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Biomedical subjects

R C Sergott

Publications and source records attributed to R C Sergott.

At least 55 records · Page 3Linked to original sources
PubMed1993

Optic nerve decompression improves hemodynamic parameters in papilledema.

PURPOSE: The purpose of this study is to examine changes in color Doppler imaging parameters before and after optic nerve sheath decompression (ONSD) for chronic papilledema caused by pseudotumor cerebri (PTC). METHODS: Color Doppler imaging was performed within 48 hours before surgery and within 48 hours after the procedure using a color Doppler unit with a 7.5-MHz phased linear transducer. Pulsed Doppler spectrum analyses were recorded digitally on videotape from the ophthalmic, central retinal, and short posterior ciliary arteries, using a 0.4 x 0.6-mm sample volume. RESULTS: Blood flow velocities in the ophthalmic, short posterior ciliary, and central retinal arteries of 24 eyes were significantly decreased compared with a healthy age-matched group. Eyes with visual acuities worse than 20/30 before surgery had significantly decreased velocities in the ophthalmic, short posterior ciliary, and retinal arteries, whereas in eyes with visual acuities better than 20/30, only the short posterior ciliary and central retinal arteries demonstrated decreased velocities. In addition, Gosling's pulsatility index was increased for the central retinal artery but not the ophthalmic or short posterior ciliary arteries. Thirteen eyes improving in visual acuity and field after ONSD demonstrated significant improvement in all color Doppler imaging parameters for the short posterior ciliary arteries. The ophthalmic artery diastolic velocity also increased significantly but the central retinal artery parameters did not change. The eyes that remained stable or worsened did not demonstrate significant postoperative changes. CONCLUSION: These results suggest that some of the visual loss from chronic papilledema may be due to ischemia, and worsening visual acuity correlates with greater impairment of the retrobulbar circulation. One of the mechanisms by which ONSD improves visual function may be reversal of this ischemic process.

Arteries↗
PubMed1993

Successful scleral buckling procedures decrease central retinal artery blood flow velocity.

BACKGROUND: Limited data suggest that scleral buckling procedures may decrease posterior segment blood flow. How this may affect functional outcome remains unknown. METHODS: In a prospective, controlled study, color Doppler imaging was used to measure blood flow velocities in the central retinal and ophthalmic arteries of both eyes in patients with unilateral rhegmatogenous retinal detachments before and after primary scleral buckle repair. Encircling elements were used in all patients. Fellow eyes served as controls. RESULTS: Data from six consecutive patients did not show significant preoperative circulatory abnormalities in either artery compared with the controls. There was a statistically significant reduction in mean central retinal artery blood flow velocities of up to 53% in the immediate postoperative period. Ophthalmic artery blood flow velocities, however, did not significantly change after the procedure. Successful retinal reattachment with the expected visual improvement was achieved in all patients with this primary surgery. CONCLUSIONS: Scleral buckling procedures with encircling elements decrease blood flow velocities in the central retinal artery but leave the ophthalmic artery unaffected. Good anatomic and functional results still can be achieved despite these hemodynamic changes.

Adult↗
PubMed1993

Optic nerve sheath decompression may improve blood flow in anterior ischemic optic neuropathy.

PURPOSE: The purposes of this study are to evaluate the retrobulbar circulation in progressive nonarteritic ischemic optic neuropathy (NAION) and to assess changes in blood flow after optic nerve sheath decompression (ONSD). METHODS: Twenty-five patients with progressive NAION were studied using color Doppler imaging (CDI) before and after ONSD. Blood flow velocities and vascular resistance were calculated for the ophthalmic artery, central retinal artery, and posterior ciliary arteries in each eye. Contralateral eyes served as the control group. RESULTS: Preoperatively, the study group demonstrated significantly lower blood flow velocities in the central retinal artery (P < 0.002) and posterior ciliary arteries (P < 0.02) when compared with the contralateral control group. Postoperatively, there was a significant increase in blood flow velocity in the ophthalmic artery (P < 0.04) and the central retinal artery (P < 0.05) as well as a significant decrease in vascular resistance in the posterior ciliary arteries (P < 0.02) in the study group. There were no significant changes in blood flow velocity or vascular resistance in the contralateral control group. Long-term follow-up on eight patients suggests a persistence of this trend. Seventeen of the 25 operated eyes demonstrated a postoperative improvement in visual function, defined as a gain of two lines or more in Snellen visual acuity or at least 20 degrees of visual field expansion. CONCLUSIONS: These data demonstrate that eyes with acute NAION have impaired blood flow when compared with the contralateral control group. Furthermore, they suggest that ONSD may improve blood flow to the ischemic optic nerve halting the progression of visual loss and in some cases improving visual function.

Adult↗
PubMed1993

Orbital colour Doppler imaging.

Colour Doppler imaging (CDI) is an ultrasonic method for qualitatively and quantitatively assessing blood flow. Recently this technique has been adapted for investigation of the orbital, optic nerve and ocular vasculature. We discuss the history, principles and methodology of this examination technique for ophthalmology. Also described are normal haemodynamic characteristics as well as the findings in common pathological states involving derangements of orbital blood flow. Although CDI is relatively new to ophthalmology it has already proved to be of benefit in conditions with altered orbital, ocular and optic nerve blood flow. In the future it is expected that the indications for the applications of CDI will become more clearly defined and that orbital CDI will be more widely available and utilised, especially in the investigation of vascular diseases of the orbit, optic nerve and retina.

Arterial Occlusive Diseases↗
PubMed1993

Amplitude of the ocular pneumoplethysmography waveform is correlated with cardiac output.

BACKGROUND AND PURPOSE: Ocular pulse amplitude, the amplitude of the ocular pneumoplethysmographic waveform, is altered in several ophthalmologic diseases that disturb ocular blood flow, implying that ocular pulse amplitude may provide an estimate of ocular blood flow. Because ocular blood flow currently cannot be quantified in humans, two experiments were undertaken to evaluate the association of ocular pulse amplitude with total body blood flow. METHODS: In experiment 1, cardiac output was determined by cardiac catheterization in 181 patients who underwent OPG-Gee testing during the same hospitalization. In experiment 2, 110 instances of atrial arrhythmia captured on ocular pneumoplethysmographic tracings were evaluated for transient changes in heart rate (R-R ratio) associated with transient changes in ocular pulse amplitude (ocular pulse amplitude ratio). RESULTS: In experiment 1, average ocular pulse amplitude in the two eyes (OPAAV) was significantly correlated with cardiac output/heart rate (r = 0.53; p < 0.0001) and cardiac index/heart rate (r = 0.43; p < 0.0001). In experiment 2, R-R ratio was significantly correlated with ocular pulse amplitude ratio (r = 0.85; p < 0.001). CONCLUSIONS: These results show that ocular pulse amplitude, a physiological measurement obtained from the globe, is correlated with cardiac output. They imply that ocular pulse amplitude may provide a clinically useful estimate of at least the pulsatile component of ocular blood flow.

Aged↗
PubMed1993

Identification of gonadotroph adenomas in men with clinically nonfunctioning adenomas by the luteinizing hormone beta subunit response to thyrotropin-releasing hormone.

Because of the recent finding that a majority of clinically nonfunctioning pituitary macroadenomas in women could be identified as of gonadotroph origin by their LH beta-subunit responses to TRH, we evaluated in this study the value of the LH beta-subunit response to TRH in identifying gonadotroph adenomas in men with clinically nonfunctioning macroadenomas. Thirty-eight consecutively studied men with clinically nonfunctioning macroadenomas were given TRH iv, and intact FSH and LH and LH beta- and alpha-subunits were measured every 15 min for 90 min before and 90 min after. TRH tests were also performed on 15 healthy, age-matched control men and on 12 men with adenomas secreting GH or PRL. Of the 38 men with clinically nonfunctioning macroadenomas, basal values were supranormal in 10 for FSH and in 6 each for alpha- and LH beta-subunits. Responses to TRH were elevated, compared to the healthy, age-matched controls, in 14 for LH beta-subunit and in 5 each for intact FSH and LH. None of the men with adenomas secreting GH or PRL exhibited supranormal responses to TRH. Of the 38 clinically nonfunctioning adenomas, 35 were established in dispersed cell culture, and 29 secreted readily detectable amounts of intact FSH, LH, and LH beta-subunit, strongly suggesting that these adenomas were of gonadotroph cell origin. We conclude that the LH beta-subunit response to TRH can identify gonadotroph adenomas in men with clinically nonfunctioning adenomas better than can basal concentrations of intact FSH and alpha-subunit, alone or combined, but not as well as it can in women.

Adenoma↗
PubMed1993

Pseudotumor cerebri: CT findings and correlation with vision loss.

OBJECTIVE: The purpose of this study was to determine if orbital and cerebral CT can be used to distinguish normal patients from those with pseudotumor cerebri, and to correlate CT findings with the severity of visual impairment. SUBJECTS AND METHODS: Seventeen patients with a clinical diagnosis of pseudotumor cerebri were compared with 20 age- and sex-matched control subjects. Thin-section coronal and axial CT scans of the orbit and whole-brain axial CT scans were available for all subjects. The diameter of the optic nerve sheath, the degree of reversal of the optic nerve head, the presence and degree of empty sellae, and ventricular and sulcal sizes were evaluated without knowledge of whether or not the subject had pseudotumor cerebri. The same parameters were compared for two subgroups of patients with pseudotumor cerebri: those with mild vision loss and those with severe vision loss. RESULTS: Patients with pseudotumor cerebri had significantly larger optic nerve sheaths than did control subjects (6.5 +/- 0.83 mm vs 5.4 +/- 0.69 mm). Radiologic evidence of papilledema with reversal of the optic nerve head was found in 12 of 17 patients compared with one of 20 control subjects. An empty sella was seen more frequently and to a greater degree in patients with pseudotumor cerebri than in control subjects (16 vs seven). Eight of nine patients with severe vision loss and four of eight patients with mild to moderate vision loss had reversal of the optic nerve head; the degree was greater in the group with severe vision loss. No difference in ventricular size or sulcal enlargement was seen between any of the groups. The opening CSF pressures of the two groups with vision loss were not significantly different (348 +/- 80 mm H2O vs 391 +/- 98 mm H2O). CONCLUSION: In addition to the role of CT in excluding intracranial disease as a basis for the clinical syndrome of pseudotumor cerebri, thin-section CT of the orbits reveals a constellation of findings, including enlarged optic nerve sheaths, reversal of the optic nerve head, and empty sellae in patients with pseudotumor cerebri. Furthermore, severe vision loss in these patients correlates with more frequent and more severe reversal of the optic nerve head.

Adolescent↗
PubMed1993

Color Doppler imaging of the ocular and orbital blood vessels.

Color Doppler imaging (CDI) is a technique that provides color-encoded blood flow information on a gray-scale two-dimensional background. Although first reported in the investigation of orbital disease in 1979, it is only in the past 1 to 2 years that CDI has become established as a tool in the assessment of vascular disease of the eye and orbit. Discussed are clinical syndromes in which CDI has been shown to demonstrate abnormalities and also assist in diagnosis and determination of etiology.

Eye↗
PubMed1993

The influence of primary open-angle glaucoma upon the retrobulbar circulation: baseline, postoperative and reproducibility analysis.

CDI is showing continued promise as a reliable, reproducible method to assess the hemodynamics of a variety of ophthalmic diseases in which vascular perfusion abnormalities are suspect. Moreover, some patients with advanced POAG appears to have abnormalities of the vasculature of the retrobulbar circulation that is corrected by trabeculectomy. Continued CDI clinical correlations with longitudinal studies are now required to elucidate the significance of this technology and these results for individual patients.

Adult↗
PubMed1992

Spontaneous remission of a third-nerve palsy in meningeal lymphoma.

We report on a patient with spontaneous remission of a third-nerve palsy who was subsequently found to have meningeal lymphoma. Initial magnetic resonance images (MRI) showed bilateral enhancement of the third nerves. Follow-up MRI 7 months later, without treatment, showed complete resolution. One year after initial presentation, the patient developed multiple lumbosacral radiculopathies and examination of a nerve root biopsy specimen disclosed a B-cell lymphoma. Serial cerebrospinal fluid analyses over the previous year showed occasional atypical cells, later found to resemble closely the biopsy cell type. We conclude that meningeal lymphoma may have a protracted course, with spontaneous remission of both clinical and neuroimaging findings.

Aged↗
PubMed1992

Hemifacial spasm: evaluation by magnetic resonance imaging and magnetic resonance tomographic angiography.

We evaluated 37 patients with hemifacial spasm and 16 age-matched control patients with other neurological disorders using magnetic resonance (MR) imaging, MR angiography, and MR tomographic angiography. MR tomographic angiography is a new technique using computer reconstruction of MR angiographic images to create coronal angiotomes that display tissue and arterial structures on the same image. Twenty-four of 37 (64.9%) patients with hemifacial spasm had ipsilateral vascular compression of cranial nerve VII or the pons noted by this technique, whereas only 1 of 16 (6.3%) control patients had compression. MR imaging and MR angiography were less sensitive and less specific in evaluating for vascular compression. This study supports vascular compression of cranial nerve VII or the pons as a cause of hemifacial spasm, and demonstrates MR tomographic angiography's value as an excellent, noninvasive technique to demonstrate the compression.

Adult↗
PubMed1992

Color Doppler imaging of the ocular ischemic syndrome.

PURPOSE: This study describes hemodynamic characteristics of the ophthalmic, central retinal, and posterior ciliary arteries in 16 eyes of 11 patients with the ocular ischemic syndrome. Understanding the hemodynamic characteristics of the retrobulbar circulation may elucidate the natural history and pathophysiology of the ocular ischemic syndrome and perhaps form the basis for rational treatment of this condition. METHODS: Color Doppler imaging, a procedure that permits rapid noninvasive imaging of the ophthalmic, central retinal, and posterior ciliary arteries, was used to quantitate peak systolic blood flow velocities and vascular resistance (pulsatility index) within these vessels in study group eyes and in an age-matched control population. RESULTS: We demonstrated markedly reduced ocular ischemic syndrome central retinal and posterior ciliary artery peak systolic velocities compared with control group eyes. Central retinal and posterior ciliary artery vascular resistance (pulsatility index) was greater in ocular ischemic eyes versus control group eyes. Reversal of ophthalmic artery blood flow was detected in 12 of 16 ocular ischemic syndrome eyes. Study group eyes with poor vision had no detectable posterior ciliary arterial blood flow. CONCLUSION: Color Doppler imaging quantitates hemodynamic characteristics of the retrobulbar circulation in the ocular ischemic syndrome. There is markedly reduced peak systolic velocity and increased vascular resistance in ocular end arteries such as the central retinal and posterior ciliary arteries. Ophthalmic artery reversal of flow seems to represent collateral blood flow to lower resistance vascular beds. Posterior ciliary artery hypoperfusion may correlate with poor vision in the ocular ischemic syndrome.

Aged↗
PubMed1992

Gaze-induced amaurosis from central retinal artery compression.

Color Doppler imaging was used to evaluate a patient with gaze-induced amaurosis caused by an intraconal orbital mass. The time-velocity waveform demonstrated abnormally high vascular resistance in the central retinal artery of the affected eye in the primary position. Abduction of the affected eye resulted in transient visual loss with an unreactive pupil. This same maneuver during color Doppler imaging resulted in a dramatic reduction of blood flow in the central retinal artery. Two months after surgical excision of the mass, the gaze-evoked amaurosis was no longer present, and color Doppler imaging demonstrated normal blood flow in the central retinal artery. This suggests that impaired retinal and optic nerve blood flow are responsible for gaze-induced amaurosis from compressive orbital lesions.

Adolescent↗
PubMed1992

Color Doppler imaging of the eye and orbit. A synopsis of a 400 case experience.

Color Doppler imaging (CDI) is a recent advance in ultrasonography that allows simultaneous two-dimensional imaging of structure and blood flow. Doppler information is superimposed in color over a conventional gray-scale ultrasound image. Using this technique we have examined 400 eyes. The central retinal artery, posterior ciliary arteries, ophthalmic artery, the central retinal vein and the vortex veins could be located in all normal eyes. Using the color image as a guide, Doppler spectral analysis is used for quantitative assessment of blood flow velocity in these vessels. We also studied patients with intraocular tumors, arterial and venous retinal occlusions, orbital vascular anomalies and tumors. Color Doppler imaging is a new and promising modality for the study of ocular and orbital hemodynamics.

Blood Flow Velocity↗
PubMed1992

In vivo modulation of oligodendrocyte function by an anti-receptor antibody.

The receptor for reovirus serotype 3 (Reo3R) is biochemically, pharmacologically, and antigenically related to the adrenergic receptors. Previous studies have demonstrated that anti-Reo3R antibodies and Reo3R-binding peptides alter oligodendrocyte differentiation in culture. In the present studies, antibodies and peptides that bind the Reo3R were found to alter myelin morphology in vivo. Microinjection of purified anti-Reo3R antibody into guinea pig optic nerves produced expansion of the adaxonal oligodendrocyte cytoplasm, separation of myelin lamellae, widening of Schmidt-Lanterman clefts, myelin vesiculation, and demyelination. A divalent Reo3R-binding peptide reproduced some of these changes. Anti-Reo3R antibodies and Reo3R-binding peptides alter oligodendrocyte function in vivo resulting in myelin changes. These effects appear to be mediated directly by Reo3R perturbation, at least in part, rather than through activation of additional effector mechanisms.

Amino Acid Sequence↗
PubMed1991

Neuro-imaging and positron emission tomography of congenital homonymous hemianopsia.

Congenital homonymous hemianopsia is an uncommon asymptomatic visual field defect discovered typically in young adult life that is caused by a diverse group of insults to the retrochiasmal afferent visual system occurring prenatally, at birth, or during early childhood. We treated eight patients with congenital homonymous hemianopsia; seven with damage involving the optic radiations and one with an abnormality of the optic tract. We performed positron emission tomography using 18F-fluoro-2-deoxyglucose on two patients with dense homonymous hemianopsias, lesions of the contralateral optic radiations, and largely intact occipital cortex. These studies showed minimal abnormalities in resting visual cortex glucose metabolism of the affected visual cortex.

Adolescent↗