To become part of the team-patient experiences of participating in decision-making for a new treatment (proton beam therapy).

PURPOSE: The aim of this study was to explore patients' experience of participation in the treatment decision of proton beam therapy versus conventional radiotherapy. BACKGROUND: Proton beam therapy (PBT) has become a treatment option for some cancer patients receiving radiotherapy. The decision to give PBT instead of conventional radiotherapy (CRT) needs to be carefully planned together with the patient to ensure that the degree of participation is based on individuals' preferences. There is a knowledge gap of successful approaches to support patients' participation in the decision-making process, which is particularly important when it comes to the situation of having to choose between two treatment options such as PBT and CRT, with similar expected outcomes. METHOD: We conducted a secondary analysis of qualitative data collected from interviews with patients who received PBT for their brain tumor. Transcribed verbatims from interviews with 22 patients were analyzed regarding experiences of participation in the decision-making process leading to PBT. FINDINGS: Participants experienced their participation in the decision-making process to a varying degree, and with individual preferences. Four themes emerged from data: to be a voice that matters, to get control over what will happen, being in the hand of doctors' choice, and feeling selected for treatment. CONCLUSION: A decision for treatment with PBT can be experienced as a privilege but can also cause stress as it might entail practical issues affecting everyday life in a considerable way. For the patient to have confidence in the decision-making process, patients' preferences, expectations, and experiences must be included by the healthcare team. Including the patient in the healthcare team as an equal partner by confirming the person enables and facilitates for patients' voice to be heard and reckoned with. Person-centered care building on a partnership between patients and healthcare professionals should provide the right basis for the decision-making process.

Evaluating patient reported outcomes and experiences in a novel proton beam clinic - challenges, activities, and outcomes of the ProtonCare project.

BACKGROUND: The ProtonCare Study Group (PCSG) was formed with the purpose to develop and implement a framework for evaluation of proton beam therapy (PBT) and the related care at a novel clinic (Skandionkliniken), based on patient reported data. METHOD: A logic model framework was used to describe the process of development and implementation of a structured plan for evaluation of PBT for all diagnoses based on patient reported data. After the mission for the project was determined, meetings with networks and stakeholders were facilitated by PCSG to identify assumptions, resources, challenges, activities, outputs, outcomes, and outcome indicators. RESULT: This paper presents the challenges and accomplishments PCSG made so far. We describe required resources, activities, and accomplished results. The long-term outcomes that were outlined as a result of the process are two; 1) Improved knowledge about health outcomes of patients that are considered for PBT and 2) The findings will serve as a base for clinical decisions when patients are referred for PBT. CONCLUSION: Using the logical model framework proved useful in planning and managing the ProtonCare project. As a result, the work of PCSG has so far resulted in long-lasting outcomes that creates a base for future evaluation of patients' perspective in radiotherapy treatment in general and in PBT especially. Our experiences can be useful for other research groups facing similar challenges. Continuing research on patients´ perspective is a central part in ongoing and future research. Collaboration, cooperation, and coordination between research groups/networks from different disciplines are a significant part of the work aiming to determine the more precise role of PBT in future treatment options.

Single institution followed by national implementation of systematic surgical quality control and feedback for radical prostatectomy: a 20-year journey.

PURPOSE: The demand for objective and outcome-based facts about surgical results after radical prostatectomy (RP) is increasing. Systematic feedback is also essential for each surgeon to improve his/her performance. METHODS: RP outcome data (e.g., pT-stage and margin status) have been registered at Sahlgrenska University Hospital (SUH) since 1988 and patient-related outcome measures (PROM) have been registered since 2001. The National Prostate Cancer Registry (NPCR) has covered all Regions in Sweden since 1998 and includes PROM-data from 2008. Initially PROM was on-paper questionnaires but due since 2018 all PROMs are collected electronically. In 2014 an on-line "dashboard" panel was introduced, showing the results for ten quality-control variables in real-time. Since 2017 all RP data on hospital, regional, and national levels are publicly accessible on-line on "www.npcr.se/RATTEN". RESULTS: The early PROM-data from SUH have been used for internal quality control. As national clinical and PROM-data from the NPCR have been made accessible on-line and in real-time we have incorporated this into our pre-existing protocol. Our data are now internally available as real-time NPCR reports on the individual surgeons' results, as well as ePROM data. We can compare the results of each surgeon internally and to other departments' aggregated data. The public can access data and compare hospital level data on "RATTEN". CONCLUSIONS: The process of quality control of RP locally at SUH, and nationally through the NPCR, has been long but fruitful. The online design, with direct real-time feedback to the institutions that report the data, is essential.

Altered cerebral pain processing of noxious stimuli from inflamed joints in rheumatoid arthritis: An event-related fMRI study.

OBJECTIVE: To our knowledge, this is the first study assessing brain activation in response to painful stimulation over disease-relevant (finger joint) vs. neutral area (thumb nail) in patients suffering from rheumatoid arthritis (RA) compared to healthy controls (HC). METHOD: Thirty-one RA patients and 23 HC underwent functional magnetic resonance imaging (fMRI) while stimulated with subjectively calibrated painful pressures corresponding to a pain sensation of 50 mm on a 100 mm VAS scale (P50) at disease-affected finger joint and thumbnail (left hand), and corresponding sites in HC. RESULTS: Compared to controls, RA patients had significantly increased pain sensitivity (lower P50) at the inflamed joints but not at the thumbnail. RA patients exhibited significantly less activation in regions related to pain- and somatosensory processing (S1, M1, anterior insula, S2, SMG and MCC) during painful joint stimulation, compared to HC. No group difference in cerebral pain processing was found for the non-affected thumbnail. Within RA patients, significantly less brain activation was found in response to painful stimulation over disease-affected joint compared to non-affected thumbnail in bilateral S1, bilateral S2, and anterior insula. Further, RA patients exhibited a right-sided dlPFC deactivation, psycho-physiologically interacting (PPI) with the left dlPFC in response to painful stimulation at disease-affected joints. CONCLUSION: The results indicate normal pain sensitivity and cerebral pain processing in RA for non-affected sites, while the increased sensitivity at inflamed joints indicate peripheral/spinal sensitization. Brain imaging data suggest that disease-relevant pain processing in RA is marked by aberrations and a failed initiation of cortical top-down regulation.

Alterations in resting state connectivity along the autism trait continuum: a twin study.

Autism spectrum disorder (ASD) has been found to be associated with alterations in resting state (RS) functional connectivity, including areas forming the default mode network (DMN) and salience network (SN). However, insufficient control for confounding genetic and environmental influences and other methodological issues limit the generalizability of previous findings. Moreover, it has been hypothesized that ASD might be marked by early hyper-connectivity followed by later hypo-connectivity. To date, only a few studies have explicitly tested age-related influences on RS connectivity alterations in ASD. Using a within-twin pair design (N=150 twins; 8-23 years), we examined altered RS connectivity between core regions of the DMN and SN in relation to autistic trait severity and age in a sample of monozygotic (MZ) and dizygotic (DZ) twins showing typical development, ASD or other neurodevelopmental conditions. Connectivity between core regions of the SN was stronger in twins with higher autistic traits compared to their co-twins. This effect was significant both in the total sample and in MZ twins alone, highlighting the effect of non-shared environmental factors on the link between SN-connectivity and autistic traits. While this link was strongest in children, we did not identify differences between age groups for the SN. In contrast, connectivity between core hubs of the DMN was negatively correlated with autistic traits in adolescents and showed a similar trend in adults but not in children. The results support hypotheses of age-dependent altered RS connectivity in ASD, making altered SN and DMN connectivity promising candidate biomarkers for ASD.

Foam posturography: standing on foam is not equivalent to standing with decreased rapidly adapting mechanoreceptive sensation.

Standing on a foam surface is believed to exaggerate balance deficits by decreasing the reliability of somatosensory information from cutaneous mechanoreceptors on the plantar soles (i.e. base of feet) and by altering the effectiveness of ankle torque. The aim was to further document the nature of foam posturography testing by comparing between standing on foam and standing with decreased Rapidly Adapting Mechanoreceptive Sensation (RAMS). Sixteen healthy adults (mean age 20.8 years) were tested with posturography, standing with eyes open and closed on a solid surface and on foam, with and without decreased plantar RAMS. Standing balance was measured as torque variance and further analyzed by being divided into three spectral categories. Plantar cutaneous hypothermic anesthesia by ice-cooling was used to decrease RAMS. Plantar mechanoreceptive sensation was precisely determined with tactile sensitivity and vibration perception tests. Vibration perception was significantly decreased by hypothermic anesthesia, but tactile sensitivity was not. The anterior-posterior torque variance was significantly larger for frequencies less than 0.1 Hz under eyes closed conditions when standing on a solid surface with decreased RAMS compared to normal sensation. No effect of decreased RAMS was seen with eyes open on a solid surface, nor on foam with eyes open or closed. Decreased RAMS produced body sway responses on a solid surface that were different in spectral composition, amplitude, direction and that responded differently to vision compared with standing on foam. Hence, this study showed that RAMS contributes to postural control but reduction in RAMS does not produce a similar challenge as standing on foam.

Mandibulotomy access to tumour sites: fewer complications for postoperative compared with preoperative radiotherapy.

The purpose of this study was to compare complication rates at the mandibulotomy site between patients receiving preoperative radiotherapy (RT) and those receiving postoperative RT during treatment for oral and oropharyngeal cancer where the surgical procedure required a mandibular osteotomy to gain access to the tumour. Sixty-four consecutive patients treated during the period 2000-2015 were available for analysis. Their medical records were reviewed retrospectively. All patients were followed for at least 1year postoperatively. A subgroup of patients received RT on several occasions or long before the mandibulotomy, therefore the statistical comparisons focused on the two groups of patients receiving RT on one occasion and within 6 months prior to or following surgery. Seventeen patients presented a total of 29 complications, yielding an overall complication rate of 27%. Orocutaneous fistula was the most common complication. Patients who received RT preoperatively presented a higher complication rate (9/15; 60%) when compared to those who received RT postoperatively (2/31; 6.5%) (odds ratio 21.8, P<0.001). This study demonstrated fewer complications in the mandibulotomy area exposed to postoperative RT compared with preoperative RT. It is therefore suggested that, when possible, RT should be given postoperatively if combination treatment with RT and surgery, including a mandibulotomy, is planned.

Alcohol intoxication at 0.06 and 0.10% blood alcohol concentration changes segmental body movement coordination.

Alcohol intoxication is the cause of many falls requiring emergency care. The control of upright standing balance is complex and comprises contributions from several partly independent mechanisms like coordination, feedback and feedforward control and adaptation. Analysis of the segmental body movement coordination offers one option to detect the severity of balance problems. The study aims were (1) to investigate whether alcohol intoxication at 0.06 and 0.10% blood alcohol concentration (BAC) affected the segmental movement pattern under unperturbed and perturbed standing; (2) whether alcohol affected the ability for movement pattern adaptation; (3) whether one's own subjective feeling of drunkenness correlated to the movement pattern used. Twenty-five participants (13 women and 12 men, mean age 25.1 years) performed tests involving alcohol intoxication. Body movements were recorded at five locations (ankle, knee, hip, shoulder and head) during quiet standing and pseudorandom pulses of calf muscle vibration for 200 s with eyes closed or open. There was no significant effect of alcohol on the general movement pattern in unperturbed stance or on adaptation. However, when balance was repeatedly perturbed, knee movements became significantly less correlated to other body movements over time at 0.10% BAC and when visual information was unavailable, suggesting that the normal movement pattern could not be maintained for a longer period of time while under 0.10% BAC intoxication. Subjective feelings of drunkenness correlated often with a changed upper body movement pattern but less so with changed knee movements. Thus, an inability to relate drunkenness with changed knee movements may be a contributing factor to falls in addition to the direct effect of alcohol intoxication.

Change of body movement coordination during cervical proprioceptive disturbances with increased age.

BACKGROUND: To date, there are very few studies on postural stability in older adults using body movement recordings to capture the postural movement pattern. Moreover, the importance of proprioception at key areas such as the calf or neck on the postural movement pattern in older adults has rarely been investigated. OBJECTIVE: To investigate whether the body movement coordination strategy to calf or neck vibration was affected by aging. METHODS: Body movement measurements were taken at five locations (ankle, knee, hip, shoulder and head) from 18 younger (mean age 29.1 years) and 16 older (mean age 71.5 years) adult subjects using a 3D movement measuring system while subjected to 50 s of pseudo-random calf or neck vibratory stimulation pulses with eyes open or closed. The positions from the knee, hip, shoulder and head markers were correlated against one another to give an indication of the body coordination. RESULTS: During quiet standing, older adults had greater correlation between the head and trunk than the young. There was an age effect in the body movement coordination strategy. Older adults had a different movement pattern with neck vibration involving mainly more independent knee movements, indicating balance difficulty. CONCLUSIONS: Neck vibration affects the movement pattern in older adults more compared with younger adults and calf vibration, suggesting that, the regulation of body orientation in older adults is more difficult, especially during cervical proprioceptive disturbances.

Effects of dyslexia on postural control in adults.

Dyslexia has been shown to affect postural control. The aim of the present study was to investigate the difference in postural stability measured as torque variance in an adult dyslexic group (n=14, determined using the Adult Dyslexia Checklist (ADCL) and nonsense word repetition test) and an adult non-dyslexic group (n=39) on a firm surface and on a foam block and with eyes open and eyes closed. Another aim was to investigate the correlation between ADCL scores and postural stability. Findings showed that ADCL scores correlated with torque variance in the anteroposterior direction on foam with eyes closed (p=0.001) and in the lateral direction on the foam surface with eyes closed (p=0.040) and open (p=0.010). General Linear Model analysis showed that high dyslexia scores were associated with increased torque variance (p<0.001). However, we found no significant difference between dyslexics and non-dyslexics, though there were indications of larger torque variance in the dyslexics. The findings suggest that adults with high dyslexic ADCL scores may experience sub-clinical balance deficits. Hence, assessing motor ability and postural control in those with high ADCL scores is motivated.

Vestibular PREHAB and gentamicin before schwannoma surgery may improve long-term postural function.

BACKGROUND: Unilateral vestibular deafferentation (uVD), as performed in vestibular schwannoma surgery, results in a chronic vestibular deficit, though most of the insufficiency can be compensated by other sensory input. By vestibular training (prehabituation) performed before surgery, motor adaptation processes can be instigated before the actual lesion. The adaptation processes of the altered sensory input could be affected if the vestibular ablation and surgery were separated in time, by pretreating patients who have remaining vestibular function with gentamicin. OBJECTIVE: To determine whether presurgical deafferentation would affect postsurgery postural control also in a long-term perspective (6 months). METHOD: 41 patients subjected to trans-labyrinthine schwannoma surgery were divided into four groups depending on the vestibular activity before surgery (with no clinical significant remaining function n = 17; with remaining function n = 8), whether signs of central lesions were present (n = 10), and if patients with remaining vestibular activity were treated with gentamicin with the aim to produce uVD before surgery (n = 6). The vibratory posturography recordings before surgery and at the follow-up 6 months after surgery were compared. RESULTS: The subjects pretreated with gentamicin had significantly less postural sway at the follow-up, both compared with the preoperative recordings and compared with the other groups. CONCLUSION: The results indicate that by both careful sensory training and separating the surgical trauma and the effects of uVD in time, adaptive processes can develop more efficiently to resolve sensory conflicts, resulting in a reduction of symptoms not only directly after surgery but also perhaps up to 6 months afterwards.

Effects of ageing on adaptation during vibratory stimulation of the calf and neck muscles.

BACKGROUND: The ability to adapt and habituate based on prior experiences is important for human movement control, fall prevention and for the ability to enhance performance during various human activities. However, little is known about the ability for the elderly to adapt to balance perturbations in the lateral direction. OBJECTIVE: To determine whether adaptation, i.e., the ability to adjust postural control to handle balance perturbations better over time, differed in the elderly subjects compared with young subjects in the anteroposterior and lateral directions, and whether the site of the balance perturbation or the presence or absence of vision affected the response. METHODS: Postural stability was measured as anteroposterior and lateral torque variance in a young group (n = 18 (9 female and 9 male), average age = 29.1 years) and an elderly group (n = 16 (5 female and 11 male), average age = 71.5 years) with eyes open and closed during balance perturbations from calf and neck vibrations. After a 30-s period of quiet stance, these vibrations were repeated over a period of 200 s, so the adaptive responses could be analyzed by splitting the data into 50-s periods. RESULTS: The adaptive responses in the anteroposterior and lateral directions were different. Adaptation in the anteroposterior direction occurred to an almost equal extent in the elderly and young, whereas adaptation in the lateral direction was markedly larger in the elderly in all tests except for neck vibration with eyes closed. Age, vision and vibration site were all influential factors for recorded body movements, but no significant combined effects were found. CONCLUSION: Balance perturbation instigates an adaptive response in the elderly in both the anteroposterior and lateral directions. However, during perturbation, age and vision are both very influential factors for the stability, thus associating the previously documented age-related decline in visual functioning with a higher risk of falls in this age range.

Effects of proprioceptive vibratory stimulation on body movement at 24 and 36h of sleep deprivation.

OBJECTIVE: To investigate whether postural stability and adaptation differed after a normal night of sleep, after 24h (24 SDep) and 36h (36 SDep) of sleep deprivation while subjected to repeated balance perturbations. Also, to determine whether there was any correlation between subjective alertness scores and objective posturographic measurements. Lastly, to investigate the effects of vision on the stability during sleep deprivation. METHODS: Body movements at five locations were recorded in 18 subjects (mean age 23.8years) using a 3D movement measurement system while subjected with eyes open and closed to vibratory proprioceptive calf stimulation after a normal night of sleep, 24 and 36 SDep. RESULTS: The clearest sleep deprivation effect was reduced ability to adapt head, shoulder and hip movements, both with eyes open and eyes closed. Additionally, several near falls occurred after being subjected to balance perturbations for 2-3min while sleep deprived. Unexpectedly, postural performance did not continue to deteriorate between 24 and 36h of sleep deprivation, but showed some signs of improvement. Subjective scores of sleepiness correlated poorly with actual changes in postural control performance. CONCLUSIONS: Sleep deprivation might affect postural stability through reduced adaptation ability and lapses in attention. Subjective alertness might not be an accurate indicator of the physiological effects of sleep deprivation. SIGNIFICANCE: Sleep deprivation could increase the risk of accidents in attention demanding tasks. There is a need for objective evaluation methods to determine actual performance capacity during sleep deprivation.

Effects of 24-h and 36-h sleep deprivation on human postural control and adaptation.

This study investigated whether human postural stability and adaptation were affected by sleep deprivation and the relationship between motor performance and subjective scores of sleepiness (visuo-anlogue sleepiness scores, VAS). Postural stability and subjective sleepiness were examined in 18 healthy subjects (mean age 23.8 years) following 24 and 36 h of continued wakefulness, ensured by portable EEG recordings, and compared to a control test where the assessments were made after a normal night of sleep. The responses were assessed using posturography with eyes open and closed, and vibratory proprioceptive stimulations were used to challenge postural control. Postural control was significantly affected after 24 h of sleep deprivation both in anteroposterior and in lateral directions, but less so after 36 h. Subjective VAS scores showed poor correlation with indicators of postural control performance. The clearest evidence that sleep deprivation decreased postural control was the reduction of adaptation. Also several near falls after 2-3 min during the posturographic tests showed that sleep deprivation might affect stability through momentary lapses of attention. Access to vision, somewhat, but not entirely reduced the effect of sleep deprivation. In conclusion, sleep deprivation can be a contributing factor to decreased postural control and falls.

The effect of foam surface properties on postural stability assessment while standing.

A common assessment of postural control often involves subjects standing on a compliant surface, such as a foam block, to make balance tests more challenging. However, the physical properties of the foam block used by different researchers can vary considerably. The objective of this study was to provide an initial approach for investigating whether two of the foam properties, i.e. density and elastic modulus, influenced recorded anteroposterior and lateral torque variance with eyes open and eyes closed. Thirty healthy adults (mean age 22.5 years) were assessed with posturography using three different types of foam block placed on a force platform. These blocks were categorised: firm foam, medium foam and soft foam by their elastic modulus. To investigate the spectral characteristics of recorded body movements, variance values were calculated for total movements, movements <0.1Hz and movements >0.1Hz. Results showed that anteroposterior and lateral torque variances >0.1Hz were larger when standing on the firm foam compared with medium and soft foam and in turn were larger on the medium foam compared with the soft foam with eyes closed. Moreover, GLM and correlation analysis demonstrated that the properties of the foam blocks affected anteroposterior torque variance >0.1Hz and lateral torque variance in all frequency ranges. In addition, the stabilising effect of vision in the anteroposterior direction had a greater influence when the subjects' stability was increasingly challenged by the support surface, as illustrated by the higher torque variance values. In conclusion, caution should be taken when analysing balance deficits with foam test setups, because the foam properties may influence the recorded body movements.

The effects of foam surface properties on standing body movement.

CONCLUSION: The properties of a foam surface significantly affect body movement variance. Therefore, studies where different kinds of foam have been used may not provide congruent results. OBJECTIVES: To investigate whether different properties of foam affect body movement variance (32 subjects, mean age 22.5 years) in terms of linear head, shoulder, hip and knee movements. Subjects repeated tests with eyes open and closed, to also determine the effect of vision on the different surfaces. SUBJECTS AND METHODS: Body movement was captured on three different foam surfaces and on a control solid surface over 2 min using a Zebris ultrasound measuring system. The foam surfaces were categorized by their firmness as firm foam, medium foam and soft foam. RESULTS: Body movement variance increased significantly when standing on all foam surfaces compared with the solid surface. However, movement variance was larger when standing on the firm foam compared with the softer foams, except in the anteroposterior total and low frequency ranges. We also found that the body movement pattern differed when standing on foam and firm surfaces, with greater reliance on movements at the knee to give postural stability on foam than on the solid surface. Vision clearly reduced all body movement variances, but particularly within the high frequency range.

Effects of 24-hour and 36-hour sleep deprivation on smooth pursuit and saccadic eye movements.

Sleep restrictions and sleep deprivation have become common in modern society, as many people report daily sleep below the recommended 8 hours per night. This study aimed to examine the effects of sleep deprivation on oculomotor performance by recording smooth pursuit and saccadic eye movements after 24 and 36 hours of sleep deprivation. Another objective was to determine whether detected changes in oculomotor performance followed fluctuations according to a circadian rhythm and/or subjective Visuo-Analogue sleepiness Scale scores. Oculomotor responses were recorded from 18 subjects using electronystagmography, and comprised measurements of accuracy (i.e., the percentage of time the eye movement velocity was within the target velocity boundaries), velocity and latency. Continuous EEG recordings were used to validate that subjects had remained awake throughout the 36-hour period. Our findings showed that sleep deprivation deteriorated smooth pursuit gain, smooth pursuit accuracy and saccade velocity. Additionally, the ratio between saccade velocity and saccade amplitude was significantly decreased by sleep deprivation. However, as the length of sleep deprivation increased, only smooth pursuit gain deteriorated further, whereas there were signs of improvement in smooth pursuit accuracy measurements. The latter observation suggests that smooth pursuit accuracy might be affected by the circadian rhythm of alertness. Surprisingly, high subjective scores of sleepiness correlated in most cases with better saccade performance, especially after 36 hours of sleep deprivation, suggesting that awareness of sleepiness might make subjects perform better during saccade assessments. To conclude, oculomotor function clearly decreased after sleep deprivation, but the performance deteriorations were complex and not necessarily correlated with subjectively felt sleepiness.

The role of long-term physical exercise on performance and brain activation during the Stroop colour word task in fibromyalgia patients.

The Stroop colour word test (SCWT) has been widely used to assess changes in cognitive performance such as processing speed, selective attention and the degree of automaticity. Moreover, the SCWT has proven to be a valuable tool to assess neuronal plasticity that is coupled to improvement in performance in clinical populations. In a previous study, we showed impaired cognitive processing during SCWT along with reduced task-related activations in patients with fibromyalgia. In this study, we used SCWT and functional magnetic resonance imagingFMRI to investigate the effects of a 15-week physical exercise intervention on cognitive performance, task-related cortical activation and distraction-induced analgesia (DIA) in patients with fibromyalgia and healthy controls. The exercise intervention yielded reduced fibromyalgia symptoms, improved cognitive processing and increased task-related activation of amygdala, but no effect on DIA. Our results suggest beneficial effects of physical exercise on cognitive functioning in FM.

Cervical muscle afferents play a dominant role over vestibular afferents during bilateral vibration of neck muscles.

A previous study showed that vibratory stimulation of neck muscles in humans induced short-latency electromyographic (EMG) activation of lower leg muscles, producing postural reactions at the feet. These findings indicated that cervical proprioception contributes to stabilization of stance through rapidly integrated pathways. However, as vibration may excite both proprioceptive and vestibular afferents, and because of the proximity of neck muscles to the vestibular apparatus, neck muscle vibration could also have activated the vestibular system thereby contributing to the effect observed. To investigate any possible contribution of vestibular stimulation, vibratory stimuli were applied bilaterally and separately to the splenius muscles of the neck and the planum mastoideum overlying the vestibular organs. Ten normal subjects, with eyes closed, were exposed to vibratory stimulation of two different amplitudes and frequencies. Responses were assessed by EMG activity recorded from tibialis anterior and gastrocnemius muscles of both legs and by changes in center of pressure as measured by a force platform. Results indicated that vibration induced reproducible EMG and postural responses in the anteroposterior direction, particularly on cessation of vibration. EMG and postural responses were considerably lower and less consistent with mastoid vibration compared with neck muscles vibration. Previous reports suggest that vibratory stimulation could propagate to the vestibular organs and generate a vestibular-induced postural activation. However, our findings indicate that cervical muscles afferents play a dominant role over vestibular afferents when vibration is directed towards the neck muscles.

Improved postural control through repetition and consolidation.

Research regarding the optimal frequency of training in postural control rehabilitation has been sparse. Posturography with vibratory proprioceptive stimulation was performed with eyes open and closed on 36 healthy subjects divided into 3 groups. Each group was tested 5 times, though with different time-intervals; 20 minutes, 3 hours and 24 hours respectively. Two different adaptive processes seems to be involved in the formation of a new movement pattern when exposed to a postural disturbance, one fast adaptation active during each test occasion and a second adaptation active between the consecutive tests. As the same adaptation pattern was found regardless the repetition time interval, the results imply either that the consolidation process of the new motor memory is time-independent or that the stimulus was sufficiently strong to induce fast consolidation thus leaving the time-interval unimportant. The findings suggest that it is primarily the number of repetitions in the exercises that governs the outcome of training, whereas the time interval between the exercises is of less importance.