Commentary: Effect of Spinal Cord Stimulation on Early Disability Pension in 198 Failed Back Surgery Syndrome Patients: Case-Control Study

Neurosurgery, May 2019

Visocchi, Massimiliano

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Commentary: Effect of Spinal Cord Stimulation on Early Disability Pension in 198 Failed Back Surgery Syndrome Patients: Case-Control Study

The impact of spinal cord stimulation (SCS) on working capability and factors behind permanent disability in patients with failed back surgery syndrome (FBSS) is the topic of the paper1 just published in Neurosurgery. No doubt at all that, considering the limited number of papers describing the effect of SCS on working capability in a well-defined patient cohort in a case-control setting, the data presented are of interest to the readers of the Journal and to all the functional neurosurgeons involved in this discipline. In the manuscript, the authors1 critically evaluate the data obtained and its usefulness in the long-term follow-up of these patients. As matter of fact, technically the topic of the paper deals with neuropathic pain which results from a lesion or disease affecting the somatosensory system at either peripheral or central level. The most common neuropathic pain is pain radiating from the lower back to the lower extremities. SCS is an effective treatment and can be used for any neuropathic pain, but the most common indication is FBSS. The baseline characteristics included gender, age, location, and duration of pain, previous lumbar procedures, level and reason for operation, spinal fusion, and type of electrode; patients were divided into three groups: SCS trial only, SCS permanent, and SCS explants. On the basis of a systematic review, the evidence suggested that SCS is effective in reducing the chronic neuropathic pain of FBSS. It has been shown previously that SCS efficacy decreases as the number of previous measures or the duration of pain increases. The conclusion of the study1 is that permanent SCS usage was associated with reduced sick leave and Disability Pension (DP) although the authors conclude that prospective study will be required to assess possible predictive value. In other words, patient selection is mandatory in order to better distinguish patients who would most likely benefit from the stimulator. As one of the Reviewers of this interesting paper, I appreciated the information and the socially reverberating considerations of the authors—ie, costs for DP, rehabilitation etc—nevertheless, I suggested to widen the discussion also spanning on the extensive indication of SCS to other debilitating diseases like cerebral stroke, also responsible for strong working capability impairments, and social costs2–4 and minimal consciousness disorders and vegetative states.5 So far, SCS is a well-known and world-wide accepted surgical neurorehabilitative procedure,6 which claims progressively more and more consideration in the newborn, so called reconstructive neurosurgery.7 My suggestions were responded to as follows: “The reviewer presents an interesting point of view about the possibilities of spinal cord stimulation. According to reviewer suggestion, we extended the Discussion a bit to other indications of SCS that are causing difficult functional impairments and economic burden. However, our study population consists only of FBSS patients. We do not treat cerebral stroke or vegetative state patient with SCS therapy. Thereby we cannot analyze the effect of SCS on these diseases. We are looking forward to future studies on this topic.” Finally in the paper, the authors1 report that SCS has been recognized to have an impact as a part of rehabilitation of patients with FBSS. Other common indications of SCS include CRPS and refractory angina pectoris. Some studies have also been made on the efficacy of SCS in other disabling diseases causing complicated functional impairment and social costs like the cerebral stroke and minimal consciousness disorders and vegetative state. In future research, these topics could be approached from the point of view of rehabilitation and pensions because these diseases also affect the working-age population and are responsible for strong working capability impairments. This leads to a question of what the role of reconstructive neurosurgery as a part of rehabilitation is in the future. Personally, I continue to be convinced that when we analyze the neuromodulating effects of SCS in general on pain and in particular on the low back pain, ie, neuropathic pain, the exact underlying mechanisms are not still fully understood. Moreover, I do not feel confident to rule out at all possible mediation of a central hemodynamic effect on the pain neuromodulating mechanism on specific transmitting and integrating sensory areas or nuclei. Contrary to cervical SCS, cauda equine stimulation, as well as lower thoracic SCS, have been demonstrated with SPECT and TCD, to change cerebral blood flow (CBF), both with a decrease in CBF (more likely; Figure 1) but also (very rarely) with an increase, as widely demonstrated in our clinical and experimental Labs. Changes in CBF were repeatable in time (Figure 2). In other words, nerve root stimulation and thoracic spinal cord, when stimulated dorsally, can modulate CBF probably with different mechanisms.8,9 In personal previous studies the role of sympathetic/parasympathetic balance was published, stressing the concept of the indirect mediation of SCS in producing CBF changes (reversible functional sympaticolysis). Beside the neurovegetative mechanism, more other possible factors were proposed in order to better identify the complex biochemical—humoral network promoting CBF changes during SCS, including substance P (SP), vasoactive intestinal polypeptide (VIP) and calcitonin gene-related peptide (CGRP) and many others humoral factors. Finally, we also demonstrated a competitive effect of SCS in CO2 cerebral autoregulation in terms of a reduced vascular response to increased CO2 concentrations.10 The fact that a decrease in CBF can also be associated with an effect on the pain modulating interference during neurostimulation was further confirmed by my Group with our observation on Trigeminal Gasserian Ganglion stimulation (TGS).11 In fact, interference of trigeminal pathways on systemic hemodynamics has been reported in several papers in the past four decades, but in our paper we also found an action on cerebral hemodynamic autoregulation CO2 mediated in terms of an enhanced vascular response to increased CO2 concentrations during TGS. FIGURE 1. View largeDownload slide Different TCD responses (increase/decrease) waveform at different spine level of stimulation. SCS at lower thoracic level is more likely to produce a decrease of the waveform signal or no changes compared with cervical level. FIGURE 1. View largeDownload slide Different TCD responses (increase/decrease) waveform at different spine level of stimulation. SCS at lower thoracic level is more likely to produce a decrease of the waveform signal or no changes compared with cervical level. FIGURE 2. View largeDownload slide TCD waveform at different time of SCS at lower thoracic level with the same change entity. FIGURE 2. View largeDownload slide TCD waveform at different time of SCS at lower thoracic level with the same change entity. My personal feeling is that the better understanding of the autoregulation mechanisms of CBF, as well as metabolic changes associated with SCS, and more generally with neurostimulation, are the primary gates to be opened and investigated in order to better address pharmacological and neuroaugmentative surgical procedures in the treatment of pain (ie, FBSS) and in the prevention in early DP. Disclosure The author has no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. REFERENCES 1. Kaijankoski H , Nissen M , Ikäheimo T-M , von und zu Fraunberg M , Airaksinen O , Huttunen J . Effect of spinal cord stimulation on early disability pension in 198 failed back surgery syndrome patients: case-control study . Neurosurgery  . published online ahead of print: 2019 ; 84 ( 6 ): 1225 - 1232 . 2. Visocchi M , Cioni B , Pentimalli L , Meglio M : Increase of cerebral blood flow and improvement of brain motor control following spinal cord stimulation in ischemic spastic hemiparesis: case report . Stereotact Funct Neurosurg  . 1994 ; 62 ( 1-4 ): 103 – 107 . Google Scholar Crossref Search ADS PubMed   3. Visocchi M , Giordano A , Calcagni M , Cioni B , Di Rocco C , Meglio M . Spinal cord stimulation and cerebral blood flow in stroke: personal experience . Stereotact Funct Neurosurg  . S. Karger AG, Basel 2001 ; 76 ( 3-4 ): 262 – 268 . Copyright 2002. Google Scholar Crossref Search ADS PubMed   4. Visocchi M , della Pepa GM , Esposito G et al. . Spinal cord stimulation and cerebral haemodynamics: updated mechanism and therapeutic implications . Ster Funct Neurosurg  . 2011 ; 89 ( 5 ): 263 – 274 . Google Scholar Crossref Search ADS   5. Della Pepa GM , Fukaya C , La Rocca G , Zhong J , Visocchi M . Neuromodulation of vegetative state through spinal cord stimulation: where are we now and where are we going? Stereotact Funct Neurosurg  . 2013 ; 91 ( 5 ): 275 – 287 . Google Scholar Crossref Search ADS PubMed   6. Giugno A , Gulì C , Basile L , Graziano F , Maugeri R , Visocchi M , Iacopino DG . Spinal cord stimulation: an alternative concept of rehabilitation? ActaNeurochir Suppl  . 2017 ; 124 : 15 – 18 . doi: 10.1007/978-3-319-39546-3_3 . 7. Visocchi M . Reconstructive Neurosurgery: a Challenge . Acta Neurochir Suppl  . 2017 ; 124 : 1 – 4 . doi: 10.1007/978-3-319-39546-3_1 . Google Scholar Crossref Search ADS PubMed   8. Visocchi M . Spinal Cord Stimulation and Cerebral Haemodynamics . Acta Neurochir (Austria Wien)  . 2006 ; 99 : 111 – 116 . 9. Visocchi M . Neuromodulation of cerebral bloof flow by spinal cord electrical stimulation: the role of the Italian school and state of art . J Neurosurg Sci  . 2008 ; 52 ; 41 – 47 . Google Scholar PubMed   10. Visocchi M , della Pepa GM , Esposito G et al. . Spinal cord stimulation and cerebral haemodynamics: updated mechanism and therapeutic implications Ster . Stereotact Funct Neurosurg  . 2011 ; 89 : 263 – 274 . Google Scholar Crossref Search ADS PubMed   11. Visocchi M , Chiappini F , Cioni B , Meglio M . Cerebral autoregulation and trigeminal stimulation. A TCD study . Stereotact Funct Neurosurg  . 1996 ; 66 : 184 – 192 . Google Scholar Crossref Search ADS PubMed   Copyright © 2018 by the Congress of Neurological Surgeons This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)


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Visocchi, Massimiliano. Commentary: Effect of Spinal Cord Stimulation on Early Disability Pension in 198 Failed Back Surgery Syndrome Patients: Case-Control Study, Neurosurgery, 2019, E291-E293, DOI: 10.1093/neuros/nyy575