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Biomedical subjects

P D Purdy

Publications and source records attributed to P D Purdy.

At least 19 recordsLinked to original sources
PubMed2001

Transluminal stent-assisted angiplasty of the intracranial vertebrobasilar system for medically refractory, posterior circulation ischemia: early results.

OBJECTIVE: Symptomatic vertebrobasilar artery stenosis portends a poor prognosis, even with medical therapy. Surgical intervention is associated with considerable morbidity, and percutaneous angioplasty alone has demonstrated mixed results, with significant complications. Recent advances in stent technology have allowed for a novel treatment of symptomatic, medically refractory, vertebrobasilar artery stenosis. We report on a series of patients with medically refractory, posterior circulation stenosis who were treated with transluminal angioplasty and stenting at two medical centers in the United States. METHODS: A retrospective analysis of data for 11 consecutive patients with symptomatic, medically refractory, intracranial, vertebral or basilar artery stenosis was performed. All patients were treated with percutaneous transluminal angioplasty and stenting. Short-term clinical and angiographic follow-up data were obtained. RESULTS: Among 11 patients who were treated with stent-assisted angioplasty of the basilar or vertebral arteries, there were three periprocedural deaths and one delayed death after a pontine stroke. Other complications included a second pontine infarction, with subsequent residual diplopia. The remaining seven patients (64%) experienced symptom resolution and have resumed their preprocedural activities of daily living. Angiographic follow-up examinations demonstrated good patency of the stented lesions for five of seven survivors (71%); one patient exhibited minimal intrastent intimal hyperplasia, and another patient developed new stenosis proximal to the stent and also developed an aneurysm within the stented portion of the basilar artery. The last patient exhibited 40% narrowing of the treated portion of the vessel lumen. CONCLUSION: Recent advances in stent technology allow negotiation of the proximal posterior circulation vasculature. Although the treatment of vertebrobasilar artery stenosis with angioplasty and stenting is promising, long-term angiographic and clinical follow-up monitoring of a larger patient population is needed.

Adult↗
PubMed2001

Rupture of intracranial aneurysms during endovascular coiling: management and outcomes.

OBJECTIVE: In this study, the incidence, etiologies, and management with respect to clinical outcome of patients with iatrogenic aneurysmal rupture during attempted coil embolization of intracranial aneurysms are reviewed. METHODS: A retrospective analysis was conducted of 274 patients with intracranial aneurysms treated with Guglielmi detachable coils over a 6-year period from 1994 to 2000. Patient medical records were examined for demographic data, aneurysm location, the number of coils deployed preceding and after aneurysmal rupture, the etiology of the rupture, and the clinical status on admission and at the time of discharge. RESULTS: Of 274 patients with intracranial aneurysms treated with coil embolization, six (2%) had an intraprocedural rupture. Of these six, two were women and four were men. The mean age was 67 years (range, 52-85 yr). Mean follow-up time was 8 months (range, 0-25 mo). Aneurysmal rupture resulted from detachment of the last coil in three patients, detachment of the third coil (of four) in one patient, and insertion of the first coil in another patient. In one patient, the aneurysmal rupture was a result of catheter advancement before detachment of the last coil. The Glasgow Outcome Scale score at last follow-up examination was 1 in two patients, 2 in two patients, and 5 in two patients. CONCLUSION: The rate of rupture of aneurysms during coil embolization is approximately 2 to 4%. The clinical outcome may be related to the timing of the rupture and the number of coils placed before rupture. If extravasation of contrast agent is seen, which suggests intraprocedural rupture, further coil deposition should be attempted if safely possible.

Aged↗
PubMed2000

The use of stents in the management of neurovascular disease: a review of historical and present status.

In the mid-1960s, radiologists began experimenting with stents for use in the peripheral vasculature in the hope of treating vascular insufficiency resulting from vessel stenosis in a nonsurgical manner. The 1990s saw stents move into the neurovascular arena for the management of a variety of disease processes, including arterial and venous sinus stenosis, arterial dissection, arterial aneurysms, and arteriovenous fistulae. This article reviews the current status of stenting in regard to the management of neurovascular maladies.

Angioplasty, Balloon↗
PubMed2000

Endovascular problem solving with intravascular stents.

BACKGROUND AND PURPOSE: Intravascular stents are being used with increasing frequency in interventional neuroradiology. They provide the potential to expand the therapeutic capabilities of the endovascular therapist and stand to revolutionize endovascular intervention within both the intracranial and extracranial vessels. We present our application of stent technology to further the understanding of endovascular rescue from procedural complications and the solving of complex clinical problems. METHODS: Three patients underwent unplanned placement of intravascular stents. In two patients a stent was used to provide stabilization of an irretrievable intravascular device; in the third patient a stent was used to provide a scaffolding for proximal external carotid sacrifice. RESULTS: Stent deployment was successful in all patients. The intravascular devices stabilized by stent placement included unraveled fragments of a Guglielmi detachable coil (GDC) and a partially deployed coronary stent. Proximal external carotid sacrifice was achieved with the aid of a stent in one patient to control hemorrhage from recurrence of laryngeal cancer. No periprocedural neurologic complications were encountered. Six-month follow-up angiography in one patient showed only minimal myointimal hyperplasia induced by stent-stabilized GDC fragments adjacent to the internal carotid vessel wall. CONCLUSION: Stents can be used to provide stabilization of irretrievable intravascular devices or as a scaffolding for proximal vessel sacrifice. These applications may allow endovascular rescue of procedural complications and solve unique clinical problems.

Aged↗
PubMed2000

Remote vascular catastrophes after neurovascular interventional therapy for type 4 Ehlers-Danlos Syndrome.

Type 4 Ehlers-Danlos Syndrome (EDS 4) is the most malignant form of Ehlers-Danlos Syndrome, often accompanied by neurovasacular complications secondary to vessel dissection or aneurysms. The fragile nature of connective tissue in these patients makes exovascular and endovascular treatment hazardous. We have treated four patients with EDS 4 over the last 8 years by using neuroendovascular procedures. Two of these individuals suffered remote vascular injuries around the time of their procedures and ultimately died. The circumstances surrounding their deaths will make up the body of this report.

Adolescent↗
PubMed1999

Percutaneous transluminal angioplasty and stenting of midbasilar stenoses: three technical case reports and literature review.

OBJECTIVE AND IMPORTANCE: Symptomatic basilar artery stenosis is a highly morbid disease process. Recent technological and pharmaceutical advances make endovascular treatment of this disease process possible. CLINICAL PRESENTATION: We report three cases of patients with a symptomatic basilar artery stenosis despite anticoagulation. INTERVENTION: All patients were successfully treated with a flexible coronary stent and perioperative antiplatelet medications without incident. Poststenting angiography demonstrated a normal-caliber artery with patent perforators. In one case, a poststenting cerebral blood flow study revealed improved perfusion. CONCLUSION: A new generation of stents and balloons makes access to intracranial intradural arterial pathological abnormalities possible. Such devices may well revolutionize the management of ischemic and hemorrhagic intracranial cerebrovascular disease.

Aged↗
PubMed1997

Scanning electron microscopic findings in a basilar tip aneurysm embolized with Guglielmi detachable coils.

With the growing use of endovascular therapy for intracranial aneurysms, it is important that we understand at a cellular level the processes that lead to lesion obliteration. We present autopsy findings, including electron and light microscopic studies, of a basilar artery aneurysm that was successfully embolized with the Guglielmi detachable coil system 4 weeks before the patient died.

Aged↗
PubMed1996

Radiation dermatitis after spinal arteriovenous malformation embolization: case report.

Few cases of radiation injury related to lengthy interventional neuroradiologic procedures have been reported, although concern has been heightened, as evidence by a 1994 FDA Public Health Advisory. We report a case of radiation-induced dermatitis in a patient undergoing multiple diagnostic and embolization procedures for treatment of a spinal arteriovenous malformation.

Adult↗
PubMed1996

Use of intravascular stents in the treatment of internal carotid and extracranial vertebral artery pseudoaneurysms.

The management of extracranial carotid or vertebral artery pseudoaneurysms is controversial. Although some of these lesions resolve spontaneously, many clinicians opt to treat them with trapping procedures that result in vessel sacrifice. We describe two cases in which an intravascular stent was used to obliterate an aneurysm of the extracranial vertebral artery and the internal carotid artery, respectively, while maintaining the patency of the parent vessel. The technique, which has been successful in experimental animal models, shows promise for application in humans.

Aneurysm, False↗
PubMed1994

Human brain responses to different image contrasts.

Human brain activity was evoked by a dynamic random-dot display in which a square-wave grating appeared and disappeared at regular intervals. Grating visibility was determined by one of four different contrasts: texture, stereo disparity, luminance, or color. Scalp fields measured with 31 electrodes were used to estimate epicortical potential fields. The estimation procedure required detailed anatomical data for each subject. These were obtained from magnetic resonance images. A three-dimensional digitizer and a stereotactic headgear were used to accurately merge the frame of reference of the magnetic resonance image with that of the evoked potential. Epicortical potential fields provided a better indicator of where brain activity is evoked than did scalp fields. These procedures also corrected for anatomical variations between scalp and brain from subject to subject. In two right-handed female subjects, evoked activity was observed in the left posterior parietal and the right occipital, parieto-occipital and posterior temporal cortices. Evoked activity was observed in the left parietal cortex for luminance processing, in the right parietal cortex for texture processing and in the right temporal cortex for color processing, which was selective for the particular contrast.

Brain↗
PubMed1994

Detection of cerebral hypoperfusion during trial carotid occlusion with reversal following extracranial-intracranial bypass prior to permanent occlusion.

The authors describe a patient with a large intracavernous aneurysm of the right internal carotid artery and a marked decrease in focal brain blood flow induced by temporary carotid balloon occlusion. The patient subsequently underwent a superficial temporal to middle cerebral artery bypass followed by successful carotid occlusion using detachable balloons placed proximal to the aneurysm. Postoperative rCBF demonstrated normal perfusion in the region of the right internal carotid artery distribution as well as normalization of perfusion to a previous area of baseline perfusion abnormality. Cerebral brain blood flow imaging was useful in the initial evaluation as well as the management of this patient.

Aged↗
PubMed1994

Diagnostic applications of simultaneously acquired dual-isotope single-photon emission CT scans.

PURPOSE: To report the development and validation of a technique of dual tracer single-photon emission CT brain imaging using technetium-99m hexamethylpropyleneamine oxime and iodine-123 iodoamphetamine agents and the application of this technique in patients with a variety of diagnoses. METHODS: Contamination between the two isotopes' energy windows was calculated by opening both energy windows while scanning a group of patients using a single isotope. To compare uniformity of I-123 down-scatter, Tc-99m studies were performed both before and after the administration of I-123 in five of 24 dual studies. The 24 patients studied with the dual-isotope technique were evaluated during acetazolamide testing, trial balloon occlusion, or embolization of an arteriovenous malformation. RESULTS: In a dual acquisition, average count contamination of an I-123 study by Tc-99m was less than 1% of the total I-123 counts, and contamination of a Tc-99m study by I-123 was approximately 12% of the total Tc-99m counts. Tc-99m studies performed both before and after the administration of I-123 demonstrated that contaminating counts do not adversely affect scan interpretation. Dual-tracer scans were completed in all 24 patients, 10 of whom showed changes after intervention. CONCLUSIONS: Dual-tracer single-photon emission CT brain scans of adequate diagnostic quality are possible using Tc-99m and I-123.

Acetazolamide↗
PubMed1993

Functional brain imaging: dipole localization and Laplacian methods.

The performance of two methods, used to localize brain activity from evoked potential fields measured on the scalp, was assessed in a tank model of the human head. This physical model contained a human skull encased in a polymer simulating the resistivity and geometry of brain and scalp. The dipole localization method mislocalized the positions of known dipole sources by several centimeters. The mislocalization was systematic. The dipoles were localized too deeply in the head. The Laplacian method yielded a field resembling the brain surface field (epicortical potential field) provided that the iso-potential contours of the scalp field closed within the measurement range. Clipping resulted in a serious mislocalization of the position of the peak of the epicortical potential field.

Brain Mapping↗
PubMed1993

Inferring regional brain activity from evoked potential fields on the scalp.

A new method is described to calculate epicortical potential fields from scalp fields based on linear algebra. It requires detailed anatomical information, for each subject, obtained from MR images. The calculation is validated in a physical model of the human head and applied to human subjects. The results suggest that the method yields reliable epicortical fields that help to localize evoked cortical activity in humans.

Brain↗
PubMed1993

Estimating regional brain activity from evoked potential fields on the scalp.

Potential fields on the surface of the brain were estimated from discretely sampled scalp fields in human subjects. Relatively simple methods of linear algebra were combined with detailed anatomical information from magnetic resonance imaging. The method was verified using a tank model of the human head that encased a fully hydrated human skull in a polymer matrix of controlled resistivity matching that of human brain and scalp. Brain surface fields evoked by checkerboard contrast reversal, spread less than their scalp field counterparts, and provided information helpful in localizing brain activity.

Brain↗
PubMed1993

Denervated human skeletal muscle: MR imaging evaluation.

Because determination of neurologic integrity after severe limb trauma is crucial in patient care, the authors assessed magnetic resonance (MR) imaging as a tool to map denervated motor units of skeletal muscle in patients with traumatic peripheral neuropathy. Denervation was confirmed in 22 patients with use of electromyography, surgery, or both. MR imaging was performed with moderately T1- and T2-weighted spin-echo and short-tau inversion-recovery (STIR) sequences. MR imaging was unreliable in depicting acute denervation. Muscles of patients with subacute denervation had prolonged T1 and T2, which contributed to conspicuous hyperintensity on STIR images. Chronically denervated muscles showed marked atrophy, variable changes on STIR images, and conspicuous fatty infiltration on T1-weighted images. Normal variants in motor unit anatomy were seen in denervated muscle volumes outside the expected distribution of the injured nerve. MR imaging is promising for the noninvasive mapping and monitoring of denervated muscle in subacute and chronic phases of peripheral neuropathy.

Extremities↗