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  • Deep brain stimulation: indications and evidence.

    12 December 2017

    Deep brain stimulation is a minimally invasive targeted neurosurgical intervention that enables structures deep in the brain to be stimulated electrically by an implanted pacemaker. It has become the treatment of choice for Parkinson's disease, refractory to, or complicated by, drug therapy. Its efficacy has been demonstrated robustly by randomized, controlled clinical trials, with multiple novel brain targets having been discovered in the last 20 years. Multifarious clinical indications for deep brain stimulation now exist, including dystonia and tremor in movement disorders; depression, obsessive-compulsive disorder and Tourette's syndrome in psychiatry; epilepsy, cluster headache and chronic pain, including pain from stroke, amputation, trigeminal neuralgia and multiple sclerosis. Current research argues for novel indications, including hypertension and orthostatic hypotension. The development, principles, indications and effectiveness of the technique are reviewed here. While deep brain stimulation is a standard and widely accepted treatment for Parkinson's disease after 20 years of experience, in chronic pain it remains restricted to a handful of experienced, specialist centers willing to publish outcomes despite its use for over 50 years. Reasons are reviewed and novel approaches to appraising clinical evidence in functional neurosurgery are suggested.

  • Awake stereotactic brainstem biopsy via a contralateral, transfrontal, transventricular approach.

    12 December 2017

    The authors describe a novel approach to stereotactic biopsy of lesions of the lateral pons and medial cerebellar peduncle, and its diagnostic success without morbidity. A contralateral approach laterally expands the accessible infratentorial area. It may also confer a theoretical reduction in neurological deficit with passage through non-dominant right hemisphere.

  • Deep brain stimulation in childhood: an effective treatment for early onset idiopathic generalised dystonia.

    12 December 2017

    BACKGROUND: Early onset idiopathic generalised dystonia is a progressive and profoundly disabling condition. Medical treatment may ameliorate symptoms. However, many children have profound, intractable disability including the loss of ambulation and speech, and difficulties with feeding. Following the failure of medical management, deep brain stimulation (DBS) of the globus pallidus internus (GPi) has emerged as an alternative treatment for the disorder. METHODS: We describe four children who presented with dystonia. RESULTS: Following the failure of a range of medical therapies, DBS systems were implanted in the GPi in an attempt to ameliorate the children's disabilities. All children found dystonic movements to be less disabling following surgery. Compared with preoperative Burke, Fahn and Marsden Dystonia Rating Scale scores, postoperative scores at 6 months were improved. CONCLUSIONS: DBS is effective in improving symptoms and function in children with idiopathic dystonia refractory to medical treatment. Whilst surgery is complex and can be associated with intraoperative and postoperative complications, this intervention should be considered following the failure of medical therapy.

  • Switching off micturition using deep brain stimulation at midbrain sites.

    12 December 2017

    Most of the time the bladder is locked in storage mode, switching to voiding only when it is judged safe and/or socially appropriate to urinate. Here we show, in humans and rodents, that deep brain stimulation in the periaqueductal gray matter can rapidly and reversibly manipulate switching within the micturition control circuitry, to defer voiding and maintain urinary continence, even when the bladder is full. Manipulation of neural continence pathways by deep brain stimulation may offer new avenues for the treatment of urinary incontinence of central origin.

  • Twiddler's syndrome in a patient with a deep brain stimulation device for generalized dystonia.

    12 December 2017

    Deep brain stimulation (DBS) is the technique of neurostimulation of deep brain structures for the treatment of conditions such as essential tremor, dystonia, Parkinson's disease and chronic pain syndromes. The procedure uses implanted deep brain stimulation electrodes connected to extension leads and an implantable pulse generator (IPG). Hardware failure related to the DBS procedure is not infrequent, and includes electrode migration and disconnection. We describe a patient who received bilateral globus pallidus internus DBS for dystonia with initially good clinical response, but the device eventually failed. Radiographs showed multiple twisting of the extension leads with disconnection from the brain electrodes and a diagnosis of Twiddler's syndrome was made. Twiddler's syndrome was first described in patients with cardiac pacemakers. Patients with mental disability, elderly and obese patients are at increased risk. Twiddler's syndrome should be suspected whenever there is a failure of the DBS device to relieve symptoms previously responsive to stimulation. Surgical correction is usually required.

  • Intra-operative deep brain stimulation of the periaqueductal grey matter modulates blood pressure and heart rate variability in humans.

    12 December 2017

    INTRODUCTION:   Deep brain stimulation applied to the periaqueductal grey matter (PAG) of the midbrain in humans has been shown to increase or decrease arterial blood pressure during rest and to resist the postural fall on standing. The mechanism by which this effect is elicited is unknown. We hypothesize that PAG stimulation modulates performance of the autonomic nervous system. METHODS:   Five consecutive male patients of a mean age of 49.1 years underwent PAG stimulation for intractable pain syndromes. Intra-operatively, blood pressure and heart rate were recorded continuously while patients were awake (four patients) or under general anesthesia (one patient). Recordings were made for 100 sec before stimulation, 100 sec during stimulation at one or two electrode locations within the PAG, and for 100 sec after stimulation. RESULTS:   Stimulation altered not only systolic and diastolic blood pressure but also heart rate. During stimulation, systolic blood pressure increased in three electrode positions by 7.2-10.2 mmHg, decreased in two electrode positions by 3.1-11.5 mmHg, and was unchanged in two electrode positions. Heart rate variability also changed during stimulation. Percentage systolic blood pressure change was positively correlated with change in high-frequency power (Pearson's r= 0.685, p= 0.09, N= 7), low-frequency : high-frequency power ratio (r= 0.667, p= 0.10, N= 7), and low-frequency power (r= 0.818, p= 0.02, N= 7), the latter of which was statistically significant. The percentages of the variance explained (r(2)) were 46.9, 44.5, and 66.9, respectively. CONCLUSIONS:   PAG stimulation modulates autonomic nervous system activity and thereby elicits changes in cardiovascular performance. Understanding of the mechanisms by which this therapy causes cardiovascular modulation will inform future innovation in this field with the aim of improving the efficacy and safety of patient treatment options.

  • Deep brain stimulation for cluster headache.

    12 December 2017

    Cluster headache is a severely debilitating disorder that can remain unrelieved by current pharmacotherapy. Alongside ablative neurosurgical procedures, neuromodulatory treatments of deep brain stimulation (DBS) and occipital nerve simulation have emerged in the last few years as effective treatments for medically refractory cluster headaches. Pioneers in the field have sought to publish guidelines for neurosurgical treatment; however, only small case series with limited long-term follow-up have been published. Controversy remains over which surgical treatments are best and in which circumstances to intervene. Here we review current data on neurosurgical interventions for chronic cluster headache focusing upon DBS and occipital nerve stimulation, and discuss the indications for and putative mechanisms of DBS including translational insights from functional neuroimaging, diffusion weighted tractography, magnetoencephalography and invasive neurophysiology.

  • Pre-operative DTI and probabilisitic tractography in four patients with deep brain stimulation for chronic pain.

    14 December 2017

    This study aimed to examine, using diffusion tensor imaging (DTI), differences in electrode placement in four patients undergoing deep brain stimulation for chronic neuropathic pain of varying aetiology. A pre-operative DTI was obtained for each patient, who was then implanted with deep brain stimulation electrodes in the periventricular/periaqueductal grey area with good pain relief. Using seeds from the postoperative MRI scan, probabilistic tractography was performed from the pre-operative DTI.

  • Use of surface electromyography to assess and select patients with idiopathic dystonia for bilateral pallidal stimulation.

    12 December 2017

    OBJECT: The object of this study was to identify a preoperative physiological index by using surface electromyography (EMG) signals that would correlate with clinical outcome in dystonic patients following bilateral pallidal stimulation. METHODS: In 14 patients with spasmodic torticollis, generalized dystonia, and myoclonic dystonia, surface EMG signals were recorded from the most affected muscle groups. Although the dystonia affected different body segments, the EMG signals in all patients could be decomposed into bursting and sustained components. Subsequently, a ratio of the EMG amplitude was calculated between the two components and then correlated with clinical outcome. Patients who experienced rapid improvement following bilateral pallidal stimulation had a significantly higher EMG ratio compared with those who did not. Furthermore, a significant correlation was found between the EMG ratio and clinical improvement during the 12-month period following pallidal stimulation. CONCLUSIONS: The authors concluded that surface EMG studies could be used to predict the clinical outcome of and to select patients for pallidal stimulation for dystonia.

  • The costs and benefits of deep brain stimulation surgery for patients with dystonia: an initial exploration.

    12 December 2017

    Objectives.  To perform a preliminary cost-utility and cost-benefit of deep brain stimulation (DBS) in the treatment of dystonia, Materials and Methods.  We conducted a prospective study of 26 patients undergoing DBS for the treatment of dystonia. We performed a cost-utility analysis using the Euroquol (EQ-5D) questionnaire. A cost-benefit analysis used the willingness-to-pay principle and costs of treatment were calculated retrospectively in order to calculate the cost-benefit. Results.  We found that the EQ-5D score improved from 29 to 76.2 points after surgery, an incremental utility of 0.47. There was an overall gain of 0.94 quality-adjusted life-years (QALY) with a cost of £33,980 per QALY. Conclusions.  DBS for dystonia, while an expensive treatment, compares favorably to therapies that are commonly used for other conditions.