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Biomedical subjects

R K Dortzbach

Publications and source records attributed to R K Dortzbach.

At least 19 recordsLinked to original sources
PubMed1992

Sympathetic nerve anatomy in the cavernous sinus and retrobulbar orbit of the cynomolgus monkey.

We present new information regarding the sympathetic nerve anatomy in the cavernous sinus and retrobulbar orbit of the cynomolgus monkey. Postganglionic sympathetic nerves were identified using an immunoperoxidase technique in which the primary antiserum was directed against tyrosine hydroxylase, the rate-limiting enzyme in norepinephrine synthesis. Our work is unique in adapting this staining method to paraffin-embedded tissue. This technique allows sympathetic nerve fibers to be distinguished from other autonomic, sensory, and motor nerves. A large sympathetic nerve bundle lateral to the internal carotid artery in the cavernous sinus gave off one or more branches that leave the artery to encircle the abducens nerve. Further division occurs within the cavernous sinus, but all sympathetic nerve fibers destined for the orbit entered it through the superior orbital fissure. None pass through the optic canal. In the orbit, sympathetics were associated with the ophthalmic artery and some of its branches and with the sensory root to the ciliary ganglion. After entering the ganglion, the sympathetic fibers were lost to detection in most specimens, but they were again seen in a single short ciliary nerve in one instance. Sympathetic nerve fibers were not detected adjacent to several structures identified in the human anatomy literature, such as the intracranial and intracanalicular segments of the ophthalmic artery, the nasociliary nerve, the long ciliary nerves, the nerve to the inferior oblique muscle, or the lacrimal artery and nerve.

Animals↗
PubMed1991

Problems associated with conjunctivodacryocystorhinostomy.

Fifty-eight patients (69 eyes) underwent conjunctivodacryocystorhinostomy for lacrimal canalicular obstruction. The cause of lacrimal obstruction and the results and complications of the operation were analyzed. Trauma and idiopathic disease were the most common causes of lacrimal canalicular obstruction in 24 of 69 (34.8%) eyes each. Relief of epiphora was achieved in 68 of the 69 eyes (98.5%). The complications included tube displacement in 40 of the 69 eyes (57.9%), tube obstruction in 19 of the 69 eyes (27.5%), and infection of the lacrimal sac in four of the 69 eyes (5.8%). Despite frequent complications, most Jones tubes can be made to function satisfactorily. Conjunctivodacryocystorhinostomy remains the best surgical treatment at this time for permanent loss of canalicular function.

Adolescent↗
PubMed1991

Canalicular stenosis following probing for congenital nasolacrimal duct obstruction.

A canalicular stenosis was identified in 29 of 66 (44%) children and 35 of 80 (44%) lacrimal drainage systems undergoing silicone intubation for congenital nasolacrimal duct obstruction, having previously had unsuccessful probings. The stenoses were equally divided between boys and girls and between right and left sides. There was no significant difference in age at the time of probing, number of prior probings, or age at intubation between children with and without canalicular stenosis. Stenoses may be congenital or acquired as a result of faulty probing. Any child undergoing a second lacrimal procedure after a failed probing should be evaluated for evidence of a canalicular stenosis. If a stenosis is present, a silicone stent should be placed to try to salvage the canaliculus.

Child, Preschool↗
PubMed1990

The pathophysiology of the anophthalmic socket. Part I. Analysis of orbital blood flow.

A wide variety of complications of the anophthalmic socket develop in patients after enucleation, including enophthalmos, superior sulcus deformities, eyelid malpositions, implant migration and extrusion, poor prosthetic motility, and socket contraction. Changes in the orbital blood flow and metabolic activity of the socket tissues and atrophy of the orbital fat occurring after enucleation have been suggested as two theoretical mechanisms that result in the development of these clinical conditions. Lack of scientific evidence and a limited understanding of the pathophysiologic basis of the features of anophthalmos led us to evaluate the validity of these proposed mechanisms in an animal model. Selected parameters of the normal orbits were compared with the contralateral anophthalmic orbits at different time intervals after surgery. Orbital blood flow was studied with selective ophthalmic artery angiography and radioactive microsphere techniques. Ophthalmic arteriography demonstrated symmetric caliber and filling characteristics of the major orbital vessels of the control and experimental orbits, although their topographic course was slightly more tortuous in the anophthalmic socket. Results of radioactive microsphere analysis of capillary blood flow per weight of the different orbital tissue compartments of the animals in the long-term group showed no significant difference between the normal and anophthalmic sockets. These findings provide evidence that the circulation dynamics and blood flow to orbital tissues do not change after enucleation surgery.

Angiography↗
PubMed1990

The pathophysiology of the anophthalmic socket. Part II. Analysis of orbital fat.

The pathophysiologic mechanisms responsible for the clinical features of the anophthalmic socket are poorly understood. Atrophy of orbital fat has been thought to be a major contributing cause of enophthalmos and the superior sulcus deformities that develop after enucleation, but it has never been demonstrated histopathologically or confirmed by scientific analysis. This study was undertaken to investigate the changes that occur in the orbital fat compartment of the anophthalmic socket in an animal model by measuring orbital soft tissue mass and evaluating adipocyte cell size. Instead of reduction in the tissue mass, a statistically significant greater weight of the fat and connective tissue compartment was found in the anophthalmic orbit by nearly 13% compared to the control orbit in the animals in the long-term group. No significant change in the mean maximal diameter of adipocytes developed 7 months after enucleation. These analyses do not support the concept that orbital fat atrophy or a reduction of metabolic activity occurs in the anophthalmic socket in this animal model. From these results and our previous findings that the circulation dynamics and blood flow to orbital tissues do not change after enucleation, we propose that the pathophysiologic basis of the problems associated with anophthalmos is a disturbance in the spatial architecture and interrelationships of the multiple tissue components of the orbit, not a change in the orbital blood flow or development of fat atrophy.

Adipose Tissue↗
PubMed1989

A search for lymphatic drainage of the monkey orbit.

Colloid solutions of technetium Tc 99m and india ink injected into the retrobulbar space of the cynomolgus monkey outside the extraocular muscle cone were removed from the orbit by the lymphatic vessels of the conjunctiva and eyelids and were then concentrated within the lymph nodes that drained the conjunctival and eyelid areas. Colloid solutions injected into the retrobulbar space inside the extraocular muscle cone did not reach the conjunctiva and did not collect in any lymph nodes over a 24-hour period. Within the orbit, the injected colloids spread along the planes of the connective-tissue septa. No lymphatic vessels were identified within the orbits posterior to the conjunctiva. Small amounts of india ink left the posterior orbit and ultimately entered the contralateral orbit. This posterior pathway did not lead to lymphatic vessels or lymph nodes and therefore does not appear to represent a prelymphatic pathway.

Animals↗
PubMed1989

Medial orbital wall fractures: complications and management.

Medial wall fractures are often overlooked during routine radiographic examination and rarely develop complications. We present complications associated with medial wall fracture in six cases. Complications from medial rectus muscle entrapment include restricted and painful abduction, pseudo-sixth-nerve paresis and pseudo-Duane's-retraction syndrome. Massive orbital emphysema, in one case, was responsible for temporary loss of vision prior to definitive treatment. Two patients developed severe enophthalmos secondary to the medial wall fractures. We suggest that orbital exploration is indicated for painful or limited ocular motility, significant diplopia, severe orbital emphysema, or severe enophthalmos. An inferior approach to the medial wall through the lower eyelid provides good exposure and minimal cosmetic deformity. Postoperative complications included transient paresis of the medial rectus muscle, residual motility disturbance, and residual enophthalmos.

Adolescent↗
PubMed1989

Magnetic resonance imaging of the orbit. Part I. Physical principles.

Magnetic resonance has twin capabilities. It can provide anatomical (magnetic resonance imaging, MRI) and physiochemical (magnetic resonance spectroscopy) information. Nuclei with an odd mass number, particularly hydrogen in free water, have electromagnetic properties. When placed in a strong static magnetic field and excited by radiofrequency waves of a specific wavelength, these nuclei emit a signal. The MR signal can then be digitized, stored in a computer, and subsequently converted into an image. Factors that affect these images are tissue parameters (T1 and T2 time constants, proton density, and flow) and radiofrequency pulse sequences. Surface coils are useful for improving images of the orbit. The magnet can have a major and potentially dangerous influence on the surrounding environment, and access to the MRI area must be carefully controlled. Shielding of the MRI room prevents external factors from adversely affecting the MRI unit and the images produced.

Equipment Design↗
PubMed1989

Magnetic resonance imaging of the orbit. Part II. Clinical applications.

Imaging of the orbit with magnetic resonance imaging (MRI) provides better anatomic detail with T1-weighted sequences and superior visualization of pathologic conditions with T2-weighted sequences. Compared with computerized tomography (CT), MRI has the following advantages: lack of ionizing radiation, direct multiplanar imaging, better contrast resolution, lack of bone artifacts, visualization of bone marrow, superior study of certain neurological disorders, and spectroscopy. Compared with CT, MRI has the following disadvantages: prolonged examination, poorer ability to detect orbital calcifications and cortical bone destruction, poorer spatial resolution, fewer suitable patients, certain image artifacts, high cost of MRI units, and higher cost of MRI examinations.

Humans↗
PubMed1988

Destructive cysts of the maxillary sinus affecting the orbit.

Symptomatic maxillary sinus cysts are diagnosed less frequently than similar cysts of the frontal and ethmoidal sinuses and are rarely reported in the ophthalmic literature. Patients with cysts of the maxillary sinus may present to the ophthalmologist with proptosis, enophthalmos, diplopia, ptosis, epiphora, and, rarely, decreased visual acuity. Four patients with maxillary sinus mucoceles are presented; one of these patients had a concurrent retention cyst in the orbit. Clinical history, radiologic findings, and histopathologic mechanisms are discussed. Mucocele is a recognized complication of the Caldwell-Luc procedure and midface trauma. Blockage of the sinus ostia was the cause previously proposed to explain antral mucocele development. Clinical and histopathologic features may support more than one single mechanism for the pathogenesis of maxillary sinus cysts. Maxillary sinus mucocele or retention cysts should be considered in the differential diagnosis of exophthalmos or enophthalmos following blowout fracture of the orbital floor.

Adult↗
PubMed1988

Upper eyelid crease surgical approach to dermoid and epidermoid cysts in children.

The treatment of choice for subcutaneous and orbital dermoid and epidermoid cysts in children is surgical excision. Numerous surgical approaches have been advocated to excise these lesions from the eyelid and anterosuperior orbit. Our technique for this procedure involves an approach through an upper eyelid crease incision. The advantages over alternative methods include (1) excellent exposure of eyelid and anterior orbital structures, (2) familiarity to most eyelid surgeons, (3) minimal dissection with little risk to vital anatomic structures, (4) simple wound closure, and (5) excellent final cosmetic result with a scar that is well-hidden. We have utilized this technique in 24 patients with excellent results and no complications.

Child, Preschool↗
PubMed1987

Bio-electric conductivity potentials in experimental skin grafts.

Prior investigations have established that changes in bio-electric potentials accompany the processes of wound creation and healing. In order to investigate these changes in an experimental full-thickness skin graft model, grafts were harvested from the dorsa of eight albino rabbits. Changes in potential were recorded over a period of 32 days, using silver-silver chloride electrodes and a recording polygraph. The potential measured across the skin graft became increasingly more electropositive until, between days 1 and 2, the potential abruptly reversed polarity. This negative potential lasted until day 4, when the conductivity again became positive, with a slow return to baseline measurements by day 32. Although these observations may indicate a bio-electric counterpart to the cellular events of wound healing, more study is needed.

Animals↗
PubMed1987

The anatomy and histology of the anophthalmic socket--is the myofibroblast present?

For some anophthalmic patients, the contracted socket is a severe problem that precludes the wearing of a prosthesis. A normal and cosmetically acceptable appearance is dependent on the ability of a socket to retain a prosthesis. The disfigurement and distress caused by the contracted socket and its inability to accommodate a prosthesis may have a profound detrimental effect on the patient's career, self-esteem, and psychosocial interactions. The tissue dynamics at work in the anophthalmic socket and in the contracting socket are not yet understood. There are many unanswered questions regarding the histology and anatomy of the normal, as well as the contracting, socket. The tissue responsible for clinical contraction has not been identified. This thesis, using the cynomolgus monkey socket as an experimental model, investigated healing in both the normal and contracting socket. Qualitative observations of the anatomy and histology of eight sockets were made. Two of the sockets were treated with Croton oil to induce contractions. Biopsy specimens from two human sockets, one contracted and the other merely volume deficient, were also examined. Histopathology of the normal and contracting sockets were compared. Myosin subfragment 1 staining of actin for electron microscopy and immunoperoxidase staining of actin for light microscopy were performed on selected specimens. The myofibroblast, probably a modified fibroblast, is known to be present in the early stages of open wound healing and in contracting scar tissue elsewhere in the body. The myofibroblast has been incriminated as an agent generating contractile force. Under the conditions of this experiment, cells with the characteristics of myofibroblasts were identified by both immunoperoxidase staining and electron microscopy. They were found in healing noncontracting and contracting sockets. Cytoplasmic actin was also distinguished in arterioles, venules, capillaries, myoepithelial cells, smooth muscle, and skeletal muscle.

Actins↗
PubMed1986

Eyelid necrosis in an anophthalmic patient.

A 72-year-old woman with chronic lymphocytic leukemia developed periorbital swelling, erythema, and discharge involving her anophthalmic left socket in the course of pseudomonas aeruginosa septicemia. Histopathologic examination of debrided eyelid tissues revealed ischemic necrosis of the eyelid margin and deeper eyelid tissues. Underlying malignancy, disseminated systemic infection, and alteration in the vascular supply to the eyelids following enucleation may have contributed to the development of ischemic eyelid necrosis in this patient.

Aged↗
PubMed1985

The role of aminocaproic acid in lacrimal surgery in dyskeratosis congenita.

A 14-year-old boy with bilateral epiphora since birth had absent lacrimal puncta, oral leukoplakia, agenesis of the nails, cutaneous dyschromia, and pancytopenia, findings noted in the rare syndrome of dyskeratosis congenita. Bilateral conjunctivodacryocystorhinostomy was complicated by persistent hemorrhage despite preoperative platelet transfusion. The hemorrhage was controlled by administration of an antifibrinolytic agent, aminocaproic acid. Lacrimal excretory anomalies may be the initial manifestation of a serious systemic disorder, dyskeratosis congenita. Surgical management in this disorder should include appropriate hematologic support.

Adolescent↗