Temporal association between sleep spindles and ripples in the human anterior and mediodorsal thalamus.

Sleep spindles are major oscillatory components of Non-Rapid Eye Movement (NREM) sleep, reflecting hyperpolarization-rebound sequences of thalamocortical neurons. Reports suggest a link between sleep spindles and several forms of high-frequency oscillations which are considered as expressions of pathological off-line neural plasticity in the central nervous system. Here we investigated the relationship between thalamic sleep spindles and ripples in the anterior and mediodorsal nuclei (ANT and MD) of epilepsy patients. Whole-night LFP from the ANT and MD were co-registered with scalp EEG/polysomnography by using externalized leads in 15 epilepsy patients undergoing a Deep Brain Stimulation protocol. Slow (~12 Hz) and fast (~14 Hz) sleep spindles were present in the human ANT and MD and roughly, 20% of them were associated with ripples. Ripple-associated thalamic sleep spindles were characterized by longer duration and exceeded pure spindles in terms of spindle power as indicated by time-frequency analysis. Furthermore, ripple amplitude was modulated by the phase of sleep spindles within both thalamic nuclei. No signs of pathological processes were correlated with measures of ripple and spindle association, furthermore, the density of ripple-associated sleep spindles in the ANT showed a positive correlation with verbal comprehension. Our findings indicate the involvement of the human thalamus in coalescent spindle-ripple oscillations of NREM sleep.

Factors affecting postural instability after more than one-year bilateral subthalamic stimulation in Parkinson's disease: A cross-sectional study.

BACKGROUND: Balance impairment in Parkinson's disease is multifactorial and its changes due to subthalamic stimulation vary in different studies. OBJECTIVE: We aimed to analyze the combination of predictive clinical factors of balance impairment in patients with Parkinson's disease treated with bilateral subthalamic stimulation for at least one year. METHODS: We recruited 24 patients with Parkinson's disease treated with bilateral subthalamic stimulation and 24 healthy controls. They wore an Opal monitor (APDM Inc.) consisting of three-dimensional gyroscopes and accelerometers in the lumbar region. We investigated four stimulation conditions (bilateral stimulation OFF, bilateral stimulation ON, and unilateral right- and left-sided stimulation ON) with four tests: stance on a plain ground with eyes open and closed, stance on a foam platform with eyes open and closed. Age, disease duration, the time elapsed after implantation, levodopa, and stimulation responsiveness were analyzed. The distance of stimulation location from the subthalamic motor center was calculated individually in each plane of the three dimensions. We analyzed the sway values in the four stimulation conditions in the patient group and compared them with the control values. We explored factor combinations (with age as confounder) in the patient group predictive for imbalance with cluster analysis and a machine-learning-based multiple regression method. RESULTS: Sway combined from the four tasks did not differ in the patients and controls on a group level. The combination of the disease duration, the preoperative levodopa responsiveness, and the stimulation responsiveness predicted individual stimulation-induced static imbalance. The more affected patients had more severe motor symptoms; primarily, the proprioceptive followed by visual sensory feedback loss provoked imbalance in them when switching on the stimulation. CONCLUSIONS: The duration of the disease, the severity of motor symptoms, the levodopa responsiveness, and additional sensory deficits should be carefully considered during preoperative evaluation to predict subthalamic stimulation-induced imbalance in Parkinson's disease.

The use of weekly text messaging over 6 months was a feasible method for monitoring the clinical course of low back pain in patients seeking chiropractic care.

OBJECTIVE: This study critically evaluates a new method of collecting frequent data using mobile phones and text messages. Fluctuating conditions such as low back pain (LBP) need frequent monitoring to describe the clinical course in detail and to account for individual and subgroup variations. STUDY DESIGN AND SETTING: In this multicentre prospective observational study, 262 subjects with nonspecific LBP were followed with weekly text messages for 6 months, with the question "How many days this previous week has your low back pain been bothersome?" The text replies were instantly recorded in a data file to be merged with baseline and follow up data (age, gender, pain intensity, duration, and self- rated health) collected through ordinary questionnaires. The response rate, user-friendliness, and compliance of this method were evaluated. RESULTS: The mean response rate for the text messages throughout the study was 82.5% and was unaffected by season. The method was found to be user friendly. Dropout was not affected by age and gender, but compliance was possibly somewhat affected by outcome. CONCLUSION: Weekly text messages are a useful method of data collection to examine the clinical course of LBP in the primary care sector.

Clustering patients on the basis of their individual course of low back pain over a six month period.

BACKGROUND: Several researchers have searched for subgroups in the heterogeneous population of patients with non-specific low back pain (LBP). To date, subgroups have been identified based on psychological profiles and the variation of pain. METHODS: This multicentre prospective observational study explored the 6- month clinical course with measurements of bothersomeness that were collected from weekly text messages that were sent by 176 patients with LBP. A hierarchical cluster analysis, Ward's method, was used to cluster patients according to the development of their pain. RESULTS: Four clusters with distinctly different clinical courses were described and further validated against clinical baseline variables and outcomes. Cluster 1, a "stable" cluster, where the course was relatively unchanged over time, contained young patients with good self- rated health. Cluster 2, a group of "fast improvers" who were very bothered initially but rapidly improved, consisted of patients who rated their health as relatively poor but experienced the fewest number of days with bothersome pain of all the clusters. Cluster 3 was the "typical patient" group, with medium bothersomeness at baseline and an average improvement over the first 4-5 weeks. Finally, cluster 4 contained the "slow improvers", a group of patients who improved over 12 weeks. This group contained older individuals who had more LBP the previous year and who also experienced most days with bothersome pain of all the clusters. CONCLUSIONS: It is possible to define clinically meaningful clusters of patients based on their individual course of LBP over time. Future research should aim to reproduce these clusters in different populations, add further clinical variables to distinguish the clusters and test different treatment strategies for them.

The Nordic Maintenance Care Program: when do chiropractors recommend secondary and tertiary preventive care for low back pain?

BACKGROUND: Among chiropractors the use of long-term treatment is common, often referred to as "maintenance care". Although no generally accepted definition exists, the term has a self-explanatory meaning to chiropractic clinicians. In public health terms, maintenance care can be considered as both secondary and tertiary preventive care. The objective of this study was to explore what factors chiropractors consider before recommending maintenance care to patients with low back pain (LBP). METHOD: Structured focus group discussions with Swedish chiropractors were used to discuss pre-defined cases. A questionnaire was then designed on the basis of the information obtained. In the questionnaire, respondents were asked to grade the importance of several factors when considering recommending maintenance care to a patient. The grading was done on a straight line ranging from "Very important" to "Not at all important". All members of the Swedish Chiropractors' Association (SCA) were invited to participate in the discussions and in the questionnaire survey. RESULTS: Thirty-six (22%) of SCA members participated in the group discussions and 129 (77%) returned the questionnaires. Ninety-eight percent of the questionnaire respondents claimed to believe that chiropractic care can prevent future relapses of back pain. According to the group discussions tertiary preventive care would be considered appropriate when a patient improves by 75% or more. According to the results of the questionnaire survey, two factors were considered as "very important" by more than 70% of the respondents in recommending secondary preventive care, namely frequency past year and frequency past 10 years of the low back pain problem. Eight other factors were considered "very important" by 50-69% of the respondents, namely duration (over the past year and of the present attack), treatment (effect and durability), lifestyle, work conditions, and psychosocial factors (including attitude). CONCLUSION: The vast majority of our respondents believe that chiropractic treatment can prevent relapses of back pain. When recommending secondary preventive care, past frequency of the problem is considered. For tertiary preventive care, the patient needs to improve considerably before a recommendation of maintenance care is made.

The Nordic Subpopulation Research Programme: prediction of treatment outcome in patients with low back pain treated by chiropractors--does the psychological profile matter?

BACKGROUND: It is clinically important to be able to select patients suitable for treatment and to be able to predict with some certainty the outcome for patients treated for low back pain (LBP). It is not known to what degree outcome among chiropractic patients is affected by psychological factors. OBJECTIVES: To investigate if some demographic, psychological, and clinical variables can predict outcome with chiropractic care in patients with LBP. METHODS: A prospective multi-center practice-based study was carried out, in which demographic, clinical and psychological information was collected at base-line. Outcome was established at the 4(th )visit and after three months. The predictive value was studied for all base-line variables, individually and in a multivariable analysis. RESULTS: In all, 55 of 99 invited chiropractors collected information on 731 patients. At the 4(th )visit data were available on 626 patients and on 464 patients after 3 months. Fee subsidization (OR 3.2; 95% CI 1.9-5.5), total duration of pain in the past year (OR 1.5; 95% CI 1.0-2.2), and general health (OR 1.2; 95% CI 1.1-1.4) remained in the final model as predictors of treatment outcome at the 4(th )visit. The sensitivity was low (12%), whereas the specificity was high (97%). At the three months follow-up, duration of pain in the past year (OR 2.1; 95% CI 1.4-3.1), and pain in other parts of the spine in the past year (OR1.6; 1.1-2.5) were independently associated with outcome. However, both the sensitivity and specificity were relatively low (60% and 50%). The addition of the psychological variables did not improve the models and none of the psychological variables remained significant in the final analyses. There was a positive gradient in relation to the number of positive predictor variables and outcome, both at the 4(th )visit and after 3 months. CONCLUSION: Psychological factors were not found to be relevant in the prediction of treatment outcome in Swedish chiropractic patients with LBP.

The Nordic maintenance care program--case management of chiropractic patients with low back pain: a survey of Swedish chiropractors.

BACKGROUND: Chiropractic treatment for low back pain (LBP) can often be divided into two phases: Initial treatment of the problem to attempt to remove pain and bring it back into its pre-clinical or maximum improvement status, and "maintenance care", during which it is attempted to maintain this status. Although the use of chiropractic maintenance care has been described and discussed in the literature, there is no information as to its precise indications. The objective of this study is to investigate if there is agreement among Swedish chiropractors on the overall patient management for various types of LBP-scenarios, with a special emphasis on maintenance care. METHOD: The design was a mailed questionnaire survey. Members of the Swedish Chiropractors' Association, who were participants in previous practice-based research, were sent a closed-end questionnaire consisting of nine case scenarios and six clinical management alternatives and the possibility to create one's own alternative, resulting in a "nine-by-seven" table. The research team defined its own pre hoc choice of "clinically logical" answers based on the team's clinical experience. The frequency of findings was compared to the suggestions of the research team. RESULTS: Replies were received from 59 (60%) of the 99 persons who were invited to take part in the study. A pattern of self-reported clinical management strategies emerged, largely corresponding to the "clinically logical" answers suggested by the research team. In general, patients of concern would be referred out for a second opinion, cases with early recovery and without a history of previous low back pain would be quickly closed, and cases with quick recovery and a history of recurring events would be considered for maintenance care. However, also other management patterns were noted, in particular in the direction of maintenance care. CONCLUSION: To a reasonable extent, Swedish chiropractors participating in this survey appear to agree on the clinical management for different cases of LBP.

The Nordic back pain subpopulation program: the long-term outcome pattern in patients with low back pain treated by chiropractors in Sweden.

OBJECTIVES: (1) To describe the low back pain (LBP) pattern at baseline; (2) to describe the long-term outcome pattern; (3) to investigate the presence of distinct subgroups in relation to outcome; (4) to establish whether short-term outcome is a predictor of long-term outcome. METHODS: A 3- to 6- and 12- to 18-month, multicenter practice-based, prospective descriptive study was performed in private chiropractic practices in Sweden. Fifty-eight of 64 previously compliant chiropractors each recruited a maximum of 30 consecutive patients with LBP. Complete baseline clinical information was provided on 1054 patients, of which 93% were interviewed approximately 3 months later, and 57% responded to a questionnaire at approximately 12 months. Chiropractic treatment was decided by the treating chiropractor. Twelve descriptive subgroups were created based on (1) duration of LBP at baseline, (2) duration of LBP in the past year, and (3) LBP pattern in the past year. The predictive value was tested for outcome status at the fourth visit. Information on self-reported LBP status and improvement over the past months were collected. RESULTS: Patients were spread in a U-shaped fashion from benign to severe with the 2 extreme groups being most prevalent. About half the participants reported "no LBP in the past week" at 3 months and somewhat fewer at 12 months. Almost 75% claimed to be definitely better at 3 months, and approximately 50% at 12 months. Specific predictive subgroups can be identified, mainly in relation to the past-year history of LBP. Improvement at the fourth visit is a predictor of long-term outcome. CONCLUSION: Knowledge of specific subgroups may improve the quality of care and the selection of homogeneous study populations in clinical trials.

The Nordic Back Pain Subpopulation Program: validation and improvement of a predictive model for treatment outcome in patients with low back pain receiving chiropractic treatment.

OBJECTIVE: The aim of this study was to develop a predictive model for treatment outcome in patients with low back pain (LBP) receiving chiropractic treatment. METHODS: This multicenter practice-based predictive validity study was conducted in private chiropractic practices in Sweden. Of 64 previously compliant chiropractors, 58 recruited a maximum of 30 consecutive patients with LBP each. Information was provided on 1061 patients, of which 1057 questionnaires were valid. Chiropractic treatment was decided by the treating chiropractor. The outcome variable was the self-reported "definite improvement" at the fourth visit. The predictor variables included model 1, 3 hypothesized prognostic groups (best, intermediate, and least favorable) based on clinical information collected at baseline and at the second visit; and 4 additional models based on the following variables: age, sex, pain intensity during past 24 hours, description of disability, duration and pattern of pain during present attack, total duration of pain, and pain pattern during the past 12 months. RESULTS: Three of our factors were best at predicting the absence of improvement by the fourth visit and were able to correctly classify 79% of patients and to cover 74% of the receiver operated characteristics curve. These were (1) no definite overall improvement by the second treatment, (2) presence of leg pain, and (3) the minimum total duration of pain over the last 12 months being 30 days. CONCLUSION: In this study, patients with LBP who also had leg pain and LBP occurring sufficiently frequently or having lasted sufficiently long to add up to at least 30 days in the past year, and who did not report definite general improvement by the second treatment were not good candidates for short-term recovery. It is suggested that patients who fit the criteria of potential nonresponders should be carefully monitored to allow a selective approach of care.