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Biomedical subjects

H M Keller

Publications and source records attributed to H M Keller.

At least 19 recordsLinked to original sources
PubMed1988

[Vascular cause of hemianopsia].

Hemianopsia of vascular origin can be caused by diseases in the carotid circulation (optic tract, proximal third of the optic radiation), as well as in the vertebrobasilar arterial system (middle and distal thirds of the optic tract, striate area/calcarina). Hemianopsia of ischemic origin must be differentiated from hemianopia in the presence of an enlarging aneurysm, a space-occupying intracranial lesion (hemorrhage, neoplasia), and inflammatory disease, occasionally in metabolic disorders. To detect the exact cause of a hemianopia in a given patient, recording of the patient's precise history and clinical-neurological, clinical-ophthalmological, and clinical-internal examinations are mandatory, as well as additional diagnostic procedures. Of these, the most important are neurovascular ultrasound examinations (extracranial, transcranial and B-mode/duplex Doppler examination), CT and MRI scans, and cardiological examination with echocardiography. The choice of these additional and costly examinations and their sequence in the diagnostic work-up in a given patient has to be adapted to the patient.

Aged↗
PubMed1986

Fibromuscular hyperplasia: extension of the disease and therapeutic outcome. Results of the University Hospital Zurich Cooperative Study on Fibromuscular Hyperplasia.

92 patients with fibromuscular hyperplasia (FMH) seen at the University Hospital Zurich were studied. Renovascular FMH was the most frequent manifestation of the disease (89%). FMH of the cerebral arteries was seen in 26%. The intestinal and subclavian arteries were involved in 9% each and the iliac arteries in 5% of the patients. In 2 patients each FMH of the abdominal aorta or the coronary arteries, respectively, was found. 26% of the patients had systemic disease with involvement of 2 or more arteries. Half of the patients with bilateral renovascular disease showed additional extrarenal FMH. All patients with renovascular FMH were hypertensive (mean blood pressure 194 +/- 34/119 +/- 18 mm Hg). Surgery, percutaneous transluminal angioplasty (PTA) and medical therapy were equally effective in controlling blood pressure. The cure rates were 52% in patients undergoing surgery and 50% in those treated with PTA. The complication rate, however, was higher with surgery (11%) than with PTA (3%). 62% of the patients treated medically were normotensive. Major side effects occurred in 4.8%. The outcome of curative interventions (surgery or PTA) was influenced by the extension of FMH. In unilateral disease the cure rate was significantly higher (62%) than in systemic FMH (28%; p less than 0.03). Patients with strict bilateral disease were cured in 50%. We conclude: (a) PTA seems to be the treatment of choice in renovascular FMH because of a high cure and a low complication rate and (b) the outcome of curative interventions seems markedly influenced by the extension of FMH in these patients.

Adult↗
PubMed1985

Early cortical median nerve somatosensory evoked potentials. Prognostic value in anoxic coma.

Subcortical and early cortical median nerve somatosensory evoked potentials (SEPs) were examined in 26 patients in hypoxic coma. The amplitude ratio between the negative slope of the scalp response and the following positive trough was determined. The latency difference between the major negative component recorded from the upper neck, N14, and the initial negative potential from the scalp, N20, was also measured. The mean of these parameters in both hemispheres was referred to as mean central conduction time (MCCT) and mean amplitude ratio (MAR). There was a significant difference in MAR in patients with a bilaterally recordable scalp response between those with a good and those with a bad outcome, but no difference in MCCT. Comparison of SEP findings with postmortem examinations suggests that a reduced MAR may yield an estimate of cortical damage in hypoxic coma.

Adult↗
PubMed1984

[Cerebrovascular Doppler studies--a potent tool in neuroangiology].

Cerebrovascular disease is caused in about half of the patients by obstructions in the extracranial cerebral arteries. In the other half, stroke is due in roughly equal proportions to obstructive intracranial arterial lesions, emboli from the heart, or intracranial hemorrhage. Half of the patients with major ischemic stroke had previous warning signs in the form of transient ischemic attacks (TIA), reversible ischemic neurologic deficit (RIND) or infarction with only minor residual deficit not limiting daily activity, professional skills, and quality of life. Investigation of patients with warning signs of impending ischemic stroke is mandatory in order to prevent other events with possible major disability, but also, in patients with acute infarction, in order to choose the appropriate early therapy and rehabilitation. Routine cerebrovascular Doppler examination based on continuous-wave equipment has been successfully used to detect extracranial arterial obstructions. In the authors' experience of more than 12000 patients this noninvasive diagnostic tool makes it possible-in conjunction with the patient's history and the results of the clinical examination-to differentiate between obstructions needing surgery and lesions small enough to warrant medical treatment. Minor lesions which do not disturb blood flow locally, or accessible to available continuous-wave Doppler equipment, can be detected with real-time ultrasound imaging systems, i.e. B-mode or B-mode-Doppler-(duplex) systems in addition to routine Doppler examination. These complex systems also serve to follow-up patients with minor lesions which are not treated, or treated medically, in regard to deterioration, possible invariability, or even regression of a lesion.

Adult↗
PubMed1984

[Doppler analysis of blood flow of the supratrochlear artery: age specific pattern analysis in healthy and hypertensive patients].

Averaged Doppler blood flow signals of the supratrochlear artery were used to evaluate age-dependent parameters and ratios in 102 patients with essential hypertension as the only risk factor, and in 74 normotensive healthy volunteers. The first and second systolic peak values (A and B), the minimal value in between A and B (K), the value of the incisura (I), the value of the diastolic peak (D), the time interval between the R-peak of the ECG and A (ti), the duration of the systolic rising phase (ts), and the time interval between the R-peak of the ECG and the footpoint of the systolic rising phase (ti-ts) were used as parameters, and (A-K)/A, A/B, and (D-I)/A were used as ratios. The (A-K)/A-ratio and A/B decreased with age and differed significantly between hypertensive patients 41 to 70 years of age and normotensive controls, between ineffectively treated hypertensive patients 31 to 70 years of age and normotensive controls, and between ineffectively treated hypertensive patients with normalized blood pressure under an antihypertensive regimen in the age group 41 to 60 year. B-values increased, I- and D-values did not change, the (D-I)/A-ratio decreased, the time interval (ti) and (ti-ts) decreased, and the duration of the systolic rising phase (ts) increased with age, but no significant difference was found for all these parameters and ratios between any comparable groups. Our findings suggest that the age-dependent pattern of blood flow signals may represent vascular alterations which are markedly accelerated in hypertensive patients as compared to age-matched normotensive controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

[Evaluation of coma using evoked brain potentials].

Subcortical sensory evoked potentials are of growing importance in assessing brain damage in comatose patients. First, they are not susceptible to sedative and narcotic drugs; second, the investigation can easily be performed in the intensive care unit; and third, off-line results are immediately available. Subcortical somatosensory evoked potentials (SEP) proved to be more reliable in assessing brain function than brainstem auditory evoked potentials (BAEP). Our own experience with this method is illustrated by several case reports.

Adult↗
PubMed1982

Cerebrovascular Doppler-ultrasound examination in children: principle, indication and findings.

The cerebrovascular Doppler examination (cv-Doppler) is a reliable noninvasive method for the diagnosis of obstructions in the extracranial cerebral arteries, and of major arteriovenous shunts in adult patients. The method was applied in 38 children aged 4 months to 17 years. 25 patients with symptoms of cerebrovascular disease underwent cerebral angiography. Six patients had extracranial arterial obstruction, all correctly diagnosed by Doppler. Six children had obstruction of the middle cerebral artery, four were indirectly predicted by Doppler. Four of these twelve patients had extra-intracranial bypass surgery. The patency of the anastomosis could be documented in all cases by Doppler. Ten children had arterio-venous shunts. Of these, 7 patients with an av-angioma and one patient with a carotid-cavernous-sinus fistula were diagnosed correctly by Doppler, as was the cessation of pathologically increased blood flow in the feeding and draining vessels in the 5 patients who had surgical intervention. cv-Doppler results were normal in 3 cases with normal angiography. These results demonstrate that cv-Doppler examination can be useful also in children for the diagnosis of cerebrovascular disease and noninvasive documentation of the hemodynamic effect of neurovascular surgery.

Adolescent↗
PubMed1982

Persistent cervical intersegmental artery as a cause of recurrence of a traumatic carotid-cavernous fistula: case report, with emphasis on Doppler ultrasound diagnosis.

In a 16-year-old boy, minor symptoms of an arteriovenous shunt into the cavernous sinus recurred 3 months after the performance of a trapping operation of the internal carotid artery on the side of a traumatic carotid-cavernous sinus fistula. An arterial and venous cerebrovascular Doppler examination demonstrated increased blood flow in the periorbital veins of both sides, with a pathological flow direction, i.e., from intra- to extracranial. Furthermore, an internal-like artery was found at the level of the carotid bifurcation on the side of the trapped internal carotid artery, and increased blood flow was registered in the homolateral vertebral artery. Angiography confirmed occlusion of the internal carotid artery 0.5 cm distal to the carotid bifurcation, but showed blood flow from the homolateral vertebral artery through a persistent 3rd cervical intersegmental artery into the trapped portion of the internal carotid artery. The latter fed blood into the cavernous sinus through the still-existing arteriovenous fistula. Insufficient involution of the 3rd cervical intersegmental artery was assumed. Obviously, this collateral artery dilated in the presence of a major blood pressure gradient between the vertebral artery and the trapped segment of the internal carotid artery. Thus, a persistent cervical intersegmental artery can be a cause for a recurrent carotid-cavernous sinus fistula.

Adolescent↗