Biomedical subjects

M Samii

Publications and source records attributed to M Samii.

At least 163 records · Page 9Linked to original sources

PubMed1997

Proliferation potential and histological features in neurofibromatosis 2-associated and sporadic meningiomas.

The authors compared the histological appearance and proliferation potential of 35 meningiomas in patients with neurofibromatosis 2 (NF2) and 30 sporadic meningiomas in age- and gender-matched patients without NF2. The NF2 meningiomas showed more mitotic figures (p < 0.001) and nuclear pleomorphism (p = 0.003) than the sporadic meningiomas; however, the incidence of meningothelial, fibroblastic, and transitional subtypes occurred equally in both groups. The proliferation potential was significantly higher in the 35 meningiomas removed from 23 patients with NF2 than in the 30 sporadic meningiomas removed in the 30 patients without NF2 (mean MIB-1 labeling indices: 2.5 vs. 1.75, p = 0.0147). The higher proliferation potential of the NF2 meningiomas may reflect differences in molecular biology between sporadic and NF2 meningiomas and may be related to an earlier onset, multiplicity, and more aggressive behavior of NF2 tumors.

Adolescent↗

PubMed1997

Surgical reconstruction of the musculocutaneous nerve in traumatic brachial plexus injuries.

Over the last 16 years, 345 surgical reconstructions of the brachial plexus were performed using nerve grafting or neurotization techniques in the Neurosurgical Department at the Nordstadt Hospital, Hannover, Germany. Sixty-five patients underwent graft placement between the C-5 and C-6 root and the musculocutaneous nerve to restore the flexion of the arm. A retrospective study was conducted, including statistical evaluation of the following pre- and intraoperative parameters in 54 patients: 1) time interval between injury and surgery; 2) choice of the donor nerve (C-5 or C-6 root); and 3) length of the grafts used for repairs between the C-5 or C-6 root and the musculocutaneous nerve. The postoperative follow-up interval ranged from 9 months to 14.6 years, with a mean +/- standard deviation of 4.4 +/- 3 years. Reinnervation of the biceps muscle was found in 61% of the patients. Comparison of the different preoperative time intervals (1-6 months, 7-12 months, and > 12 months) showed a significantly better outcome in those patients with a preoperative delay of less than 7 months (p < 0.05). Reinnervation of the musculocutaneous nerve was demonstrated in 76% of the patients who underwent surgery within the first 6 months postinjury, in 60% of the patients with a delay of between 6 and 12 months, and in only 25% of the patients who underwent surgery after 12 months. Comparison of the final outcome according to the root (C-5 or C-6) that was used for grafting the musculocutaneous nerve showed no statistical difference. Furthermore, statistical analysis (regression test) of the length of the grafts between the donor (C-5 or C-6 root) nerve and the musculocutaneous nerve displayed an inverse relationship between the graft length and the postoperative outcome. Together, these results provide additional information to enhance the functional outcome of brachial plexus surgery.

Adolescent↗

PubMed1996

Meningiomas involving the parasellar region.

The authors report on 180 cases of meningiomas involving the parasellar region, which have been surgically treated between 1978 and 1993. Most of the tumors originated in the middle cranial fossa (66%). Half of the patients had visual deficits, and palsy of the eye movements was observed in 25% of the cases. Depending on the tumor origin and extension, the surgical approach was chosen. Total tumor resection varied very much, depending mostly on the tumor extension, and the pattern of growth. The overall total resection (Simpson I-II) was 57%. The postoperative results were good in 77% of the cases, and surgical mortality was 3%.

Adolescent↗

PubMed1996

Surgical results of spinal meningiomas.

We report on 94 spinal meningiomas in 88 patients operated between September 1977 and August 1994 which were followed for up to 13 years (mean 24 +/- 35 months). Complete tumour resection led to postoperative improvement of every preoperative deficit or symptom. En plaque, recurrent, anterior, and low thoracic or lumbar meningiomas were likely to be resected incompletely. Partial tumour removal, arachnoid scarring, primary dural suture, recurrent meningiomas, and male sex were independent factors predisposing to clinical recurrence. Cauterization instead of resection of the tumor matrix was not associated with a higher recurrence rate.

Adolescent↗

PubMed1996

Meningiomas of the cerebellopontine angle.

Meningiomas of the cerebellopontine angle (CPA) represent a clinically and surgically interesting entity. The opportunity of complete surgical excision and the incidence of impairment of nerval structures largely depend on the tumour biology that either leads to displacement of surrounding structures by an expansive type of growth or to an enveloping of nerval and vascular structures by an en plaque type of growth. As the origin and the direction of growth are very variable, the exact tumour extension in relation to the nerval structures and the tumour origin can be identified sometimes only at the time of surgery. Out of a series of 230 meningiomas of the posterior skull base operated between 1978 and 1993, data of 134 meningiomas involving the cerebellopontine angle are presented. There were 20% male and 80% female patients, age at the time of surgery ranging from 18 to 76 years, on the average 51 years. The clinical presentation was characterized by a predominant disturbance of the cranial nerves V (19%), VII (11%), VIII (67%) and the caudal cranial nerves (6%) and signs of ataxia (28%). 80% of the meningiomas were larger than 30 mm in diameter, 53% led to evident brainstem compression or dislocation and 85% extended anteriorly to the internal auditory canal. Using the lateral suboccipital approach in the majority of cases and a combined presigmoidal or combined suboccipital and subtemporal approaches in either sequence in 5%, complete tumour removal (Simpson I and II) was accomplished in 95% and subtotal tumour removal in 5%. Histologically the meningiotheliomatous type was most common (49%) followed by the mixed type (19%), fibroblastic (16%), psammomatous (7%), hemangioblastic (7%) and anaplastic (2%) types. Major post-operative complications were CSF leakage (8%) requiring surgical revision in 2% and hemorrhage (3%) requiring revision in 2%. While the majority of neurological disturbances showed signs of recovery, facial nerve paresis or paralysis was encountered in 17%, and facial nerve reconstruction was necessary in 7%. Hearing was preserved in 82% with improvement of hearing in 6%. The variability of tumour extension, the implications and limitations for complete surgical excision are discussed along with the experiences from the literature.

Adolescent↗

PubMed1996

Management of petroclival meningiomas: a critical analysis of surgical treatment.

Treatment of petroclival meningiomas have been a matter of discussion in neurosurgery. Since the advent of microsurgery, and with development of new skull base approaches more recently, the treatment of these tumours has become standardised, and the post-operative results considerably improved. However, potential complications have been related with the surgical removal of these lesions. The authors describe their experience and summarise the major reports of the literature on this subject.

Adolescent↗

PubMed1996

Spinal chordomas--results of treatment over a 17-year period.

Among a series of 511 spinal tumours treated in the Department of Neurosurgery at the Nordstadt Hospital in Hannover, Germany, between September 1977 and August 1994, 23 operations for spinal chordomas in 9 patients (3 females, 6 males) were performed. After an average period of 7 +/- 12 months (2 weeks to 5 years) patients presented at an average age of 45 +/- 17 years with pain (68%), gait ataxia (14%), motor weakness (9%) or sphincter disturbances (9%). A complete resection was achieved in 11 operations and a subtotal tumour removal in 12 instances. After subtotal removal, 5 tumours were treated postoperatively using local high dose radiotherapy (60-70 Gy). Overall, every chordoma recurred with the passage of time unless en-bloc resection of the tumour had been performed. The recurrence-free interval tended to be longer after radiotherapy. Analysis of postoperative results revealed a significant positive effect of radiotherapy for motor function, pain, Karnofsky score, and survival. In conclusion, en-bloc resection should be performed whenever localization and extension of the tumour allow one to do so. Surgery should be followed by local high dose radiotherapy.

Chordoma↗

PubMed1996

The surgical treatment of Chiari I malformation.

A retrospective study was undertaken on 133 patients with a Chiari I malformation treated within the last 16 years at the Departments of Neurosurgery at the Nordstadt Hospital Hannover, Germany, and the University of California, Los Angeles, U.S.A. Ninety-seven patients presented with symptoms related to accompanying syringomyelia and 4 with associated syringobulbia. They underwent 149 surgical procedures and were followed for a mean of 39 +/- 52 months. A decompression at the foramen magnum was performed in 124 patients, while 22 of those with syringomyelia were treated by shunting (7 syringosubarachnoid shunts, 15 syringoperitoneal or -pleural shunts), and 3 by ventriculoperitoneal shunts for hydrocephalus. Except for ventriculoperitoneal shunting, at least a short-term decrease in size of an associated syrinx was observed for all procedures in the majority of cases. However, no long-term benefit was observed for syrinx shunting operations. The best clinical long-term results were obtained with decompression of the foramen magnum in patients with (86% free of a clinical recurrence) and without syringomyelia (77% free of a clinical recurrence). We advise against syrinx shunting, a large craniectomy, and obex plugging which are associated with higher recurrence rates. Instead, surgery should consist of a small craniectomy, opening of the dura, archnoid dissection to establish normal cerebrospinal fluid (CSF) outflow from the 4th ventricle, and a fascia lata dural graft.

Adult↗

PubMed1996

The neuroimaging and clinical spectrum of neurofibromatosis 2.

Neurofibromatosis 2 (NF2) is an autosomal dominant disease predisposing to multiple tumors of the central and peripheral nervous system. Bilateral vestibular schwannomas are the hallmark of the disease. To define the clinical spectrum of the disease, we performed gadolinium-enhanced magnetic resonance imaging of the brain and spine as well as neurological, dermatological, and ocular examinations in 48 patients with NF2 diagnosed with the National Institutes of Health diagnostic criteria. Patients were ascertained from patient workshops and publications and from referral as a result of vestibular schwannoma surgery. Vestibular schwannomas were found in 46 patients (96%, 43 bilateral and 3 unilateral), spinal tumors were found in 43 (90%), posterior subcapsular cataracts were found in 30 (63%), meningiomas were found in 28 (58%), and trigeminal schwannomas were found in 14 (29%). The presenting symptoms included hearing loss or tinnitus in 15 patients (31%), multiple or nonspecific symptoms in 15 (31%), skin tumors in 12 (25%), and ocular symptoms in 6 (13%). When the complete spine was imaged, spinal tumors were more common in patients with NF2 than has previously been reported. This is a noteworthy finding, because spinal tumors are a major cause of NF2 morbidity and mortality.

Adolescent↗

PubMed1996

Surgical results for meningiomas of the craniocervical junction.

OBJECTIVE: We have undertaken a retrospective analysis of 38 patients who were operated on for 40 meningiomas of the craniocervical junction between September 1977 and August 1995 to determine which factors influenced resectability, complications, and postoperative outcomes. METHODS: Radiological examinations, clinical data, and operation notes were evaluated, and additional follow-up information was obtained from outpatient examinations, telephone calls, and questionnaires. RESULTS: Four groups could be distinguished according to dural attachment as follows: 1) 15 spinocranial meningiomas originated from the spinal canal and extended intracranially; 25 craniocervical meningiomas of intracranial origin were divided into 2) meningiomas of the lower clivus (10 patients with 11 tumors), 3) lateral meningiomas (11 patients with 12 tumors), and 4) posterior meningiomas (2 patients). Standard midline or lateral suboccipital approaches with opening of the foramen magnum and laminectomy of the involved cervical segments were sufficient for the great majority of tumors. In seven instances only, drilling the posterior third of an occipital condyle was needed. Twelve of 15 spinocranial meningiomas and 13 of 25 craniocervical meningiomas could be removed totally. One patient underwent ventriculoperitoneal shunting only. With a rate of 63% of totally removed and 30% of subtotally removed meningiomas in this region, we observed clinical recurrences for two patients only. Complications were encountered in 30% of patients, predominantly with recurrent and/or infiltrative or en plaque meningiomas. Whereas motor weakness and gait ataxia tended to improve postoperatively, cranial nerve deficits usually remained unaltered. CONCLUSION: The relationship of the tumor to neighboring structures, i.e., the vertebral artery in particular, determines its resectability. We recommend using extreme caution with recurrent or en plaque meningiomas and tumors associated with extensive arachnoid scarring.

Adolescent↗

PubMed1996

Xenon/CT CBF measurements as valuable diagnostic tool in a case of bilateral occlusive cerebrovascular disease associated with intracranial aneurysm.

A patient with the coincidental occurrence of a right internal carotid artery (ICA) stenosis and asymptomatic ipsilateral infraclinoidal ICA aneurysm is presented. CBF measurements including testing of the cerebrovascular reserve capacity (CRC) demonstrated a compromise of cerebral blood flow (CBF) within the anterior circulation of the affected side. We treated the patient in one operation by aneurysm clipping and subsequent carotid endarterectomy (CEA). 10 months later she presented with an occlusion of the contralateral ICA. CBF measurements showed sufficient resting flow and CRC on both sides. One year later repeat measurements disclosed a lowered resting CBF and diminished CRC on the affected side. Extracranial/Intracranial (EC/IC) artery bypass improved both symptoms and CBF/CRC values. The authors propose to treat symptomatic ICA stenosis and concurrent silent ipsilateral intracranial aneurysms at once if the patient is eligible for aneurysm surgery. CBF measurements should be performed before surgery. In a medically compromised patient carotid endarterectomy alone appears to be justifiable. In cases of symptomatic aneurysm and concurrent ICA stenosis a CEA can be added to aneurysm clipping to improve the hemodynamic situation for a better postoperative management. Xenon/CT investigations are suitable to provide important cerebral blood flow information. Together with angiography and clinical judgment it allows to identify patients with hemodynamic insufficiency. These are suitable candidates for an operative procedure to augment cerebral blood flow and to improve symptoms.

Blood Flow Velocity↗

PubMed1996

Alteration of rCBF in skull base lesions.

Cerebral functional imaging methods provide complementary information on brain function and large vessels regulatory controls which are compromised in cranial base lesions. The presence of a skull base tumor can alter regional cerebral blood flow (rCBF) in adjacent and remote brain tissue. This report presents the results of 104 CBF studies in 66 patients with skull base lesions (aged 17-75 years). The lesions included 36 meningiomas, 21 neurinomas and 9 other tumors. Regional CBF in tumor and brain tissue was measured prior to treatment using stable xenon enhanced computed tomography (Xenon(/T). For the quantitative analysis, regions of interest were delineated on tumor regions, cerebral and cerebellar hemispheres including peritumoral regions. In order to assess the remote effect of cerebellopontine angle (CPA) tumors, the brainstem, cerebellar, and cerebral blood flow were measured in 26 cases. The average brainstem CBF for patients with good outcome was higher than the average brainstem CBF for patients with poor outcome. This indicates that CBF studies in posterior fossa can be useful in predicting the prognosis of CPA tumor patients. We report a series of 16 patients with cavernous sinus tumors in whom the internal carotid artery was affected by the tumor. In nearly all cases Xenon/CT CBF studies with acetazolamide test showed no significant difference in hemispheric perfusion and a sufficient cerebrovascular reserve capacity. Interhemispheric asymmetry was present only in one patient. These results possibly indicate that i.v. administration of acetazolamide might contribute in selecting patients with higher risk for ischemic deficits after cavernous sinus surgery. Skull base meningiomas showed very high blood flow with a wide range. Local CBF in the peripheral region of meningiomas was higher than in the central region. Blood flow values in the peritumoral areas are about 30% lower than those of the ipsilateral hemisphere. In individual cases, blood flow values in the peritumoral low-density area on CT were extremely low. It is concluded that CBF studies in skull base tumors are valuable in treatment planning. Xenon/CT can be useful additional diagnostic procedure in the evaluation of skull base surgery candidates.

Acetazolamide↗

PubMed1996

Surgical treatment of epidermoid cysts of the cerebellopontine angle.

A total of 40 patients with epidermoid cysts of the cerebellopontine angle (CPA) underwent surgery between 1980 and 1993. Total resection was achieved in 30 cases (75%); in 10 cases (25%) parts of the cyst capsule were left because they adhered to the brainstem and vascular structures of the CPA. One patient with very large bilateral epidermoid cysts, who underwent complete bilateral resection in one stage, died of pulmonary aspiration and infection. As of their latest clinical and radiological follow-up examinations (mean 5.7 years), 93% of the patients are able to lead useful lives. Three cases of cyst regrowth have been observed thus far. Modern radiological tools and microsurgery techniques have considerably improved the completeness of cyst resection and reduced postoperative mortality and morbidity rates; however, there still are some cases in which complete resection is impossible without producing severe neurological deficits.

Adult↗

PubMed1996

Meningiomas of the tentorial notch: surgical anatomy and management.

Twenty-five meningiomas located at the tentorial notch were surgically treated between 1978 and 1993 at the Neurosurgical Department of Nordstadt Hospital in Hannover, Germany. Nineteen meningiomas were classified as originating from the lateral tentorial incisura (Group I) and six were from the posteromedial tentorial incisura (Group II). Clinically, the most common symptom was trigeminal neuralgia, followed by headache. Neuroradiologically, 64% of the meningiomas were larger than 30 X 30 mm. Further evaluation revealed signs of brainstem compression in 88% of the patients. Radical surgical removal (Simpson I and II) was achieved in 88% of the cases. There was no mortality. Follow up revealed that 80% of patients were able to return to their premorbid activity. Surgical approaches to the tentorial notch included the suboccipital retrosigmoidal or the combined subtemporal-presigmoidal approach for Group I tentorial notch meningiomas; and the supracerebellar-infratentorial or the suboccipital-transtentorial approaches for Group II meningiomas. Because the best surgical approach to the tentorial incisura is still a matter of debate, the anatomy of the tentorial incisura, the clinical presentation of the patients, diagnostic indications, surgical findings, and follow up are discussed, with reference to the literature.

Adult↗

PubMed1996

[Contralateral approach to clivus tumors using the transmaxillary-transethmoid approach].

A modified transmaxillary transethmoid approach to the clivus is described. A paranasal incision is performed on the side contralateral to the major tumor extension. The approach provides preservation of the lacrimal duct, and the bony structures of the pyriform aperture. By removing the frontal process of the maxilla and if necessary the medical orbital wall, a wide access is created that can be further enlarged by dissecting the medial concha, ethmoid sinus and posterior parts of the nasal septum. Cerebrospinal fluid leakage is treated by a special technique.

Adolescent↗

PubMed1996

Microendoscopy of the internal auditory canal in vestibular schwannoma surgery.

Intraoperative microendoscopy was performed for eight patients to access the fundus of the internal auditory canal after retrosigmoid transmeatal surgery of vestibular schwannomas. The transmeatal procedure is usually limited laterally by the labyrinth block. The restricted opening of the internal auditory canal bears a potential risk of incomplete tumor resection. For eight patients with vestibular schwannomas, intraoperative microendoscopy was performed after tumor resection to expose the "blind" area of the internal auditory canal fundus. An excellent view of the fundus contents was obtained, including Cranial Nerves VII and VIII and the crista transversa. Tumor remnants were not observed in this series. Microendoscopy was shown to be an ideal adjunct to hearing-preserving transmeatal surgery of vestibular schwannomas, enabling the removal of intracanalicular tumors with direct control of the lateral intracanalicular nerve portions.

Adolescent↗

PubMed1995

Hearing preservation in acoustic tumour surgery.

900 acoustic neurinomas were removed by the suboccipital approach at Nordstadt Neurosurgical Department from 1978 to 1992 by the same surgeon (M. S.). While 247 patients were deaf on the involved side before surgery, there were 653 patients ears with some preoperative hearing. Preservation of the cochlear nerve was always attempted, and the overall-rate of hearing preservation was 38% (249 of 653), regardless of pre- and postoperative quality of hearing or of tumour sizes. In small tumour sizes below 3 cm of diameter preservation rate was 51%, in large tumours above 3 cm of diameter it was 22%. A classification system of hearing quality was made up considering pure tone audiometric hearing losses (PTA HL) at 1 to 3 kHz, and individual maximum speech discrimination scores. The usefulness of the preserved hearing is further evaluated considering the quality of hearing in the contralateral ear, and by application of other classification schemes. Presentation of the surgical strategies and their refinements by personal experience provide the base for discussion questioning whether and how further progress may still be anticipated.

Adult↗

PubMed1995

Acoustic neurinomas associated with vascular compression syndromes.

Trigeminal neuralgia and hemifacial spasm are caused by vascular compression of the cranial nerves at the brainstem in the majority of cases. Trigeminal neuralgia occurring in 3.3% of acoustic neurinomas is usually assumed to be a sign of large tumour size; if associated with small tumour size, an additional pathology, such as typical vascular compression must be suspected and has to be explored at surgery. While facial paresis will usually lead to immediate radiological diagnosis of a possible cerebellopontine angle (CPA) neoplasm, facial spasm is usually not expected to be associated with a CPA tumour. We report on clinical presentation, operative findings, surgical treatment and results in 9 cases of small acoustic neurinomas associated with trigeminal neuralgia and on 4 cases associated with hemifacial spasm. The importance of the clinical characteristics is stressed; if these are typical of a vascular compression syndrome, further exploration at the time of tumour surgery and specific treatment by vascular decompression are necessary.

Adult↗