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Biomedical subjects

M Samii

Publications and source records attributed to M Samii.

At least 37 records · Page 2Linked to original sources
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↗
PubMed2001

Auditory brainstem implant: part I. Auditory performance and its evolution over time.

OBJECTIVE: Evaluation of auditory performance and its evolution over time in patients with the auditory brainstem implant. STUDY DESIGN: Prospective study. SETTING: Tertiary referral center. PATIENTS AND METHODS: Between May 1996 and April 2000, 14 patients with neurofibromatosis type 2 underwent implantation with a multichannel auditory brainstem implant. Auditory performance data were obtained in 13 patients who had used their device on a regular daily basis for 1 to 41 months (average 19 months). Hearing evaluation was based on the results of four tests (vowel confusion, consonant confusion, Freiburger numbers, and speech-tracking test), which were performed with and without lip-reading at regular intervals after device activation. RESULTS: 12 patients received auditory sensation through the auditory brainstem implant immediately after device activation. In one patient, because of postoperative electrode migration, device activation was not successful. In this case, after the electrode array was repositioned, activation was successful. The results of the audiovisual mode 2 weeks after device activation revealed a lip-reading enhancement above the chance level in about 50% of the patients in the vowel confusion and speech-tracking tests and in 70% of the patients in the consonant confusion test. Lip-reading enhancement improved within the first 6 months and then entered a plateau phase, which was more prominent in the monosyllabic vowel and consonant tests. In the auditory alone mode, more than half of the patients showed their first positive result in the vowel test 3 months after device activation, but it took about 6 months until half of the patients revealed a result above the chance level in the consonant and Freiburger numbers tests. Open set speech recognition in the auditory alone mode (in the speech-tracking test) was not common and happened relatively late (within 1 year or later). DISCUSSION AND CONCLUSION: Although auditory sensation appeared immediately after device activation, a period of 6 months was necessary for relearning and adaptation of the central auditory system to the altered form of auditory information presented by the auditory brainstem implant.

Adult↗
PubMed2001

Acute care in neurosurgery: quantity, quality, and challenges.

OBJECTIVE: Part of the daily routine in neurosurgery is the treatment of emergency room admissions, and acute cases from other departments or from outside hospitals. This acute care is not normally included in performance figures or budget management, nor analysed scientifically in respect of quantity and quality of care provided by neurosurgeons. METHOD: Over a 1 year period, all acute care cases managed by two neurosurgical on call teams in a large northern German city, were recorded prospectively on a day by day basis. A large database of 1819 entries was created and analysed using descriptive statistics. RESULTS: The minimum incidence of patients requiring neurosurgical acute care was estimated to be 75-115/100 000 inhabitants/year. This corresponds to a mean of about 6/day. Only 30% of patients came directly via the emergency room. The fate of 70% of patients depended initially on the "neurosurgical qualification" of primary care doctors and here deficits existed. Although most intracerebral and subarachnoid haemorrhages were managed with the participation of neurosurgeons, they were not involved in the management of most mild and moderate traumatic brain injuries. Within 1 year the additional workload from acute care amounted to 1000 unplanned admissions, 900 acute imaging procedures, and almost 400 emergency operations. CONCLUSION: The current policy in public health, which includes cuts in resources, transport facilities, and manpower, is not compatible with the demonstrated extent of acute neurosurgical care. In addition to routine elective work, many extra admissions, evening or night time surgery, and imaging procedures have to be accomplished. An education programme for generalists is required to improve overall patient outcome. These conclusions hold special importance if health authorities wish to not only maintain present standards but aim to improve existing deficits.

Adolescent↗
PubMed2001

Osteochondroma of the cervical spine causing occipital nerve neuralgia. Case report.

Osteochondroma is a rare tumor of the cervical spine. The authors present a rare case of osteochondroma narrowing the C 1/2 foramen and causing occipital neuralgia. Complete removal of the tumor was performed with release of the pain. The literature is reviewed and etiology, diagnosis, treatment and differential diagnosis are discussed.

Bone Neoplasms↗
PubMed2001

Artificial elevation of brain tissue glycerol by administration of a glycerol-containing agent. Case report.

In recent years the development of secondary brain damage and derangement of neurochemical parameters after severe head injury has been monitored using microdialysis. Provided the blood-brain barrier is intact, glycerol is regarded as a potential marker for membrane phospholipid degradation. The authors report a case in which marked elevation of interstitial glycerol was induced after exogenous administration of a glycerol-containing agent. A 25-year-old man was injured in a motorcycle accident and was admitted to the authors' institution with a unilateral dilated and fixed pupil and a Glasgow Coma Scale score of 3. Computerized tomography scans revealed a large subdural hematoma on the left side, subsequent midline shift, and generalized edema. Emergency craniotomy was performed for evacuation of the hematoma. The patient was prepared for multisensory monitoring and a microdialysis catheter was inserted into his left frontal lobe. After a routine enema containing 85% glycerol had been administered, the authors measured a marked increase in glycerol in the dialysate. This occurred while the patient was in as stable a condition as could be expected given the circumstances. The increase in interstitial glycerol in the injured tissue was most likely due to an impaired blood-brain barrier. Thus, the interstitial glycerol concentration had been corrupted by exogenous glycerol, and the marker properties of glycerol in this case became questionable. Consequently, administration of glycerol, which is frequently found in various infusions and emulsions, can promote secondary brain damage by adversely shifting osmotic gradients.

Adult↗