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  • Deep brain stimulation as a treatment for neuropathic pain: A longitudinal study addressing neuropsychological outcomes

    24 October 2018

    Deep brain stimulation (DBS) of the periventricular/periaqueductal gray area and sensory thalamus can reduce pain intensity in patients with neuropathic pain. However, little is known about its impact on quality of life, emotional well-being, and cognition. This study followed up 18 patients who had received DBS for neuropathic pain. Each participant had previously undergone psychometric evaluation of each of the above areas as part of a routine presurgical neuropsychological assessment. Commensurate measures were employed at a follow-up assessment at least 6 months postsurgery. DBS significantly improved mood, anxiety, and aspects of quality of life. Improvements correlated with reduced pain severity. However, the sample continued to show impairments in most areas when compared against normative data published on nonclinical samples. There was little change in general cognitive functioning, aside from deterioration in spatial working memory. However, improvements in pain severity were associated with less improvement (and even deterioration) on measures of executive cognitive functioning. Improvements in emotional well-being also were correlated with changes in cognition. These results suggest that DBS of the periventricular/periaqueductal gray and/or sensory thalamus improves quality of life and emotional well-being in sufferers, although there is some indication of executive dysfunction, particularly among those reporting greatest pain alleviation. Perspective This article examines the neuropsychological outcomes of DBS surgery as a treatment for neuropathic pain. This intervention was found to improve pain severity, emotional well-being, and quality of life, although such benefits may be accompanied by reduced ability on tasks measuring executive functioning. © 2014 by the American Pain Society.

  • Deep brain stimulation as a treatment for neuropathic pain: a longitudinal study addressing neuropsychological outcomes.

    24 October 2018

    UNLABELLED: Deep brain stimulation (DBS) of the periventricular/periaqueductal gray area and sensory thalamus can reduce pain intensity in patients with neuropathic pain. However, little is known about its impact on quality of life, emotional well-being, and cognition. This study followed up 18 patients who had received DBS for neuropathic pain. Each participant had previously undergone psychometric evaluation of each of the above areas as part of a routine presurgical neuropsychological assessment. Commensurate measures were employed at a follow-up assessment at least 6 months postsurgery. DBS significantly improved mood, anxiety, and aspects of quality of life. Improvements correlated with reduced pain severity. However, the sample continued to show impairments in most areas when compared against normative data published on nonclinical samples. There was little change in general cognitive functioning, aside from deterioration in spatial working memory. However, improvements in pain severity were associated with less improvement (and even deterioration) on measures of executive cognitive functioning. Improvements in emotional well-being also were correlated with changes in cognition. These results suggest that DBS of the periventricular/periaqueductal gray and/or sensory thalamus improves quality of life and emotional well-being in sufferers, although there is some indication of executive dysfunction, particularly among those reporting greatest pain alleviation. PERSPECTIVE: This article examines the neuropsychological outcomes of DBS surgery as a treatment for neuropathic pain. This intervention was found to improve pain severity, emotional well-being, and quality of life, although such benefits may be accompanied by reduced ability on tasks measuring executive functioning.

  • Injecting realism in surgical training-initial simulation experience with custom 3D models.

    24 October 2018

    UNLABELLED: The traditionally accepted form of training is direct supervision by an expert; however, modern trends in medicine have made this progressively more difficult to achieve. A 3-dimensional printer makes it possible to convert patients imaging data into accurate models, thus allowing the possibility to reproduce models with pathology. This enables a large number of trainees to be trained simultaneously using realistic models simulating actual neurosurgical procedures. The aim of this study was to assess the usefulness of these models in training surgeons to perform standard procedures that require complex techniques and equipment. METHODS: Multiple models of the head of a patient with a deep-seated small thalamic lesion were created based on his computed tomography and magnetic resonance imaging data. A workshop was conducted using these models of the head as a teaching tool. The surgical trainees were assessed for successful performance of the procedure as well as the duration of time and number of attempts taken to learn them. FINDINGS: All surgical candidates were able to learn the basics of the surgical procedure taught in the workshop. The number of attempts and time taken reflected the seniority and previous experience of each candidate. DISCUSSION: Surgical trainees need multiple attempts to learn essential procedures. The use of these models for surgical-training simulation allows trainees to practice these procedures repetitively in a safe environment until they can master it. This would theoretically shorten the learning curve while standardizing teaching and assessment techniques of these trainees.

  • Utility of multimaterial 3D printers in creating models with pathological entities to enhance the training experience of neurosurgeons.

    24 October 2018

    The advent of multimaterial 3D printers allows the creation of neurosurgical models of a more realistic nature, mimicking real tissues. The authors used the latest generation of 3D printer to create a model, with an inbuilt pathological entity, of varying consistency and density. Using this model the authors were able to take trainees through the basic steps, from navigation and planning of skin flap to performing initial steps in a craniotomy and simple tumor excision. As the technology advances, models of this nature may be able to supplement the training of neurosurgeons in a simulated operating theater environment, thus improving the training experience.

  • Reciprocal interactions between the human thalamus and periaqueductal gray may be important for pain perception.

    24 October 2018

    Pain perception can be altered by activity in the periaqueductal gray (PAG). The PAG can decrease the incoming nociceptive signals at the level of the spinal dorsal horn, but it is not clear whether the PAG can also affect the sensory thalamus, ventral posterolateral and ventral posteromedial thalamic nuclei, to modulate pain. However, the PAG and the thalamus have direct connections with each other; so we postulated that the PAG may also modulate pain by inhibiting the sensory nuclei in the thalamus, and that these may also reciprocally influence the PAG. Here, by analyzing the local field potentials recorded from the sensory thalamus and the PAG in chronic pain patients with deep brain stimulation electrodes, we show that PAG stimulation inhibited the sensory thalamus with decreasing thalamic delta, theta, alpha and beta power, and sensory thalamus stimulation excited the PAG with increasing PAG delta and theta power. We demonstrate that the PAG and the sensory thalamus interact reciprocally at short latency, which may be related to pain modulation.

  • Everything to gain: Sir Hugh Cairns' treatment of central nervous system infection at Oxford and abroad.

    24 October 2018

    Antibiotics have revolutionized survival from central nervous system (CNS) infections. Sixty years after the death of Sir Hugh Cairns, we present archive material of historical interest from the Radcliffe Infirmary in Oxford from the time of his first trials of penicillin for CNS infection. We discuss Cairns' important wartime and subsequent contributions to antibiosis in CNS infection and include drawings by Audrey Arnott illustrating the surgical techniques used to treat abscesses at the time.

  • Deep brain stimulation of the anterior cingulate cortex: targeting the affective component of chronic pain.

    24 October 2018

    Deep brain stimulation (DBS) has shown promise for relieving nociceptive and neuropathic symptoms of refractory chronic pain. We assessed the efficacy of a new target for the affective component of pain, the anterior cingulate cortex (ACC). A 49-year-old man with neuropathic pain underwent bilateral ACC DBS. Patient-reported outcome measures were collected before and 2 years after surgery using a Visual Analogue Scale, Short-Form 36 quality of life survey, McGill pain questionnaire, EuroQol-5D questionnaires (EQ-5D; Health State) and neuropsychological assessments. The patient improved with DBS. Two years after surgery, the Visual Analogue Scale decreased from 6.7 to 3.0, McGill pain questionnaire improved by 42% and EQ-5D Health State increased by 150%. Stimulating the ACC at 130 Hz, 330 µs and 3 V facilitated neuropathic pain relief. The DBS remained efficacious during the 2-year follow-up period. Affective ACC DBS can relieve chronic neuropathic pain refractory to pharmacotherapy and restore quality of life.

  • A non-Gaussian LCMV beamformer for MEG source reconstruction

    24 October 2018

    Evidence suggests that magnetoencephalogram (MEG) data have characteristics with non-Gaussian distribution, however, standard methods for source localisation assume Gaussian behaviour. We present a new general method for non-Gaussian source estimation of stationary signals for localising brain activity in the MEG data. By providing a Bayesian formulation for linearly constraint minimum variance (LCMV) beamformer, we extend this approach and show that how the source probability density function (pdf), which is not necessarily Gaussian, can be estimated. The proposed non-Gaussian beamformer is shown to give better spatial estimates than the LCMV beamformer, in both simulations incorporating non-Gaussian signal and in real MEG measurements. © 2013 IEEE.