resection was performed and the plexus tissue identified and removed. The rare occurrence of ectopic choroid plexus tissue within cysts of the CNS is discussed.

Arachnoid Cysts↗
PubMed2000

Auditory brainstem implants: current neurosurgical experiences and perspective.

The objective of this study was to present aspects of the current treatment protocol, such as patient evaluation and selection for therapy, multimodality monitoring for optimal auditory brainstem implant (ABI) positioning and radiological evaluation, that might have an impact on the functional results of ABI. Out of a series of 145 patients with bilateral vestibular schwannomas 10 patients received an ABI, eight of which are reported here. Patient selection was based on disease course, clinical and radiological criteria (according to the Hannover evaluation and prognosis scaling of neurofibromatosis type 2 (NF2)), extensive otological test battery and psycho-social factors. ABI placement was controlled by multimodality electrophysiological monitoring in order to activate the auditory pathway and to prevent false stimulation of the cranial nerve nuclei or long sensory or motor tracts. Results of hearing function were correlated with patients' ages, duration of deafness, tumour extension, tumour-induced compression or deformation of the brainstem, and numbers of activated electrodes without any side-effects. Out of 59 patients with pre-operative deafness eight patients received an ABI of the Nucleus 22 type. All these patients became continuous users without any side effects and experienced improved quality of life. Speech reception in combination with lip-reading was markedly improved, with further improvement over a long period. A short duration of deafness may be favourable for achieving good results, while age was not a relevant factor. Lateral recess obstruction may necessitate a more meticulous dissection, but did not prevent good placement of the ABI in the lateral recess. Pre-existing brainstem compression did not prevent good results, but brainstem deformation and ipsi- and contralateral distortion were followed by a less favourable outcome. Among the factors that can be influenced by the therapy management are the selection of patients with a slow progressing NF2 disease, a short duration of deafness, a careful analysis of brainstem deformation and consideration of either side for implantation. Long-standing brainstem deformation might not lead to recovery, but instead lead to a low number of active electrodes and possibly only moderate results. ABI treatment is a safe procedure that can increase a patient's quality of life considerably. ABI placement along with neurophysiological control helps to prevent side effects and to improve acoustic activation. Further studies on structural and functional changes of the brainstem after previous tumour compression and distortion should increase our understanding and facilitate a decision on the best side for ABI implantation.

Adult↗
PubMed2000

Extensive monitoring during auditory brainstem implant surgery.

In patients with reduced auditory nerve function, for example due to tumour removal or an accident, hearing rehabilitation can be elicited by an auditory brainstem implant (ABI). The electrode array of the ABI manufactured by Cochlear Ltd., Sydney, consists of 21 circled contacts in a silicon carrier. This is inserted in the lateral recess of the fourth ventricle. Since 1996, in Hannover eight patients have been implanted with a cochlear ABI Nucleus 21 + 1. All of them were profoundly deaf on both sides due to neurofibromatosis type 2 (NF2). To find the optimal electrode position during surgery, a multimodal monitoring by auditory evoked potentials (AEP), electromyography (EMG) and somatosensory evoked potentials (SEP) was performed. When monitoring AEPs, the function of the implant can be checked first by the stimulus artefact. By analysing the AEPs in more detail, the optimal positioning of the electrode on the cochlear nucleus can be found. If systems other than the auditory system are stimulated this will be revealed in one or more of the AEP, EMG and SEP recordings. According to the literature, AEPs stimulated by an ABI consist of three vertex positive peaks with latencies shorter than 4 ms. Typical AEPs are correlated with good post-operative hearing sensation. Comparing these AEPs with AEPs stimulated acoustically or electrically at different sites of the auditory system, it can be assumed that the first peak corresponds to J3, the second to J4 and the last to J5. From this comparison it can also be concluded that no potentials should occur later than 5 ms. This corresponds to our findings. Post-operatively, side-effects occurred when areas of the electrode array were stimulated that showed potentials with latencies longer than 5 ms intra-operatively. Our results indicate that monitoring is an essential aid for the surgeon in finding the optimal electrode position. Positioning solely with reference to anatomical landmarks may not be enough to find the optimal functional position.

Adult↗
PubMed2000

Auditory brainstem implant in auditory rehabilitation of patients with neurofibromatosis type 2: Hannover programme.

An auditory brainstem implant (ABI) is indicated for patients suffering from bilateral neural deafness. The most affected patients are those with neurofibromatosis type 2 (NF2). An implantation is possible either at the same time as, or after, surgical removal of an acoustic neuroma. This paper demonstrates the results of eight out of 11 patients with NF2, seven of whom received an ABI after tumour removal. Pre-operatively, all of them were deaf. Post-operatively, the first fitting served to determine the individual stimulation parameters for each electrode. The stimulation-dependent side-effects were eliminated by reducing the stimulus intensity without causing negative effects on the hearing with the ABI. Only in one case was an open set understanding achieved within the first year. However, all patients had a better speech understanding when they combined their hearing with the ABI and their lip-reading abilities. There is no correlation between the performance with ABI and the tumour size or the duration of deafness.

Adolescent↗
PubMed2000

Disruption of intracerebral progression of C6 rat glioblastoma by in vivo treatment with anti-CD44 monoclonal antibody.

OBJECT: Glioblastoma multiforme (GBM) invasiveness is a complex process that involves recognition and attachment of GBM cells to particular extracellular matrix (ECM) molecules before migrating into proteolytically modified matrix and inducing angiogenesis. The CD44 molecule, which is a transmembrane adhesion molecule found on a wide variety of cells including GBM, has been suggested as the principal mediator of migration and invasion. The aim of the present study was to demonstrate whether an antibody specific to the standard form of CD44 (CD44s, 85-90 kD) might prevent invasion and thus disrupt progression of C6 GBM in vivo. METHODS: Immunostaining demonstrated homogeneous expression of CD44s on the surface of C6 GBM cells and tumors. Flow cytometric analysis demonstrated binding saturation of anti-CD44s monoclonal antibody (mAb) to the receptor at 1 microg/5 x 10(5) cells. Blocking of CD44s in vitro resulted in a dose-dependent progressive (up to 94+/-2.7%; mean +/- standard deviation [SD]) detachment of C6 cells from ECM-coated culture. Blocking of CD44s in vivo resulted in significantly reduced C6 brain tumors (3.6+/-0.4% [SD])--measured as the quotient: tumor surface (mm2)/brain surface (mm2) x 100--compared with untreated (19.9+/-0.9%) or sham-treated (19.2+/-1.1 to 19.3+/-2.5% [SD]) rats. Disruption of C6 GBM progression correlated with an improved food intake; treated rats were significantly less cachectic (166.6+/-16.4 g [SD]) than those that were untreated (83+/-2.7 g [SD]) or sham-treated (83.4+/-1.1 to 83+/-2.2 g [SD]) rats. CONCLUSIONS: The authors conclude that CD44s-targeted treatment with specific mAb may represent an effective means for preventing progression of highly invasive GBMs.

Animals↗
PubMed2000

Retrosigmoid intradural suprameatal approach to Meckel's cave and the middle fossa: surgical technique and outcome.

OBJECT: The goal of this study was to determine whether some petroclival tumors can be safely and efficiently treated using a modified retrosigmoid petrosal approach that is called the retrosigmoid intradural suprameatal approach (RISA). METHODS: The RISA was introduced in 1983, and since that time 12 patients harboring petroclival meningiomas have been treated using this technique. The RISA includes a retrosigmoid craniotomy and drilling of the suprameatus petrous bone, which is located above and anterior to the internal auditory meatus, thus providing access to Meckel's cave and the middle fossa. Radical tumor resection (Simpson Grade I or II) was achieved in nine (75%) of the 12 patients. Two patients underwent subtotal resection (Simpson Grade III). and one patient underwent complete resection of tumor at the posterior fossa with subtotal resection at the middle fossa. There were no deaths or severe complications in this series; all patients did well postoperatively, being independent at the time of their last follow-up examinations (mean 5.6 years). Neurological deficits included facial paresis in one patient and worsening of hearing in two patients. CONCLUSIONS: The approach described here is a useful modification of the retrosigmoid approach, which allows resection of large petroclival tumors without the need for supratentorial craniotomies. Although technically meticulous, this approach is not time-consuming; it is safe and can produce good results. This is the first report on the use of this approach for petroclival meningiomas.

Adolescent↗
PubMed2000

Nerve transfer.

Explore the source record for details and available documents.

Brachial Plexus↗
PubMed2000

Monitoring of blood parameters following anterior cervical fusion.

OBJECT: Both C-reactive protein (CRP) level and erythrocyte sedimentation rate (ESR) were measured prospectively in 51 cases in which uncomplicated cervical anterior fusion was performed. The object of the authors was to quantify the differences in the responses of these parameters recorded in the immediate postoperative period and to determine factors influencing their course. METHODS: Nineteen one-level, 23 two-level, and nine three-level procedures for disc herniation and degenerative disease of the cervical spine were performed in 22 female and 29 male patients (mean age 49.2 years). Blood samples were obtained 1 day before as well as on 10 consecutive days and 3 months following anterior cervical fusion. Serum CRP level was measured using a fluorescence polarization immunoassay and ESR was determined from the same samples. Operative time, the number of blood transfusions, and drugs administered in the postoperative period were recorded. In addition, hemoglobin, hematocrit, red blood cell count, platelet count, white cell count, and axillary body temperature were checked daily. CONCLUSIONS: Monitoring of CRP level is superior to that of ESR for early detection of infections after cervical spine surgery. Although CRP was not related to any of the factors that have been proposed to explain its peak value variance in previous studies, individual acute-phase protein metabolism response to tissue affection appears to be a more decisive element in this respect.

Adult↗
PubMed2000

Congenital arthrogryposis associated with atlantoaxial subluxation and dysraphic abnormalities. Case report.

The authors report the case of a 27-year-old woman with an arthrogryposis multiplex congenita (AMC) associated with atlantoaxial subluxation. To the authors' knowledge, this is the first report of its kind. The authors review the literature with reference to dysraphic abnormalities associated with atlantoaxial subluxation and with AMC. The patient presented with severe tetraparesis following a minor traffic accident. She underwent a procedure in which transoral decompression and dorsal stabilization were performed and, postoperatively, made a good clinical outcome. The authors stress the need for diagnostic neuroimaging of the craniocervical junction in patients with AMC.

Accidents, Traffic↗
PubMed2000

Current status and future challenges in cerebral blood flow mapping in intracranial tumors.

CBF studies have been applied in patients with cranial tumors using XenonCT in order to evaluate the blood flow of both the tumor and the peritumoral brain tissue. The histology included mostly meningiomas or gliomas, less frequently neurinomas or metastases. Blood flow was determined in tumor tissue (TBF), peritumoral areas (PTBF) and cerebral hemispheres (hCBF). The CBF was compared to normative CBF values. In supratentorial tumors characteristical blood flow patterns were found according to the histology. PTBF was usually lower in edematous tissue than in normal brain tissue. TBF in malignant gliomas revealed a heterogeneous pattern with a central core of low flow and a peripheral zone with high flow. Global CBF values in patients with malignant gliomas were lower than in controls. Meningiomas showed significantly higher blood flow compared to gliomas or neurinomas. In some cases with large cerebellopontine angle tumors a reduction in brain stem blood flow was detected. In cavernous sinus tumors with carotid artery compression CBF and cerebrovascular reserve capacity was not impaired. These findings indicate that tumor induced alterations in cerebral circulation can be detected by CBF mapping. This diagnostic tool offers a further insight into perfusion related tumor pathophysiology and may thereby optimize individual neurooncological treatment strategies.

Adult↗