PubMed Health⌕ Search

Biomedical subjects

W J Michelsen

Publications and source records attributed to W J Michelsen.

At least 19 recordsLinked to original sources
PubMed1998

Transparaspinal exposure of dumbbell tumors of the spine. Report of two cases.

The authors present a surgical technique for resection of dumbbell tumors of the spine. The transparaspinal exposure combines laminectomy and sectioning of the paraspinal muscles through a transverse incision. The procedure allows total tumor resection by means of a single posterior approach in selected patients, thus obviating the need for a combined anteroposterior operation. The advantages and disadvantages of the transparaspinal approach compared with the more extensive lateral extracavitary approach are discussed.

Adult↗
PubMed1997

[Surgical approach to benign extradural lesions of the thoracic spine].

A benign epidural lesion in the thoracic spine is rare, and usually the result of intervertebral disc herniation or infection. Not long ago patients were diagnosed late in the course of their disease and the surgical results of the standard laminectomy usually performed were grave. The development of newer imaging techniques (CT and MRI) has made diagnosis much easier, so diagnosis is often earlier, when neurological deficit is minimal. Newer neurosurgical techniques and approaches to the thoracic spoine have been developed to treat these lesions, which we describe. Clinical data on 16 patients operated from January 1996 to January 1997 are presented.

Adult↗
PubMed1996

False localizing signs in upper cervical spinal cord compression.

Proprioceptive loss, paresthesias, and atrophy of the hands can occur with disorders afflicting the upper cervical spinal cord. The diagnosis might be erroneous, because compression in this region might produce signs and symptoms that seem to originate in the lower cervical cord. This article reviews the clinical presentation and radiographic data of a consecutive series of 11 patients who presented between 1992 and 1994 with an extradural lesion above the C4 level. Each patient had a characteristic syndrome of finger and hand dysesthesia, hand atrophy, and occipital or cervical pain. These complaints usually preceded the development of spasticity and gait disturbance. Initial diagnoses included brachial plexopathy, shoulder dysfunction, viral syndrome, and cervical spondylosis at a lower segment. Cervical spondylosis or a herniated disc was the most common pathogenesis. The most commonly involved level was C3-C4. Nine patients underwent a surgical procedure; eight showed significant postoperative improvement (mean time of follow-up examination, 9.7 mo; follow-up range, 1-24 mo). One patient was lost to follow-up. Although the pathophysiology of these findings is unknown, theories include anterior spinal artery ischemia, venous obstruction, and differential decussation of the forelimb and hindlimb fibers of the corticospinal tract. Recognition of this syndrome might prevent inappropriate operative intervention in patients with coexisting pathological conditions of the lower cervical spinal cord.

Aged↗
PubMed1996

Recurrent cerebral arteriovenous malformations after negative postoperative angiograms.

Angiography has been considered to be the gold standard to judge the success of treatment for cerebral arteriovenous malformations (AVMs). Patients without residual nidus or early draining veins on postoperative angiograms are considered cured, with the risk of hemorrhage eliminated. A series of five patients with recurrent AVMs after negative postoperative angiography is described. All patients had hemispheric AVMs, presented initially with hemorrhage, and were between 5 and 13 years of age. Recurrence was noted 1 to 9 years later (at 12-16 years of age); after a hemorrhage in three patients, seizures in one, and on follow-up magnetic resonance imaging in one. Four patients underwent angiography that showed recurrence of the AVM at or adjacent to the original site. Three years postsurgery, the fifth patient died from a large intracerebral and intraventricular hemorrhage originating in the previous location of the AVM; however, the patient did not undergo angiography at the time of recurrence. The initial negative angiograms obtained postoperatively in these patients may be explained by postoperative spasm or thrombosis of a small residual malformation. However, in the authors' cumulative experience with 808 patients who have undergone complete surgical removal of AVMs (of whom 667 were older than 18 years of age), no case of recurrent AVM has been observed in an adult. Therefore, actual regrowth of an AVM may occur in children and could be a consequence of their relatively immature cerebral vasculature and may involve active angiogenesis mediated by humoral factors. The present findings argue against the assumption that AVMs are strictly congenital lesions resulting from failure of capillary formation during early embryogenesis. It is concluded that delayed imaging studies should be considered in children at least 1 year after their initial negative postoperative arteriogram to exclude a recurrent AVM.

Adolescent↗
PubMed1996

Expression of vascular endothelial growth factor in pediatric and adult cerebral arteriovenous malformations: an immunocytochemical study.

Children and adults may differ with respect to their cerebral vasculature in both normal and pathological states. The authors have identified four pediatric patients in whom a cerebral arteriovenous malformation (AVM) recurred after surgery for removal of the AVM and in whom a normal postoperative angiogram had been obtained. This phenomenon has not been observed in adults. The propensity to regrow a cerebral AVM may reflect a less mature cerebral vasculature and a disregulated angiogenic process. Recently, attention has focused on vascular endothelial growth factor (VEGF) as a possible general mediator of angiogenesis in development and neoplasia. A retrospective immunocytochemical analysis of VEGF expression in AVM tissue was conducted to test the hypothesis that VEGF expression may be found in association with the regrowth of AVMs. The results demonstrate a high degree of astrocytic VEGF expression in four (100%) of four specimens from the initial operation in the children with recurrent AVMs as compared to one (14%) of seven nonrecurrent AVMs in the pediatric and two (25%) of eight adult specimens. All of the specimens from the first operation of the recurrent group demonstrate a clear association of cellular immunoreactivity to the abnormal blood vessels, a relationship that was not observed in the specimens from the nonrecurrent groups. These observations indicate that a humoral mechanism mediated by VEGF may play a role in AVM recurrence.

Adult↗
PubMed1996

Dorsal endodermal cyst of the upper cervical spine.

This report describes a case of a rare, dorsally placed enterogenous cyst at the craniocervical junction. The patient had preoperative magnetic resonance imaging studies, followed by microsurgical removal of the cyst. The patient made an uneventful recovery from the surgery. Pathological examination revealed an enterogenous cyst. Although enterogenous cysts are more commonly found in the lower cervical or thoracic spine, it is important to recognize that they may also be found at the craniocervical junction. In addition, cysts may occur posterior to the chord. Microsurgical removal is usually effective in the treatment of these cysts.

Adolescent↗
PubMed1990

Focal headache during balloon inflation in the internal carotid and middle cerebral arteries.

Although a number of reports are available on the occurrence of headache in patients with ischemic cerebrovascular disease, most studies have recorded the frequency but not the specific sites of the pain. We report 18 patients who underwent balloon inflation in the distal internal carotid artery and middle cerebral artery stem during embolization therapy for intracerebral arteriovenous malformations. Eleven patients had reproducible patterns of headache during balloon inflation. Inflation in the proximal middle cerebral artery stem produced pain primarily in the ipsilateral temple, that in the middle of the middle cerebral artery stem produced pain referred primarily retro-orbitally, and inflation in the distal middle cerebral artery stem produced pain referred primarily to the forehead. Experimental studies have demonstrated similar patterns of referred pain. The fact that these areas of referred pain are so reproducible is of potentially great clinical importance in the approach to management of patients with cerebrovascular disease.

Adult↗
PubMed1990

Arteriovenous malformation and glioma: coexistent or sequential? Case report.

A 9-year-old girl was evaluated for behavioral changes and seizures. Initial computerized tomography and cerebral angiography revealed a left cerebral vascular mass, diagnosed as an arteriovenous malformation. An embolization procedure was attempted but was terminated before completion because the patient developed a right hemiparesis. Her right-sided neurological deficit subsequently increased with enlargement of the mass lesion. On follow-up cerebral angiography approximately 2 years later the vascular malformation was no longer demonstrated. Biopsy of the mass lesion revealed it to be an anaplastic astrocytoma. This case is reported with a review of the literature on the coexistence of a brain tumor and a vascular malformation, the difficulties in diagnosis, and possible etiologies.

Astrocytoma↗
PubMed1988

Cavernous malformations of the spinal cord.

Six patients with intramedullary cavernous malformations of the spinal cord are presented. Four men and two women presented with acute, subacute, or episodic signs and symptoms of spinal cord dysfunction, ranging in duration from 3 days to 25 years. All patients underwent operative resection of the malformation. Complete removal was achieved in five patients. Neurological function either stabilized or improved postoperatively in all patients; follow-up ranged from 4 to 84 months. The increasing awareness of the propensity for recurrent hemorrhage, clinical features, and resectability of these malformations are discussed.

Adolescent↗
PubMed1984

Occlusive vascular disease associated with cerebral arteriovenous malformations.

Selective carotid angiography and computed tomography were used in a study of the association of occlusive vascular disease with cerebral arteriovenous malformations in 13 patients. The arterial occlusions ranged from focal stenosis in the major artery supplying the malformation to complete occlusion of the supraclinoid internal carotid artery with subsequent development of "moyamoya" collaterals. The majority of the arterial occlusions were proximal to the vascular malformation. Some, however, extended distal to the major branch supplying the arteriovenous malformation (AVM). Selective angiography with subtraction techniques defines the distinct angioarchitecture of these AVMs and the associated stenoses and collateral telangiectases.

Adult↗
PubMed1984

Defective cerebrovascular autoregulation in regions proximal to arteriovenous malformations of the brain: a case report and topic review.

We report the case of a patient with a large left subfrontal arteriovenous malformation (AVM) that was supplied by the right internal carotid artery. The anomalous blood supply developed because of complete occlusion of the left internal carotid artery. When the AVM was removed, the patient experienced a hemorrhage into the right basal ganglia. The possibility that this hemorrhage was related to a defect of autoregulation in blood vessels that lie proximal to a large AVM is discussed. Even though this is a unique case, the pathophysiological events that are documented are relevant to the preoperative preparation and surgical management of all patients with AVMs.

Carotid Artery Diseases↗
PubMed1983

Orbital arteriovenous malformation with secondary capillary angiomatosis treated by embolization with silastic liquid.

A 19-year-old Caucasian man developed signs of an orbital arteriovenous malformation, which was biopsied and then treated by embolization with a rapidly polymerizing silastic liquid. The biopsy from the initial specimen showed arteries and veins that were malformed with irregular elasticas and muscularis thicknesses, but the most curious feature was a secondary endothelial cell proliferation of such proportions as to simulate in various fields a capillary hemangioma of childhood. Approximately 50% of the bulk of the tumor was the result of the secondary endothelial cell proliferation, which we presume occurred in response to the irritative circumstances of increased intracapillary pressure from the high blood flow between the abnormal arteries and veins. Four years after the tumor was treated with the silastic liquid, it recurred and was again removed surgically. On this occasion, the histopathologic study of the tissues demonstrated a persistent secondary capillary angiomatosis, as well as chronic inflammatory reaction and granulomatous response surrounding the entrapped fragments of the polymerized silastic liquid.

Adult↗
PubMed1982

Hemangiopericytomas of the spine.

Four cases of hemangiopericytoma of the spine are reported. These are rare tumors that arise from the pericytes. Due to their invasive nature and marked vascularity, and detailed radiological work-up including computed tomography and spinal angiography should be obtained before a direct surgical attack is performed. Embolization of the tumor may also be quite helpful before surgical excision and has allowed a gross total removal of the tumor in two of the cases.

Adolescent↗
PubMed1982

Carcinoma of the choroid plexus. Case report.

Carcinoma of the choroid plexus is an extremely rare disease with a particularly virulent course. A case is reported in the left lateral ventricle of a young woman who is well 1 year after total excision of the tumor. The four previously reported patients with this disease who did well (two males and two females) were all children. Three of the four were treated with surgery followed by radiotherapy, and one with surgery alone. Although it appears possible that gross total removal may be curative, radiation therapy is suggested because of the distinct possibility that even the least aggressive-appearing lesions may degenerate and become rapidly fatal. Chemotherapy, although not used in any of the cases reported, is suggested as a possible adjunct in the treatment of this disease.

Adolescent↗
PubMed1981

The diagnosis of sacral lesions.

Clinical courses are reviewed in 4 recent patients with sacral lesions, each of whom was believed on initial clinical evaluation to have symptomatic herniations of intervertebral discs. In each patient pain in the back tended to overshadow radicular symptoms, and sphincteric disturbances were not prominent. Each patient presented some related objective abnormality on general or neurologic examination. The sacral lesion was invariably visible on technically satisfactory plain roentgenograms of the spine and was obvious on sacral tomography. Conventional myelography was useful in defining communication between the lesion and the subarachnoid space, but otherwise typically it was only subtly and nonspecifically abnormal. Computerized tomography (CT) proved to be the most revealing radiographic technique, demonstrating bony detail as well as internal structure and extent of the lesion; in conjunction with metrizamide myelography, CT provided the most definitive anatomical study. The limited utility of angiography in diagnosing these lesions is discussed, as are the respective hazards of and indications for needle biopsy and open surgical exploration.

Adult↗
PubMed1981

Evaluation of low-viscosity intravascular silicone rubber with scanning electron microscope.

A low-viscosity silicone rubber polymer used as an intravascular embolization material was studied with the aid of a scanning electron microscope. The silicone polymer became permanently affixed to the vessel endothelium without observable morphologic changes in the endothelium. No evidence of late recanalization of the embolized vessels was found in our experimental sections.

Animals↗
PubMed1981

Hydromyelia: clinical presentation and comparison of modalities of treatment.

The clinical and radiographic features of 60 cases of hydromyelia area discussed. A combination of motor and sensory symptoms and signs is the usual presentation, but pure motor or sensory forms of the disease are not infrequent. Pain and scoliosis are usually associated with a high degree of blockage. A normal spinal fluid protein content in the presence of an enlarged spinal cord is of diagnostic value. Important radiographic clues include widening of the spinal cord without venous stagnation and collapse of the spinal cord visualized with the patient in the upright position. Metrizamide computed tomography is now used routinely, and the contrast agent may at times appear in the dilated central spinal canal. Decompression of the foramen magnum is the treatment of choice in the presence of an associated Arnold-Chiari malformation and is the treatment most likely to succeed. In selected cases, decompressive laminectomy and syringostomy may be indicated. Percutaneous spinal cord puncture is a safe diagnostic-therapeutic procedure which, surprisingly, may afford relief equal to that of more drastic measures. Therefore, percutaneous spinal cord puncture may be an option of therapeutic value in a disorder that is frustrating to treat.

Adolescent↗