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Biomedical subjects

J J Barton

Publications and source records attributed to J J Barton.

At least 55 records · Page 3Linked to original sources
PubMed1994

Effects of edrophonium on saccadic velocity in normal subjects and myasthenic and nonmyasthenic ocular palsies.

We measured saccadic peak velocities in 8 patients with myasthenia gravis, 9 patients with proven nonmyasthenic ocular palsies, and 3 controls. Patients followed a target moving to and from primary position at 1-second intervals for 8 minutes. We measured the amplitudes and velocities of centrifugal saccades at the start of the task, after 3 minutes of the task (fatigue) and 1 minute after receiving IV edrophonium. The effects of fatigue, though prominent in some myasthenic patients, did not distinguish between the groups. However, edrophonium increased saccadic peak velocities in myasthenic patients but decreased them in both controls and nonmyasthenic patients. Analysis of saccades by amplitude bins showed that these changes in peak velocity reflected shifts in the velocity-amplitude relationship.

Adult↗
PubMed1994

Is acquired pendular nystagmus always phase locked?

A patient with multiple sclerosis presented with oscillopsia due to an acquired pendular nystagmus that was dissociated in amplitude, being larger in the eye with a relative afferent pupil defect. Eye movement recordings showed an unusual dissociation in nystagmus frequency as well. Although the frequencies differed, the eyes remained phase locked as the right eye was oscillating exactly twice as fast as the left eye.

Adult↗
PubMed1994

Motion perception in optic neuropathy.

We tested motion perception in 15 eyes of 13 patients with optic neuropathy. Eleven of the eyes had optic neuritis. The motion perception paradigm tested subjects' ability to discriminate the direction of a global coherent motion signal amid varying levels of background noise. The results showed defective motion processing in eight of the 15 eyes. This defect was not due to low visibility (poor spatial resolution), since 11 of the 15 eyes had Snellen acuities of 20/20 or better. Neither was impaired motion perception due to decreased luminance sensitivity, since attenuating the display signal by 2.1 log units (0.6 units more than the worst relative afferent pupillary defect in any patient) in five normal eyes had no effect. Motion perception and critical flicker fusion were independent of each other. Given proposals that both depend exclusively on the same M, or transient, channel, we had not predicted this double dissociation between flicker and motion perception.

Adult↗
PubMed1993

Oscillopsia and horizontal nystagmus with accelerating slow phases following lumbar puncture in the Arnold-Chiari malformation.

Oscillopsia and nystagmus began in a woman 2 weeks after an inadvertent lumbar puncture during anesthesia for childbirth. Examination showed horizontal-torsional jerk nystagmus in all positions of gaze. Magnetic-search-coil oculography revealed accelerating slow phases, with an increase in nystagmus amplitude in darkness. Magnetic resonance images showed type 1 Arnold-Chiari malformation. Three months after occipital decompressive surgery, nystagmus had almost disappeared. Accelerating slow phases should not be considered diagnostic of congenital nystagmus, especially with an onset of oscillopsia in adult life; imaging should be considered to exclude treatable hindbrain anomalies. Lumbar puncture in patients with the Arnold-Chiari malformation may accentuate craniospinal pressure dissociation and precipitate neurological signs.

Adult↗
PubMed1993

Acquired pendular nystagmus in multiple sclerosis: clinical observations and the role of optic neuropathy.

Thirty seven patients with pendular nystagmus due to multiple sclerosis were reviewed. Most developed nystagmus later in a progressive phase of the disease. All had cerebellar signs on examination and evidence of optic neuropathy. MRI in eight patients showed cerebellar or brainstem lesions in seven; the most consistent finding was a lesion in the dorsal pontine tegmentum. Dissociated nystagmus was seen in 18 patients: in these the signs of optic neuropathy were often asymmetric and the severity correlated closely with the side with larger oscillations. This suggests that dissociations in acquired pendular nystagmus may be due to asymmetries in optic neuropathy rather than asymmetries in cerebellar or brainstem disease.

Afferent Pathways↗
PubMed1992

Term birth after midtrimester hysterotomy and selective delivery of an acardiac twin.

OBJECTIVE: Our aim was to determine whether hysterotomy and selective removal of an acardiac twin could improve the outcome of the "pump" twin. STUDY DESIGN: A literature and case review of the outcome of the acardiac twin malformation was performed. When an acardiac malformation was diagnosed at 19 weeks' gestation the patient was monitored with weekly ultrasonographic examinations. At 23 weeks' gestation, no blood flow could be demonstrated to the acardiac twin and it was thought that the continued presence of the acardiac twin posed a risk to the "pump" twin. A midtrimester hysterotomy was performed and the acardiac twin was delivered. RESULTS: After the midtrimester hysterotomy, the pregnancy progressed to term and a healthy female infant was delivered by elective cesarean section at 37 weeks' gestation. CONCLUSION: Midtrimester hysterotomy may be a useful intervention in cases of twinning when one fetus is a threat to the health of the other.

Adult↗
PubMed1991

Neuro-ophthalmologic vascular emergencies in the elderly.

The significance, management and prognosis of several disorders affecting either vision or ocular motility are discussed. Transient and persistent visual loss are common problems in the elderly. Anterior ischemic optic neuropathy is extensively reviewed because of the importance of recognizing forms due to giant cell arteritis, which require urgent treatment with steroids to prevent further visual loss. The various pathologic conditions that can affect the ocular motor nerves in the cavernous sinus are mentioned. The problem of differentiating benign ischemic lesions causing a third nerve palsy from ominous compressive palsies due to aneurysms is addressed, with emphasis on the clues provided by the pupil.

Aged↗
PubMed1990

Ultrasonography and external cephalic version at term.

Sixty-five patients with nonvertex presentations at term were evaluated by ultrasonography to determine which factors were associated with a successful external cephalic version. Amniotic fluid volume, placental localization, type of breech, position of the fetal spine, and whether the breech had descended were determined and analyzed by chi 2 analysis. Only a frank breech and an anteriorly located fetal spine were associated with a successful version. Four episodes of fetal bradycardia occurred, none requiring operative intervention. There were no episodes of maternal bleeding or dislodgement of the placenta. Fifty-eight percent of all breech presentations were converted and 62% were delivered vaginally. We conclude that ultrasonography is useful in the evaluation of patients with a nonvertex presentation at term and can be used to predict which patients are likely to undergo a successful external cephalic version.

Breech Presentation↗
PubMed1989

Prevalence of human immunodeficiency virus in a general prenatal population.

Controversy surrounds the issue of screening for the human immunodeficiency virus in pregnancy. The question remains: Which pregnant women should be tested? To answer this question, it is clear that local prevalence data of seropositivity must be known. At present, these figures are unavailable for midwestern metropolitan areas such as ours. Therefore an obstetric human immunodeficiency virus screening committee was formed to determine the prevalence of seropositivity of this virus in our obstetric clinic population. During a 14-month period of time all patients registering for prenatal care were offered human immunodeficiency virus antibody testing. A total of 585 out of 751 patients (78%) gave informed consent. Forty-two of these patients had risk factors for human immunodeficiency virus infection. The rate of seropositivity in this group was 7.1% (3 of 42). The remaining 543 patients had no risk factors and none of these patients had positive test results. From our preliminary results, screening only those prenatal patients with identified risk factors appears to be justified.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Maternal weight and pregnancy complications.

The effect of obesity alone was investigated among 16,858 women who were delivered of their infants within a 12-month period. Complete analysis was possible for 9667 patients who were divided into four weight categories and separated into two groups, with and without complications. Perinatal mortality, infant size, and the primary cesarean delivery rate were calculated for each group. Among 2597 women with antenatal complications, there was a significant increase in perinatal mortality (p less than 0.001), primary cesarean delivery (p less than 0.02), and mean infant birth weight (p less than 0.01) in the obese and the morbidly obese gravid women. Among 7070 women without antenatal complications there was a significant increase in primary cesarean delivery (p less than 0.001) and mean infant birth weight (p less than 0.01) but not perinatal mortality in the obese and the morbidly obese gravid women. Obesity alone does not appear to affect the perinatal mortality rate but it increases the likelihood of cesarean delivery in the morbidly obese patient.

Birth Weight↗
PubMed1985

Premenstrual syndrome.

PMS is a constellation of symptoms, both somatic (breast tenderness, bloating, headache) and psychologic-behavioral (irritability, hostility, depression) that recur prior to the menses in about 5% to 20% of all menstruating women. Such women should be evaluated with a thorough history and physical examination, and if the diagnosis is firmly established by observing a temporal relationship of the symptoms with the premenstruum, therapy should be initiated. When treating PMS, reassurance should always be offered to the patient along with counseling regarding life-style and dietary changes. Symptomatic relief may be provided with any number of medications, including diuretics, NSAIDs, and possibly progesterone. Oral contraceptive therapy may also be helpful. Although patience is certainly required in order to deal with this often frustrating problem, it should be remembered that patient satisfaction is commonly within reach.

Anti-Inflammatory Agents↗
PubMed1983

Bleeding ectopic decidua as a cause of intraabdominal hemorrhage. A case report.

Severe ectopic decidual reaction of the peritoneal surface as the etiology of unexpected intraabdominal hemorrhage is rare. Such a situation occurred in one of our patients after an uneventful vaginal delivery. The bleeding was discovered during postpartum sterilization, and hysterectomy was performed to control it. Six cases reported previously presented with peripartum shock and/or an acute abdomen. Three died, all of intraabdominal hemorrhage and two of them without laparotomy. Various etiologies of this disorder have been postulated, but a consistent explanation remains to be found. Intraabdominal hemorrhage, whatever its cause, must be controlled directly at laparotomy.

Adult↗