Clinical study Thalamotomy versus thalamic stimulation for multiple sclerosis tremor Richard G Bittar 1,5,6,7,8 MBBS, PHD, FRACS MBBS, PHD, FRACS, Jonathan Hyam 3 MBBS, MRCS MBBS, MRCS, Dipankar Nandi 1 MBBS, MCHIR, DPHIL MBBS, MCHIR, DPHIL, ShouYan Wang 2 PHD PHD, Xuguang Liu 3 MD, PHD MD, PHD, Carole Joint 1 RGN RGN, Peter G Bain 3 MD, FRCP MD, FRCP, Ralph Gregory 4 MD, FRCP MD, FRCP, John Stein 2 DPHIL, FRCP DPHIL, FRCP, Tipu Z Aziz 1,2,3 MD, DMEDSC, FRCS MD, DMEDSC, FRCS 1 Department of Neurosurgery, Radcliffe Infirmary, Oxford, UK, 2 University Department of Physiology, University of Oxford, Oxford, UK, 3 Division of Neurosciences, Imperial College, London, UK, 4 Department of Neurology, Radcliffe Infirmary, Oxford, UK, 5 Australasian Movement Disorder and Pain Surgery (AMPS) Clinic, Melbourne, Australia, 6 Department of Neurosurgery, The Alfred Hospital, Melbourne, Australia, 7 Department of Surgery, Montash University, Melbourne, Australia, 8 Melbourne Neurosurgery, Melbourne, Australia Summary Disabling intractable tremor occurs frequently in patients with multiple sclerosis (MS). There is currently no effective medical treatment available, and the results of surgical intervention have been variable. Thalamotomy has been the mainstay of neurosurgical therapy for intractable MS tremor, however the popularisation of deep brain stimulation (DBS) has led to the adoption of chronic thalamic stimulation in an attempt to ameliorate this condition. With the goal of examining the relative efficacy and adverse effects of these two surgical strategies, we studied twenty carefully selected patients with intractable MS tremor. Thalamotomy was performed in 10 patients, with chronic DBS admin- istered to the remaining 10. Both thalamotomy and thalamic stimulation produced improvements in postural and intention tremor. The mean improvement in postural tremor at 16.2 months following surgery was 78%, compared with a 64% improvement after thalamic stimulation (14.6 month follow-up) (P > 0.05). Intention tremor improved by 72% in the group undergoing thalamotomy, a significantly larger gain than the 36% tremor reduction following DBS (P < 0.05). Early postoperative complications were common in both groups. Permanent complications related to surgery occurred in four patients overall. Following thalamotomy, long-term adverse effects were observed in three patients (30%), and comprised hemiparesis and seizures. Only one patient in the thalamic stimulation group experienced a permanent deficit (monoparesis). We conclude that thalamotomy is a more efficacious surgical treatment for intractable MS tremor, however the higher incidence of persistent neurological deficits in patients receiving lesional surgery may support the use of DBS as the preferred surgical strategy. ª 2005 Published by Elsevier Ltd. Keywords: deep brain stimulation, thalamotomy, multiple sclerosis, tremor INTRODUCTION Fifteen percent of multiple sclerosis (MS) patients have a moder- ate or severe intractable tremor in the upper limbs, and over 25% experience tremor-related disability. 1 This tremor frequently has a significant proximal component, which is particularly disabling and may even make nursing difficult. Numerous studies have demonstrated variable outcomes following surgery for MS tre- mor, 2–7 and several factors may account for such variations. First, it is often difficult to differentiate between tremor (which may re- spond to surgery) and ataxia (which is not amenable to lesioning or stimulation), and to determine which of the two components predominates. Second, the conventional anatomical target for Par- kinsonian and essential tremor, the ventrointeromedial nucleus of the thalamus (VIM), has been automatically adopted by the major- ity of neurosurgeons treating MS tremor. 8 However, MS tremor may actually respond more favourably to lesioning or stimulation of the ventralis oralis posterior (VOP) and zona incerta (ZI) than VIM. 9 Preoperative physiological techniques are able to discern which patients are likely to benefit from surgery for MS tremor. 10,11 Thalamotomy for MS tremor is most effective in patients experi- encing a disruptive action tremor with a single frequency peak. 11 In recent years, deep brain stimulation (DBS) has been em- ployed by a growing number of functional neurosurgeons, and has been used to treat a number of disorders previously dealt with by lesioning techniques. Thalamic DBS has not been shown to be more efficacious than thalamotomy in the treatment of essential tremor, however its lower complication rate provides a strong incentive for its continuing use in this condition. 12 In this study we aim to compare the outcome of surgery for MS tremor using lesioning and DBS techniques targeting the same anatomical substrates and utilising an identical presurgical evalu- ation and selection algorithm. METHODS 20 patients with MS upper limb tremor (11 male, 9 female; mean age 42 years) underwent evaluation at the Radcliffe Infirmary, Oxford and Charing Cross Hospital, London. The diagnosis of secondary progressive MS had previously been made on clinical or laboratory grounds. 13 Each patient performed a series of visu- ally guided tracking tasks. The results of this investigation were then used to select which patients underwent surgery. The proce- dures of thalamotomy and DBS are described, together with the results of surgical treatment. Clinical assessments Tremor was assessed in three states of muscle activity: rest, pos- ture and movement. In the upper limbs, tremor was assessed at rest and in two postures: with the arms held outstretched, and with arms in the ‘‘bats-wing position” (flexed at the elbows and the forearms pronated with the fingers held near the nose). Upper Journal of Clinical Neuroscience (2005) 12(6), 638–642 0967-5868/$ - see front matter ª 2005 Published by Elsevier Ltd. doi:10.1016/j.jocn.2004.09.008 Received 19 April 2004 Accepted 29 September 2004 Correspondence to: Dr Richard G. Bittar, Australasian Movement Disorder and Pain Surgery (AMPS) Clinic, Suites 2 & 3, 228 Cotham Road, Kew, Victoria, Australia 3101. E-mail: neurosurgeon@ampsclinic.com 638