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Biomedical subjects

R D Penn

Publications and source records attributed to R D Penn.

At least 19 recordsLinked to original sources
PubMed1992

Intrathecal baclofen for spasticity of spinal origin: seven years of experience.

A total of 66 consecutive patients with severe spasticity of spinal cord origin were screened with intrathecal baclofen, and all but two responded with a two-point decrease in their Ashworth spasticity scale and/or spasm scale score. Of these, 62 elected to receive chronic intrathecal baclofen administration by means of an implanted delivery system. These patients have been followed for an average of 30 months (the first three for 81 months). Intrathecal baclofen has been well tolerated and all serious side effects were transient and have been managed by dose adjustments. The pump presently available has worked safely; the only problem has been stalling in 7% of these devices. The catheter system has had to be repaired in just over one-half of the patients and is the main cause of interruption of drug delivery. Of the 62 patients implanted, 52 (84%) continue to be treated adequately for spasticity; there are three poor long-term responders, four deaths due to underlying disease, and three whose participation has been voluntarily withdrawn. It is suggested that long-term control of spinal spasticity by intrathecal baclofen can be achieved in most patients.

Adolescent↗
PubMed1992

Intrathecal baclofen. Effects on nocturnal leg muscle spasticity.

Electromyographic activity was recorded from tibialis anterior during nocturnal polysomnography in six patients with severe spasticity of spinal origin. The patients had a baclofen reservoir system implanted subcutaneously into their lumbar subarachnoid space and were studied for two nights in a double-blind, placebo controlled, crossover design. Tibialis anterior electromyographic activity per hour of sleep was reduced on the night of baclofen infusion. In particular, less electromyographic activity occurred after arousal from sleep.

Adult↗
PubMed1991

Putative chromaffin cell survival and enhanced host-derived TH-fiber innervation following a functional adrenal medulla autograft for Parkinson's disease.

We report heretofore undescribed clinical and histological features of a patient with idiopathic Parkinson's disease who showed marked and persistent motoric benefit from an adrenal medulla autograft for 18 months following grafting. The patient returned to the preoperative level of disability prior to his death 30 months after implantation, the longest survival to date for an adrenal transplant. The graft site was primarily necrotic and large numbers of macrophages were still present at the time of death. A few tyrosine hydroxylase-immunoreactive cells were found within the graft, providing the first evidence that adrenal medullary cells may be viable and produce catecholamines following human transplantation. A dense network of tyrosine hydroxylase-immunoreactive terminals and processes was also seen ventral to the implant site and on both of its lateral borders. This response may represent sprouting by residual host dopaminergic neurons mediated by the vigorous response to injury displayed by the host striatum. The relative paucity of surviving chromaffin cells, however, provides further evidence that adrenal medulla grafts survive poorly following intracerebral implantation, and factors other than dopamine replacement may be responsible for most of the functional effects observed following chromaffin cell transplantation.

Adrenal Medulla↗
PubMed1991

United Parkinson Foundation Neurotransplantation Registry on adrenal medullary transplants: presurgical, and 1- and 2-year follow-up.

Thirteen centers participated in a multicenter database with systematic evaluation of US and Canadian patients who had adrenal medullary transplantation for Parkinson's disease. This voluntary registry collected demographic, safety, and efficacy data using the same scoring measures over a 2-year follow-up period. Baseline data on 61 patients and 2-year follow-up data on 56 patients were compared. Eighteen percent died during the study period, and one-half of these deaths were related or questionably related to the surgery. Of the remaining 45 patients with data, global improvement, defined as an improved summed score of the "on" and "off" motor and activities of daily living functions from the Unified Parkinson's Disease Rating Scale, occurred in 32% of the patients at 2 years after surgery. At follow-up, significant group improvement persisted in the amount of daily "on" time and the quality of "off" function, but other measures were no better than baseline. When the global improvement calculation was based on the total sample and included deaths and patients lost to follow-up as "not improved," only 19% were improved 2 years after surgery. Twenty-two percent of survivors had persistent psychiatric morbidity not present prior to surgery. These data document a modest group improvement in "off" function after neurotransplantation, but a serious level of mortality and morbidity.

Adrenal Medulla↗
PubMed1991

Dopamine distribution and behavioral alterations resulting from dopamine infusion into the brain of the lesioned rat.

In an effort to verify the "dopamine secretion hypothesis" as the mechanism responsible for the antiparkinsonian efficacy of adrenal medullary transplants into the brain, the effects of dopamine infusion into the brains of rats with unilateral substantia nigra lesions were examined. The apomorphine-induced rotation, characteristic of this animal model, was diminished after 7 days of continuous dopamine infusion (10 micrograms/hr) into the ipsilateral striatum, whereas intraventricular infusion was without effect. Chromatographic analysis of the dopamine distribution after 10 days of infusion into either region revealed that ipsilateral delivery of dopamine did not result in contralateral increases in dopamine content. Examination of the adjacent striatum following ipsilateral intraventricular delivery indicated that dopamine had only penetrated 1 mm. Even with intrastriatal delivery, there were still parts of the infused striatum which had below-normal levels of dopamine. The fact that striatal tissue presents a significant barrier to the penetration of dopamine is discussed in relation to adrenal medullary and fetal nigral transplants.

Adrenal Medulla↗
PubMed1979

Automated scene analysis of CT scans.

Since the advent of computed tomography, there has been an increasing realization that CT scans contain quantitative as well as qualitative information useful in the diagnostic process. Often however, the use of this information is impeded by the tedious manual outlining of the areas of interest in the scan. To alleviate this problem, we have developed a scene segmentation algorithm which will automatically delineate areas of interest in a CT scan. This procedure uses known information about the expected objects in the scan in conjuction with an algorithm to label those objects. The resultant scene segmentation divides the scan into four anatomical areas: skull, normal brain, high density lesions and CSF. After an area of interest is interactively selected by the clinician, volume, density or other quantitative measures may be computed. Limitations of the algorithm and its clinical applications are discussed.

Absorptiometry, Photon↗
PubMed1979

Pathophysiological mechanisms in cerebral palsy.

To investigate some of the pathophysiological mechanisms in cerebral palsy, surface electromyograms (EMG) were recorded from pairs of flexor/extensor muscles during both voluntary and passive flexion/extension of upper and lower limbs of 20 patients. Elbow, knee, or ankle joint angles were measured simultaneously, as well as the force required to flex/extend the limbs passively at frequencies of 0.1--1.0 Hz. In addition, single motor units were recorded from the first dorsal interosseous muscles of six of the patients. Almost all patients showed resistance to passive movements (hypertonia). This hypertonia did not necessarily impair voluntary flexion/extension movements if alternating EMG activity was maintained in at least one of the pairs of flexor/extensor muscles involved in the movement. In six severly involved patients, there was a complete breakdown in the reciprocal relationship between reciprocally acting pairs of flexor/extensor motoneurones, which resulted in synchronous activation (co-contractions) of flexor/extensor muscles during both voluntary and passive movements. In these patients the hyperactive segmental reflex added to the disabling effects of co-contractions during voluntary movements. Single motor units recorded from patients with dystonic movements were recruited with variable delays (2--10 s) and usually discharged intermittently at high frequencies (60--120/s). This abnormla motor unit discharge pattern may relate to pathology of the basal ganglia.

Adolescent↗
PubMed1978

Ventricular volume in man computed from CAT scans.

A new interactive computers has been developed to measure ventricular volume from CAT scans. Testing this system on phantoms demonstrated an accuracy to within 16%. Then a series of scans of patients with obstructive hydrocephalus was analyzed using both tradional linear measures and the computer method. None of the traditional measures were directly proportional to the calculated volume. The area measure of ventricular volume correlated well with the computer-generated values. Clinical studies which attempt to quantitate ventricular volume should use a computerized or planigraphic measure.

Cerebral Ventricles↗
PubMed1978

Evidence for changes in segmental motoneurone pools by chronic cerebellar stimulation and its clinical significance.

Electrophysiological studies in eight patients with severe motor system abnormalities are described both before and after the start of chronic electrical stimulation of the anterior cerebellum. With stimulation, at least one of following changes was found in seven of these eight patients: reversal of abdominal F amplitude ratios (flexor/extensor muscles), decreased prominence of F responses, and loss of H reflexes in at least one muscle other than the soleus. These changes indicate that cerebellar stimulation can affect the excitability of segmental motoneurone pools. Although clinical changes, particularly decrease in tone, were observed in all the patients with stimulation, the complexity of trying to relate the physiological findings to functional improvement is emphasised.

Action Potentials↗
PubMed1978

Cerebellar stimulation in man. Quantitative changes in spasticity.

The effects of chronic anterior lobe cerebellar stimulation on patients with cerebral palsy have been investigated using a new method of quanitfying muscle rigidity and stretch reflexes. The ankle is oscillated sinusoidally, compliance is measured at several frequencies, and electromyographic activity of the extensor and flexor muscles is recorded. In some patients stimulation can reduce rigidity and coactivation of muscles immediately or slowly over days or months. In others no change is found.

Adolescent↗
PubMed1978

Effects on speech of chronic cerebellar stimulation in cerebral palsy.

Chronic cerebellar stimulation of the anterior lobe is undertaken for relief of motor dysfunction in cerebellar palsy, but the effect on speech and vocal ability has been uncertain. The present study evaluated speech before cerebellar stimulation and during the immediate postoperative period in seven severely spastic/athetoid patients with congenital cerebral palsy and one patient with traumatic brain damage. Structured listening tasks were completed in blind fashion by a trained panel of speech pathologists. Group analysis revealed no significant improvement in speech intelligibility or articulatory accuracy after stimulation. With the exception of strain/strangle vocal quality, which improved considerably, vocal characteristics were not affected by cerebellar stimulation. In three of eight patients, however, improvement in certain speech characteristics was noted.

Adolescent↗
PubMed1977

Cerebral edema, mass effects, and regional blood volume in man.

The authors conducted quantitative analysis of computerized tomography (CT) scans to measure tumor size, cerebral edema, and regional blood volume in man. Mass lesions without edema caused a local reduction in blood volume. Cerebral edema also reduced blood volume in proportion to its severity. Consideration of the electrolyte changes and water shifts in white-matter edema suggested that the decrease in absorption coefficient seen in CT scans was due to the increase in water content. Thus, in cerebral edema separation of blood vessels as well as increased interstitial pressure decrease blood volume, and the regional differences in turn reflect pressure gradients within the brain.

Adult↗
PubMed1977

Chronic cerebellar stimulation and developmental reflexes.

The changes in motor function in cerebral palsy patients produced by chronic anterior lobe cerebellar stimulation were documented with the Milani-Comparetti developmental scale, which allows comparison betweenfunctional gains and reflex patterns. Two patients with marked motor retardation and primitive reflexes were followed serially over several months of stimulation. Using these measures, the efficiency of chronic stimulation can be assessed, although many years will be needed to evaluate its role in treating motor disabilities.

Adult↗
PubMed1976

Computed tomography in the diagnosis of pseudotumor cerebri.

The authors reviewed 17 patients with the clinical diagnosis of benign intracranial hypertension (pseudomotor cerebri). All of these patients underwent CT scans of the head which were interpreted as normal. Comparison of mean ventricular size with that of a group of control subjects showed no significant difference. On the basis of this study and others cited, there would appear to be almost no instances in which invasive neuroradiological procedures would be required to confirm the diagnosis of pseudotumor cerebri.

Adolescent↗
PubMed1976

Tumor volume, luxury perfusion, and regional blood volume changes in man visualized by subtraction computerized tomography.

Computer and photographic methods for producing subtractions of computerized axial tomographic (CAT) scans have been developed. By subtracting point for point a normal scan from one taken after intravenous infusion of contrast material, a picture of the contrast in the cerebral vessels is created. By this method, tumor size and degree of vascularity may be assessed. Furthermore, abnormalities in perfusion and changes in blood volume due to mass effects and edema may be detected. Subtracting scans should add to the diagnostic potential of CAT and provide a noninvasive way to study vascular changes in cerebral disease.

Aged↗
PubMed1975

Cerebral blood volume in man. Computer analysis of a computerized brain scan.

Cerebral blood volume in man can be measured by subtracting computerized axial tomogram density measurements taken before from those taken after an intravascular marker is infused into the blood. The average blood volume is 3.0 ml/100 ml of brain tissue, with a range of 2.4 to 4.25. This method can be applied in studying cerebral pathologic conditions. Areas of cerebral edema, surrounding a tumor, have a decreased blood volume.

Blood Volume↗