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Biomedical subjects

T A Cox

Publications and source records attributed to T A Cox.

16 recordsLinked to original sources
PubMed1992

Pupillary constriction during forceful eyelid closure.

Pupillary constriction during forceful eyelid closure was investigated in 30 normal subjects. The right eye of each subject was filmed with an infrared-sensitive television camera in darkness before, during, and after eyelid closure. Clinically detectable constrictions were found in nine of the 30 subjects (30%). No significant correlation was found between amplitude of constriction and age of subject or baseline pupillary diameter. Forceful eyelid closure should be considered as a technique to elicit pupillary constriction in patients with a poor near response, but many subjects will have no detectable constriction using this maneuver.

Adult↗
PubMed1992

Crystalluria in marathon runners. IV. Black subjects.

Crystal sizes (scanning electron microscopy) and distributions (Coulter Counter) as well as 24-h urinary sodium (Na) and calcium (Ca) excretions (flame atomic absorption) were determined in a group of black South African runners immediately after a marathon and again 3 weeks later. White runners and black and white control subjects were included in the study. Particle volume-size histograms for black controls and black runners were identical. There was no significant difference in the Na excretion of all the groups. However, while urinary Ca excretion was significantly raised in white runners relative to white controls, Ca excretion in black runners was unchanged relative to their controls. It is postulated that the lower rates of urinary Ca excretion may result from lower rates of Ca resorption from bone in response to the cyclical loading of running in black marathon runners. The results of this study suggest that black marathon runners are not prone to the same increased risk of renal stone formation as are white runners.

Adult↗
PubMed1992

Pupillary escape.

I performed a pupillographic study of pupillary escape to determine its effectiveness in detecting optic nerve and retinal disease. Fourteen patients and 39 normal subjects were included in the study. Only one patient had abnormal pupillary escape, even though 13 patients had relative afferent pupillary defects. Testing for pupillary escape is not a reliable clinical technique.

Adult↗
PubMed1991

Stunned left ventricular myocardium after exercise treadmill testing in coronary artery disease.

Myocardial stunning (postischemic ventricular dysfunction) occurs in dogs after coronary stenosis following treadmill exercise. Less data are available in humans regarding development of stunned myocardium after exercise. Regional wall motion changes were evaluated in 22 patients with known coronary artery disease using 2-dimensional echocardiography and exercise treadmill testing. Wall motion was scored as 1 = normal, 2 = hypokinetic, 3 = akinetic, 4 = dyskinetic. At least 1 left ventricular segment with normal resting function developed an increase in wall motion score at 15 or 30 minutes compared with values at rest. The wall motion score in the midportion of the ventricular septum increased from 1.0 at rest to 1.6 (p less than 0.004) at 30 minutes after exercise; the basal inferior wall score worsened from 1.0 at rest to 1.9 (p less than 0.01) at 30 minutes after exercise. Coronary angiographic data in these patients revealed that left anterior descending narrowing correlated best with left ventricular septal wall motion abnormalities, whereas right coronary artery and circumflex narrowing best correlated with inferior and posterior wall motion abnormalities. Eight normal adult volunteers with no history of myocardial ischemia also underwent 2-dimensional echocardiography and exercise testing. No wall motion abnormalities were observed at any time after exercise. The present study suggests that in patients with coronary artery disease, exercise treadmill testing may induce regional wall motion abnormalities of the left ventricle that persist greater than or equal to 30 minutes after exercise, an observation consistent with the phenomenon of stunned myocardium.

Adult↗
PubMed1991

Delayed visual loss due to trauma of the internal carotid artery.

The group of six patients in this study experienced delayed visual loss following head trauma. Visual loss occurred from 1 day to 13 years after the initial injury. All patients suffered indirect trauma to the internal carotid artery resulting in formation of either an aneurysm or pseudoaneurysm or a carotid-cavernous fistula. Review of the radiologic and clinical findings was performed in six patients. The diagnosis was established by computed tomography, magnetic resonance imaging, and angiography. All patients had follow-up clinical evaluation and imaging studies. Treatment by neurosurgical or interventional neuroradiologic procedures resulted in significant visual improvement in five patients. Different pathophysiologic mechanisms could be correlated with the delayed visual loss produced by the two types of lesions. The pathologic changes associated with the aneurysms/pseudoaneurysms included direct compression of optic nerves and/or chiasm and intracranial hematoma. A carotid-cavernous fistula caused delayed visual loss by either hematoma at the orbital apex or compression of the chiasm and/or optic nerves by saccular dilatation of the cavernous sinus. The delayed onset of decreased vision following head trauma should alert the physician to the possibility of a traumatic aneurysm/pseudoaneurysm or a carotid-cavernous fistula. Different neuro-ophthalmologic symptoms can usually be correlated with the pathologic changes demonstrated by neuroimaging procedures.

Adolescent↗
PubMed1991

Tonic pupil and Czarnecki's sign following third nerve palsy.

A 71-year-old woman developed abnormal pupillary function in one eye after a third nerve palsy. Stimulation with light caused segmental constriction of the pupil, the near reflex was normal, and gaze upward elicited constriction of portions of the sphincter that were unreactive to light. This combination of findings has not been reported previously. We believe that this case supports the idea that a tonic pupil can be caused by aberrant reinnervation of the ciliary ganglion.

Aged↗
PubMed1991

The clinical significance of Tournay's pupillary phenomenon.

The act of lateral gaze in some normal individuals causes the pupil of the adducting eye to be smaller than that of the abducting eye. This phenomenon was described by Tournay more than 70 years ago, but it has generally been considered to have no clinical significance. We discuss two situations, episodic anisocoria and aberrant regeneration of the third nerve, in which Tournay's phenomenon should be considered by the clinician. We also describe familial occurrence of this interesting pupillary variant.

Adolescent↗
PubMed1989

Epiphyseal dysplasia, microcephaly, nystagmus, and retinitis pigmentosa.

In 1975, we reported two brothers with epiphyseal dysplasia, microcephaly, and nystagmus; one of them also had mild mental retardation. Here we present information on the natural history, particularly with respect to the development of a new visual problem, namely, retinitis pigmentosa.

Adolescent↗
PubMed1989

A retinopathy on Guam with high prevalence in Lytico-Bodig.

A pigmentary retinopathy resembling that sometimes seen in posterior ophthalmomyiasis interna was found in 26 (53.1%) of 49 Chamorro patients from Guam who have Lytico-Bodig (also known as amyotrophic lateral sclerosis-Parkinsonism-dementia complex of Guam). In nine cases, the retinopathy was bilateral. Similar changes were found in 6 (16.2%) of 37 clinically normal individuals from southern villages on Guam that have a high incidence of Lytico-Bodig, and in 1 (3.1%) of 32 individuals from Saipan, an island north of Guam that has a low incidence of the disease. These results indicate the possibility of an association-between Lytico-Bodig and a retinopathy on Guam that may be parasitic in origin. Occurrence of a similar association in other debilitating diseases on Guam and frequency of occurrence of retinopathy in Guamanians with Lytico-Bodig after leaving Guam have yet to be determined.

Adult↗
PubMed1989

Parasellar syndrome caused by plasma cell leukemia.

A 71-year-old man had incomplete third cranial nerve palsy caused by plasma cell leukemia and a parasellar plasmacytoma. This is the first reported case of plasma cell leukemia in which a central nervous system sign was the initial manifestation. Only one previous case of intracranial plasmacytoma associated with plasma cell leukemia has been reported. The characteristics of intracranial plasmacytomas and of plasma cell leukemia are discussed.

Aged↗
PubMed1989

Pupillographic characteristics of simulated relative afferent pupillary defects.

Relative afferent pupillary defects were simulated in normal individuals by performing the alternating light test while dimming the light in front of one eye with neutral density filters. Pupillary responses were elicited using a binocular photostimulator and recorded using a binocular television pupillometer. In five subjects, four spatial variables of the pupillary response--contraction amplitude, minimum size, final size, and redilatation amplitude--were measured and compared. Contraction amplitude was found to be the best indicator of small pupil defects. In eight other subjects, the contraction amplitude elicited by using filters from 0.3 to 3.0 log units in density was plotted. Amplitude of consensual responses increased as direct responses decreased, and initial constrictions were visible in many subjects at the 1.8 log unit level. The best method for detecting relative afferent pupillary defects using the alternating light test is to compare contraction amplitudes, looking for consensual responses that are greater than direct responses.

Adult↗
PubMed1989

Relative afferent pupillary defects in multiple sclerosis.

Relative afferent pupillary defects were found in 69 of 386 patients (18%) seen by the author at the University of British Columbia Multiple Sclerosis Clinic between Feb. 1, 1985, and Apr. 30, 1987. Pupil defects were more common in patients with clinically definite multiple sclerosis, those with recent or unilateral optic neuritis and those with unilateral or asymmetric optic atrophy. A relative afferent pupillary defect was found in 15 patients with no history of optic neuritis, 5 patients with no optic atrophy and 2 patients with normal visual evoked potentials. The frequency of relative afferent pupillary defects after optic neuritis in this group of patients was much lower than that found in a previous study of patients who presented with optic neuritis.

Adolescent↗
PubMed1979

Primary aberrant oculomotor regeneration due to intracranial aneurysm.

Two elderly patients had unilateral ophthalmoparesis and retrobulbar pain. Both had subtle lid signs of aberrant regeneration of the third nerve without proceding acute oculomotor paralysis, and both were found to have intracranial aneurysms. Although primary aberrant oculomotor regeneration has been reported previously in patients with aneurysms and meningiomas, the diagnostic importance of this sign in the elderly has not been emphasized. The presence of lid elevation on downgaze associated with slowly progressive ophthalmoplegia in patients aged 65 or older suggests aneurysm in or near the cavernous sinus.

Aged↗
PubMedDate not supplied

Selective MR imaging approach for evaluation of patients with Horner's syndrome.

PURPOSE: To assess the usefulness of MR in the evaluation of patients with Horner's syndrome. PATIENTS AND METHODS: We prospectively performed MR imaging in 33 patients with Horner's syndrome (13 preganglionic and 20 postganglionic) using a protocol specifically designed for pre- and postganglionic varieties of this syndrome. Assignment of patients to pre- or postganglionic categories was performed on the basis of pharmacologic testing. RESULTS: Abnormalities in one-half of the patients with preganglionic Horner's syndrome included lateral medullary infarct, spinal cord/root disease, apical lung tumor, and paravertebral metastatic mass. Three of 20 patients with postganglionic Horner's syndrome had carotid artery dissection. CONCLUSION: Routine scanning of patients who have postganglionic Horner's syndrome with cluster headaches was not helpful in our small series.

Adolescent↗