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Biomedical subjects

J A Brodkey

Publications and source records attributed to J A Brodkey.

9 recordsLinked to original sources
PubMed1996

Cholesterol granulomas of the petrous apex: combined neurosurgical and otological management.

Cholesterol granulomas of the head are relatively rare. Isolated lesions of the cerebellopontine angle are even more uncommon. In this report, 17 cases of petrous apex cholesterol granulomas are presented and management is discussed. Symptoms at presentation included dizziness (14 patients), pressure (nine patients), tinnitus (eight patients), hearing loss (eight patients), otalgia (six patients), headache (six patients), nausea (three patients), drainage from ear (two patients), facial pain (two patients), seizure (two patients), lightheadedness (one patient), hemifacial spasm (one patient), and facial numbness (one patient). Six cases were managed without surgery and 11 patients underwent operative procedures. The approaches used included the infralabyrinthine (eight patients), transcanal-infracochlear (two patients), and translabyrinthine (one patient). The mean follow-up period for all cases was 29.5 months. Of those patients managed without surgery, symptoms improved in all except one, whose tinnitus was slightly worse. Of surgically treated patients, symptoms improved or remained the same except in one with worsened dizziness. There were nine patients with hearing present presurgery and seven whose hearing was preserved postsurgery. The authors present a case that was managed at another center where an attempt at surgical resection through a subtemporal middle fossa approach was unsuccessful. This lesion was successfully treated using an infralabyrinthine approach with drainage into the mastoid cavity. Cholesterol granulomas of the petrous apex can be managed without surgery when symptoms are stable or improve. Otherwise, a transmastoid extradural approach with simple drainage into the mastoid sinus or middle ear produces symptomatic improvement with low morbidity. Resection of petrous apex cholesterol granulomas is not necessary.

Adolescent↗
PubMed1995

Metastatic paraganglioma causing spinal cord compression.

SUMMARY OF BACKGROUND DATA: Paragangliomas are neoplasms that arise from the autonomic nervous system-associated paraganglia. Most often they are benign tumors. However, infrequently they have been reported to metastasize. Involvement of the spine is rare and usually is intradural at the level of the cauda equina. OBJECTIVES: The authors report two cases of metastatic paraganglioma to the spine, both of which resulted in myelopathy from extradural spinal cord compression. Also provided is a review of the literature. CONCLUSIONS: Paragangliomas rarely metastasize to the spine. Management of the two reported patients involved spinal cord decompression followed by spinal stabilization procedures. Long-term ambulatory status was maintained in both patients. Radiation therapy may be an important adjunctive treatment after surgical removal of these tumors.

Adult↗
PubMed1995

Hemangioblastoma of the radial nerve: case report.

A case of hemangioblastoma of the right radial nerve is presented. Hemangioblastomas are rare vascular neoplasms characteristically associated with the Von Hippel-Lindau syndrome, in which they are found in the retina, the posterior fossa, and, less often, the spinal cord. Thought of as primary central nervous system neoplasms, hemangioblastomas are rarely found adjacent to the spinal cord involving proximal nerve roots, which represent border zones between the central and peripheral nervous systems. We could find no other report of a pure hemangioblastoma situated this far distally in the peripheral nervous system. The histological findings, immunohistochemistry, and electron microscopic findings of this lesion are discussed. This case supports the hypothesis that hemangioblastoma is not derived from astrocytes, because of the location of this tumor in the peripheral nervous system and glial fibrillary acidic protein negativity.

Aged↗
PubMed1995

Focal brain injury and upregulation of a developmentally regulated extracellular matrix protein.

Tenascin is an extracellular matrix glycoprotein expressed during both normal development and neoplastic growth in both neural and nonneural tissues. During development of the central nervous system (CNS), tenascin is synthesized by glial cells, in particular by immature astrocytes, and is concentrated in transient boundaries around emerging groups of functionally distinct neurons. In the mature CNS, only low levels of the glycoprotein can be detected. The present study demonstrates that following trauma to the adult human cerebral cortex, discrete populations of reactive astrocytes upregulate their expression of tenascin and dramatically increase their transcription of the tenascin gene. The enhanced expression of tenascin may be involved in CNS wound healing, and may also affect neurite growth within and around a brain lesion.

Adult↗
PubMed1993

The complex nature of interactive neuroregeneration-related molecules.

We review the growing list of molecules that may be involved in wound healing in the central nervous system (CNS). It is known that many of these molecules are present during normal development and neoplastic growth in both neural and nonneural tissues, often in areas where pattern formation or tissue remodeling is evident; however, their functional roles are often quite elusive. In order to understand the changes that occur in and around a brain wound, we review proposed functions of neuroregeneration-related molecules in in vitro and in vivo preparations, as well as note their expression in other healing tissues including skin. A hypothesis that wound healing events in the CNS supersede neuritic growth around a lesion is presented. In contrast to the classical view of failed regeneration, there may be significant amounts of circuit reorganization that occur following injury, and such plasticity may be further enhanced by manipulating the molecular environment around a brain wound and in synaptically related structures.

Animals↗
PubMed1988

Ventricular volume regulation: a mathematical model and computer simulation.

A mathematical model of ventricular volume regulation based on fluid mechanical principles has been constructed using a systems engineering approach. The parameters used in the model are based on clinical observation, laboratory investigation, and presumptions that will be tested later. The model was constructed to be the basis of a computer simulation. Using the computer simulation, information obtained from the literature and laboratory hypotheses regarding pathophysiology, several enigmatic conditions were tested. The model predicted that over-production of cerebrospinal fluid, as in the case of choroid plexus papilloma, could by itself lead to distention of the ventricular system. In simulating pseudotumor cerebri, if cerebrospinal fluid absorption at the arachnoid villi is impaired and the brain itself is rendered incompressible by swelling, intracranial pressure rises and ventricular volume diminishes. Conversely, in normal-pressure hydrocephalus, if cerebrospinal fluid flow is restricted between the spinal and cortical subarachnoid spaces and the brain is made more compressible, the ventricular volume increases with minimal increases in intracranial pressure. This mathematical model and its associated computer simulation is useful in predicting the behavior of the volume of the cerebral ventricles to a variety of pathological phenomena.

Animals↗
PubMed1988

Resistance of the foramen of Monro.

A greyhound dog model was used to study the importance of the foramen of Monro as a resistance element to the flow of cerebrospinal fluid (CSF). Normal dogs had no pressure differential discernible despite the infusion of artificial CSF into one lateral ventricle. When CSF was withdrawn from one lateral ventricle, however, 7 of 10 dogs showed intraventricular pressure differentials at a steady state of 3.28-5.37 mm Hg. All normal dogs undergoing rapid bolus withdrawal of CSF from the ventricles developed pressure differentials. When these experiments were performed on hydrocephalic dogs, no pressure differential could be recorded. The foramen of Monro acts as a valve mechanisms that usually closes in response to CSF withdrawals.

Animals↗
PubMedDate not supplied

Etiology of ventriculomegaly in choroid plexus papilloma.

In order to test the hypothesis that overproduction of cerebrospinal fluid can cause the hydrocephalus seen in choroid plexus papillomas, adult mongrel dogs with and without hydrocephalus were subjected to high pressure intraventricular infusions of artificial cerebrospinal fluid (CSF). Pre- and postinfusion volumes were calculated, using a new method for on-line measurement of ventricular volume involving linear measurements from Conray ventriculograms. Ventricular volumes increased an average of 8% in 36 h. The dogs previously made hydrocephalic by the intracisternal injection of kaolin had a significant volume increase (34% in 36 h). Overproduction of CSF alone can produce hydrocephalus, but the presence of hydrocephalus in choroid plexus papillomas is more likely to be a result of the complex interaction of CSF overproduction and partial restriction of CSF flow.

Animals↗