Biomedical subjects

M Samii

Publications and source records attributed to M Samii.

At least 163 records · Page 9Linked to original sources

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↗

PubMed1995

Proliferative activity of acoustic neurilemomas without neurofibromatosis determined by monoclonal antibody MIB 1.

Microscopic sections obtained from paraffin blocks of 30 consecutive neurilemomas stored in 1989 were investigated immunohistochemically with the new monoclonal antibody MIB 1 directed against recombinant parts of Ki-67 antigen. The immunohistochemical staining was carried out on dewaxed microwave-oven-processed paraffin sections of formalin-fixed tumour tissues. The labelling index (LI) obtained was below 1% in 21 cases, 1-3% in 7 cases and more than 3% in 2 cases. There was no correlation between the LI and the age of the patients or the tumour size. The major advantage of MIB 1 over previous immunohistochemical methods is its usefulness in long preserved sections which are ideal for retrospective studies.

Adult↗

PubMed1995

The comparison between the growth fraction of bilateral vestibular schwannomas in neurofibromatosis 2 (NF2) and unilateral vestibular schwannomas using the monoclonal antibody MIB 1.

Formalin-fixed paraffin sections of 55 consecutive bilateral vestibular schwannomas in 46 patients with neurofibromatosis 2 (NF2), and 50 patients with unilateral vestibular schwannomas were investigated immunohistochemically with the monoclonal antibody MIB 1 directed against recombinant parts of Ki-67 antigen. The immunohistochemical staining was carried out on dewaxed microwave oven-processed paraffin sections of formalin-fixed tumour tissues. The labelling index (LI) obtained was compared to clinical and histological findings in both groups. There was no correlation between the LI and age of the patients, tumour size, or histological type of tumour (Antoni A or B). Vestibular schwannomas in NF2 showed higher LI than unilateral vestibular schwannomas: the maximal LI found per section (LI max) ranged from 0.4 to 17.6% (mean, 2.7%) in NF2 schwannomas, and from 0 to 9% (mean, 2.2%) in unilateral schwannomas. These differences may express immunohistochemically some clinical and morphological differences between bilateral and unilateral vestibular schwannomas.

Adolescent↗

PubMed1995

Syringomyelia in association with tumours of the posterior fossa. Pathophysiological considerations, based on observations on three related cases.

In this report we describe 3 patients with syringomyelia in association with tumours of the posterior fossa. In each patient the syrinx was demonstrated on pre-operative magnetic resonance imaging (MRI). After total or partial removal of the tumour the syrinx collapsed. It is concluded that the pathogenesis of syrinx formation in this entity requires interference with normal cerebrospinal fluid (CSF) flow at the foramen magnum. We suggest that the obstruction to the flow of CSF causes alterations in the passage of extracellular fluid (ECF) in the spinal cord which lead to syringomyelia.

Adolescent↗

PubMed1995

Hearing preservation in bilateral acoustic neurinomas.

Bilateral acoustic neurinomas are found in almost all patients with neurofibromatosis 2 (NF2). With better knowledge of the disease and development of diagnostic procedures, an increasing number of patients have been detected at an early stage of the disease. Preservation of hearing in these cases has become more feasible. Between 1979 and 1992, 110 acoustic neurinomas in 74 NF2 patients have been resected in this department. All tumours but 11 were completely removed. In 11 cases deliberate subtotal tumour removal was performed: bilaterally in one deaf patient for brainstem decompression, and unilaterally in nine patients with the aim of hearing preservation. In seven of these nine cases hearing was preserved. The total rate of hearing preservation was 36%. Considering only those patients with good preoperative hearing and small tumours, the rate of hearing preservation was 58%. Facial nerve preservation was 92%. Nerve reconstructions were performed in cases of facial nerve damage, with good results in most of the cases. The importance of early detection of the disease and early removal of tumours is stressed. Surgical decision making based on the author's personal experience in dealing with these cases is discussed, and some cases are illustrated.

Adolescent↗

PubMed1995

Esthesioneuroblastomas with intracranial extension. Proliferative potential and management.

A total of 15 patients with esthesioneuroblastomas were treated between 1978 and 1992 at the Neurosurgery Department, Nordstadt Hospital, Hannover. In 9 cases, the tumors invaded the anterior cranial fossa. One patient died before any surgical intervention. Eight tumors were operated by a combined paranasal and subfrontal approach. Gross total tumor removal was achieved in all cases. Apart from anosmia, the only postoperative complication was transient mental changes in one case. Immunohistochemical analyses with MIB 1 monoclonal antibodies, directed against recombinant parts of Ki-67 antigen, were performed to estimate the proliferative potential of the esthesioneuroblastomas. Most of the tumors showed high proliferating cell indexes, which ranged from 3 to 42% (mean, 16%). The proliferating cell index with MIB 1 showed a correlation with postoperative outcome, although this was not statistically significant. Esthesioneuroblastomas can be totally removed surgically. The proliferating cell index may reflect histologically the biological behavior of tumor. Long-term follow-up is mandatory, and immunohistochemical studies may be of help in predicting outcome.

Adult↗

PubMed1995

Surgical treatment of trigeminal schwannomas.

A total of 27 patients with trigeminal schwannoma were treated between 1982 and 1992 at the Neurosurgery Department of Nordstadt Hospital. Twelve cases of solitary schwannoma without any family history or physical stigmata of neurofibromatosis were included and form the basis of this study. There were four women and eight men (mean age 44 years) in this series. Duration of symptoms ranged from 2 months to 6 years. The most frequent symptoms were either pain or numbness of the ipsilateral hemiface. The surgical approach was chosen depending on the tumor type. Tumors that belonged to Type A (five cases), which were predominantly in the middle fossa, were approached using a transsylvian method; Type B (one case), which presented predominantly in the cerebellopontine angle, was operated on via a retrosigmoid suboccipital craniectomy; Type C (five cases), which were dumbbell-shaped extending into both the middle and posterior fossa, were removed via a combined temporal craniotomy-presigmoidal method; and in Type D (one case), in which tumor was primarily extracranial with intracranial extension, an infratemporal extradural approach was undertaken. There was no operative mortality or long-term disability in this series. The follow-up period ranged from 12 to 60 months; during that time magnetic resonance imaging revealed tumor recurrence in two cases after 12 and 48 months, respectively, and these were excised again. An additional 178 cases collected from the world literature are also reviewed and analyzed.

Abducens Nerve↗

PubMed1995

Surgical treatment of jugular foramen schwannomas.

Sixteen patients with schwannomas of the jugular foramen were operated on in the Department of Neurosurgery of the Nordstadt Hospital in Hannover, Germany, between 1986 and 1992. Patients with neurofibromatosis were excluded. The records of the 16 patients were retrospectively reviewed. There were five women and 11 men (mean age 43 years) with a symptom duration ranging from 6 months to 20 years (mean 5 years). The predominant symptoms were hearing loss, hoarseness, and cerebellar symptoms. Computerized tomography (CT), magnetic resonance (MR) imaging, and angiography were performed in all 16 patients. Depending on the radiological and surgical features, the tumors were classified into four types: Type A, a tumor primarily at the cerebellopontine angle with minimal enlargement of the jugular foramen (eight cases); Type B, a tumor primarily at the jugular foramen with intracranial extension (two cases); Type C, a primarily extracranial tumor with extension into the jugular foramen (one case); and Type D, a dumbbell-shaped tumor with both intra- and extracranial components (five cases). A retromastoid suboccipital craniectomy was performed for Type A tumors, and a combined cervical-mastoidectomy for Types B, C, and D. Total tumor removal was achieved in all cases. There was no operative mortality. Postoperative complications were cerebrospinal fluid leakage in one patient and mastoiditis in two patients. The follow-up period ranged from 12 to 42 months (mean 22 months). All patients were alive at the last follow-up review, and CT and/or MR imaging showed no tumor recurrence.

Adult↗

PubMed1995

Applications of MR angiography in head and neck pathology.

MR angiography is a useful examination in the area of head and neck pathology when correctly applied and tailored to a specific clinical problem. Of the cases presented in this article, the most common application is evaluation of vascular invasion or displacement to aid in surgical planning of tumor resection. Applications to evaluation of vascular thrombosis or dissection, assessment of tumor vascularity, and visualization of variant vascular anatomy and acquired vascular disease were also demonstrated.

Adolescent↗

PubMed1994

Management of occult intrasacral meningocele associated with lumbar disc prolapse.

Occult intrasacral meningocele is an uncommon condition that may produce chronic low back pain, sciatica, and bladder dysfunction. We describe a patient suffering from low back pain and radicular symptoms, in whom multimodality radiological examinations showed an intrasacral meningocele and a lumbar disc prolapse. The protruded disc was considered to be the cause of the clinical symptoms in this patient rather than the meningocele. Surgical removal of the protruded disc was performed without interference with the meningocele. Postoperatively there was recovery of the preoperative deficits. Clinical and radiographic findings in occult intrasacral meningocele are discussed and criteria for differential diagnosis with disc prolapse are stressed.

Humans↗

PubMed1994

Involvement of spinal nerves in neurofibromatosis.

Spinal tumors are a frequent form of manifestation of neurofibromatosis. Out of 171 patients, who have been operated on over a ten years period on spinal tumors, 7 patients had neurofibromatosis (4.1%). A total of 9 operations were performed, removing 20 spinal tumors. Three patients had multiple neurofibromas. Half of the neurofibromas had a dumbbell configuration with a larger extraspinal extension. In three patients a family history of neurofibromatosis and typical dermatological signs were evident. Two cases will be selected and the basic concept regarding treatment and the risks involved will be discussed.

Adolescent↗

PubMed1994

Occult dysraphism in adulthood: clinical course and management.

We present a series of 23 patients with dysraphic malformations and adult onset of symptoms (4 meningoceles, 19 spinal hamartomas). Mean age at presentation was 39 +/- 21 years (range 23-67 years). Patients were followed up for a mean period of 19 months (range 0.5-68 months). Only patients with progressive neurological disease were operated on (3 meningoceles and 16 spinal hamartomas). The remaining patients were treated conservatively and continue to be observed clinically. Two of three patients operated for meningoceles improved without recurrence of symptoms. Patients with spinal hamartomas could be divided into two groups according to their main symptom: paraparesis (group A, n = 8) or pain (group B, n = 11). Malformations in group B were typically associated with a tethered cord and tended to be more complex than in group A. The majority of patients in group A showed better long-term results than patients in group B, due to their considerably lower rate of recurrence.

Adult↗

PubMed1994

Indication, technique and results of facial nerve reconstruction.

160 patients with various intra- or extracranial pathologies were treated by microsurgical facial nerve reconstruction at Nordstadt Neurosurgical Clinic between 1978 and 1993. Facial nerve reconstruction was accomplished along the anatomical course of the facial nerve from its origin at the brainstem, within the mastoid, at the stylomastoid foramen and within the face. Mostly, reconstruction was indicated because of nerve discontinuity (n = 61), whereas facial nerve reanimation with a donor nerve such as the contralateral facial nerve or the ipsilateral hypoglossal nerve was indicated in 99 cases of loss of a proximal nerve stump. Depending on the site of the lesion reinnervation started at 5 to 15 months postoperatively lasting for 2 to 3 years with overall satisfactory results. 69% of all the patients regained good symmetry on rest, complete eye closure equivalent to House-Brackmann-Score III: Patients with complete failures either suffered of non-related diseases such as cancer leading to death before the estimated time of recovery or were exposed to radiation or received facial nerve reconstruction after long-standing facial deficit and marked muscular atrophy. The indication of the adequate method depends on the clinical course with or without preexisting facial paresis, on considering the intraoperative state of the facial nerve, the identification and microsurgical preparation of adequate nerve stumps, as well as on the adaptation techniques and the postoperative guidance of the patient. We conclude that facial nerve reconstruction by transplantation at either site of the nerve course or by reanimation with a donor nerve are effective and reliable procedures of treatment leading to satisfactory functional and cosmetic results.

Adolescent↗