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Biomedical subjects

M B Pritz

Publications and source records attributed to M B Pritz.

At least 37 records · Page 2Linked to original sources
PubMed1997

Timing of carotid endarterectomy after stroke.

BACKGROUND: Timing of carotid endarterectomy after stroke in a patient with a fixed neurological deficit remains an important but unresolved question. Early surgery has been associated with cerebral hemorrhage and infarct extension. Delayed endarterectomy exposes the patient to recurrent stroke and carotid occlusion. This review investigates the hypothesis that timing of surgery after stroke influences outcome and complications. SUMMARY OF REVIEW: This analysis critically evaluates peer-reviewed reports that retrospectively examined outcome after surgery performed "early" and "late" after stroke. The basis for intracerebral hemorrhage after endarterectomy is discussed. Clinical features that influence outcome are investigated. CONCLUSIONS: Patients undergoing carotid endarterectomy are considered a heterogeneous group based on the following features: presence of low density on cranial CT, vascular territory of the infarct, brain shift, and level of consciousness. While critical review of these retrospective studies suggests that some patients with an acute stroke can safely undergo endarterectomy shortly after the diagnosis is made, direct answers to these questions of timing of endarterectomy after stroke are best addressed by prospective studies. Nevertheless, the present review provides a basis for decision making in certain patients and for the design of future investigations.

Brain↗
PubMed1996

Spinally projecting neurons of the dorsal column nucleus in a reptile: locus of origin and trajectory of termination.

Interconnections between the dorsal column nucleus and the spinal cord were investigated in a reptile, Caiman crocodilus. After placement of an anterograde tracer into the dorsal column nucleus, descending fibers are seen to leave this nucleus to enter the dorsal funiculus where they course ventrally to terminate in lamina V of the spinal cord as far caudally as C2. Placement of a retrograde tracer into cut fibers of the cervical spinal cord identified the relay cells of the dorsal column nucleus that project to the spinal cord. These neurons were mainly clustered in a caudal and ventral part of this nucleus. The soma of these spinally projecting cells were small and were generally round or oval in shape. A number of these neurons had the long axis of their soma oriented dorsoventrally, with a primary dendrite extending dorsally. Fibers in the dorsal funiculus that originated from the spinal cord enter the caudal part of the dorsal column nucleus and turn ventral. In the dorsal column nucleus, these axons run parallel to the vertically oriented dendrites of these spinally projecting cells before termination in close relation to the cell bodies of these neurons. Quantitative observations (mean +/- standard error) were made on well labeled neurons and included several measurements: area, perimeter, and degree of eccentricity (greatest width/greatest length) in both the transverse as well as the sagittal plane. These spinally projecting neurons in Caiman are located in the dorsal column nucleus in a position similar to that of spinally projecting cells in cats.

Afferent Pathways↗
PubMed1995

The thalamus of reptiles and mammals: similarities and differences.

Certain aspects of thalamic organization in reptiles and mammals are reviewed. Features shared by the dorsal thalamus of reptiles and that of mammals include projection to the telencephalon, specific and non-specific non-telencephalic afferents, and input from the thalamic reticular nucleus. Differences between the dorsal thalamus of reptiles and that of mammals are the absence of reciprocal telencephalic efferents to the dorsal thalamus and lack of local circuit neurons in reptiles (with the exception of the dorsal geniculate complex in turtles) and their presence in mammals. A thalamic reticular nucleus is present in both reptiles and mammals. In both of these classes of vertebrates, this neuronal aggregate surrounds the dorsal thalamus along its lateral surface, projects to the dorsal thalamus, and is organized into sectors. In one group of reptiles, Caiman crocodilus, the sole reptilian group in which immunocytochemical features have been investigated in detail, the reticular nucleus contains at least three neuronal subpopulations: neurons immunoreactive for glutamic acid decarboxylase (GAD); neurons immunoreactive for parvalbumin; and cells that are not immunoreactive for parvalbumin or, probably, GAD. On the other hand, the reticular nucleus of mammals contains a single population of neurons immunoreactive for GAD, gamma amino butyric acid, and parvalbumin.

Animals↗
PubMed1994

Glutamic acid decarboxylase immunoreactivity in some dorsal thalamic nuclei in Crocodilia.

Glutamic acid decarboxylase (GAD) immunocytochemical properties of thalamic nuclei known to project to the telencephalon were investigated in reptiles, Caiman crocodilus and Alligator mississippiensis, by monoclonal antibodies to GAD epitopes designated as GAD-1, GAD-2 and GAD-5. GAD-immunoreactive puncta were observed with all three monoclonal antibodies in the following dorsal thalamic nuclei by avidin-biotin complex methodology: dorsolateralis anterior, dorsomedialis anterior, diagonalis, rotundus, reuniens pars centralis and pars diffusa, and the medialis complex. In general, immunoreactivity to GAD was more robust in Alligator than in Caiman. GAD-2 immunoreactivity was more intense than immunoreactivity to GAD-1 or GAD-5 at similar antibody concentrations in both species. Thalamic nuclei varied in the pattern and intensity of GAD (+)puncta staining in Caiman and Alligator. No GAD-immunoreactive neurons were observed in any of these seven thalamic nuclei with any GAD antibody in either species.

Alligators and Crocodiles↗
PubMed1994

Ruptured supratentorial arteriovenous malformations associated with venous aneurysms.

Six patients with ruptured supratentorial arteriovenous malformation (AVM) and an associated venous aneurysm (ectasia, dilatation, varix, pouch) are described. At presentation, patients ranged in age from 16 to 61 years and were equally distributed according to sex. Maximal AVM diameter was between 2.5 and 5.0 cm at presentation while the maximal size of the venous aneurysm ranged between 0.75 and 3.0 cm. One patient had multiple venous pouches while 5 patients had a single venous aneurysm. Three patients had a single bleed; 1 patient had 2 bleeds; and 2 patients had 3 bleeds. Hemorrhage around the venous aneurysm was seen in 4 of 5 patients who underwent magnetic resonance imaging of the brain. One patient, who suffered 3 bleeds over a several year period, had both an increase in the size of the venous aneurysm as well as enlargement of the AVM. The following features did not appear to influence hemorrhage: AVM size or location; venous aneurysm size or location; age; sex; pattern; location or number of draining veins; or external circulation feeders. These observations suggest that a venous aneurysm may increase the risk of hemorrhage from a supratentorial AVM and may be an ominous feature.

Adolescent↗
PubMed1994

Usefulness of a fiber optic Swan-Ganz catheter to monitor oxygen transport during volume expansion in a patient with ischemic neurologic deficits from aneurysmal subarachnoid hemorrhage.

The usefulness of a fiber optic Swan-Ganz catheter to monitor oxygen transport during volume expansion in a patient with ischemic neurologic deficits due to aneurysmal subarachnoid hemorrhage is illustrated. Usefulness of oxygen delivery and oxygen consumption measurements are presented. The role of oxygen transport in addition to cardiac hemodynamics and volume status in the management of these neurologic symptoms is emphasized.

Blood Volume↗
PubMed1994

The transsylvian approach to middle cerebral artery bifurcation/trifurcation aneurysms.

A transsylvian approach to treat aneurysms located at the bifurcation/trifurcation of the middle cerebral artery (MCA) is described. This surgical route traces a distal MCA branch retrogradely into the Sylvian fissure whereupon a secondary MCA branch and the main stem of the MCA (M1) are identified before aneurysm clipping. The advantages, and disadvantages of this approach are discussed. The transsylvian route should be considered as an alternative to the traditional pterional approach, which utilizes proximal to distal dissection of the MCA, in situations when the M1 is long or when the pterional approach is inadvisable.

Cerebral Angiography↗
PubMed1994

Pupillary changes after intracisternal injection of papaverine.

Pupillary changes attributed to intracisternal papaverine injection were observed in three patients who underwent pterional craniotomy and clipping of a supratentorial aneurysm in which the oculomotor nerve was not manipulated. A fixed and dilated pupil on the side of the craniotomy lasted 2 to 4 hours after intracisternal papaverine instillation. These observations suggest that a dilated, nonreactive pupil subsequent to an uncomplicated pterional craniotomy for aneurysm, in which oculomotor nerve trauma has not occurred, may not be an ominous finding but may represent a transient phenomenon related to intracisternal papaverine injection.

Adult↗
PubMed1994

Morphological and GAD immunocytochemical properties of the dorsal lateral geniculate nucleus in a reptile.

Morphological and glutamic acid decarboxylase (GAD) immunocytochemical properties of the dorsal part of the lateral geniculate nucleus were investigated in reptiles, Caiman crocodilus. GAD immunoreactive neurons, although sparse, were found in the dorsal part of the lateral geniculate nucleus. In addition, puncta and fibers immunoreactive for GAD were also observed in this same nucleus. These results in Caiman utilizing GAD are similar to observations on the dorsal part of the lateral geniculate nucleus of other reptiles in which antisera to gamma amino butyric acid (GABA) were used.

Alligators and Crocodiles↗
PubMed1994

Anatomical identification of a telencephalic somatosensory area in a reptile, Caiman crocodilus.

Telencephalic projections of a thalamic somatosensory area were investigated in a reptilian species, Caiman crocodilus, by means of horseradish peroxidase (HRP) neurohistochemistry. Injections of HRP into the medialis complex labeled axons that leave the ventral aspect of this nucleus to enter the dorsal peduncle of the lateral forebrain bundle where they ascend. These fibers course rostrally to enter the central portion of the lateral forebrain bundle. Here, axons turn dorsally, pass through, and probably synapse on, interposed neurons of the ventrolateral area, to end in a central portion of the dorsal ventricular ridge (DVR). These findings were confirmed by HRP injections into this somatosensory area of the DVR that retrogradely labeled neurons in the medialis complex. This telencephalic somatosensory area identified in transverse sections was then reconstructed onto a surface view of the DVR. The locus of this forebrain somesthetic region was then compared with the location of the DVR projection areas of auditory (nucleus reuniens) and visual (nucleus rotundus) thalamic nuclei. This analysis suggested two features. First, telencephalic terminal zones of dorsal thalamic nuclei were largely separate and non-overlapping. Second, the locus of termination in the DVR of each thalamic nucleus reflected each nucleus's topography in the dorsal thalamus. Additional parallels in the neural circuitry of auditory, visual, and somatosensory systems that synapse in the midbrain and project to the DVR are documented.

Afferent Pathways↗
PubMed1994

Anatomical identification of a postsynaptic dorsal column system in a reptile, Caiman crocodilus.

The presence of a postsynaptic dorsal column system was investigated in reptiles, Caiman crocodilus. Several experiments were undertaken. First, a cytoarchitectonic analysis of the spinal cord was performed to identify its laminar organization. Second, the termination of dorsal root fibers in the dorsal horn of the upper cervical cord, brachial enlargement, and lumbar intumescence was studied utilizing anterograde tracing techniques. Third, placement of retrograde tracers into the dorsal column nucleus identified spinal cord neurons that projected to the dorsal column nucleus. These experiments document that, in addition to direct primary dorsal root input, a second pathway exists whereby nonfacial somatosensory information can reach the dorsal column nucleus in this reptilian group. This neural path arises primarily from neurons in the ipsilateral lamina V and, to a much lesser extent, from lamina IV in the cervical area and, to a far smaller degree, from the thoracic and lumbar dorsal horn. Each of these laminae whose neurons project to the dorsal column nucleus receive direct dorsal root input. This neural circuit in Caiman is similar to a neural pathway described in pigeons and several mammalian groups. These observations suggest that a postsynaptic dorsal column system is phylogenetically ancient and may well be a feature common to all amniotes.

Afferent Pathways↗
PubMed1993

Aneurysms of the anterior inferior cerebellar artery.

Aneurysms of the anterior inferior cerebellar artery (AICA) are rare lesions. Three AICA aneurysms that differed in clinical presentation, anatomical location, and morphology are presented to illustrate the radiologic evaluation, perioperative management, surgical treatment and prevention of complications of these uncommon lesions.

Adult↗
PubMed1993

Neuronal subpopulations in a reptilian thalamic reticular nucleus.

In reptiles, Caiman crocodilus, some neurons in the thalamic reticular nucleus are immunoreactive for parvalbumin. Utilizing double-labeling experiments with fluorescent tracers and indirect fluorescence immunocytochemistry, some of these parvalbumin immunoreactive neurons were found to project to the dorsal thalamus. Other thalamic reticular neurons not immunoreactive for parvalbumin were also found to terminate in the dorsal thalamus. These findings suggest that the thalamic reticular nucleus in Caiman contains at least two chemically, and perhaps functionally, distinct neuronal subpopulations.

Animals↗
PubMed1992

Interconnections between the pretectum and visual thalamus in reptiles, Caiman crocodilus.

Interconnections between the visual thalamus and the pretectum were investigated in one species of reptiles, Caiman crocodilus, by injections of horseradish peroxidase into nucleus rotundus. Nucleus pretectalis was identified as a major target of rotundal efferents as well as a significant input to nucleus rotundus. The presence of a pretectal nucleus with neural connections and topographic location similar to nucleus pretectalis of Caiman has been described in lizards and pigeons. Taken together, these observations suggest that this pretectal nuclear group and its associated fiber path may be a feature common to all non-mammalian amniotes.

Alligators and Crocodiles↗
PubMed1992

A second auditory area in the non-cortical telencephalon of a reptile.

Injections of horseradish peroxidase (HRP) into a caudocentral portion of the non-cortical telencephalon of Caiman known as the dorsolateral area (dorsal ventricular ridge) resulted in retrogradely labeled neurons throughout the entire extent of the ipsilateral nucleus reuniens. HRP-positive cells were most numerous in nucleus reuniens pars diffusa with only sparse labeling of neurons in nucleus reuniens pars centralis. The results of the present experiment, when compared with those of a prior study that determined the telencephalic connections of nucleus reuniens pars centralis, suggested that these two forebrain areas are separate. Staining with succinate dehydrogenase and acetylcholinesterase revealed that nucleus reuniens pars centralis and pars diffusa and their respective telencephalic projection areas can be differentiated on the basis of histochemical features. These findings in Caiman suggest that certain thalamic and telencephalic auditory areas in birds and crocodilians are most likely the result of common ancestry rather than examples of parallel evolution.

Acetylcholinesterase↗