Peter Bain

Publications (11)39.83 Total impact

• Article: Spatiotemporal visualization of deep brain stimulation-induced effects in the subthalamic nucleus.

  Nada Yousif, Roman Borisyuk, Nicola Pavese, Dipankar Nandi, Peter Bain
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  ABSTRACT: Deep brain stimulation (DBS) is a successful surgical therapy used to treat the disabling symptoms of movement disorders such as Parkinson's disease. It involves the chronic stimulation of disorder-specific nuclei. However, the mechanisms that lead to clinical improvements remain unclear. Consequently, this slows the optimization of present-day DBS therapy and hinders its future development and application. We used a computational model to calculate the distribution of electric potential induced by DBS and study the effect of stimulation on the spiking activity of a subthalamic nucleus (STN) projection neuron. We previously showed that such a model can reveal detailed spatial effects of stimulation in the vicinity of the electrode. However, this multi-compartmental STN neuron model can fire in either a burst or tonic mode and, in this study, we hypothesized that the firing mode of the cell will have a major impact on the DBS-induced effects. Our simulations showed that the bursting model exhibits behaviour observed in studies of high-frequency stimulation of STN neurons, such as the presence of a silent period at stimulation offset and frequency-dependent stimulation effects. We validated the model by simulating the clinical parameter settings used for a Parkinsonian patient and showed, in a patient-specific anatomical model, that the region of affected tissue is consistent with clinical observations of the optimal DBS site. Our results demonstrated a method of quantitatively assessing neuronal changes induced by DBS, to maximize therapeutic benefit and minimize unwanted side effects.
  European Journal of Neuroscience 07/2012; 36(2):2252-9. · 3.63 Impact Factor
• Article: Apomorphine-induced necrotic ulcers.

  Jeban Ganesalingam, Peter Bain
  Movement Disorders 09/2011; 26(12):2182. · 4.51 Impact Factor
• Article: Altered eye-to-foot coordination in standing parkinsonian patients during large gaze and whole-body reorientations.

  Dimitri Anastasopoulos, Nafsica Ziavra, Eugenia Savvidou, Peter Bain, Adolfo M Bronstein
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  ABSTRACT: We investigated whether turning problems in Parkinson's disease may be the result of abnormal horizontal multisegmental angular coordination. Ten mildly affected patients and controls stood upright and voluntarily reoriented eyes and body to illuminated targets of eccentricities up to ±180 degrees. The effects of target location, visibility, and predictability on movement parameters were evaluated. Patients' latencies were normal. Control subjects foveated large eccentricity targets with a single gaze shift in approximately 30% of predictable trials. Patients rarely did so (10% of predictable trials) because of reduced head-in-space and trunk velocity. This resulted in massive foveation delays in patients-an average of half a second for displacements of 180 degrees. The covariation of eye, head, and trunk rotations was quantified statistically by means of principal components analysis. In both groups, the combined movement was initially stereotyped and two principal components accounted for nearly all data variance-the original three mechanical degrees of freedom (i.e., eye-head-trunk) are reduced to two kinematic degrees of freedom. However, in patients, the eye contributed more, and the head and trunk less, to the gaze shift than in control subjects. Although the eye-to-foot turning synergy is preserved in early-stage parkinsonism, quantitative differences are prominent, particularly a larger ocular (and smaller head-trunk) contribution in patients. Turning problems in Parkinson's disease do not result from inability to assemble multisegmental movements, as patients' ability to control numerous degrees of freedom is preserved. However, trunk bradykinesia reduces the frequency of single-step gaze shifts, thus prolonging target acquisition time. Preserved eye motion compensates for trunk slowness.
  Movement Disorders 06/2011; 26(12):2201-11. · 4.51 Impact Factor
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  Article: Evaluating the impact of the deep brain stimulation induced electric field on subthalamic neurons: a computational modelling study.

  Nada Yousif, Nuri Purswani, Richard Bayford, Dipankar Nandi, Peter Bain, Xuguang Liu
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  ABSTRACT: Deep brain stimulation (DBS) is an effective surgical treatment used to alleviate the symptoms of neurological disorders, most commonly movement disorders. However, the mechanism of how the applied stimulus pulses interact with the surrounding neuronal elements is not yet clearly understood, slowing progress and development of this promising therapeutic technology. To extend previous approaches of using isolated, myelinated axon models used to estimate the effect of DBS, we propose that taking into account entire neurons will reveal stimulation induced effects overlooked by previous studies. We compared the DBS induced volume of tissue activated (VTA) using arrays of whole cell models of subthalamic nucleus (STN) excitatory neurons consisting of a cell body and an anatomically accurate dendritic tree, to the common models of axon arrays. Our results demonstrate that STN neurons have a higher excitation threshold than axons, as stimulus amplitudes 10 times as large elicit a VTA range a fifth of the distance from the electrode surface. However, the STN neurons do show a change in background firing rate in response to stimulation, even when they are classified as sub-threshold by the VTA definition. Furthermore the whole neuron models are sensitive to regions of high current density, as the distribution of firing is centred on the electrode contact edges These results demonstrate the importance of accurate neuron models for fully appreciating the spatial effects of DBS on the immediate surrounding brain volume within small distances of the electrode, which are overlooked by previous models of isolated axons and individual neurons.
  Journal of neuroscience methods 04/2010; 188(1):105-12. · 2.30 Impact Factor
• Article: STN vs. Pallidal Stimulation in Parkinson Disease: Improvement With Experience and Better Patient Selection.

  Alexander L Green, Richard G Bittar, Peter Bain, Richard B Scott, Carol Joint, Ralph Gregory, Tipu Z Aziz
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  ABSTRACT: Objectives.  This is a prospective study to determine the outcomes of subthalamic nucleus (STN) vs. globus pallidus internus (GPi) deep brain stimulation (DBS) at our institution. Materials and Methods.  We studied a total of 39 patients - 29 with STN and 10 with GPi DBS over a period of up to 6 years. Mean ages in the two groups were similar (59 and 60 years, respectively) and disease duration prior to implantation was similar (9.6 and 11.7 years, respectively). Unified Parkinson Disease Rating Scale (UPDRS) was recorded preoperatively and at follow-up (at least at 6-month intervals). Medications also were recorded, and each patient's levodopa equivalent units (LEU) were calculated. Results were analyzed using a paired Student's t-test. Results.  LEU reduced significantly (p < 0.05) in the STN group (5.7 to 3.7) but not the GPi group. Both targets significantly improved part 3 and part 4 scores of the UPDRS but GPi DBS did not improve part 2 scores (activities of daily living). STN DBS had much better outcome on the motor "off" scores of the UPDRS, whereas GPi only improved tremor. A comparison of the "earliest 10" and "most recent 10" STN patients showed a significant improvement in outcome in the most recent cases. Conclusions.  In our group, STN was more effective for alleviating the symptoms of Parkinson disease, even in older patients with significant dyskinesias. Better patient selection and greater experience have led to more improvement in the more recent patients.
  Neuromodulation 01/2006; 9(1):21-7. · 1.19 Impact Factor
• Article: Failure of chronic pallidal stimulation in dystonic patients is a medical emergency.

  John Yianni, Dipankar Nandi, M Ch, Jonathan Hyam, Vanessa Elliott, Peter Bain, Ralph Gregory, Tipu Aziz
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  ABSTRACT: Deep brain stimulation (DBS) therapy is a continually expanding field of functional neurosurgery for the treatment of movement disorders and neuropathic pain. However, occurrence of adverse events related to implanted hardware cannot be ignored, particularly in patients with dystonic conditions. We report on two such patients who required emergency hospital admission and pulse generator re-implantation following sudden and unexpected cessation of DBS effectiveness resulting from battery failure.
  Neuromodulation 01/2004; 7(1):9-12. · 1.19 Impact Factor
• Article: Globus pallidus internus deep brain stimulation for dystonic conditions: a prospective audit.

  John Yianni, Peter Bain, Nir Giladi, Marieta Auca, Ralph Gregory, Carole Joint, Dipankar Nandi, John Stein, Richard Scott, Tipu Aziz
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  ABSTRACT: In the current era of functional surgery for movement disorders, deep brain stimulation (DBS) of the globus pallidus internus (GPi) is emerging as the favoured target in the treatment of patients with dystonia. The results of 25 consecutive patients with medically intractable dystonia (12 with generalised dystonia, 7 with spasmodic torticollis, and 6 with other types of dystonia) treated with GPi stimulation are reported. Although comparisons were limited by differences in their respective neurological rating scales, chronic DBS benefited all groups, resulting in clear and progressive improvements in their condition. This study clearly demonstrates that DBS of the GPi provides amelioration of intractable dystonia.
  Movement Disorders 05/2003; 18(4):436-42. · 4.51 Impact Factor
• Article: Globus pallidus internus deep brain stimulation for dystonic conditions: A prospective audit

  John Yianni MRCS, Peter Bain MA, MD, FRCP, Nir Giladi MD, Marieta Auca MD, Ralph Gregory FRCP, Carole Joint RGN, Dipankar Nandi MCH, John Stein BM, BCH, DPhil, M.Appl.Sci Richard Scott PhD, FRCS Tipu Aziz MD, John Yianni, Peter Bain, Nir Giladi, Marieta Auca, Ralph Gregory, Carole Joint, Dipankar Nandi, John Stein, Richard Scott, Tipu Aziz
  [show abstract] [hide abstract]
  ABSTRACT: In the current era of functional surgery for movement disorders, deep brain stimulation (DBS) of the globus pallidus internus (GPi) is emerging as the favoured target in the treatment of patients with dystonia. The results of 25 consecutive patients with medically intractable dystonia (12 with generalised dystonia, 7 with spasmodic torticollis, and 6 with other types of dystonia) treated with GPi stimulation are reported. Although comparisons were limited by differences in their respective neurological rating scales, chronic DBS benefited all groups, resulting in clear and progressive improvements in their condition. This study clearly demonstrates that DBS of the GPi provides amelioration of intractable dystonia. © 2002 Movement Disorder Society
  Movement Disorders 03/2003; 18(4):436 - 442. · 4.51 Impact Factor
• Article: Unilateral and bilateral pallidotomy for idiopathic Parkinson's disease: a case series of 115 patients.

  Simon G Parkin, Ralph P Gregory, Richard Scott, Peter Bain, Peter Silburn, Bruce Hall, Richard Boyle, Carole Joint, Tipu Z Aziz
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  ABSTRACT: Lesioning of the internal pallidum is known to improve the symptoms of idiopathic Parkinson's disease (PD) and alleviate dyskinesia and motor fluctuations related to levodopa therapy. The benefit obtained contralateral to a single lesion is insufficient in some cases when symptoms are bilaterally disabling. However, reports of unacceptably high rates of adverse effects after bilateral pallidotomy have limited its use in such cases. We report on the outcome of unilateral (UPVP) and bilateral (BPVP) posteroventral pallidotomy in a consecutive case series of 115 patients with PD in the United Kingdom and Australia. After 3 months, UPVP resulted in a 27% reduction in the off medication Part III (motor) Unified Parkinson's Disease Rating Scale score and abolition of dyskinesia in 40% of cases. For BPVP, these figures were increased to 31% and 63%, respectively. Follow-up of a smaller group to 12 months found the motor scores to be worsening but benefit to dyskinesia and activities of daily living was maintained. Speech was adversely affected after BPVP, although the change was small in most cases. Unilateral and bilateral pallidotomy can be performed safely without microelectrode localisation. Bilateral pallidotomy appears to be more effective, particularly in reducing dyskinesia; in our experience, the side effects have not been as high as reported by other groups.
  Movement Disorders 08/2002; 17(4):682-92. · 4.51 Impact Factor
• Article: Quality of life outcomes following surgical treatment of Parkinson's disease.

  Alastair Gray, Iain McNamara, Tipu Aziz, Ralph Gregory, Peter Bain, Joanna Wilson, Richard Scott
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  ABSTRACT: We assessed the impact of surgical treatment of Parkinson's disease on quality of life using generic quality of life instruments and utility scores. The Medical Outcomes Study short form health survey SF-36 and Parkinson's Disease Questionnaire PDQ-39 were used before and 3-6 months after surgery to assess quality of life, and the results were converted into utility valuations. Ninety-seven patients were studied; 33 underwent unilateral thalamotomy, 33 unilateral pallidotomy, 20 bilateral pallidotomy, six subthalamic nucleus (STN) lesions, four mixed lesions, and in one case bilateral STN stimulation. All dimensions of the SF-36 except role mental and mental health showed statistically significant improvement following surgery. The PDQ-39 recorded significant improvements in the mobility, stigma, and bodily discomfort dimensions. The rating scale and time trade-off scales showed statistically significant gains in utility of 8% and 3%, respectively. Gains were particularly marked in the bilateral pallidotomy group. Differences in patient characteristics and selection made direct comparisons between procedures unreliable. Quality of life in patients with advanced Parkinson's disease is amenable to measurement; such measurement provides tentative evidence of significant gains in quality of life following some neurosurgical procedures.
  Movement Disorders 02/2002; 17(1):68-75. · 4.51 Impact Factor
• Article: Deep brain stimulation for tremor [correction of trauma]: patient selection and evaluation.

  Günther Deuschl, Peter Bain
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  ABSTRACT: The selection of patients with movement disorders for deep brain stimulation is becoming a common neurological and neurosurgical task. Deep brain stimulation is suitable for different forms of tremor, which can often not be treated with medication. This suitability applies for essential tremor, monosymptomatic tremor at rest, cerebellar or multiple sclerosis tremor, Holmes' tremor, primary writing tremor or tremor in neuropathies. The appropriate selection of patients is critical for the outcome of surgical relief of tremors. Considering the risks of any stereotactic intervention, the following must apply: (1) motor symptoms lead to a relevant disability in activities of daily living, despite optimal medical treatment; (2) biological age of the patient; (3) neurosurgical contraindications; (4) the patient is neither demented nor severely depressed. If these conditions are fulfilled, the individual chances of improvement of the target symptoms need to be checked, based on the following guidelines: (1) the kind of tremor, (2) the natural course of the tremor, (3) the chances for medical treatment in a particular patient, (4) the outcome of surgery in a specific condition, (5) the individual risks for a patient to suffer from complications. The outcome of surgery for tremor depends on the clinical type and distribution. Distal limb tremors are easier to treat than proximal limb tremors. Intention tremor is more difficult to treat than rest or postural tremor. The indication for surgical treatment depends on the analysis of the individual risk-benefit ratio, which also has to take into account the patients' social, professional, and familial background. The patient needs to be well informed about his individual risk-benefit ratio and of alternative treatments, before undergoing stereotactic surgery.
  Movement Disorders 02/2002; 17 Suppl 3:S102-11. · 4.51 Impact Factor