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Biomedical subjects

E L Foltz

Publications and source records attributed to E L Foltz.

At least 19 recordsLinked to original sources
PubMed1991

Hydrocephalus: overdrainage by ventricular shunts. A review and recommendations.

Selected literature review of the clinical course of patients with ventricular shunts for hydrocephalus shows that the effects of cerebrospinal fluid overdrainage are subdural hematoma, craniosynostosis, slit ventricle syndrome, and low intracranial pressure syndrome. These occur sequentially at different age groups, but approximate averages of incidence and time of occurrence after first shunt reveal an overall incidence of 10%-12% for at least one of these appearing at 6.5 years after shunting. The basic etiology, diagnosis, and variety of treatment modalities available are reviewed, including the need for shunt closing intracranial pressure control. Included is a hydrocephalus program designed to minimize the need for long-term extracranial shunts and to maximize therapeutic intracranial procedures for hydrocephalus.

Cerebral Ventricles↗
PubMed1990

CSF pulsatility in hydrocephalus: respiratory effect on pulse wave slope as an indicator of intracranial compliance.

The effect of inspiration and expiration on the systolic slope of the cerebrospinal fluid (CSF) pulse wave has been studied in 83 shunted and non-shunted patients undergoing diagnostic tests for suspected hydrocephalus. A ratio of the systolic CSF pulse slope on inspiration to the same in expiration (I/E ratio or index) has proved statistically valid in identifying non-hydrocephalic patients from hydrocephalic patients and in separating hydrocephalic patients into arrested, communicating and aqueductal stenosis hydrocephalus. The I/E ratio depends on the comparative damping effect of intracranial venous venting on the systolic CSF pulse slope during inspiration (I) when venous volume is evacuated from the cranium by negative mediastinal pressure, and during expiration (E) when cranial venous volume flow to heart is minimal due to positive mediastinal pressure. The low cranial venous outflow on expiration produces little effect on the normal damping of the systolic CSF pulse slope. The high venous outflow on inspiration produces a loss of damping, causing a high systolic CSF pulse slope. Therefore, exhausted cranial venous volume, or exhausted intracranial compliance, produces an I/E ratio approaching 1.0, whereas a normal I/E ratio is between 2.0 and 3.0. The I/E ratio can presumably be used to assess intracranial compliance changes occurring before the dangerous late intracranial pressure (ICP) upward surge related to the volume-pressure curve in all clinical problems of increasing ICP. The I/E ratio may be used likewise to assess the urgency of treatment for any hydrocephalus and increased intracranial pressure problem, i.e. the closer to unity the greater the urgency.

Adolescent↗
PubMed1988

Head trauma and nonsurvival--a sample survey.

A retrospective survivor study of 42 patients with severe brain and multisystem injury is presented. All patients were treated with vigorous trauma/neurosurgical techniques. Thirty-seven patients in this series had a Glasgow Coma Score of 3 at the initial examination, and none survived. Since all 37 patients at initial emergency room evaluation showed persistent apnea at 40-60 minutes after injury, a diagnosis of dead on arrival (DOA) might have been appropriate. Cost analysis shows that the direct cost for the 37 cases was $27,000 per patient, or $990,000 for the 37 patients with no survivors. A diagnosis of DOA would have been $200 per patient. Many implications can be derived from these figures.

Adolescent↗
PubMed1988

Symptomatic low intracranial pressure in shunted hydrocephalus.

Fourteen patients with ventricular cerebrospinal fluid shunts in place for chronic hydrocephalus presented with a history and neurological deficits usually associated with high intracranial pressure (ICP) caused by an obstructed shunt system. However, the symptoms were characteristically present when the patient was upright and active, and were usually relieved by lying down. The symptoms of intermittent headache, nausea, emesis, lethargy, and diplopia were associated with paresis of upward gaze or minimal strabismus. Measurement of ICP showed unexpected dramatically low levels with a marked drop in pressure when the patient was in the upright position, whereas ICP was near normal when the patient was supine. The low ICP was corrected by insertion of a high-pressure Flo-Control valve into the shunt system already in place. Postoperatively, the immediate clinical improvement and more normal ICP measurements were striking. The important clinical finding in this group of patients was the presence of disabling symptoms which occurred when the patients were up and active and which were relieved by lying down. Measurements of ICP with the patient in the supine and then in the upright position were critical in establishing an accurate diagnosis of symptomatic low ICP in these hydrocephalic patients with indwelling shunts. With the patient in the Trendelenburg position, ICP showed a marked increase, as expected; in some patients this position was prescribed as treatment for several days before surgery.

Adolescent↗
PubMed1987

Hydrocephalus: increased intracranial pressure and brain stem auditory evoked responses in the hydrocephalic rabbit.

The auditory evoked response (AER) was used to study the effect of increased intracranial pressure (ICP) on the auditory pathway in normal New Zealand rabbits and in those made hydrocephalic by intracisternal injections of kaolin. AERs were studied: (a) in the normal and then in the hydrocephalic animal; and (b) in the hydrocephalic animal during further ICP elevation by cerebrospinal fluid infusion. The AER was obtained from ongoing electroencephalographic activity after rarefaction auditory clicks presented at 90 dB sound pressure equivalent. In comparing base line normal AERs to those found in hydrocephalic conditions, a statistically significant increase in latency for AER components N2, P2, and P5 was noted in hydrocephalic rabbits. Increased ICP in the hydrocephalic model showed an increase in the latencies of AER components for P0 and P1 at 250 mm H2O, and a prolongation of P3-P5 central conduction time at 700 mm H2O above base line cerebrospinal fluid pressure. In addition, a decrease in the P4/N5 amplitude and an increase in P1-P3 central conduction times at 700 mm H2O was observed. The differences between normal and hydrocephalic rabbit AER base lines may be the result of the chronically increased ICP and presumed chronic anatomical changes within the auditory pathway due to kaolin itself. The differences in the AER from base line hydrocephalus to acute increased ICP may indicate that the hydrocephalic system is more sensitive to acute neuropraxic pressure effects on the brain stem auditory structures than is the normal brain.

Animals↗
PubMed1985

Evaluation of signal detection theory on the effects of psychotropic drugs on critical flicker-fusion frequency in normal subjects.

Critical flicker-fusion frequency (CFF) has often been applied to psychotropic drug evaluation as a measure of cortical arousal. There are several variables that must be considered for proper conclusions to be obtained from CFF experimental data. Psychological variables such as subject response bias are especially difficult to control. We studied the effects of single oral doses of 10 mg diazepam and 10 mg amphetamine sulfate on CFF values obtained by a block up-down spatial forced-choice method on 13 healthy volunteers (seven males and six females). Signal detection theory was also used to obtain the non-parametric value P(A) as a measure of sensory function and B as a measure of the psychological function of response bias. As a group, amphetamine increased CFF (Hz) and P(A) and diazepam decreased CFF (Hz) and P(A), with the most significant effects observed at 2 and 3 h after drug administration. B scores showed more individual variation with a trend towards a low score, or a tendency to report more flicker responses after diazepam. Separated by sex, the males had a higher percentage of subjects that demonstrated a reduction of CFF after diazepam, while the females had a higher percentage that demonstrated an increase in CFF after amphetamine. The results suggest that CFF changes following diazepam and amphetamine are mostly changes in sensory function and not changes in response bias. It is possible to apply signal detection theory to flicker-fusion studies and the accounting of bias by controlling, measuring or eliminating it is essential in interpretation of CFF data.

Amphetamine↗
PubMed1985

Acute negative intracranial pressure effects on the auditory evoked response in rabbits.

Recent clinical experience has shown that significant neurological symptoms and deficits occur in patients who have been shunted for hydrocephalus when "overshunting" produces unusual negative intracranial pressure (ICP). Therefore, the effect of acute negative ICP .on the early auditory evoked response (AER) was studied in the normal New Zealand rabbit. ICP was reduced to -50, -100, and -150 mm H2O below base line pressure. The AER after rarefaction auditory stimulation was obtained from ongoing electroencephalographic activity at the base line ICP and at each of the three negative ICP levels. Off-line statistical evaluation of the AER showed minimal changes in the absolute and interpeak latencies of N-0 to P-5 at some negative pressures. However, no statistically significant changes were observed for any of the measures for grouped data. At the negative ICP levels studied, the cerebrospinal fluid (CSF) pulse pressure was considerably augmented over base line measures. Such augmentation of the CSF pulse pressure may be the cause of the minimal effects observed on the AER, which may be due to a neuropraxic effect rather than ischemia from cerebral perfusion pressure changes.

Animals↗
PubMed1979

Cerebrospinal fluid bulk flow study: radioiodinated serum albumin (R131ISA) and technetium-99m-labeled diethylenetriaminepentaacetic acid (DTPA) retention in the ventricles of normal and hydrocephalic dogs.

Eight normal dogs were studied and then made hydrocephalic (kaolin induced) to demonstrate and compare the use of R131ISA and 99mTcDTPA in cerebrospinal fluid (CSF) bulk flow studies. The radioisotopes were simultaneously injected into the CSF space in the cisterna magna of normal dogs and into the lateral ventricles of hydrocephalic dogs after an equal volume of CSF had been removed. The average dose of RISA was 100 muCi, and for TcDTPA it was 7 mCi. A bag of lactated Ringer's solution (500 ml) was used as a control phantom after being injected with the same dose of isotope as used in the animals. Brain scans were obtained with the gamma ray camera at 4 and 24 hours after injection. We used four criteria to evaluate results: clinical state of the animal, CSF ventricular pressures with challenges, percentage of retained isotope in counts per minute, and ventricular size at postmortem examination. The results demonstrate that the amount of isotope retention over 20 hours and the clinical state of the dog are better correlated when RISA is used than when TcDTPA is used. The study indicates that RISA is more reliable than TcDTPA as an indicator of CSF bulk flow in both normal and hydrocephalic dogs.

Animals↗
PubMed1977

Effect of fosfomycin on the fecal microflora of man.

Use of broad-spectrum antibiotics is known to cause changes in the intestinal microflora of man. The present study was initiated to determine the effect of oral fosfomycin calcium on several groups of microorganisms indigenous to the gut. Data from this double-blind study indicate that 2 g of fosfomycin given daily in four divided doses for 28 days increased the incidence of soft stools. No significant changes in numbers of staphylococci or Candida were observed during treatment. Although there was no significant change in total coliforms, the numbers of E. coli decreased markedly from 10(5) to 10(2) organisms/g feces. Concurrent with this decrease, the Klebsiella-Enterobacter counts increased from 10(3) to 10(6) organisms/g feces. Two weeks posttreatment the E. coli and the Klebsiella-Enterobacter counts approached pretreatment levels. These observations are similar to those reported for ampicillin. During the course of treatment when the E. coli dropped precipitously the few surviving E. coli still were suceptible to fosfomycin as determined by an agar diffusion disc test.

Anti-Bacterial Agents↗
PubMed1977

Malignant hyperthermia.

The authors report the case of an infant with noncommunicating hydrocephalus, Arnold-Chiari malformation, and a lumbar myelomeningocele, in whom malignant hyperthermia occurred. The genetics and presumed etiology of this unusual problem are reviewed. The management is directed toward establishing effective cooling measures, reversing tissue hypoxia, and correcting respiratory and metabolic acidosis.

Acidosis↗
PubMed1976

Pharmacokinetics of methyldopa in man.

Single doses of methyldopa were administered orally and intravenously as aqueous solutions to 12 healthy volunteers in a crossover study. Serial plasma and urine samples were analyzed specifically for methyldopa and its O-sulfate conjugate. Kinetic analyses of the results indicated that methyldopa disposition could be adequately represented by a two-compartment open model. Renal excretion accounted for about two-thirds of the plasma clearance of methylodopa. Absorption profiles were constructed with the aid of the pharmacokinetic model and contrasted with estimates of absorption which were model-independent. The mean fraction reaching the systemic circulation as methyldopa was estimated to be 0.25 (range 0.08-0.62 for n = 11). Although most of the absorption occurred within the first 5 hours oral administration, a minor component, suggestive of limited enterohepatic circulation, persisted from 9 to 36 hours. O-sulfate conjugation was route-dependent and appeared to be derived predominantly, if not exclusively, as a first-pass effect of absorption and/or enterophepatic circulation.

Administration, Oral↗
PubMed1976

Avoidance behavior and ileum motility post-cingulumotomy in monkey.

Two experiments were conducted utilizing rhesus monkeys to determine (i) the effects of cingulumotomy on conditioned-avoidance acquisition and extinction and (ii) the effects of avoidance learning on distal ileum motility in control- and cingulum-lesioned animals. Active (AAR) and passive (PAR) avoidance schedules singly or in combination were employed during short daily periods (less than 2 hr) of "shaping," training, acquisition, and extinction. The data indicated that the control-lesion and cingulum groups did not differ in the acquisition or extinction of an AAR. The cingulum group, however, showed a significant deficit in the acquisition of a PAR and a noticeably slower rate of lever pulling during avoidance trials in the combined avoidance training sessions. The results also suggested that ileum motility and avoidance behavior parallel on another, i.e., if either changed the other often changed in the same direction; that cingulum monkeys seemed to be less "reactive" than control-lesion monkeys; and that cingulum animals may been somewhat more regular in their percent daily motility patterns than the control animals.

Animals↗
PubMed1975

Follow-up comparison of hydrocephalus with and without myelomeningocele.

A series of 454 hydrocephalic patients with and without myelomeningocele and with and without treatment is reviewed. The survival rates for hydrocephalus alone and for hydrocephalus with myelodysplasia are comparable. The authors reach the conclusion that treatment of the hycrocephalic process and its complications is the most critical therapeutic consideration. Mental retardation is the major unalterable cause for failure to develop independence; some lesser emotional causes can be modified by encouragement. Repeated reassessment of the patient's condition and adjustment are important. Before treatment is started parents or guardians should be fully informed of the child's future potential for independent life and mental development.

Abnormalities, Multiple↗