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Biomedical subjects

D P Becker

Publications and source records attributed to D P Becker.

At least 145 records · Page 8Linked to original sources
PubMed1983

Effects of therapeutic pentobarbital coma on multimodality evoked potentials recorded from severely head-injured patients.

We sought to determine whether pentobarbital (PB) coma compromises the use of evoked potentials (EPs) in the assessment of brain dysfunction and of the prognosis of severely head-injured patients. Therefore, the effects of therapeutic PB on somatosensory (SEPs, BSEPs), visual (VEPs), and auditory (BAEPs) evoked potentials recorded from 20 patients early after injury were analyzed. Seventeen head-injured patients served as controls. EP studies were obtained shortly after admission (Mean Day 2, PB present) and approximately 2 weeks after injury (Mean Day 15, PB absent). The mean serum level of PB in the treatment group was 1.9 mg/100 ml. The drug effect was assessed by comparisons between the PB and the control groups. Statistical analyses were based on differences observed between two studies in the same patient. Analyses of covariance (F tests) were performed on data from all modalities. Wave form complexity was minimally affected by the drug. Middle and long latency components of the SEP were depressed by PB, and latencies of BSEP peaks and the early components of the SEP were delayed. The amplitude of some VEP peaks was reduced by PB. The BAEP was not significantly altered. All of the observed effects of PB were determined to be due to the hypothermia exhibited by PB-treated patients (mean temperature, 36.1 degrees C), which was not seen in the control group (mean, 37.8 degrees C). It is concluded that, with appropriate interpretation, EPs can be used to monitor brain function in head-injured patients when PB therapy is used.

Adult↗
PubMed1983

Effects of naloxone on systemic and cerebral responses to experimental concussive brain injury in cats.

This study examined the effects of bolus injections of naloxone hydrochloride, a specific narcotic antagonist, on systemic cardiovascular function, intracranial and cerebral perfusion pressures, blood gas status, and cortical encephalograms (EEG's) in 38 cats after two different grades of experimental brain injury. Naloxone had no prolonged effects on uninjured control animals. However, as compared to a saline-injected control group, naloxone significantly reversed the hypotension and reduction in pulse pressure seen after higher grades of injury. These changes persisted for at least 60 minutes after injection and were accompanied by increased intracranial and perfusion pressures. More severely injured hypotensive cats injected with naloxone also had higher values of arterial pO2 and pH, lower pCO2, as well as higher EEG amplitudes. In less severely injured normotensive cats, naloxone produced greater effects on cardiovascular variables and intracranial pressure when injected 15 minutes rather than 45 minutes after injury. These data suggest that endogenous opiates may contribute to some instances of hypotension seen after concussive brain injury. Levels of endogenous opiates may also increase transiently even with lesser degrees of injury not associated with hypotension. The possible clinical application of narcotic antagonists to the treatment of head injury is discussed.

Animals↗
PubMed1983

The National Traumatic Coma Data Bank. Part 1: Design, purpose, goals, and results.

This paper describes the pilot phase of the National Traumatic Coma Data Bank, a cooperative effort of six clinical head-injury centers in the United States. Data were collected on 581 hospitalized patients with severe non-penetrating traumatic head injury. Severe head injury was defined on the basis of a Glasgow Coma Scale (GCS) score of 8 or less following nonsurgical resuscitation or deterioration to a GCS score of 8 or less within 48 hours after head injury. A common data collection protocol, definitions, and data collection instruments were developed and put into use by all centers commencing in June, 1979. Extensive information was collected on pre-hospital, emergency room, intensive care, and recovery phases of patient care. Data were obtained on all patients from the time of injury until the end of the pilot study. The pilot phase of the Data Bank provides data germane to questions of interest to neurosurgeons and to the lay public. Questions are as diverse as: what is the prognosis of severe brain injury; what is the impact of emergency care; and what is the role of rehabilitation in the recovery of the severely head-injured patient?

Accidents↗
PubMed1983

Chart for outcome prediction in severe head injury.

An analysis of clinical and demographic data of 264 patients with severe head injury showed that a combination of the Glasgow Coma Scale (GCS) score, oculocephalic responses, and age can provide a simple but reliable prediction of outcome in severe head injury. Addition of other clinical data, excluding intracranial pressure and evoked potentials, improved the predictability only negligibly. A simple chart, which is constructed from the application of the logistic regression model, can be used to determine the odds of a good outcome from the combination of the three factors. A method is given by which the GCS score of a patient with a missing verbal response score can be accurately approximated in order to complete the chart. Among other values, the odds of a good outcome provide the clinician with a reliable measure of the relative severity of a patient's injury. The accuracy of the chart in prediction is expected to be 80% or above.

Adult↗
PubMed1983

Mannitol causes compensatory cerebral vasoconstriction and vasodilation in response to blood viscosity changes.

There is no proof that osmotic agents such as mannitol lower intracranial pressure (ICP) by decreasing brain water content. An alternative mechanism might be a reduction in cerebral blood volume through vasoconstriction. Mannitol, by decreasing blood viscosity, would tend to enhance cerebral blood flow (CBF), but the cerebral vessels would constrict to keep CBF relatively constant, analogous to pressure autoregulation. The cranial window technique was used in this study to measure the pial arteriolar diameter in cats, together with blood viscosity and ICP changes after an intravenous bolus of 1 gm/kg of mannitol. Blood viscosity decreased immediately; the greatest decrease (23%) occurred at 10 minutes, and at 75 minutes there was a "rebound" increase of 10%. Vessel diameters decreased concomitantly, the largest decrease being 12% at 10 minutes, which is exactly the same as the 12% decrease in diameter associated with pronounced hyperventilation (PaCO2 30 to 19 mm Hg) in the same vessels; at 75 minutes vessel diameter increased by 12%. With hyperventilation, ICP was decreased by 26%; 10 minutes after mannitol was given, ICP decreased by 28%, and at 75 minutes it showed a rebound increase of 40%. The correlation between blood viscosity and vessel diameter and between vessel diameter and ICP was very high. An alternative explanation is offered for the effect of mannitol on ICP, the time course of ICP changes, "rebound effect," and the absence of influence on CBF, all with one mechanism.

Animals↗
PubMed1982

The morphological correlates of primate cerebrospinal fluid absorption.

Arachnoid villi from cynomolgus monkeys subjected to various states of cerebrospinal fluid (CSF) absorption have been examined with scanning (SEM) and transmission (TEM) electron microscopy. Pressures within the superior sagittal sinus and the subarachnoid space were rigidly controlled, both prior to and during perfusion fixation and, as such, we created and studied conditions of normal, absent and increased cerebrospinal fluid absorption. Under normal conditions, the most prominent feature of the CSF/blood interface was the presence of endothelial intracytoplasmic vacuoles. The presence of these vacuoles was suggested with SEM and readily confirmed with TEM. Occasionally, these vacuoles coalesced with both the CSF and sagittal sinus fronts, thereby creating transcellular channels as identified by TEM or surface pores as seen with SEM. Villi perfused during conditions of no CSF flow exhibited none of the previously described vacuoles, channels, or pores, whereas increased CSF flows were associated with increased numbers of these structures. The significance of these findings was discussed in relation to CSF absorption and to previously reported ultrastructural studies.

Animals↗
PubMed1982

Operative treatment in head injury.

Improved outcome will result only from improvement in the total care of the head-injured patient. Each aspect of care is dependent on the other: rescue services; aggressive emergency evaluation and resuscitation; monitoring of the patient's physical, chemical, and neurological status; CT scanning; and intensive medical therapy and early rapid surgical decompression. The injured brain is particularly prone to further secondary insults. Intracranial mass lesions must be removed quickly and thoroughly; the brain should be handled in a careful and gentle fashion intraoperatively, and medical complications should be prevented. Dysfunctional cells in a marginal state can only be expected to return to normal with the proper management and environment.

Adolescent↗
PubMed1982

The dynamics of neuronal dysfunction and recovery following severe head injury assessed with serial multimodality evoked potentials.

Serial studies of visual, auditory, and somatosensory evoked potentials (EP's) obtained from 139 severely head-injured patients up to 1 year after trauma were analyzed to ascertain whether or nor EP's can be used to monitor neurological recovery or deterioration following secondary insults. The EP data were analyzed using a grading system of abnormality developed previously, and patients were grouped by the most severe EP abnormality found in any modality during an early study (mean Day 3). The findings showed differential recovery trends depending on the severity of EP abnormality obtained on the initial study and presence of secondary insult. If EP's were normal early after injury, they remained so for up to 1 year, and these patients did well clinically. The EP's that were absent did not improve, and the patients had poor outcomes. Secondary insults did not affect the EP's or the outcomes of patients in these two groups. When EP's that were initially mildly abnormal became normal or remained no worse than mildly abnormal, patients had favorable outcomes in spite of complications. In contrast, deterioration of EP's with secondary insult indicated poor patient outcome. Severe EP abnormalities which improved over time led to favorable outcomes. However, persistence or deterioration of severe abnormalities indicated a poor outcome. Changes in EP's over time were better indicators of outcome than the presence or absence of complications. The results suggest that EP's may be used to assess neural recovery and the consequences of secondary insults to the brain. Four case reports are included to exemplify results.

Adolescent↗
PubMed1981

Traumatic acute subdural hematoma: major mortality reduction in comatose patients treated within four hours.

To discover which factors contributed to recovery after surgical intracranial decompression, we reviewed the records of 82 consecutive comatose patients with traumatic acute subdural hematoma (ASDH) who were treated in a single center under a uniform protocol. The delay from injury to operation was the factor of greatest therapeutic importance. Patients who underwent surgery within the first four hours had a 30 per cent mortality rate, as compared with 90 percent in those who had surgery after four hours (P less than 0.0001). Other important prognostic variables included results of the initial neurologic examination, sex, multimodality-evoked potentials, and postoperative intracranial pressure (ICP). If all patients with traumatic ASDH were taken directly to hospitals equipped to diagnose and remove the hematoma within four hours of injury, mortality rates could be reduced considerably.

Accidents, Traffic↗
PubMed1981

The role of postischemic recirculation in the development of ischemic neuronal injury following complete cerebral ischemia.

The neuronal response to complete cerebral ischemia (CCI) of 5-15 min duration was evaluated at the light and electron microscopic level subsequent to postischemic recirculation periods of up to 60 min. Following postischemic reperfusion, the homogeneous neuronal changes characteristic of permanent CCI were modified into a heterogeneous pattern of selectively vulnerable neuronal responses. Four basic types of neuronal injury were represented within this heterogeneous neuronal population. The Type I neuronal response was most numerous and consisted of chromatin clumping, nucleolar condensation and a breakdown of polysomes. This response may represent a reversal of some of the neuronal changes observed after permanent CCI. In addition to the above changes, Type II neurons contained swollen mitochondria and Golgi saccules which appeared as microvacuoles under the light microscope. Type III neurons displayed varying degrees of neuronal shrinkage and numerous swollen mitochondria. Type IV neurons were markedly shrunken and electron-dense with few identifiable subcellular structures. The distribution of Type I neurons was random but the other neuronal responses occurred in "selectively vulnerable" brain regions. The number of Type II, III, and IV neurons increased with extended insult durations but were unaffected by the length of recirculation. Ten minutes of CCI represented the threshold for a significant increase in the number of severely altered neurons. These findings suggest that considerable neuronal injury may be present after 10-15 min of CCI, and the lack of a recirculation period following CCI appears to afford the brain parenchyma an extensive degree of structural protection.

Animals↗
PubMed1981

Pituitary microadenoma: a radiological-surgical correlative study.

In this study, the authors evaluated the correlation between the radiological changes in the sella (using thin-section, complex motion tomography) and the location of pituitary microadenomas at surgery. A significant discrepancy was noted between the tomographic and surgical location of the tumor in 14 of 55 patients. The authors caution about absolute reliance upon tomography for making the diagnosis of pituitary microadenoma in a given patient.

Adenoma↗
PubMed1981

Computed tomography in the evaluation of incidence and significance of post-traumatic hydrocephalus.

Two hundred consecutive patients with severe head injury underwent sequential computed tomography (CT) on admission, after 4, 14, and 90 days, and after one year. Ventricular enlargement was evaluated in the surviving patients, based upon serial CT examinations. Significant ventricular enlargement was further evaluated with radionuclide cisternography. A significant correlation was shown between clinical outcome and presence or absence of ventricular enlargement. Radionuclide cisternography provided an additional means of determining those patients whose recovery was impaired by persistent obstruction of cerebrospinal fluid circulation and who would therefore benefit from cerebrospinal fluid shunting.

Adult↗