Feature domain-specific movement intention detection for stroke rehabilitation with brain-computer interfaces.

Brain-computer interface (BCI) driven electrical stimulation has been proposed for neuromodulation for stroke rehabilitation by pairing intentions to move with somatosensory feedback from electrical stimulation. Movement intentions have been detected in several studies using different techniques, with temporal and spectral features being the most common. A few studies have compared temporal and spectral features, but conflicting results have been reported. In this study, the aim was to investigate if complexity measures can be used for movement intention detection and to compare the detection performance based on features extracted from three different domains (time, frequency and complexity) from single-trial EEG. Two data sets were used where four different isometric palmar grasps or dorsiflexions were performed while continuous EEG was recorded. 39 healthy subjects performed or imagined these movements and 11 stroke patients attempted to perform the movements. The EEG was pre-processed and divided into two epoch classes: Background EEG (2 s) and movement intention (2 s). To obtain an estimated detection performance, temporal, spectral and complexity features were extracted and classified (linear discriminant analysis) after the feature vector was reduced using sequential forward selection. The results show that accuracies between 82-87% and 74-80% are obtained for foot and hand movements, respectively. The temporal feature domain was the most dominant for foot movement intention detection, while the spectral features contributed more to the hand movement detection. The complexity features could be used to detect movement intentions, but the performance was much lower compared to temporal and spectral features.

Lumbar spondylolysis: a life long dynamic condition? A cross sectional survey of 4.151 adults.

Lumbar spondylolysis (LS) has been the subject of several studies focusing on adolescent athletes. Few, if any, studies have examined LS in the general population. Lysis of the pars interarticularis of the vertebra may be associated with slipping (olisthesis), or it may be stable. In the present survey of lumbar radiographs and general epidemiological data recorded from the Copenhagen Osteoarthritis Study cohort of 4.151 subjects (age range, 22-93 years), we identified the distribution and individual risk factors for LS-development. Men were significantly more at risk of L5 spondylolysis (P = 0.002). There were no sex-specific significant differences regarding LS-incidence at the L4 level. We found no significant differences of risk of LS between nulliparous or multiparous women (L4 P = 0.54/L5 P = 0.35). Furthermore, we found no significant relationship between age at menopause and LS-development. Increased lumbar lordosis was associated to L4/L5 spondylolysis in men (L4 P < 0.001/L5 P = 0.008). In women increased lumbar lordosis had a significant association with L5 spondylolysis (P < 0.001). Increased pelvic inclination was associated with L5 spondylolysis in both men and women (P < 0.001). There were no sex-specific differences regarding the occurrence of simultaneous slips/non-slips. In men, no individual risk factors for L4 slips with concomitant LS were found. In women slipped LS of L4 were significantly associated to aging (P < 0.001) and with decreased pelvic inclination (P = 0.001). In men slipped LS of L5 was significantly associated to increased BMI (P = 0.002), but not to aging (P = 0.10). In women, slips of L5 LS were significantly correlated to aging (P = 0.005), to BMI recorded at the time of radiographic examination (P = 0.006), and BMI measured 17 years before radiographic index examination (P = 0.004). The present study contrasts with commonly held views regarding lumbar spondylolysis. The prevalence of LS increases throughout life and is apparently not a condition restricted to adolescence. Although the cross-sectional nature of the present study prevents an exact estimate of the age at onset; future, sequential studies of the cohort may provide us with some important answers on this topic. Apart from aging-obesity, lordotic angle and pelvic inclination were found to be individual risk factors for LS.

A review of the radiological anatomy of the round window.

Experimental studies on dried temporal bones in various projections combined with studies of the anatomical details marked with metal wires and/or barium paste have been performed to define the round window and its anatomical relation to surrounding structures. The exact plane of the round window was not found to be tomographically demonstrable and the term to describe the dehiscence in the lateral wall of the promontory below and posterior to that of the oval window should be the niche of the round window. Previous radiologically described pathological changes at the round window should be reviewed.

Roentgenography of paranasal sinuses during treatment of nasal polyposis.

Seventeen patients had severe nasal polyposis. Local treatment with beclomethasone dipropionate caused marked reduction in the size of polyps and the nasal obstruction, and the effect continued throughout the treatment period. In all cases roentgenographic examination showed clouding of the nasal cavity and the paranasal sinuses, especially of the maxillary and ethmoidal sinuses. After three months of treatment, no change in the opacity of the sinuses was found. In spite of that, the symptomatic effect of the treatment was successful.