Biomedical subjects

P B Licht

Publications and source records attributed to P B Licht.

8 recordsLinked to original sources

PubMed2001

Tracheal cancer in Denmark: a nationwide study.

OBJECTIVE: Most published series on tracheal cancer reflect single institution experiences. We used the nationwide Danish Cancer Registry to report on characteristics and treatment of tracheal cancers in Denmark. METHODS: One hundred and nine cases of primary tracheal cancers were extracted from the registry in the period 1978-1995. The clinical data, histological distribution and treatment modalities were analyzed. The cancers were staged in four groups (stage I-IV) according to size, location and spread. RESULTS: Seventeen cases were diagnosed at autopsy. Ninety-two cases were diagnosed in vivo and 84% of these within 3 months after the first consultation. Sixty-three percent of the cancers were squamous cell carcinomas and only 7% were adenoid cystic carcinomas. The disease was at stage I in 21%, stage II in 23%, stage III in 6% and stage IV in 50%. The majority of the patients received radiotherapy as single treatment. Only nine patients were offered surgery (six were resected and three were found inoperable). The overall survival rates for cases diagnosed in vivo were 1-year 32%, 2-year 20% and 5-year 13%. For the resected patients the 5- and 15-year survival rates were 50%. CONCLUSIONS: Tracheal cancers were rare and adenoid cystic carcinomas not as frequent as generally believed. Surgery was rarely offered. A resectability rate of only 10% is not adequately explained by selection bias and indicates a nihilistic attitude based on ignorance about surgical treatment of tracheal cancers. A more dedicated and aggressive approach with centralized workup and radical treatment is strongly recommended.

Adult↗

PubMed2001

Endovascular treatment of severe symptomatic stenosis of the internal carotid artery: early and late outcome.

OBJECTIVES: To report a 6 year experience with carotid percutaneous transluminal angioplasty (CPTA) in a selected group of patients. MATERIAL AND METHOD: We retrospectively reviewed our experience after performing 54 CPTAs, with (n=18) or without (n=36) stent deployment, over a period of 6 years from 1993 to 1999. All patients, except one, suffered from focal hemispheric neurologic symptoms. During the same time period 284 patients underwent carotid endarterectomy. The selection of the 54 patients (16%) for CPTA was based on the carotid angiogram and the sole inclusion criterion for endovascular treatment was a short, concentric, and smooth stenosis of more than 70% without ulceration or severe calcification. All patients who had a patent internal carotid artery after the last control were invited for a clinical duplex examination and all duplex examinations were carried out by a single experienced observer. RESULTS: Early outcome (<30 days): CPTA was judged technically successful in 50 cases (93%). Ten patients (18%) experienced a neurological event in relation to the procedure and one patient (2%) suffered a major stroke. One stent occluded within 30 days. LATE OUTCOME: Forty-six patients (85%) entered the follow-up study after a median of 34 months (range 1-80 months). Six patients (13%) had recurrent symptoms. The colour-duplex examination (n=45) showed internal carotid artery occlusion in 2 patients (5%), and restenosis (>70%) in 10 patients (22%). We found no significant difference in the reoccurrence of neurological symptoms or the rate of restenosis between patients treated with and without stent (Log Rank 0.28, p=0,59). ICA was patent without restenosis in 60% after 48 months in patients treated with CPTA alone, and in 76% after 3 months in patients treated with a stent (N.S.). CONCLUSION: CPTA in a selected group of patients has a mortality and major stroke rate comparable to that of carotid endarterectomy. However, the risk of transient neurological events was high, as well as the incidence of restenosis (>70%) after 3 years. We still consider CPTA an experimental procedure. The indications for this treatment must be clarified if CPTA should be an alternative to surgery with a comparable neurological complication rate.

Adult↗

PubMed1999

Vertebral artery flow and cervical manipulation: an experimental study.

BACKGROUND: Spinal manipulation therapy is used by millions of patients each year to relieve symptoms caused by biomechanical dysfunction of the spine. Cerebrovascular accidents in the posterior cerebral circulation are a feared complication, but little research has been done on vertebral artery hemodynamics during cervical manipulation. OBJECTIVE: The purpose of this study was to develop an experimental model for investigations of volume blood flow changes in the vertebral arteries during premanipulative testing of these vessels and during spinal manipulation therapy of the cervical spine. DESIGN AND SETTING: An experimental study in a university biomedical laboratory. MATERIAL AND METHODS: The vertebral arteries were exposed in 8 adult pigs after extensive mediastinal dissection. Volume blood flow was measured on both sides simultaneously by advanced transit-time flowmetry. RESULTS: After cervical manipulation, the vertebral artery volume blood flow increased significantly for 40 seconds before returning to baseline values in less than 3 minutes. We found no significant changes in volume flow during premanipulative testing of the vertebral arteries (DeKleyn's test). CONCLUSION: We present an experimental model for investigations of vertebral artery hemodynamics during biomechanical interventions. We found a modest and transient effect of cervical manipulation on vertebral artery volume flow. The model may have further applications in future biomechanical research, for example, to determine whether any of several spinal manipulative techniques imposes less strain on the vertebral artery, thereby reducing possible future cerebrovascular accidents after such treatment.

Analysis of Variance↗

PubMed1999

Volume flow estimation by colour duplex.

OBJECTIVE: To assess the accuracy of volume blood flow using a digitised colour duplex scanner. DESIGN: Observer-blinded experimental study. MATERIALS AND METHODS: Method comparison was performed with linear regression analysis of 89 paired observations in 11 anaesthetised pigs. A Siemens Sonoline Elegra ultrasound system was used for transcutaneous volume flow estimation using invasive transit time flowmetry by Cardiomed as a reference. RESULTS: For the individual measurement we found a standard error of the estimate (SEE) of 22 ml/min. For the regression line, however, the SEE was only 0.2 ml/min. CONCLUSIONS: Digitised colour-duplex sonography has a volume flow measurement error that is too high for single measurements in the individual patient for the method to be useful in clinical decision making, but sufficient for examinations of groups and comparison of groups.

Animals↗

PubMed1998

Triplex ultrasound of vertebral artery flow during cervical rotation.

BACKGROUND: Reviewing the literature on vertebral artery flow during cervical rotation shows various results. Furthermore, most studies have investigated exclusively the effects of contralateral rotation employing less-than-optimal Doppler ultrasound technique. OBJECTIVE: The aim of this study was to use the latest advancement in Doppler ultrasound technology to investigate flow velocity in the vertebral artery during both ipsilateral and contralateral cervical rotation in normal subjects. DESIGN AND SETTING: A prospective, controlled study in a university hospital vascular laboratory. PARTICIPANTS: Twenty healthy university students. RESULTS: Peak flow velocity decreased significantly during contralateral rotation and increased significantly during ipsilateral rotation. The differences, however, were modest. We found no correlation between peak flow velocity and systolic blood pressure. CONCLUSION: With modern Doppler ultrasound technique, preventing some sources of error in measuring, our finding during contralateral rotation were in accordance with most previous studies showing a decrease in peak flow velocity. For the first time, however, we report an increased flow velocity in the vertebral artery during ipsilateral rotation.

Adult↗

PubMedDate not supplied

Is there a role for premanipulative testing before cervical manipulation?

BACKGROUND: Spinal manipulative therapy is used millions of times every year to relieve symptoms from biomechanic dysfunction of the cervical spine. Concern about cerebrovascular accidents after cervical manipulative therapy is common but rarely reported. Premanipulative tests of the vertebral artery are presumed to identify patients at risk but controversy exists about their usefulness. OBJECTIVE: The aim of this study was to examine vertebral artery blood flow in patients with a positive premanipulative test for contraindication to spinal manipulative therapy and to investigate if chiropractors would reconsider treating such patients if dynamic vascular Doppler examination was normal. DESIGN AND SETTING: A prospective study at a university hospital vascular laboratory. METHODS: Chiropractors in private practice from 3 Danish counties referred patients with a positive premanipulative test for an examination of vertebral artery blood flow. Premanipulative testing was performed by an experienced chiropractor. Flow velocities were measured in both vertebral arteries by color duplex sonography. In addition, chiropractors were asked if they would treat their patient despite a positive premanipulative test if the vascular ultrasound examination was normal. RESULTS: A total of 20 consecutive patients with a positive premanipulative test were referred. Five were excluded because symptoms could not be reproduced during the vascular examination. In the remaining patients, no significant difference in peak flow velocity or time-averaged mean flow velocity with different head positions was found. Nineteen of 21 chiropractors would treat a patient with a positive premanipulative test if the vascular examination was normal. Eight of the patients with a positive manipulative test were treated without complications. Six are now symptom-free, and 2 have improved symptoms. The remaining 8 patients refused manipulation and continue to have the same symptoms. CONCLUSION: It appears that a positive premanipulative test is not an absolute contraindication to manipulation of the cervical spine. If the test is able to identify patients at risk for cerebrovascular accidents, we suggest patients with a reproducible positive test should be referred for a duplex examination of the vertebral artery flow. If duplex flow is normal, the patient should be eligible for cervical manipulation despite the positive premanipulative test.

Adult↗

PubMedDate not supplied

Vertebral artery volume flow in human beings.

BACKGROUND: A number of studies have investigated vertebral artery flow velocity. Because perfusion relates to the volume of blood flowing through the vessel, this parameter is of great importance when vertebral artery hemodynamics are investigated. We could not find any such Doppler studies in the literature, possibly because of known errors with previous techniques. New advanced color-coded duplex sonography has since been validated and may be used with confidence for volume flow investigations. OBJECTIVE: To use advanced color-coded duplex sonography to investigate volume flow through the vertebral arteries during cervical rotation, as well as before and after spinal manipulation therapy. DESIGN AND SETTING: A randomized controlled study at a university hospital vascular laboratory. PARTICIPANTS: Twenty university students. RESULTS: Volume blood flow through the vertebral arteries does not change with cervical rotation or after spinal manipulation therapy. CONCLUSION: This appears to be the first in vivo Doppler study on human vertebral artery volume blood flow. Our results indicate that in symptom-free subjects there is no change in vertebral artery perfusion during rotation in spite of significant changes in flow velocity. This finding, as well as the observed changes in flow velocity reported by others, may be explained by a positional change in the vertebral artery diameter. In addition, we have investigated volume blood flow in the vertebral arteries before or after spinal manipulation therapy but found no significant changes.

Adult↗

PubMedDate not supplied

Vertebral artery flow and spinal manipulation: a randomized, controlled and observer-blinded study.

BACKGROUND: Several studies have been published on the effect of cervical rotation alone upon blood flow in the vertebral arteries. However, we have not found articles addressing the question of how spinal manipulative therapy per se affects the vertebral artery flow. OBJECTIVE: The aim of the present study was to investigate whether any changes occur in peak flow velocity in the vertebral artery after spinal manipulative therapy as measured using the latest Doppler ultrasound technology. DESIGN AND SETTING: A randomized, controlled and observer-blinded study at a university hospital vascular laboratory. PARTICIPANTS: Twenty university students with a "biomechanical dysfunction" in the cervical spine. RESULTS: We observed no change in peak flow velocity immediately after spinal manipulative therapy and found no correlation between peak flow velocity and systolic blood pressure. CONCLUSION: To the best of our knowledge, this is the first study comparing flow velocity in the vertebral artery before and after spinal manipulative therapy. We found no significant changes in otherwise healthy subjects with a biomechanical dysfunction of the cervical spine. Major changes in peak flow velocity might in theory explain the pathophysiology of cerebrovascular accidents after spinal manipulative therapy. However, in uncomplicated spinal manipulative therapy, this potential risk factor was not prevalent.

Adult↗