Stochastic resonance in the human vestibular system - Noise-induced facilitation of vestibulospinal reflexes.

BACKGROUND: There is strong evidence that the presence of noise can enhance information processing in sensory systems via stochastic resonance (SR). OBJECTIVES: To examine the presence of SR in human vestibulospinal reflex function. METHODS: Healthy subjects were stimulated with 1 Hz sinusoidal GVS of varying amplitudes (0-1.9 mA). Coherence between GVS input and stimulation-induced motion responses was determined and psychometric function fits were subsequently used to determine individual vestibulospinal reflex thresholds. This procedure was repeated with additional application of imperceptible white noise GVS (nGVS). RESULTS: nGVS significantly facilitated the detectability of weak subthreshold vestibular inputs (p < 0.001) and thereby effectively lowered the vestibulospinal threshold in 90% of participants (p < 0.001, mean reduction: 17.5 ± 14.6%). CONCLUSION: This finding provides evidence for the presence of SR-dynamics in the human vestibular system and gives a functional explanation for previously observed ameliorating effects of low-intensity vestibular noise stimulation on balance control in healthy subjects and patients with vestibular hypofunction.

Noise-Enhanced Vestibular Input Improves Dynamic Walking Stability in Healthy Subjects.

BACKGROUND: White noise galvanic vestibular stimulation (GVS) is thought to enhance the sensitivity of vestibular organs. OBJECTIVE: To examine the effects of noise-enhanced vestibular input on the walking performance in healthy subjects walking with eyes closed. METHODS: Walking performance of 17 healthy subjects (mean age 28.8 ± 1.7 years) at slow, preferred, and fast speeds was examined during three different conditions: (1) walking with eyes open (EO) as baseline condition, (2) walking with eyes closed and sham noisy GVS (EC), and (3) walking with eyes closed and non-zero amplitude noisy GVS set to 80% of the individual sensory threshold for GVS (EC-GVS). Ten gait parameters were examined: stride time, stride length, base of support, swing time percentage, double support time percentage as well as gait asymmetry, bilateral phase coordination and the coefficient of variation (CV) of stride time, stride length and base of support. RESULTS: Noisy GVS improved stride time CV by 36% (p < 0.034), stride length CV by 31% (p < 0.037), base of support CV by 14% (p < 0.009), and bilateral phase coordination by 23% (p < 0.034). The ameliorating effects of noisy GVS on locomotion function were primarily observable during slow walking speeds. CONCLUSION: Noise-enhanced vestibular input is effective in improving locomotion function and is accompanied by a subjectively felt improvement of walking balance. It predominantly targets the variability and bilateral coordination characteristics of the walking pattern, which are critically linked to dynamic walking stability. Noisy GVS might present an effective treatment option to improve walking performance in patients with bilateral vestibular dysfunction.

Postural imbalance and falls in PSP correlate with functional pathology of the thalamus.

OBJECTIVE: To determine how postural imbalance and falls are related to regional cerebral glucose metabolism (PET) and functional activation of the cerebral postural network (fMRI) in patients with progressive supranuclear palsy (PSP). METHODS: Sixteen patients with PSP, who had self-monitored their frequency of falls, underwent a standardized clinical assessment, posturographic measurement of balance during modified sensory input, and a resting [¹8F]FDG-PET. In addition, patients performed an fMRI paradigm using mental imagery of standing. Results were compared to healthy controls (n = 16). RESULTS: The frequency of falls/month in patients (range 1-40) correlated with total PSP rating score (r = 0.90). Total sway path in PSP significantly correlated with frequency of falls, especially during modulated sensory input (eyes open: r = 0.62, eyes closed: r = 0.67, eyes open/head extended: r = 0.84, eyes open/foam-padded platform: r = 0.87). Higher sway path values and frequency of falls were associated with decreased regional glucose metabolism (rCGM) in the thalamus (sway path: r = -0.80, falls: r = -0.64) and increased rCGM in the precentral gyrus (sway path: r = 0.79, falls: r = 0.64). Mental imagery of standing during fMRI revealed a reduced activation of the mesencephalic brainstem tegmentum and the thalamus in patients with postural imbalance and falls. CONCLUSIONS: The new and clinically relevant finding of this study is that imbalance and falls in PSP are closely associated with thalamic dysfunction. Deficits in thalamic postural control get most evident when balance is assessed during modified sensory input. The results are consistent with the hypothesis that reduced thalamic activation via the ascending brainstem projections may cause postural imbalance in PSP.

[Integrated Center for Research and Treatment of Vertigo, Balance and Ocular Motor Disorders]. / Integriertes Forschungs- und Behandlungszentrum für Schwindel, Gleichgewichts- und Okulomotorikstörungen.

The German BMBF (German Ministry of Education and Research) has decided to establish an Integrated Center for Research and Treatment of Vertigo, Balance and Ocular Motor Disorders (IFB(LMU)) in Munich in 2010. After funding over a 10-year period, the long-term continuation of the IFB(LMU) by the medical faculty and the hospital is envisioned. Vertigo is one of the most common complaints in medicine. Despite its high prevalence patients with vertigo generally receive either inappropriate or inadequate treatment. This deplorable situation is internationally well known and its causes are multiple: insufficient interdisciplinary cooperation, no standardized diagnostics and therapy, the failure to translate findings of basic science into clinical applications and the scarcity of clinical multicenter studies. The IFB(LMU) will constitute a suitable tool with which these structural, clinical, and scientific deficits can be overcome. It will also make possible the establishment of an international interdisciplinary referral center. Munich has become the site of a unique concentration of leading experts on vertigo, balance and ocular motor disorders, both in the clinical and basic sciences. Academic structures have paved the way for the creation of an interdisciplinary horizontal network that also allows structured, vertical academic career paths via the Bachelor's and Master's degree programs in neuroscience, a Graduate School of Systemic Neurosciences, and the Munich Center for Neuroscience "Brain and Mind". The IFB(LMU) has the following objectives with regard to structure and content: to create an independent patient-oriented clinical research center under the auspices of the Medical Faculty but with autonomic administration and budget; to overcome existing clinical and academic barriers separating the traditional specializations, to establish a standardized interdisciplinary longitudinal and transversal network at one site for the management of patients. This should professionalize both the management and the international recruitment of patients (integrated care, telemedicine); to organize the study infrastructure for prospective multicenter clinical studies as well as to free clinical scientists from administrative tasks; to promote translational research with a focus on the innovative topics of molecular functional and structural imaging, experimental and clinical pharmacotherapy, clinical research of vertigo and balance disorders, mathematical modelling, interaction between biological and technical systems (robotics) and research on functionality and the quality of life; to offer new attractive educational paths and career images for medical doctors, students of the natural sciences and engineers in clinical research in order to overcome traditional hierarchical structures. This should promote the principles of efficiency and self-reliance; to supplement the existing excellence with up to eight groups of young scientists and up to eight professorships (tenure track). This should also be seen as an incentive that will attract the best young scientists; to incorporate IFB(LMU) competence into the existing medical and biological graduate schools. The IFB(LMU) is a unique reference center worldwide.

[Polysomnographic as a therapeutic aid in of psychogenic-functioning paraplegia]. / Polysomnographie als therapeutische Hilfe bei psychogen-funktioneller Paraplegie.

The case of a patient with complete sensory and motor paraplegia for more than 1 year is presented. Leg movements were documented during sleep by video and electromyographic recording because a psychogenic cause of the symptoms was suspected. We showed the video to the patient, which illustrated that leg movements were possible. This resulted in fast and complete resolution of the neurologic symptoms. The patient has now been free of them for more than 3 years. This example suggests that the achievement of consciousness of normal motor function is a therapeutic approach for long-standing improvement of psychogenic paralysis.

Kinetic cavity preparation--hit or flop?

The preparation of dental hard tissues is carried out primarily with rotating instruments and is known to have some shortcomings. Kinetic cavity preparation (KCP) seems to be a desirable alternative. Nevertheless, scientific investigations and clinical experiences revealed numerous disadvantages which have led to a clear limitation of its use. For example, KCP can not replace the normal conditioning of enamel by acid etching. The hopes connected with the re-introduction of this technology for conservative dentistry have not been fulfilled.

[Behavior of thiobarbituric acid reactive substances, alpha-tocopherol, glutathione and selenium during hypertension in pregnancy]. / Verhalten von thiobarbitursäurereaktiven Substanzen (TBARS), alpha-Tocopherol, Glutathion und Selen während der hypertensiven Erkrankung in der Schwangerschaft.

PATIENTS AND METHOD: In a longitudinal study the changes of serum or plasma levels of TBARS, alpha-tocopherol, glutathione and selenium were investigated comparing 46 pregnant women with hypertensive syndrome and 18 women with normal pregnancies. RESULTS AND CONCLUSIONS: A significant increase in TBARS serum level was found in women suffering from hypertension. There was no correlation between the severity of hypertension and the extent of the TBARS rise. An absolute deficiency of the antioxidants alpha-tocopherol, glutathione and the elements selenium, calcium, magnesium, iron and zinc as a cause or a consequence of hypertension in pregnancy could be excluded. Low serum levels of copper and selenium could decrease the activity of glutathione peroxidase (Gpx) resulting in higher levels of TBARS and glutathione during the last trimester of pregnancy and delivery. Increased concentrations of iron in women with hypertensive syndrome may affect the formation of lipid peroxides. The outcome of children was unaffected by increased lipid peroxide levels when an antihypertensive therapy was consequently performed.

Volatile constituents of the dried leaves of Cassia angustifolia and C. acutifolia (Sennae folium).

The official drug Sennae folium (obtained from Cassia angustifolia and/or C. acutifolia) was found to contain small amounts of volatiles (0.047% based on dry weight) which were analyzed in detail by GC and GC/MS. More than 200 compounds could be detected, 122 of them were identified, representing about 90.7% of the peak area of the total mixture. The volatile constituents can be classified into monoterpenoids (8.8% for sample A and 34.6% for B), sesquiterpenoids (4.2% and 4.0%, respectively), phenylpropanoids (4.2%/15.2%), fatty acids and esters (54.3%/14.2%), and miscellaneous compounds (19.3%/22.7%). Apart from hexadecanoic acid which was strong in both samples (36.8%/9.7%), the occurrence of menthol, geranylacetone, and (E)-anethole is of interest.

In vivo and in vitro effects of extracts from Cassia aubrevillei in onchocerciasis.

A traditional herbal drug, called "Ganna Ganna", is used in rural areas of Liberia to treat onchocerciasis. It is prepared from the bark of the "Ganna Ganna" tree, which was identified as Cassia aubrevillei. An aqueous extract was prepared from the bark according to informations from local people and its effects on microfilaria (mf) density and pruritus were studied in eleven patients with onchocerciasis. In four patients a 1.8-4.8 fold increase in mf density was observed after three weeks and in two patients mf counts dropped to almost zero. Histology and embryogram of adult worms, isolated after treatment, revealed no significant changes. All patients reported a rapid decline of pruritus and this effect lasted for up to three months. The in vitro effect of different extracts on mf viability was tested. The alcoholic extract gave the best results, killing mf within 24 h at concentrations of 50 micrograms/ml. Chrysophanic acid, an anthraquinone identified in the drug, also showed good in vitro microfilaricidal activity. It is concluded, that "Ganna Ganna" could be a useful adjuvant in the therapy of onchocerciasis and that further evaluation of the drug seems promising.