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Biomedical subjects

R Willinsky

Publications and source records attributed to R Willinsky.

At least 37 records · Page 2Linked to original sources
PubMed1991

Current status of radiosurgery for arteriovenous malformations.

Cerebral arteriovenous malformations (AVM), regardless of the mode of discovery, have an annual risk of hemorrhage of approximately 4 percent. A progressive obliterative vasculitis culminating in the occlusion of an AVM may be induced by the administration of radiation doses of approximately 20 Gy given in a single fraction. The process takes about two years and occlusion occurs in approximately 80% of patients so treated. Such a dose may be accurately administered to AVMs up to 3 cm in diameter with very little radiation imparted to the adjacent brain by means of multiple highly collimated radially arranged cobalt sources (the Gamma Knife) or by means of a modified linear accelerator turned through an arc or arcs with the target AVM as the centre of rotation. The Gamma Knife and the modified linear accelerator have nearly equal accuracy. Recent experience with modified linear accelerators indicates efficacy equal to the Gamma Knife. Both devices are effective treatment for small AVMs but the cost of modifying a pre-existing linear accelerator is only a few percent of the acquisition and installation costs of the Gamma Knife.

Evaluation Studies as Topic↗
PubMed1991

Endovascular treatment of intracerebral arteriovenous malformations: experience in 49 cases.

The authors report the results of treatment in 49 consecutive patients with brain arteriovenous malformations (AVM's) who underwent therapeutic embolization with liquid adhesive agents between 1984 and 1988 at the Toronto Western Hospital. Thirty-three patients had no other treatment and were followed up with angiography at 2 years and clinically from 2 to 6 years. Of the other 16 patients, 10 had adjunctive radiosurgery and six underwent surgical resection following embolization. Seven (14%) of the 49 patients had a morphological cure effected by embolization as evidenced on their 2-year follow-up angiograms: these have remained clinically stable. Twelve patients developed neurological deficits after embolization; eight (16% of the series) were transient and four (8%) were permanent. Two patients (4%) had a delayed hemorrhage after incomplete obliteration of their malformations. Endovascular treatment resulted in clinical improvement in 15 (33%) of the other 46 patients. None of the patients who initially presented with hemorrhage had a rebleed following embolization. It is concluded that endovascular treatment with liquid embolic material can be an integral part of the multidisciplinary treatment protocol for patients with brain AVM's.

Cerebral Angiography↗
PubMed1990

Angiography in the investigation of spinal dural arteriovenous fistula. A protocol with application of the venous phase.

The authors present their protocol for spinal angiography in their investigation of dural arteriovenous fistula (DAVF). The protocol has been used in approximately 120 patients from 1983 to the present at Bicetre Hospital. The approach is based on the fact that venous congestion is responsible for the myelopathy of DAVF. If the venous phase of the spinal circulation is normal, this alone rules out DAVF as the cause of the patient's symptoms. If there is stasis in the spinal circulation, this is consistent with DAVF, and thus complete spinal angiography is necessary. Complete angiography includes the selective intercostal arteries, including the lateral sacrals, as well as the supply to the cervical cord and posterior fossa.

Angiography↗
PubMed1990

The variable presentations of craniocervical and cervical dural arteriovenous malformations.

The authors reviewed four patients with dural arteriovenous malformations in the upper spinal axis. Two were at the foramen magnum and two were lower cervical. The patients presented with subarachnoid hemorrhage, a slowly progressive cervical myelopathy, a rapidly progressive thoracic myelopathy, and tinnitus with a sixth nerve palsy. This report emphasizes the importance of studying both the intracranial dural vessels as well as the supply to the cervical spine in searching for a spinal arteriovenous malformation. Subarachnoid hemorrhage with negative cerebral angiography requires spinal angiography if there are any signs or symptoms suggesting cord or nerve root dysfunction. Embolization by an endovascular approach resulted in an angiographic cure in two patients. A combination of embolization and surgery resulted in obliteration of the arteriovenous malformation in one patient. Embolization achieved a clinical cure in one patient, and clinical improvement in two patients.

Adult↗
PubMed1989

[True and false cerebral venous malformations. Venous pseudo-angiomas and cavernous hemangiomas].

The authors report their classification of venous anomalies and abnormalities within the central nervous system. The so-called venous angiomas are developmental venous anomalies (D.V.A.). The different forms encountered express the extreme variations in the transcerebral venous system. Their symptomatic character depends on the aging changes that the cerebral venous system undergoes or the frequent association of D.V.A. with cavernomas of the central nervous system. The cavernous hemangiomas are true tumors that present a proliferative character. They are localized in the dura or in the extradural space intracranially or at the spinal level. They must be considered as tumors and can be seen at angiography as they present a fine parenchymatous stain. The cavernomas of the central nervous system are true vascular malformations of the venous type; they are locally multiple, but can also be disseminated within the intracranial space. Some familial forms have been reported. They are often associated with D.V.A. They have a high bleeding potential, which does not carry a high morbidity or mortality incidence. However, the natural history of this lesion is poorly known at present. The spinal cord posterior fossa and paraventricular localizations present probably the least favorable localizations. Only the cavernomas deserve to belong to the vascular malformation group. The same comments and observations apply to spinal cord venous lesions.

Brain Neoplasms↗
PubMed1988

Cerebral arteriovenous malformations (C. AVM) and associated arterial aneurysms (AA). Analysis of 101 C. AVM cases, with 37 AA in 23 patients.

We report a series of 101 patients with cerebral arteriovenous malformations (CAVM), in which 23 cases presented with one or several arterial aneurysm(s) (AA). Each AA could be classified into distal intra-lesional, proximal or remote. Patients with CAVM + AA tend to be older and more frequently present with epilepsy, haemorrhage events and neurological deficits. Of these 23 patients, 16 had their AVM treated partially or totally by embolization. In our series, the endovascular treatment of the arteriovenous shunt with a proximal AA on the same vessel has resulted in at least a regression, and sometimes a disappearance of the arterial ectasia. Although partial treatment of the AVM does no erase the risk of haemorrhage from the malformation itself, it may diminish the chance of developing a flow-related AA or any other expression of the high-flow angiopathy.

Embolization, Therapeutic↗
PubMed1988

Cerebral micro arteriovenous malformations (mAVMs). Review of 13 cases.

In a personal series of 152 cerebral vascular malformation, 13 patients had small (less than 1 cm) parenchymal arteriovenous malformations (mAVMs) with small nidus or fistula and a single normal-sized feeding artery and draining vein. All 13 patients presented with intracerebral haematomas (ICHs). The average age in this group was 31 years with no sex dominance; 8 patients had no antecedent symptoms. In 11 patients the small AMV could be demonstrated angiographically, with the remaining 2 malformations evident at surgery. In addition, all these mAVMs, being superficial (95% cortical), were surgically removable with no perioperative morbidity. They were not accessible by endovascular approach. This population group narrows the concept of occult vascular lesions if high quality angiographic studies are performed. mAVMs are by nature CT and MRI occult.

Adolescent↗
PubMed1988

Brain arteriovenous malformations: analysis of the angio-architecture in relationship to hemorrhage (based on 152 patients explored and/or treated at the hopital de Bicêtre between 1981 and 1986).

The authors studied the charts and angiograms of 178 patients with cerebral vascular lesions. The angiographic features of these malformations could be grouped into the following categories: arterial variations, arterial aneurysms, arterial infundibulum, arterial stenosis, venous variation, venous stenosis, venous ectasia, arteriovenous fistula, transcerebral vascularization and external carotid supply. The age and sex of the patients as well as the topography and angiographic features were correlated with the incidence of hemorrhage. We found that deep and posterior fossa malformations, as well as temporal, insular and callosal localizations, were more likely to have bled. We also found that older males (40-50 years) with associated aneurysms and younger females (20-30 years) with venous stenosis were more likely to have bled.

Adolescent↗
PubMed1987

Petrous internal carotid aneurysm causing epistaxis: balloon embolization with preservation of the parent vessel.

A patient with severe, recurrent posterior epistaxis was shown at angiography to have an aneurysm of the petrous portion of the internal carotid artery (ICA). Since childhood, she had had pain related to eustachian tube blockage by the aneurysm. An endovascular balloon embolization of the aneurysm was successful with preservation of the parent artery. The treatment resulted in resolution of the symptoms. The report confirms the usefulness of an angiographic protocol in evaluating vascular problems.

Adult↗
PubMed1987

Intracavernous branches of the internal carotid artery (ICA). Comprehensive review of their variations.

Since we started to work in the lateral sellar region (in 1973), a large volume of angiographic material has provided us with exceptional variations that added to the anatomic facts obtained from our dissections. At present, these anatomic facts remain, but the way we look at them and the way we use them for endovascular treatments, has created a need for a different type of approach and understanding. In this report, we present a flexible anatomical view of the intracavernous branches of the internal carotid artery and a scheme to understand and predict the anatomical variations of these collaterals. Four embryonic vessels play an important role in the variations of the arterial supply to the lateral cavernous region: the dorsal ophthalmic artery, the stapedial artery, the trigeminal artery and the primitive maxillary artery. In general each of them partially regresses leaving behind a remnant. However there is a spectrum from their persistence to incomplete regression, resulting in variations of the supply to their distal territories. The term "meningohypophyseal" should be abandoned because it is misleading and improperly used. Complete agenesis is known for a long time; in case of segmental agenesis of the ICA each of the embryonic vessels presented above may represent an alternate route to bypass the agenesis. The ICA is not a direct feeding artery but a succession of independant segments which can be the site of various anomalies. An embryonic transdural circle can be individualized; it is constituted by the trigeminal arteries posteriorly, the ICA siphon anteriorly, the transsellar anastomosis and internal maxillary artery connections. Although regressions usually occur in this embryonic transdural circle, its derivatives congenital and acquired arterial pathologies. It also constitutes the key system in determining the arterial variations of the perisellar region.

Carotid Artery, Internal↗
PubMed1984

MR imaging of orbital tumors with CT and ultrasound correlations.

Fourteen patients with various orbital space-occupying lesions were studied by magnetic resonance (MR) imaging with a 0.15 T imager using spin-echo and inversion-recovery pulse sequences. Computed tomographic and ultrasonographic (US) examinations were done in 13 of these patients. All 14 lesions could be demonstrated by MR. Magnetic resonance was found to be better than US but not as good as CT in providing morphological details. Regarding tissue characterization, US was the most useful among the three modalities. With the T2-weighted spin-echo pulse sequence, a possible trend in tissue characterization could be shown. From our preliminary experience, we conclude that MR imaging using a 0.15 T resistive magnet offers no distinct advantage over the combination of CT and US in the diagnosis of orbital tumors.

Adult↗
PubMedDate not supplied

MR features of tuberculous arachnoiditis.

Although tuberculosis is an uncommon cause of spinal arachnoiditis, it needs to be differentiated from other causes of arachnoiditis because it is a treatable disease. Myelography, which is the imaging modality of choice for the chronic adhesive stage of tuberculous arachnoiditis, usually reveals irregularity of the thecal sac, nodularity and thickening of nerve roots, clumping of roots to each other or to the thecal sac, or CSF block. Recently Gd-diethylenetriamine pentaacetic acid enhanced MRI has been found to be useful for the active phase of tuberculous infection, effectively demonstrating abnormally thickened and enhancing meninges, intra- and extramedullary tuberculous nodules, and spinal cord changes. We present the MRI features in a case of acute tuberculous arachnoiditis.

Adult↗
PubMedDate not supplied

Tortuous, engorged pial veins in intracranial dural arteriovenous fistulas: correlations with presentation, location, and MR findings in 122 patients.

BACKGROUND AND PURPOSE: Tortuous, engorged veins can be identified on the venous phase of the brain circulation in patients with venous congestion related to an intracranial dural arteriovenous fistula (DAVF). The term pseudophlebitic pattern (PPP) has been used to describe this finding. The purpose of this study was to determine the prevalence of PPP in patients with intracranial DAVF and to analyze the relationship of this sign to presentation, location of the fistula, presence of retrograde leptomeningeal venous drainage, and MR findings. METHODS: We retrospectively reviewed the charts and imaging findings of 130 patients with intracranial DAVF. In 122 patients the venous phase of the brain circulation was adequately assessed. The PPP was graded as mild, moderate, or severe. RESULTS: PPP was found in 51 patients (42%). Thirty-two (73%) of the 44 patients who had a hemorrhage, neurologic deficit, or seizure had PPP as compared with 16 (21%) of the 75 who had a bruit or orbital signs. The three patients with either congestive heart failure or increasing head circumference had PPP. Fourteen (88%) of the 16 who had fistula of the superior sagittal sinus, straight sinus, or superior petrosal sinus had PPP. PPP was seen in 46 (81%) of 57 patients who had retrograde leptomeningeal venous drainage and in five (8%) of the 65 who had only sinosal drainage. Fourteen (88%) of the 16 who had white matter T2 hyperintensity on MR images had severe PPP. CONCLUSION: The PPP reflects venous congestion and is associated with an aggressive presentation with or without retrograde leptomeningeal venous drainage. PPP may be a useful prognostic indicator and should be considered in treatment decisions.

Adolescent↗
PubMedDate not supplied

Hypertrophic olivary degeneration: metaanalysis of the temporal evolution of MR findings.

BACKGROUND AND PURPOSE: Hypertrophic olivary degeneration (HOD) is usually caused by a lesion in the triangle of Guillain and Mollaret and presents clinically as palatal tremor. Although the imaging features have been well described, the temporal course of hypertrophy and T2 signal increase in the inferior olivary nucleus (ION) has not been fully characterized. Our purpose was to evaluate the time course of MR imaging features of HOD caused by a lesion within the triangle of Guillain and Mollaret. METHODS: The temporal progression of HOD in 45 patients with symptomatic palatal tremor was obtained by extrapolation of combined MR imaging data from six patients treated at our institution and 39 patients reported in the literature. The MR examinations and reports were reviewed for presence of hyperintense signal in the ION on T2-weighted images, hypertrophy of the ION, and an inciting lesion in the triangle of Guillain and Mollaret. The interval between the MR examination and the inciting lesion was determined. RESULTS: Increased olivary signal on T2-weighted images first appeared 1 month after the inciting lesion and persisted for at least 3 to 4 years. Olivary hypertrophy initially developed 6 months after the acute event and resolved by 3 to 4 years. CONCLUSION: Visible changes on MR images in the ION in patients with a lesion in the triangle of Guillain and Mollaret correlate well with the described sequential histopathologic findings.

Disease Progression↗
PubMedDate not supplied

Micro-arteriovenous malformations of the brain: superselective angiography in diagnosis and treatment.

PURPOSE: We assessed the usefulness of superselective angiography in patients with micro-arteriovenous malformations. PATIENTS AND METHODS: Five patients had superselective angiography for either diagnosis or treatment of brain arteriovenous malformations having a nidus of less than 1 cm. All patients presented with an intracerebral hematoma. RESULTS: In one patient superselective angiography confirmed the presence of a shunt that was suspected due to visualization of an early vein on the follow-up angiogram; in another patient superselective angiography was helpful in defining the topography of the malformation; in the remaining three patients, superselective angiography was used for embolization of the malformation. We were unsuccessful in achieving a complete angiographic cure in these 3; however, superselective angiography revealed an aneurysm in one that was obliterated by the liquid adhesive embolic agent. CONCLUSION: With the recent advances in microcatheters, superselective angiography has a promising role in defining the topography and angioarchitecture of micro-arteriovenous malformations. Micro-arteriovenous malformations may not be angiographically evident at the time of initial hemorrhage due to the hematoma. With future technical advances it may be possible to completely obliterate these malformations by embolization alone.

Adolescent↗