Piet V. Hoogland

Anatomical and pathological considerations in percutaneous vertebroplasty and kyphoplasty: a reappraisal of the vertebral venous system.

Objectives. To focus attention of the clinician on the anatomy and (patho)physiology of the vertebral venous system, so as to offer a tool to better understand and anticipate (potential) complications that are related to the application of percutaneous vertebroplasty and kyphoplasty. Background. Percutaneous vertebroplasty and kyphoplasty are newly developed, minimally invasive techniques for the relief of pain and for the strengthening of bone in vertebral body lesions. With the clinical implementation of these techniques, a number of serious neurologic and cardiopulmonary complications have been reported in the international medical literature. Most complications appear to be related to the extrusion of bone cement into the vertebral venous system. Methods. The literature about complications of percutaneous vertebroplasty and kyphoplasty is reviewed, and the anatomic and (patho)physiologic characteristics of the vertebral venous system are reported. Based on what is currently known from the anatomy and physiology of the vertebral venous system, the procedures of percutaneous vertebroplasty and kyphoplasty are analyzed, and suggestions are made to improve the safety of these techniques. Conclusions. Thorough knowledge of the anatomic and (patho)physiologic characteristics of the vertebral venous system is mandatory for all physicians that participate in percutaneous vertebroplasty and kyphoplasty. To reduce the risk of cement extrusion into the vertebral venous system during injection, vertebral venous pressure should be increased during surgery. This can be achieved by operating the patient in the prone position and by raising intrathoracic venous pressure with the aid of the anesthesiologist during intravertebral instrumentation and cement injection. Intensive theoretical and practical training, critical patient selection, and careful monitoring of the procedures, also taking into account patient positioning and intrathoracic and intra-abdominal pressures, will help to facilitate low morbidity outcomes inthese very promising minimally invasive techniques.

Morphology of the human internal vertebral venous plexus: A cadaver study after intravenous araldite CY 221 injection

Reviewing the literature on the vascular anatomy of the spinal epidural space, it appeared that the knowledge of the internal vertebral venous plexus is limited. Injection studies of the entire internal vertebral venous plexus after application of modern techniques, to the best of our knowledge, have never been performed. Based on the clinical importance of these structures, it was decided to study the human vertebral venous system after Araldite CY 221 injection, in order to update the morphological characteristics of the internal vertebral venous system.

Ultrastructure of giant and small thalamic terminals of cortical origin: a study of the projections from the barrel cortex in mice using Phaseolus vulgaris leuco-agglutinin (PHA-L).

SummaryBy means of tracing with the lectin Phaseolusvulgaris leucoagglutinin (PHA-L), we examined in the thalamus of the mouse, the axon terminals of fibers originating in the barrel cortex. Vibratome sections of the brain were subjected to PHA-L immunocytochemistry and processed for light and electron microscopy. We observed small (0.5–0.8 μm in diameter) varicosities of labeled fibers in the nucleus ventrobasalis (VB) and the nucleus posterior (PO) as well as labeled giant terminals (3–5 μm in diameter) in PO. The analysis involved examination of serial sections and computer-aided reconstruction of several terminals. The small varicosities in VB appear to be small axon terminals forming distinct asymmetric synapses with small dendritic profiles. Some labeled terminals are apposed to, but not synaptically related with, the cell bodies of neurons in VB that are retrogradely labeled with PHA-L. The small varicosities seen with the light microscope in PO are terminals forming asymmetric synapses with dendritic shafts. The giant terminals in PO appear as large, vesicle-filled profiles forming part of synaptic glomeruli, i.e. complexes of one corticothalamic terminal engulfing several excrescences of a single dendrite. A giant terminal forms several asymmetric synapses (about 8) with these excrescences, as well as numerous (up to 15) puncta adhaerentia. The glomeruli are enveloped in glial lamellae, and they are often found at the bifurcations of primary dendritic segments. We suggest that the small terminals in VB are in the service of feedback signalling from the barrel cortex to its principal thalamic relay nucleus; the functional importance of this projection may reside in increased spatio-temporal discrimination. We interpret the giant terminals in PO as elements serving feed-forward processing, allowing the barrel cortex to influence, via PO, parts of the motor pathway modulating the animals ongoing behavior.

Distribution of dopamine in the forebrain and midbrain of the red-eared turtle, Pseudemys scripta elegans, reinvestigated using antibodies against dopamine.

The distribution of dopamine (DA) immunoreactivity in the forebrain and midbrain of the red-eared turtle, Pseudemys scripta elegans, was studied using recently developed antibodies against DA. DA-containing cells were found around the glomeruli of the olfactory bulb but not in the telencephalon proper. In the diencephalon DA cells were observed in the preoptic region, several parts of the periventricular hypothalamic nucleus, the periventricular organ, the ependymal wall of the infundibular recess, the lateral hypothalamic area and the pretectal posterodorsal nucleus. In the midbrain DA cells were found in the ventral tegmental area, the substantia nigra and the presumed reptilian homologue of the mammalian A8 cell group. Dopaminergic fibers and terminals were observed throughout the whole brain, particularly in the telencephalon and diencephalon. The olfactory tubercle, the striatum and the nucleus accumbens appear to have the most dense innervation, but the anterior olfactory nucleus and the septal area also show numerous DA fibers and terminals. Cortical areas are in general not densely innervated by DA fibers. Compared to the results obtained for a lizard, Gekko gecko, with the same antibodies, the results of the present study are very similar as regards the distribution of DA neurons, fibers and terminals. In having better developed DA cell groups in the midbrain and a stronger innervation of the striatum, Pseudemys resembles mammals more than does Gekko. In contrast, the many cerebrospinal fluid-contacting DA neurons in the hypothalamus of Pseudemys are a primitive feature of the diencephalon. The previous immunohistochemical study of Gekko, a lizard, and the present account of Pseudemys, a turtle, indicate that at least two different lines of evolution exist within the reptiles with regard to the DA innervation of the dorsal ventricular ridge. One, including turtles and, probably, crocodilians with a weak DA innervation; and another, represented by lizards, with a strong DA immunoreactivity.

Distribution of Choline Acetyltransferase Immunoreactivity in the Telencephalon of the Lizard Gekko gecko

The presumptive cholinergic elements in the telencephalon of the lizard Gekko gecko were demonstrated with the AB8 anti-choline acetyltransferase (ChAT) antibody. Somata positive for ChAT were observed in the striatum, nucleus accumbens, the dorsal ventricular ridge, nucleus olfactorius anterior, tuberculum olfactorium, diagonal band of Broca, septum, bed nucleus of the medial forebrain bundle and lateral preoptic area. Staining of the neuropil was most conspicuous in the striatum but also occurred in the medial cortex and nucleus septi impar. The results indicate that the distribution of ChAT-positive somata in the telencephalon in reptiles is comparable to that in mammals; however, the relation of cholinergic somata and ChAT-positive neuropil seen in the striatum of G. gecko is different from that in mammals.

Telencephalic projections to the eye in Python reticulatus

The afferent connections of the eye of Python reticulatus have been studied with HRP, Nuclear yellow and Granular blue. It appeared that in this snake the eye receives afferent connections from basal telencephalic areas both ipsi- and contralaterally. Following experiments in which Granular blue was injected into one eye and Nuclear yellow into the other eye no double labeling occurred.

A direct projection from the nucleus oculomotorius to the retina in rats

The centrifugal projection to the eye has been studied in rats with anterograde and retrograde tracing techniques. As a retrograde tracer Nuclear Yellow (NY) was used. Following NY injections into the vitreous body of the eye, labeled neurons were exclusively found bilaterally in nucleus oculomotorius. The course and termination site of the retinopetal fibers were studied with the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHA-L). Iontophoretic injections of PHA-L in nucleus oculomotorius resulted in labeling of retinopetal fibers which reach the eye via the optic tract and optic nerve. Preterminal arborizations were found in the inner nuclear layer of the retina. In addition, labeled fibers have been observed which seem to terminate within the optic tract and optic nerve. It is suggested that the projection from the nucleus oculomotorius to the retina constitutes a link in the multisynaptic efferent pathway from the visual cortex to the eye, by which the visual cortex can influence the functioning of the retina.

Soft tissue damage after minimally invasive THA

Background and purpose Minimally invasive surgery (MIS) for hip replacement is thought to minimize soft tissue damage. We determined the damage caused by 4 different MIS approaches as compared to a conventional lateral transgluteal approach. Methods 5 surgeons each performed a total hip arthroplasty on 5 fresh frozen cadaver hips, using either a MIS anterior, MIS anterolateral, MIS 2-incision, MIS posterior, or lateral transgluteal approach. Postoperatively, the hips were dissected and muscle damage color-stained. We measured proportional muscle damage relative to the midsubstance cross-sectional surface area (MCSA) using computerized color detection. The integrity of external rotator muscles, nerves, and ligaments was assessed by direct observation. Results None of the other MIS approaches resulted in less gluteus medius muscle damage than the lateral transgluteal approach. However, the MIS anterior approach completely preserved the gluteus medius muscle in 4 cases while partial damage occurred in 1 case. Furthermore, the superior gluteal nerve was transected in 4 cases after a MIS anterolateral approach and in 1 after the lateral transgluteal approach. The lateral femoral cutaneous nerve was transected once after both the MIS anterior approach and the MIS 2-incision approach. Interpretation The MIS anterior approach may preserve the gluteus medius muscle during total hip arthroplasty, but with a risk of damaging the lateral femoral cutaneous nerve.

Labeling of neurons following intravenous injections of fluorescent tracers in mice

Several fluorescent tracers were injected intravenously in the tail veins of adult mice, and the distribution of these substances in the central nervous system and sensory and autonomic ganglia was investigated. Injections of the blue tracers Granular Blue, True Blue and Fast Blue resulted in labeling of the somatomotor and visceromotor nuclei of the brainstem and spinal cord, the paraventricular, supraoptic and arcuate nuclei of the hypothalamus, the area postrema and the sensory and sympathetic ganglia. Following i.v. injections of Nuclear Yellow, labeling occurred only in the median eminence, the area postrema and the sensory and sympathetic ganglia.

Septal complex of the telencephalon of lizards: III. Efferent connections and general discussion

The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combining retrograde and anterograde neuroanatomical tracing. The results confirm the classification of septal nuclei into three main divisions. The nuclei composing the central septal division (anterior, lateral, medial, dorsolateral, and ventrolateral nuclei) displayed differential projections to the basal telencephalon, preoptic and anterior hypothalamus, lateral hypothalamic area, dorsal hypothalamus, mammillary complex, dorsomedial anterior thalamus, ventral tegmental area, interpeduncular nucleus, raphe nucleus, torus semicircularis pars laminaris, reptilian A8 nucleus/ substantia nigra and central gray. For instance, only the medial septal nucleus projected substantially to the thalamus whereas the anterior septum was the only nucleus projecting to the caudal midbrain including the central gray. The anterior and lateral septal nuclei also differ in the way in which their projection to the preoptic hypothalamus terminated. The midline septal division is composed of the dorsal septal nucleus, nucleus septalis impar and nucleus of the posterior pallial commissure. The latter two nuclei projected to the lateral habenula and, at least the nucleus of the posterior pallial commissure, to the mammillary complex. The dorsal septal nucleus projected to the preoptic and periventricular hypothalamus and the anterior thalamus, but its central part seemed to project to the caudal midbrain (up to the midbrain central gray). Finally, the ventromedial septal division (ventromedial septal nucleus) showed a massive projection to the anterior and the lateral tuberomammillary hypothalamus.