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Editorial commentary

Deep brain stimulation surgery under general anaesthesia with microelectrode recording: the best of both worlds or a little bit of everything? Peter C Warnke The factions of functional neurosurgeons performing deep brain stimulation (DBS) for movement disorders are fairly well separated. The physiology aficionados subscribe to the doctrine that only meticulous microelectrode recording (MER) in the awake patient without any sedative interference gives optimal results. The believers in the accuracy of imaging claim that targeting the subthalamic nucleus (STN) the globus pallidum internus can be achieved precisely from MRI or MR/CT fusion alone with equally good outcomes as measured on the Unified Parkinson’s Disease Rating Scale (UPDRS) and the ability to postoperatively cut the Levodopa (L-DOPA) equivalent amount of medication. Fluchere and colleagues seem to have found a Salomonic compromise that could satisfy both camps.1 In an impressively large cohort of 126 patients they used ‘controlled anaesthesia’—up to this day I believed all anaesthesia is controlled or at least should be—with low concentration sevoflurane and no propofol to keep patients asleep. Doing so they claim to still get useful MERs and even assess muscle tone and partially tremor. The paper wholly focuses on clinical outcomes and compares those with series done with patients awake and under local anaesthesia showing equivalent results. So no more need to put patients through the ordeal of awake surgery? Not quite that simple. First the paper would have benefited logarithmically if the authors had shown some of their MERs with typical STN patterns. This is crucial Correspondence to Professor Peter C Warnke, Department of Neurosurgery, The University of Chicago, 5841 South Maryland Avenue, Chicago, IL 60637, USA; [email protected]

as others have shown that MER can clearly be impaired even under light anaesthesia and the papers the authors quote also actually show serious limitations.2 3 Second the groups using pure imageguided lead placement show equally good clinical outcomes obviating the need for MER altogether.4 So why try to record with modified anaesthesia at all? The problem lies in the simplified view that focuses purely on clinical rating scales and surgical complications. DBS is a symptomatic and not a causal treatment. To this very day we still do not exactly know how DBS works on the neuronal level and in order to optimise treatment it needs to be fine-tuned and individualised. Any insight into this and progress will come from neurophysiological studies under physiological conditions, that is, in the awake patient. Also cognitive and mood-related side effects—albeit rare—which can happen even with precise placement of the electrode in the STN can only be assessed in the awake patient.5 Not the least teststimulation in the non-anaesthesised patient in the OR shows clinical efficacy immediately which is also tremendously reassuring for the patient. The proponents of pure image-guided DBS surgery will argue that all which really counts is clinical outcome—which seems to be very similar—and the rest is more academic. The point remains that all studies using general anaesthesia including the one from Fluchere and colleagues are retrospective and uncontrolled, that is, plagued by selection bias thus representing at best class III evidence. A randomised prospective and controlled trial would solve the schism among functional neurosurgeons. Given that we are treating a physiological manifestation of Parkinson’s func-

Warnke PC. J Neurol Neurosurg Psychiatry October 2014 Vol 85 No 10

tional neurosurgery is very much applied neurophysiology. Under these circumstances and taking the data limitations into consideration to give physiological targeting and immediate clinical correlation away is premature. In selected patients who just cannot have awake surgery—and that is still a very small number—the approach by Fluchere and colleagues might be a worthy one. Contributors This editorial was originally planned as a joint contribution of Dr Roy Bakay—an eminent functional neurosurgeon and mentor to many in the field—and myself. During its preparation, sadly, Dr Bakay passed away. I have tried my best to incorporate his thoughts and views as expressed in the discussions we had regarding the editorial. Competing interests None. Provenance and peer review Commissioned; internally peer reviewed.

To cite Warnke PC. J Neurol Neurosurg Psychiatry 2014;85:1063. Received 27 January 2014 Accepted 5 February 2014 Published Online First 3 March 2014

▸ J Neurol Neurosurg Psychiatry 2014;85:1063. doi:10.1136/jnnp-2014-307745






Fluchere F, Witjas T, Eusebio A, et al. Controlled general anaesthesia for subthalamic nucleus stimulation in Parkinson’s disease. J Neurol Neurosurg Psychiatry 2014;85:1167–73. Hertel F, Züchner M, Weimar I, et al. Implantation of electrodes for deep brain stimulation of the subthalamic nucleus in advanced Parkinson’s disease with the aid of intraoperative microrecording under general anesthesia. Neurosurgery 2006;59:E1138. Maltête D, Navarro S, Welter ML, et al. Subthalamic stimulation in Parkinson disease: with or without anesthesia? Arch Neurol 2004;61:390–2. Foltynie T, Zrinzo L, Martinez-Torres I, et al. MRI-guided STN DBS in Parkinson’s disease without microelectrode recording: efficacy and safety. J Neurol Neurosurg Psychiatry 2011;82:358–63. Chen SY, Tsai ST, Lin SH, et al. Subthalamic deep brain stimulation in Parkinson’s disease under different anesthetic modalities: a comparative cohort study. Stereotact Funct Neurosurg 2011;89:372–80.


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Deep brain stimulation surgery under general anaesthesia with microelectrode recording: the best of both worlds or a little bit of everything? Peter C Warnke J Neurol Neurosurg Psychiatry 2014 85: 1063 originally published online March 3, 2014

doi: 10.1136/jnnp-2014-307745 Updated information and services can be found at:

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Deep brain stimulation surgery under general anaesthesia with microelectrode recording: the best of both worlds or a little bit of everything?

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