Somatosensory activations during the observation of touch and a case of vision-touch synaesthesia.
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In this study, we describe a new form of synaesthesia in which visual perception of touch elicits conscious tactile experiences in the perceiver. We describe a female subject (C) for whom the observation of another person being touched is experienced as tactile stimulation on the equivalent part of C's own body. Apart from this clearly abnormal synesthetic experience, C is healthy and normal in every other way. In this study, we investigate whether C's 'mirrored touch' synesthetic experience is caused by overactivity in the neural system that responds to the observation of touch. A functional MRI experiment was designed to investigate the neural system involved in the perception of touch in a group of 12 non-synesthetic control subjects and in C. We investigated neural activity to the observation of touch to a human face or neck compared with the observation of touch to equivalent regions on an object. Furthermore, to investigate the somatosensory topography of the activations during observation of touch, we compared activations when observing a human face or neck being touched with activations when the subjects themselves were touched on their own face or neck. The results demonstrated that the somatosensory cortex was activated in the non-synesthetic subjects by the mere observation of touch and that this activation was somatotopically organized such that observation of touch to the face activated the head area of primary somatosensory cortex, whereas observation of touch to the neck did not. Moreover, in non-synesthetic subjects, the brain's mirror system-comprising premotor cortex, superior temporal sulcus and parietal cortex-was activated by the observation of touch to another human more than to an object. C's activation patterns differed in three ways from those of the non-synesthetic controls. First, activations in the somatosensory cortex were significantly higher in C when she observed touch. Secondly, an area in left premotor cortex was activated in C to a greater extent than in the non-synesthetic group. Thirdly, the anterior insula cortex bilaterally was activated in C, but there was no evidence of such activation in the non-synesthetic group. The results suggest that, in C, the mirror system for touch is overactive, above the threshold for conscious tactile perception. (+info)
Bilateral subthalamic nucleus stimulation improves balance control in Parkinson's disease.
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BACKGROUND: Parkinson's disease (PD), the most common basal ganglia degenerative disease, affects balance control, especially when patients change balance strategy during postural tasks. Bilateral chronic stimulation of the subthalamic nucleus (STN) is therapeutically useful in advanced PD, and reduces the motor signs of patients. Nevertheless, the effects of STN stimulation on postural control are still debatable. AIMS: To assess the impact of bilateral STN stimulation on balance control in PD and to determine how basal ganglia related sensorimotor modifications act on neurosensorial organisation of balance and motor postural programming. METHODS: Twelve subjects aged 45-70 years underwent unified Parkinson's disease rating scale motor (part III) clinical tests, static and dynamic posturography, including sensory organisation and adaptation tests, shortly before and six months after bilateral implantation of electrodes into the STN. RESULTS: The postoperative static test showed an improvement in postural control precision both in eyes open and eyes closed conditions. The dynamic test highlighted the decreased number of falls and the ability of the patients to develop more appropriate sensorimotor strategies when stimulated. The sensory organisation test showed an improvement of equilibrium score and, thus, a better resolution of sensorial conflicts. CONCLUSIONS: STN stimulation allowed a reduction in rigidity and therefore an improvement in the ability to use muscular proprioception as reliable information, resulting in vestibulo-proprioceptive conflict suppression. STN stimulation has a synergistic effect with levodopa for postural control. Accordingly, non-dopaminergic pathways could be involved in postural regulation and STN stimulation may influence the functioning of these pathways. (+info)
Sexual function in men and women after anterior surgery for chronic low back pain.
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Sexual dysfunction after anterior lumbar fusion has mainly been focused on male biological function (retrograde ejaculation). The aim of the present study is to assess the effect of fusion surgery for chronic low back pain on the sex-related quality of life. Apart from routine prospective questionnaires, additional gender-specific mailed questionnaires produced retrospective data on sexual enjoyment and function after 2 years of follow-up. Patients randomised to non-surgical treatment and anterior or posterior fusion were compared. We found that surgically treated patients had a significantly better sex life than those non-surgically treated. The improved sex life was significantly associated with the reduced back pain. The improvement after anterior fusion, however, was counteracted by a trend towards disturbed orgasm and genital sensation in women, and a significant disturbance of ejaculation and genital sensation in men. In view of the increased frequency of anterior lumbar surgery with the strong promotion of disc replacement, the findings in the present small retrospective pilot study should be tested in larger prospective trials. (+info)
Attenuation of sensory and affective responses to heat pain: evidence for contralateral mechanisms.
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Attenuation of responses to repeated sensory events has been thoroughly studied in many modalities; however, attenuation of pain perception has not yet benefitted from such extensive investigation. Described here are two psychophysical studies that examined the effects of repeated exposure to thermal stimuli, assessing potential attenuation of the perception of pain and its possible spatial specificity. Twenty-two subjects were presented thermal stimuli to the volar surface of the right and left forearms. Twelve subjects in study 1 received the same stimuli and conditions on each of five daily experimental sessions, whereas 10 subjects in study 2 received thermal stimuli, which were restricted to one side for four daily sessions and then applied to the other side on the fifth session. Ratings of warmth intensity, pain intensity, and pain unpleasantness were recorded while the subjects performed a thermal sensory discrimination task. Results of study 1 demonstrate that repeated stimulation with noxious heat can lead to long-term attenuation of pain perception; results of study 2 extend these findings of attenuation to both pain intensity and unpleasantness and show that this effect is highly specific to the exposed body side for both aspects of the pain experience. We suggest that the functional plasticity underlying this attenuation effect lies in brain areas with a strong contralateral pattern of pain-related activation. (+info)
Implementing a clinical assessment protocol for sensory and skeletal function in diabetic neuropathy patients at a university hospital in Brazil.
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CONTEXT AND OBJECTIVE: Physiotherapy can contribute towards recovering or preventing physical and sensory alterations in diabetic neuropathy patients. Our objective was to create and apply a protocol for functional assessment of diabetic neuropathy patients' lower limbs, to guide future physiotherapy. DESIGN AND SETTING: Clinical study at the University Hospital and teaching/research center of Universidade de Sao Paulo. METHODS: An intentional sample of diabetic neuropathy patients was utilized. The protocol was divided into: (1) preliminary investigation with identification of relevant clinical diabetes and neuropathy characteristics; (2) thermal, tactile and proprioceptive sensitivity tests on the feet; (3) evaluations of muscle function, range of motion, lower limb function, foot anthropometry. RESULTS: The patients' mean age was 57 years, and they had had the diagnosis for 13 years on average. Distal numbness and tingling/prickling were present in 62% and 67%, respectively. There were tactile sensitivity alterations above the heel in 50%, with thermal sensitivity in 40% to 60%. The worst muscle function test responses were at the triceps surae and foot intrinsic muscles. Longitudinal plantar arches were lowered in 50%. Decreased thermal and tactile sensitivity of the heels was found. There was a general reduction in range of motion. CONCLUSIONS: The results provided detailed characterization of the patients. This protocol may be easily applied in healthcare services, since it requires little equipment, at low cost, and it is well understood by patients. (+info)
Effects of smoking on neuropathic pain in two people with spinal cord injury.
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BACKGROUND/OBJECTIVE: To describe an apparent relationship between smoking and the neuropathic pain experience in people with spinal cord injury (SCI). METHOD: Case Reports. PARTICIPANTS/METHODS: Two individuals treated at a rehabilitation center. The first was a 38-year-old white man with a T1 2 SCI, American Spinal Injury Association (ASIA) impairment scale (AIS) A, secondary to motor vehicle crash. Duration of injury was 14 years. He reported burning pain in his legs, and has smoked 1/2 pack per day for the last 15 years. The second was a 55-year-old African American man with a T6 SCI, AIS A, secondary to gunshot wound. Duration of injury was 22 years. He was a 40-year 1/2 to 1 pack per day smoker, who, after injury, consistently experienced burning, radicular pain, rated 7/10, around the level of the injury. SUMMARY: The first subject rated his pain as 4/10 when not smoking and 7/10 when smoking. The pain subsided 30 minutes after smoking was discontinued. He noted an immediate increase in neuropathic pain when smoking. The second subject quit smoking for 1 month and immediately noted that the pain disappeared, rating it 0/10. After he resumed smoking, his radicular pain was 8.5/10 in the morning and 5/10 in afternoon. CONCLUSIONS: No similar reports have been published, based on a MEDLINE search. Nicotinic receptors have been implicated in pain perception. It is unclear to what extent these 2 cases generalize to the SCI population. We plan to explore this via survey and experimental research. Smoking cessation may have a dual benefit of increased health and decreased neuropathic pain. (+info)
Facial sensory symptoms in medullary infarcts.
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OBJECTIVE: To investigate the correlation between facial sensory abnormalities and lesional topography in eight patients with lateral medullary infarcts (LMIs). METHOD: We reviewed eight sequential cases of LMIs admitted to the Neurology Division of Hospital das Clinicas/Sao Paulo University between July, 2001 and August, 2002 except for one patient who had admitted in 1996 and was still followed in 2002. All patients were submitted to conventional brain MRI including axial T1-, T2-weighted and Fluid attenuated inversion-recovery (FLAIR) sequences. MRIs were evaluated blindly to clinical features to determine extension of the infarct to presumed topographies of the ventral trigeminothalamic (VTT), lateral spinothalamic, spinal trigeminal tracts and spinal trigeminal nucleus. RESULTS: Sensory symptoms or signs were ipsilateral to the bulbar infarct in 3 patients, contralateral in 4 and bilateral in 1. In all of our cases with exclusive contralateral facial sensory symptoms, infarcts had medial extensions that included the VTT topography. In cases with exclusive ipsilateral facial sensory abnormalities, infarcts affected lateral and posterior bulbar portions, with slight or no medial extension. The only patient who presented bilateral facial symptoms had an infarct that covered both medial and lateral, in addition to the posterior region of the medulla. CONCLUSION: Our results show a correlation between medial extension of LMIs and presence of contralateral facial sensory symptoms. (+info)
A controlled crossover study of the selective serotonin reuptake inhibitor citalopram in irritable bowel syndrome.
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INTRODUCTION: Selective serotonin reuptake inhibitors (SSRIs) are frequently used in the treatment of irritable bowel syndrome (IBS) although evidence of their efficacy is scarce. AIM: Twenty three non-depressed IBS patients were recruited from a tertiary care centre and included in a crossover trial comparing six weeks of treatment with the SSRI citalopram (20 mg for three weeks, 40 mg for three weeks) with placebo. IBS symptom severity was the primary outcome measure, and depression and anxiety scores were also measured. The effect of acute administration of citalopram on colonic sensitivity and on colonic response to feeding was investigated as a putative predictor of symptomatic response to the drug. RESULTS: After three and six weeks of treatment, citalopram significantly improved abdominal pain, bloating, impact of symptoms on daily life, and overall well being compared with placebo. There was only a modest effect on stool pattern. Changes in depression or anxiety scores were not related to symptom improvement. The effect of acute administration of citalopram during a colonic barostat study did not predict clinical outcome. Analysis of the first treatment period as a double blind parallel arm study confirmed the benefit of citalopram over placebo. CONCLUSIONS: The SSRI citalopram significantly improves IBS symptoms, including abdominal pain, compared with placebo. The therapeutic effect is independent of effects on anxiety, depression, and colonic sensorimotor function. (+info)