Equivalence of cell survival data for radiation dose and thermal dose in ablative treatments: analysis applied to essential tremor thalamotomy by focused ultrasound and gamma knife.

Thermal dose and absorbed radiation dose have historically been difficult to compare because different biological mechanisms are at work. Thermal dose denatures proteins and the radiation dose causes DNA damage in order to achieve ablation. The purpose of this paper is to use the proportion of cell survival as a potential common unit by which to measure the biological effect of each procedure. Survival curves for both thermal and radiation doses have been extracted from previously published data for three different cell types. Fits of these curves were used to convert both thermal and radiation dose into the same quantified biological effect: fraction of surviving cells. They have also been used to generate and compare survival profiles from the only indication for which clinical data are available for both focused ultrasound (FUS) thermal ablation and radiation ablation: essential tremor thalamotomy. All cell types could be fitted with coefficients of determination greater than 0.992. As an illustration, survival profiles of clinical thalamotomies performed by radiosurgery and FUS are plotted on a same graph for the same metric: fraction of surviving cells. FUS and Gamma Knife have the potential to be used in combination to deliver a more effective treatment (for example, FUS may be used to debulk the main tumour mass, and radiation to treat the surrounding tumour bed). In this case, a model which compares thermal and radiation treatments is valuable in order to adjust the dose between the two.

Imaging findings in MR imaging-guided focused ultrasound treatment for patients with essential tremor.

BACKGROUND AND PURPOSE: MR imaging-guided focused sonography surgery is a new stereotactic technique that uses high-intensity focused sonography to heat and ablate tissue. The goal of this study was to describe MR imaging findings pre- and post-ventralis intermedius nucleus lesioning by MR imaging-guided focused sonography as a treatment for essential tremor and to determine whether there was an association between these imaging features and the clinical response to MR imaging-guided focused sonography. MATERIALS AND METHODS: Fifteen patients with medication-refractory essential tremor prospectively gave consent; were enrolled in a single-site, FDA-approved pilot clinical trial; and were treated with transcranial MR imaging-guided focused sonography. MR imaging studies were obtained on a 3T scanner before the procedure and 24 hours, 1 week, 1 month, and 3 months following the procedure. RESULTS: On T2-weighted imaging, 3 time-dependent concentric zones were seen at the site of the focal spot. The inner 2 zones showed reduced ADC values at 24 hours in all patients except one. Diffusion had pseudonormalized by 1 month in all patients, when the cavity collapsed. Very mild postcontrast enhancement was seen at 24 hours and again at 1 month after MR imaging-guided focused sonography. The total lesion size and clinical response evolved inversely compared with each other (coefficient of correlation = 0.29, P value = .02). CONCLUSIONS: MR imaging-guided focused sonography can accurately ablate a precisely delineated target, with typical imaging findings seen in the days, weeks, and months following the treatment. Tremor control was optimal early when the lesion size and perilesional edema were maximal and was less later when the perilesional edema had resolved.

Distal biceps tendon anatomy: a cadaveric study.

BACKGROUND: The anatomy of the distal biceps tendon and aponeurosis has not been studied in detail. METHODS: Seventeen cadaver elbows were dissected with loupe magnification to identify the details of the distal biceps tendon and the lacertus fibrosus. RESULTS: In ten of the seventeen specimens, the distal biceps tendon was in two distinct parts, each a continuation of the long and short heads of the muscle. The remaining seven specimens showed interdigitation of the muscle distally. The tendon continued from each muscle belly. The short head inserted distal to the radial tuberosity and was positioned to be a more powerful flexor of the elbow, while the tendon of the long head inserted on the tuberosity further from the axis of rotation of the forearm and was positioned to be a stronger supinator. The bicipital aponeurosis consisted of three layers and completely encircled the ulnar forearm flexor muscles. The aponeurosis may be important in stabilizing the tendons distally. CONCLUSIONS: The double tendon insertion may allow an element of independent function of each portion of the biceps, and, during repair of an avulsion, the surgeon should ensure correct orientation of both tendon components.

A fractured peace: a changing pattern of violence.

Since the paramilitary cease-fire in Northern Ireland in August 1994 we have seen a change in the pattern of so called 'punishment attacks'. Shootings with low velocity handguns have been replaced by severe beatings to the extremities from multiple assailants using iron bars or similar weapons. In the 18 months prior to the cease-fire there were 177 punishment shootings, which were usually relatively minor and did not require any plastic surgical expertise. Between August 1994 and November 1996, however, there were 461 punishment beatings. These beatings result in much greater morbidity and require considerable orthopaedic and plastic surgical input. In the Northern Ireland Plastic and Maxillofacial Unit we have treated 18 patients with a mean age of 22.9 years (range 16-32 years) who have been the victims of punishment beatings. These patients sustained multiple injuries, all with severe soft tissue involvement; 70% had compound fractures. The majority of patients had multiple wounds. Four patients with compartment syndrome as a result of their injuries required fasciotomies. Soft tissue reconstruction included split skin grafting (4 patients), fasciocutaneous flaps (4 patients), adipofascial flaps (2 patients), local muscle flaps (2 patients) and free muscle transfers (2 patients). Six patients required more than one procedure for soft tissue reconstruction because of multiple injuries. Each patient had a cumulative mean time in theatre of 6.7 hours. The mean hospital stay was 22.2 days (range 2-52 days). This change in the pattern of injury has led to an increased use of plastic surgical resources. Patient morbidity is significantly greater than when guns are used, and permanent disability is often the result.

Social deprivation and premature mortality: regional comparison across England.

OBJECTIVE: To investigate the pattern and size of the relationship between social deprivation in electoral wards and premature mortality for each health region in England. DESIGN: Ecological study using 1981 census variables and data on mortality for 1981-5. SETTING: 14 regional health authorities in England. MAIN OUTCOME MEASURE: Mortality under the age of 65 years from all causes, coronary heart disease, and smoking related diseases in men and women. RESULTS: Increasing deprivation was significantly associated with mortality from all causes, coronary heart disease, and smoking related diseases. The relationship was linear with no apparent threshold. Correlation coefficients were generally greater for deaths from all causes and smoking related diseases and for men compared with women. The slope of the relationship between deprivation and mortality varied among regions. Variations in mortality still existed between regions for equal levels of deprivation. CONCLUSION: Deprivation of an area and premature mortality are strongly linked. The effects of deprivation can be seen throughout the range of affluence and are not limited to the poorest areas. Current targets for reducing coronary heart disease mortality may be achievable if the mortality in poor areas can be reduced to the rates in affluent areas.

Baby bottles and family rattles. Children and substance abuse.

Research shows that problem behaviors manifested early tend to persist into later life. Problem drinking does not necessarily commit the young adolescent to a life course of this behavior, but it does alter the probabilities. Conversely, early abstinence is a strong predictor of later healthful behavior. An important observation is that alcohol and other drug use tends to decrease along with smoking decreases. Young adolescents tend to believe that most of their peers engage in a particular type of behavior whether that is the actual case or not. There is a tendency across populations of adolescents to overestimate such behaviors by a factor of six or eight. In one study, school children estimated that about two-thirds of their peers smoked while the actual figure was about one-tenth. Adolescents tend to have weak orientation to the future, especially in regard to consequences of risk-taking behavior. College-bound adolescents tend to have a longer view of the future than those who do not pursue college, but in general adolescents think, "It can't happen to me," or, "It's so far off that I just can't think about it." They are focused on the here and now. Many youngsters when they think about it have a dismal view of the future. They are doubtful about their own ability to influence events in ways that build toward a rewarding life.(ABSTRACT TRUNCATED AT 250 WORDS)