LETTERS TO THE EDITOR
LETTER TO THE EDITOR REGARDING BPERIPHERAL NERVE STIMULATION COMPARED WITH USUAL CARE FOR PAIN RELIEF OF HEMIPLEGIC SHOULDER PAIN[ AM J PHYS MED REHABIL 2014;93:17Y27
To the Editor: The reviewers read with interest this article that describes the efficacy of therapeutic single-lead peripheral nerve stimulation in the treatment of hemiplegia with shoulder pain (HSP) as compared with those receiving usual and customary Btreatment.[1 In the reviewers’ brief review of the literature, they identified 31 direct causes of shoulder pain in HSP alphabetically ranging from acromioclavicular dislocation to thoracic outlet syndrome. In addition, diaphragmatic irritation and cardiomyopathy, among others, were also reported as remote sources of HSP. As the authors also acknowledged, no one etiology has been identified as the inciting agents in HSP, and they can also be multifactorial.2 Although the authors list a number of exclusion criteria that eliminated subjects from this study, the primary inclusion diagnosis in both groups seemed to be Bidiopathic.[ Diagnosis, from the Greek diaignn skein, is the act of specifically identifying a disease from its signs and symptoms, thereby ensuring a specific plan of treatment tailored to this taxon. Idiopathic is, by definition, not a diagnosis but instead an admission that no singular cause has been identified as the inciting agent. In both cohorts, subluxation occurred in approximately 55% of the samples, suggesting that it played a prominent role as a direct cause or as a prominent contributor to the HSP. Arm-weighted distraction of the tethered structures of the shoulder and the neck including, among others, the bicipital tendon and/or the cervical spinal roots can be pain generators presenting as a tendinitis and/or cervical radiculopathy, respectively, in association with degenerative cervical disk disease. Immobility itself can contribute to the development of a subdeltoid bursitis, which, when untreated, can culminate with an adhesive capsulitis. Proximal venous occlusion of the subclavian vein as it passes under both the pectoralis major and the minor muscles can present as distal hand edema mimicking a sympathetic dystrophy. In both cohorts, the patients deserve a specific diagnosis with then an opportunity to receive diagnostic-specific treatment rather than historically related treatment, which has evolved from electric eels as well as electrostatic devices to the present single-lead and/or multilead peripheral nerve stimulation.3 This study’s results rest on the assumption that both cohorts are homogeneous and are therefore comparable. Instead, the descriptor, Bidiopathic[ would suggest otherwise. Without a definitive diagnosis for each subject, there is the potential for significant variability within each group www.ajpmr.com
and between each cohort. This heterogeneity introduces the distinct possibility that the reported statistical outcome in this relatively small sample, as well as one with excessive variability, occurred by a Brandom effect.[4
REFERENCES 1. Wilson RD, Gunzler DD, Bennett ME, et al: Peripheral nerve stimulation compared with usual care for pain relief of hemiplegic shoulder pain: A randomized controlled trial. Am J Phys Med Rehabil 2014;93:17Y28 2. Teasell RW: The painful hemiplegic shoulder. Phys Med Rehabil State Art Rev 1998;12:489Y500 3. Stillings D: A survey of the history of electrical stimulation for pain to 1900. Med Instrum 1975;9:255Y9 4. Cornell JE, Mulrow CD, Localio R, et al: Random-effects metaanalysis of inconsistent effects: A time for change. Ann Intern Med 2014;160:267Y70
Myron M. LaBan, MD, MMSc Julie A. Ferris, MD Department of Physical Medicine and Rehabilitation Oakland University William Beaumont School of Medicine Royal Oak, Michigan DOI: 10.1097/PHM.0000000000000160
AN ETIOLOGICAL PARADIGM SHIFT FOR CHRONIC HEMIPLEGIC SHOULDER PAIN To the Editor: The authors appreciate the interest in the recently published article, BPeripheral Nerve Stimulation Compared with Usual Care for Pain Relief of Hemiplegic Shoulder Pain.[1 This study provides evidence that peripheral nerve stimulation is an efficacious treatment of hemiplegic shoulder pain (HSP) and reduces pain to a greater extent and with longer durability than usual care does. It has been correctly pointed out that there was no attempt by the study authors to provide a diagnosis for the occurrence of HSP based on the nociceptive and biomechanical models. This was not an oversight; rather, it is a result of an alternative paradigm of thought regarding the etiology of chronic HSP considered to be distinct from the etiology of acute HSP. That is, HSP may initially be the result of 1 of 31 or more of the direct causes of HSP, but maladaptive changes in the central nervous system are responsible for the pain persisting beyond the initial injury. It is apparent that identifiable pathologies on imaging studies have low correlation to the presence of HSP.2Y4 Furthermore, there is a growing body of evidence to suggest that the nociceptive and biomechanical models should be reconsidered in favor of a central sensitization process in the etiology of chronic HSP.5Y8 Letters to the Editor
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
929
The assertion that the study results are not valid because of heterogeneity of the cohorts deserves reexamination. The design of this study included randomized treatment allocation so that treatment status would not be confounded by either measured or unmeasured baseline characteristics.9 A review of baseline demographics (Table 1) indicates that the randomization procedure performed as expected to create well balanced cohorts, even with the small sample sizes in this study.1 There is no indication of lack of balance, and this is supported by the acknowledgement in the letter that glenohumeral subluxation occurs in similar proportions in both of the cohorts. Thus, the results should be considered valid and not caused by chance. Finally, the study authors embrace the need for exploration of the mechanism of action of peripheral nerve stimulation. At this point, there is no evidence to suggest the way in which peripheral nerve stimulation achieves pain relief or which subjects will receive benefit from treatment. When considering mechanism of action, all mechanisms should be exploredVincluding somatosensory function, anatomic pathology, biomechanics, genetic predisposition, and psychologic traits, among others. REFERENCES 1. Wilson RD, Gunzler DD, Bennett ME, et al: Peripheral nerve stimulation compared with usual care for pain relief of hemiplegic shoulder pain: A randomized controlled trial. Am J Phys Med Rehabil 2014;93:17Y28 2. Tavora DG, Gama RL, Bomfim RC, et al: MRI findings in the painful hemiplegic shoulder. Clin Radiol 2010;65:789Y94
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Letters to the Editor
3. Shah RR, Haghpanah S, Elovic EP, et al: MRI findings in the painful poststroke shoulder. Stroke 2008;39:1808Y13 4. Hakuno A, Sashika H, Ohkawa T, et al: Arthrographic findings in hemiplegic shoulders. Arch Phys Med Rehabil 1984;65:706Y11 5. Roosink M, Renzenbrink GJ, Buitenweg JR, et al: Persistent shoulder pain in the first 6 months after stroke: Results of a prospective cohort study. Arch Phys Med Rehabil 2011;92: 1139Y45 6. Roosink M, Renzenbrink GJ, Buitenweg JR, et al: Somatosensory symptoms and signs and conditioned pain modulation in chronic post-stroke shoulder pain. J Pain 2011;12:476Y85 7. Roosink M, Buitenweg JR, Renzenbrink GJ, et al: Altered cortical somatosensory processing in chronic stroke: A relationship with post-stroke shoulder pain. NeuroRehabilitation 2011;28:331Y44 8. Soo Hoo J, Paul T, Chae J, et al: Central hypersensitivity in chronic hemiplegic shoulder pain. Am J Phys Med Rehabil 2013;92:1Y13 9. Greenland S, Pearl J, Robins JM: Causal diagrams for epidemiologic research. Epidemiology 1999;10:37Y48
Richard D. Wilson, MD Department of Physical Medicine and Rehabilitation Case Western Reserve University at MetroHealth Medical Center and Cleveland Functional Electrical Stimulation Center Case Western Reserve University, Cleveland, Ohio DOI: 10.1097/PHM.0000000000000161
Am. J. Phys. Med. Rehabil. & Vol. 93, No. 10, October 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
LETTER TO THE EDITOR REGARDING BPERIPHERAL NERVE STIMULATION COMPARED WITH USUAL CARE FOR PAIN RELIEF OF HEMIPLEGIC SHOULDER PAIN[ AM J PHYS MED REHABIL 2014;93:17Y27
To the Editor: The reviewers read with interest this article that describes the efficacy of therapeutic single-lead peripheral nerve stimulation in the treatment of hemiplegia with shoulder pain (HSP) as compared with those receiving usual and customary Btreatment.[1 In the reviewers’ brief review of the literature, they identified 31 direct causes of shoulder pain in HSP alphabetically ranging from acromioclavicular dislocation to thoracic outlet syndrome. In addition, diaphragmatic irritation and cardiomyopathy, among others, were also reported as remote sources of HSP. As the authors also acknowledged, no one etiology has been identified as the inciting agents in HSP, and they can also be multifactorial.2 Although the authors list a number of exclusion criteria that eliminated subjects from this study, the primary inclusion diagnosis in both groups seemed to be Bidiopathic.[ Diagnosis, from the Greek diaignn skein, is the act of specifically identifying a disease from its signs and symptoms, thereby ensuring a specific plan of treatment tailored to this taxon. Idiopathic is, by definition, not a diagnosis but instead an admission that no singular cause has been identified as the inciting agent. In both cohorts, subluxation occurred in approximately 55% of the samples, suggesting that it played a prominent role as a direct cause or as a prominent contributor to the HSP. Arm-weighted distraction of the tethered structures of the shoulder and the neck including, among others, the bicipital tendon and/or the cervical spinal roots can be pain generators presenting as a tendinitis and/or cervical radiculopathy, respectively, in association with degenerative cervical disk disease. Immobility itself can contribute to the development of a subdeltoid bursitis, which, when untreated, can culminate with an adhesive capsulitis. Proximal venous occlusion of the subclavian vein as it passes under both the pectoralis major and the minor muscles can present as distal hand edema mimicking a sympathetic dystrophy. In both cohorts, the patients deserve a specific diagnosis with then an opportunity to receive diagnostic-specific treatment rather than historically related treatment, which has evolved from electric eels as well as electrostatic devices to the present single-lead and/or multilead peripheral nerve stimulation.3 This study’s results rest on the assumption that both cohorts are homogeneous and are therefore comparable. Instead, the descriptor, Bidiopathic[ would suggest otherwise. Without a definitive diagnosis for each subject, there is the potential for significant variability within each group www.ajpmr.com
and between each cohort. This heterogeneity introduces the distinct possibility that the reported statistical outcome in this relatively small sample, as well as one with excessive variability, occurred by a Brandom effect.[4
REFERENCES 1. Wilson RD, Gunzler DD, Bennett ME, et al: Peripheral nerve stimulation compared with usual care for pain relief of hemiplegic shoulder pain: A randomized controlled trial. Am J Phys Med Rehabil 2014;93:17Y28 2. Teasell RW: The painful hemiplegic shoulder. Phys Med Rehabil State Art Rev 1998;12:489Y500 3. Stillings D: A survey of the history of electrical stimulation for pain to 1900. Med Instrum 1975;9:255Y9 4. Cornell JE, Mulrow CD, Localio R, et al: Random-effects metaanalysis of inconsistent effects: A time for change. Ann Intern Med 2014;160:267Y70
Myron M. LaBan, MD, MMSc Julie A. Ferris, MD Department of Physical Medicine and Rehabilitation Oakland University William Beaumont School of Medicine Royal Oak, Michigan DOI: 10.1097/PHM.0000000000000160
AN ETIOLOGICAL PARADIGM SHIFT FOR CHRONIC HEMIPLEGIC SHOULDER PAIN To the Editor: The authors appreciate the interest in the recently published article, BPeripheral Nerve Stimulation Compared with Usual Care for Pain Relief of Hemiplegic Shoulder Pain.[1 This study provides evidence that peripheral nerve stimulation is an efficacious treatment of hemiplegic shoulder pain (HSP) and reduces pain to a greater extent and with longer durability than usual care does. It has been correctly pointed out that there was no attempt by the study authors to provide a diagnosis for the occurrence of HSP based on the nociceptive and biomechanical models. This was not an oversight; rather, it is a result of an alternative paradigm of thought regarding the etiology of chronic HSP considered to be distinct from the etiology of acute HSP. That is, HSP may initially be the result of 1 of 31 or more of the direct causes of HSP, but maladaptive changes in the central nervous system are responsible for the pain persisting beyond the initial injury. It is apparent that identifiable pathologies on imaging studies have low correlation to the presence of HSP.2Y4 Furthermore, there is a growing body of evidence to suggest that the nociceptive and biomechanical models should be reconsidered in favor of a central sensitization process in the etiology of chronic HSP.5Y8 Letters to the Editor
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
929
The assertion that the study results are not valid because of heterogeneity of the cohorts deserves reexamination. The design of this study included randomized treatment allocation so that treatment status would not be confounded by either measured or unmeasured baseline characteristics.9 A review of baseline demographics (Table 1) indicates that the randomization procedure performed as expected to create well balanced cohorts, even with the small sample sizes in this study.1 There is no indication of lack of balance, and this is supported by the acknowledgement in the letter that glenohumeral subluxation occurs in similar proportions in both of the cohorts. Thus, the results should be considered valid and not caused by chance. Finally, the study authors embrace the need for exploration of the mechanism of action of peripheral nerve stimulation. At this point, there is no evidence to suggest the way in which peripheral nerve stimulation achieves pain relief or which subjects will receive benefit from treatment. When considering mechanism of action, all mechanisms should be exploredVincluding somatosensory function, anatomic pathology, biomechanics, genetic predisposition, and psychologic traits, among others. REFERENCES 1. Wilson RD, Gunzler DD, Bennett ME, et al: Peripheral nerve stimulation compared with usual care for pain relief of hemiplegic shoulder pain: A randomized controlled trial. Am J Phys Med Rehabil 2014;93:17Y28 2. Tavora DG, Gama RL, Bomfim RC, et al: MRI findings in the painful hemiplegic shoulder. Clin Radiol 2010;65:789Y94
930
Letters to the Editor
3. Shah RR, Haghpanah S, Elovic EP, et al: MRI findings in the painful poststroke shoulder. Stroke 2008;39:1808Y13 4. Hakuno A, Sashika H, Ohkawa T, et al: Arthrographic findings in hemiplegic shoulders. Arch Phys Med Rehabil 1984;65:706Y11 5. Roosink M, Renzenbrink GJ, Buitenweg JR, et al: Persistent shoulder pain in the first 6 months after stroke: Results of a prospective cohort study. Arch Phys Med Rehabil 2011;92: 1139Y45 6. Roosink M, Renzenbrink GJ, Buitenweg JR, et al: Somatosensory symptoms and signs and conditioned pain modulation in chronic post-stroke shoulder pain. J Pain 2011;12:476Y85 7. Roosink M, Buitenweg JR, Renzenbrink GJ, et al: Altered cortical somatosensory processing in chronic stroke: A relationship with post-stroke shoulder pain. NeuroRehabilitation 2011;28:331Y44 8. Soo Hoo J, Paul T, Chae J, et al: Central hypersensitivity in chronic hemiplegic shoulder pain. Am J Phys Med Rehabil 2013;92:1Y13 9. Greenland S, Pearl J, Robins JM: Causal diagrams for epidemiologic research. Epidemiology 1999;10:37Y48
Richard D. Wilson, MD Department of Physical Medicine and Rehabilitation Case Western Reserve University at MetroHealth Medical Center and Cleveland Functional Electrical Stimulation Center Case Western Reserve University, Cleveland, Ohio DOI: 10.1097/PHM.0000000000000161
Am. J. Phys. Med. Rehabil. & Vol. 93, No. 10, October 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
