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Biomedical subjects

A A Zamani

Publications and source records attributed to A A Zamani.

At least 19 recordsLinked to original sources
PubMed2001

Initial experience with intraoperative magnetic resonance imaging in spine surgery.

STUDY DESIGN: A case series of 12 patients who underwent spine surgery in an intraoperative magnetic resonance imager (IMRI). OBJECTIVES: To determine the advantages, limitations, and potential applications to spine surgery of the IMRI. SUMMARY OF BACKGROUND DATA: Existing stereotactic navigational systems are limited because images are obtained before surgery and are not updated to reflect intraoperative changes. In addition, they necessitate manual registration of fiducial landmarks on the patient's anatomy by the surgeon to the previously obtained image data set, which is a potential source of error. The IMRI eliminates these difficulties by using intraoperative acquisition of MRI images for surgical navigation with the capacity for both image update and image-guided frameless stereotaxy. The IMRI is a novel cryogenless superconducting magnet with an open configuration that allows the surgeon full access to the patient during surgery and intraoperative imaging. METHODS: T1- and T2-weighted fast spin echo images were obtained for localization, after surgical exposure and after decompression during the course of 12 spine surgeries performed in the IMRI. RESULTS: The authors performed a series of 12 procedures in the IMRI that included three lumbar discectomies, three anterior cervical discectomies with allograft fusion, three cervical vertebrectomies with allograft fusion, two cervical foraminotomies, and one decompressive cervical laminectomy. The system provided rapid and accurate localization in all cases. The adequacy of decompression by MRI during surgery was confirmed in 10 of 12 cases. CONCLUSIONS: The IMRI provided accurate and rapid localization in all cases and confirmed the adequacy of decompression in the majority of cases. Future applications of the IMRI to spine surgery may include intraoperative guidance for resection of spine and spinal cord tumors and trajectory planning for spinal endoscopy or screw fixation.

Adult↗
PubMed2001

Clear cell pleomorphic xanthoastrocytoma: case report.

Pleomorphic xanthoastrocytoma (PXA) is a well-described astrocytic neoplasm with distinctive clinical and pathological features. Although most patients with PXAs are cured by surgical excision, other patients experience malignant progression and tumor recurrence. We describe a 47-year-old woman with a left temporal lobe PXA that had classic histopathological characteristics as well as extensive clear cell and focal papillary changes, and some anaplastic findings. The patient has now suffered two recurrences after complete resection. The case illustrates a rare, previously undescribed histological variant of PXA, with a prominent clear cell and focal papillary morphology. The study of histologically similar cases is needed to determine whether this variant is always associated with a greater likelihood of recurrence.

Astrocytoma↗
PubMed2000

Cerebellopontine angle tumors: role of magnetic resonance imaging.

The cerebellopontine (CP) angle is bound anterolaterally by the posterior aspect of the petrous temporal bone and posteromedially by the cerebellum and pons. It contains important vascular structures and cranial nerves and is subject to a certain gamut of lesions, notably tumors with interesting radiological manifestations. Radiological investigation of these lesions has seen significant improvement in recent decades. Magnetic resonance is the imaging modality of choice for lesions of the CP angle and internal auditory canal. Lesions of the CP angles usually are divided into those native to the angle (vestibular schwannoma, meningioma, epidermoid, arachnoid cyst, metastases, lipoma, etc.) and those extending to the angle from adjacent structures (gliomas, ependymomas, choroid plexus papillomas, vascular malformations). Vestibular schwannomas are by far the most important lesion of the CP angle.

Arachnoid Cysts↗
PubMed2000

MR imaging of arthritides of the cervical spine.

Indications for MR imaging have broadened with the development of multiplanar capability, superb soft tissue contrast, and high sensitivity for detecting pathologic alterations. These developments are especially valuable in the analysis of the spine, where multiple anatomic structures reside, each with varying physical properties. MR imaging is unsurpassed in demonstrating early structural and proliferative changes that occur in inflammatory and related arthritides, and in evaluating complications that can cause significant morbidity, and even death. The role of MR imaging in the evaluation of cervical spinal arthritis continues to evolve, as its role in identifying patients for surgical intervention becomes clearer.

Amyloidosis↗
PubMed1999

Parasagittal solitary fibrous tumor of the meninges. Case report and review of the literature.

The clinical, radiologic and pathologic features of a case of parasagittal solitary fibrous tumor of the meninges are reported. The patient was a 44 year-old male who presented with a complex partial seizure and a history of headaches and confusion. Radiological studies showed a large extra-axial dural-based mass in the right parietal region, predominantly isointense with gray matter and hypointense with respect to white matter on T1-weighted images, and hypointense with respect to gray matter on T2-weighted images. At surgery, the mass was very vascular, quite firm and very adherent to the convexity. Histologically the tumor was composed of spindle-shaped cells growing in fascicles within a collagenous matrix. Solitary fibrous tumor of the meninges is a newly described entity, which should be kept in mind in the clinical and radiological differential diagnosis of extra-axial brain tumors.

Adult↗
PubMed1999

Intraoperative MR imaging guidance for intracranial neurosurgery: experience with the first 200 cases.

PURPOSE: To review preliminary experience with an open-bore magnetic resonance (MR) imaging system for guidance in intracranial surgical procedures. MATERIALS AND METHODS: A vertically oriented, open-configuration 0.5-T MR imager was housed in a sterile procedure room. Receive and transmit surface coils were wrapped around the patient's head, and images were displayed on monitors mounted in the gap of the magnet and visible to surgeons. During 2 years, 200 intracranial procedures were performed. RESULTS: There were 111 craniotomies, 68 biopsies, 12 intracranial cyst evaluations, four subdural drainages, and five transsphenoidal pituitary resections performed with the intraoperative MR unit. In each case, the intraoperative MR system yielded satisfactory results by allowing the radiologist to guide surgeons toward lesions and to assist in treatment. In two patients, hyperacute hemorrhage was noted and removed. The duration of the procedure and the complication rate were similar to those of conventional surgery. CONCLUSION: Intraoperative MR imaging was successfully implemented for a variety of intracranial procedures and provided continuous visual feedback, which can be helpful in all stages of neurosurgical intervention without affecting the duration of the procedure or the incidence of complications. This system has potential advantages over conventional frame-based and frameless stereotactic procedures with respect to the safety and effectiveness of neurosurgical interventions.

Adolescent↗
PubMed1999

Idiopathic pinealitis. Case report.

This 63-year-old man presented with complaints of "having a feeling of falling backward" over a 3-month period. Results of his general physical examination, laboratory studies, and neurological examination were unremarkable. A magnetic resonance image revealed a 1.8 x 1.4 x 1.2-cm enhancing mass in the posterior third ventricle just above the corpora quadrigemina. The pineal gland was found to be diffusely enlarged at operation and separable from the posterior thalamus and was totally resected. The patient had an uneventful postoperative course but continues to be somewhat confused. The lesion consisted of a remarkable chronic inflammatory cell infiltrate permeating the pineal lobules and was composed of T and B lymphocytes, macrophages, eosinophils, and mast cells. Immunoperoxidase studies did not demonstrate Langerhans cells, and a search for microorganisms was unrevealing. There was no evidence of neoplasia; results of immunostaining for germ cell markers and other tumor-associated antigens were negative.

B-Lymphocytes↗
PubMed1998

Neurosurgical considerations in supratentorial low-grade gliomas: experience with 175 patients.

The authors reviewed 175 low-grade hemispheric gliomas surgically treated by one surgeon (P.B.) between 1987 and 1996: 74 astrocytomas (42%), 35 oligodendrogliomas (20%), 52 mixed gliomas (30%), 12 gangliogliomas (7%), and two ependymomas (1%). Patient age ranged from 7.5 to 81.9 years (mean 39.2 years); 84 patients (48%) were males and 91 (52%) females. Postsurgical follow-up review ranged from 0.1 to 225.2 months (mean 36.2 months, median 24.9 months). Either T(2)-weighted or contrast-enhanced T(1)-weighted magnetic resonance (MR) images were used to evaluate the percentage of resection achieved and volume of residual disease postoperatively. The majority of patients (55%) had seizures as the presenting symptom, and 45% experienced preoperative symptoms for more than 12 months. Tumor enhancement was present in 21% of cases. In 66% of surgical procedures at least one of the following technical adjuncts was used: monitored local anesthesia, real-time MR imaging, stereotactic guidance with computerized tomography, three dimensional reconstruction, cortical mapping with cortical stimulation, somatosensory or visual evoked potential recording, corticography, or intraoperative ultrasound. Intraoperative MR imaging was used for 40 (22.9%) of the craniotomies and nine (5.14%) biopsies. There were no surgery-related deaths. Complications appeared in 6% of the patients. Progression to a higher-grade tumor occurred in 9.2% of patients within the 3-year follow-up period.

Journal Article↗
PubMed1997

Clinical and neuroradiographic manifestations of eastern equine encephalitis.

BACKGROUND: Eastern equine encephalitis occurs principally along the east and Gulf coasts of the United States. Recognition of the neuroradiographic manifestations of eastern equine encephalitis could hasten the diagnosis of the illness and speed the response to index cases. METHODS: We reviewed all cases of eastern equine encephalitis reported in the United States between 1988 and 1994. The records of 36 patients were studied, along with 57 computed tomographic (CT) scans and 23 magnetic resonance imaging (MRI) scans from 33 patients. RESULTS: The mortality rate was 36 percent, and 35 percent of the survivors were moderately or severely disabled. Neuroradiographic abnormalities were common and best visualized by MRI. Among the patients for whom MRI scans were available, the results were abnormal for all eight comatose patients as well as for all three noncomatose patients who subsequently became comatose. The CT results were abnormal in 21 of 32 patients with readable scans. The abnormal findings included focal lesions in the basal ganglia (found in 71 percent of patients on MRI, and in 56 percent on CT), thalami (found in 71 percent on MRI and in 25 percent on CT), and brain stem (found in 43 percent on MRI and in 9 percent on CT). Cortical lesions, meningeal enhancement, and periventricular white-matter changes were less common. The presence of large radiographic lesions did not predict a poor outcome, but either high cerebrospinal fluid white-cell counts or severe hyponatremia did. CONCLUSIONS: Eastern equine encephalitis produces focal radiographic signs. The characteristic early involvement of the basal ganglia and thalami distinguish this illness from herpes simplex encephalitis. MRI is a sensitive technique to identify the characteristic early radiographic manifestations of this viral encephalitis.

Adolescent↗
PubMed1996

Mesencephalic clefts with associated eye movement disorders.

OBJECTIVE: To describe two patients with mesencephalic midline clefts and associated eye movement disorders. DESIGN: Case reports. RESULTS: The first patient developed bilateral internuclear ophthalmoplegia with exotropia, reduced convergence, right ptosis, right fourth-nerve palsy, and right elevator palsy several years after meningitis with hydrocephalus. The second patient had bilateral internuclear ophthalmoplegia with exotropia, reduced convergence, bilateral ptosis, limited upward gaze, and right hypertropia since childhood. In both patients, magnetic resonance imaging showed a midline cleft extending from the cerebral aqueduct into the midbrain. CONCLUSION: It is likely that the clefts affected the oculomotor nuclei and medial longitudinal fasciculi, accounting for the eye movement disorders.

Adult↗
PubMed1996

Correlation of vascular endothelial growth factor messenger RNA expression with peritumoral vasogenic cerebral edema in meningiomas.

Intracranial meningiomas are often complicated by peritumoral vasogenic cerebral edema, which appears to result from increased microvascular permeability and extravasation of proteinaceous and plasma fluid into the adjacent peritumoral space. The source of such edema has long been mysterious. The contents of this paper support the concept that vascular endothelial growth factor (VEGF) production plays a significant role in edema formation. Vascular endothelial growth factor messenger RNA expression has been found in a wide range of intracranial neoplasms, including malignant gliomas, metastatic melanomas, meningiomas, and other benign tumors. Several studies have confirmed the importance of VEGF in tumorigenesis, neovascularization, and edema production. This study tests the hypothesis that the presence of peritumoral edema in meningiomas is positively correlated with increased expression of VEGF mRNA. To investigate this hypothesis, 31 meningioma specimens were subjected to Northern blot analysis, hybridization with a complementary DNA VEGF probe, and laser densitometry to determine the relative levels of VEGF mRNA expression. Magnetic resonance imaging was then used in a double-blind fashion to correlate the neuropathological tissue samples with the presence of preoperative peritumoral edema. Of 31 patients studied, 14 exhibited no edema and 17 exhibited some level of peritumoral fluid accumulation. There was a marked increase in VEGF expression in patients with edema (p = 0.0004, Wilcoxon-Mann-Whitney rank-sum test). Meningiomas with peritumoral edema exhibited 3.4 times the level of VEGF mRNA as those without edema. These data demonstrate a strong link between VEGF mRNA expression and peritumoral edema and indicate that VEGF expression is an important factor in the etiology of edema around meningiomas.

Adult↗
PubMed1993

Anatomic-radiologic basis of Lhermitte's sign in multiple sclerosis.

OBJECTIVE: To test the presumption that Lhermitte's sign in multiple sclerosis is the result of a lesion in the cervical spinal cord. DESIGN: The radiologic files of 887 patients with multiple sclerosis were reviewed. A detailed questionnaire regarding Lhermitte's sign was sent to 75 patients who had undergone magnetic resonance imaging of the brain and cervical spinal cord. Of the 64 patients who responded, 55 patients who had complete magnetic resonance imaging files were studied. The cases of two illustrative patients are presented. RESULTS: A strong association between Lhermitte's sign and abnormalities of the cervical spinal cord seen on magnetic resonance imaging was noted. Most of the abnormalities were in the posterior part of the cervical spinal cord. CONCLUSIONS: The findings confirm the presumption that a lesion in the posterior columns of the cervical spinal cord is the cause of Lhermitte's sign in multiple sclerosis.

Adult↗
PubMed1992

Lacunar thalamic stroke with pure cerebellar and proprioceptive deficits.

Case reports of two patients with cerebellar ataxia and proprioceptive sensory loss are presented. MRI of the brain revealed lesions of the ventroposterior part of the thalamus. These patients illustrate clinically the anatomical independence of cerebellar and sensory pathways in the thalamus. We suggest that the ataxic deficit is caused by interruption of cerebellar outflow pathways in the thalamus and not secondary to sensory deafferentation.

Aged↗
PubMed1985

Prolactinomas. Clinical presentation, radiologic assessment, and therapeutic options.

Of the pituitary tumors, the prolactinoma is the most common, characteristically causing amenorrhea/galactorrhea in women and symptoms secondary to mass effect in men. Direct coronal CT scanning with rapid infusion contrast enhancement is now considered the most sensitive and specific method for evaluating the pituitary. Normally the gland is either homogeneous or heterogeneous in a repetitive fashion, and measures up to 9-10 mm in height. Adenomas typically are hypodense lesions in the anterior lobe associated with mass effect--superior surface convexity, gland enlargement, bony erosion, infundibulum displacement, or vascular "tuft" shift. High field superconductive MRI is thought to be superior to CT for evaluation of macroadenomas and may soon surpass CT in the evaluation of microadenomas. Treatment remains controversial. Perhaps surgery is the best alternative for women 15 to 30 years of age with microadenomas producing prolactin less than 100 ng/ml. Patients who are either beyond the child-bearing years, present with tumors greater than 10 mm in diameter, or have microadenomas producing prolactin greater than 100 ng/ml may be better served by medical therapy using bromocriptine or pergolide mesylate.

Adult↗
PubMed1984

Spinal cord or nerve root compression in patients with malignant disease: CT evaluation.

Fifty patients with malignant disease were seen on an emergency basis because they showed clinical signs of spinal cord or nerve root compression. All were studied with high resolution computed tomography (CT) of the spine; in addition, myelography was performed on 10 of the patients. We found that 48 cases (96%) could be accurately diagnosed by CT alone. In two cases (4%) CT was inconclusive, but myelography was diagnostic; one proved to be cerebrospinal fluid seeding with nerve root involvement, and the other showed conus medullaris involvement. In the remaining eight cases studied by both techniques, correlation between CT and myelography was very good.

Adult↗
PubMed1984

Cervical chordoma presenting with intervertebral foramen enlargement mimicking neurofibroma: CT findings.

A cervical chordoma, confirmed at surgery, presented on plain spine films as a focal enlargement of the intervertebral foramen and mimicked the characteristic appearance of cervical neurofibroma. Computed tomography (CT) of the cervical spine was obtained immediately following metrizamide myelography; it demonstrated a soft-tissue mass in the enlarged intervertebral foramen that extended posteriorly to compress the spinal cord and anteriorly to compress the hypopharynx. The mass was sharply demarcated, inhomogeneous, and low in attenuation; CT density measured between those of cerebrospinal fluid and muscle. Although this CT appearance is not specific for cervical chordoma, it is unusual for neurofibroma. Cervical chordoma should be considered in the differential diagnosis of focal enlargement of cervical intervertebral foramina.

Adult↗