The phenomenon of making decisions during the experience of early breast cancer.

Breast cancer patients are faced with many decisions about their treatment, relationships and lives. The aims of this study were: to provide an understanding of the phenomenon of making decisions during the experience of early breast cancer, and to describe the types of decisions these patients are typically faced with. Previous research has focused largely on describing the different ways patients behave when making choices about treatment. However, few studies provide an understanding of the range of decisions women are likely to face, or describe what the experience of making these decisions is like. Hermeneutic phenomenology was used to inform the research. In-depth interviews were conducted with 18 breast cancer patients who had completed treatment. This study provides an understanding of the broad range of decisions with which women may be faced, and presents a new interpretation of what the experience of making decisions is like for women diagnosed with breast cancer. Five existential themes were found to be representative of the experience of making decisions: being challenged, getting ready, surviving, sharing the challenge and interrogating the future. Health professionals can use the understandings presented to improve their therapeutic relationships with patients and further assist women as they work through their experience of breast cancer.

Radiographic method to assess the prevalence of sacral spina bifida occulta.

Spina bifida occulta of the sacrum is the most common type of spinal deformity. Many authors have published data on the frequency of spina bifida occulta, with varying results. Some possible reasons for this variability could include the differing methods used to gather data and differing ways of classifying the condition. This study attempts to develop an X-ray method to study sacral spina bifida occulta in a standardized fashion, using an angulated antero-posterior technique. This technique is then used to estimate the frequency of sacral spina bifida occulta in an Australian sample. The sacra of 53 cadavers were X-rayed and the level of closure of the sacral spinal canal recorded. The X-ray technique was validated by open dissection of six of the cadavers studied and was shown to be accurate to half a sacral segment. No sacra with a completely open sacral canal were found, two sacra (4%) were open from S2 down to S5 and ten sacra (19%) were open from S3 down to S5. The most common condition (43%) recorded was where S4 and S5 only were open. Eighteen cadavers (34%) showed only S5 open, and interestingly, no sacra were recorded as having the dorsal sacral arch completely closed. A study of a larger sample will follow using the validated X-ray technique.

The experience of making treatment decisions for women with early stage breast cancer: a diagrammatic representation.

Women who are making decisions about treatment for early stage breast cancer interact with a number of people when they are considering their treatment options and the impact breast cancer will have on their lives. Previous research has considered patient preferences for involvement in treatment decision-making and proposed factors that may influence breast cancer treatment decisions. However, to date, there has been a paucity of research focusing on the experience of making treatment decisions from the women's perspective. The aim of this paper is to describe the relationships between the women, the medical practitioners and other people, and to consider features that may be influential in the experience of making treatment decisions. Two models are proposed to represent concepts that are linked to the experience of making treatment decisions. The first model proposed has been formulated to represent factors that may influence the treatment decision. The second model highlights aspects of the women's lives that may be affected. This paper discusses concepts that are presented in the conceptual models and makes suggestions for future studies relating to the experience of making treatment decisions for women with breast cancer.

The role of the muscle spindles in human masseter.

In the limb muscles, the muscle spindles have been demonstrated to be important in the maintenance of static posture. This role is supported by the close proximity of the muscle spindles to motor units that develop small forces and are fatigue-resistant, and the greater effectiveness of the input from muscle spindle afferents onto the small motoneurons supplying these motor units. In masseter, input from the muscle spindles is more effective on the larger motoneurons. This suggests that the muscle spindles may be more important in masseter for the development of large, fast forces, rather than for the maintenance of static postures. Thus muscle spindles in masseter may be important in load compensation during chewing and for the development of powerful bite forces in aggressive or defensive situations.

Estimating relative motoneurone size in human masseter muscle.

The representation of a motor unit in the macro-EMG (MacroRep) is the method of choice for determining muscle-unit size in masseter. However, before using MacroRep to infer motoneurone size, the relation between MacroRep amplitude and motoneurone size needs to be established. This is particularly important in masseter, where the diameter of the type II muscle fibres is smaller than that of the type I fibres. This unusual situation may affect the cross-sectional area of the muscle units innervated by motoneurones, disturbing the expected correlation between the MacroRep and motoneurone size. This study used H-reflex latency as an indicator of motoneurone size, and found a negative correlation between H-reflex latency and MacroRep amplitude in all simultaneously firing motor-unit pairs identified. Thus it is concluded that MacroRep amplitude provides a good estimate of relative motoneurone size in masseter, within the limits specified in the study.

Muscle spindle afferent input to motoneurons in human masseter.

The H-reflex response in large and small single motor units in human deep anterior masseter was studied to investigate the distribution of muscle spindle afferents onto masseter motoneurons. We found that only the larger units displayed H-reflex responses. This indicates preferential distribution of muscle spindle input onto large motoneurons or a skewed distribution of tonic presynaptic inhibitory mechanisms.

Recruitment stability in masseter motor units during isometric voluntary contractions.

Recruitment of single motor units (SMUs) of the masseter muscle was studied using macro representation (MacroRep) as the indicator of motor unit size. When subjects followed a slow isometric force ramp, units were usually recruited in order of MacroRep size. However, pooling the data from repeated ramps in the same subject resulted in a weak relationship between MacroRep size and force recruitment threshold, probably due to marked variations in the relative contributions of the jaw muscles, and varying levels of cocontraction, in the development of total bite force in each ramp. The force recruitment thresholds of individual SMUs showed marked variability, but recruitment threshold stability was improved when expressed as a percentage of maximum surface electromyographic (SEMG) activity in the ipsilateral masseter. Therefore the SEMG recruitment threshold was concluded to be a more stable and accurate indicator of the SMU's position in the recruitment hierarchy in a given muscle. It was concluded that SMUs in masseter are recruited according to the size principle, and that when investigating recruitment in jaw muscles, SEMG recruitment threshold should be used in preference to force recruitment threshold.

Tendon tap induces a single long-lasting excitatory reflex in the motoneurons of human soleus muscle.

The reflex responses of the soleus motor units to Achilles tendon taps were investigated. Two different techniques were used to analyse the motor unit data. The first approach was the classical technique which involved building peristimulus time histograms (PSTH) from the firing times of single motor units. The second approach was a relatively unused technique that involved plotting the instantaneous discharge frequency of the single motor unit against time (peristimulus frequencygram or PSF). Using PSTH as the indicator, we found that the tap to the tendon induced three separate reflex responses: the first response was a very short-lasting excitatory response or the jerk reflex, the second was a period of relative silence (silent period or the "trough"), and the third was a broad peak 170 ms after the stimulus. Using the same motor unit data, the PSF technique indicated that the tap to the tendon induced a single long-lasting excitatory reflex. The PSF displayed an increase starting from the latency of the jerk reflex and continuing for about 65 ms. There was no significant change in the discharge frequency at the end of the first excitatory response. Since the discharge frequency of a motoneuron has a strong positive linear relationship with the effective synaptic current it receives, it is suggested that throughout the 65-ms period the net (effective) synaptic drive to the soleus motoneurons was excitatory. It is therefore concluded that tendon tap induces a single long-lasting excitatory reflex in the motoneurons of the soleus muscle.

A new method for eliciting and studying H-reflexes in the human masseter.

A non-invasive method is presented for transmuscular stimulation of the masseteric nerve, using a frame to apply a cathode to the mandibular notch and an anode to the inside of the mouth. The H-reflex response was recorded using surface, macro and single motor-unit (SMU) electromyography (EMG) from the masseter. The latency of the reflex response representing the H-reflex in SMUs was determined from the cumulative sum of the peristimulus time histogram. This latency was then corrected using a spike-trigger averaging technique, where the SMU spikes were used as triggers and the macro EMG recording as the source. SMU latencies for the H-reflex in masseter were in the range 5.9-8.8 msec, whereas H-reflex latencies for surface EMG varied between 5.4 and 6.4 msec.