GRAY MATTERS included.2–4 More comprehensive referencing would include work from the Milan group, which has published extensively on the subject of SEEG and is a leader in this field.5–7 Later in the introduction we make the statement “There are no published data on the use of these tools in clinical practice.” The point we tried to make in our study is that we were evaluating the utility of 3DMMI in a semi-quantitative manner. Of course we do not dispute that 3DMMI is used in clinical practice, and has been reported useful in individual cases.8,9 However, we contend that there are no other prospective studies in the literature that specifically examine the utility of 3DMMI in a busy epilepsy surgery practice. This is understandable given the difficulties associated with study design, which we describe in detail in our article. We set out with this work to convey the message that 3DMMI confers added value to management, as opposed to describing new methods of image preprocessing, integration, and visualization. Linguistics aside, we hope our study serves to promote the use of 3DMMI in epilepsy surgery, which the author rightly traces back to the Talairach methodology. The challenge now is to generate a simplified pipeline that is time- and cost-efficient and that can be reproduced in other centers, so that many more patients can benefit from these tools. We hope that the EpiNav software (Centre of Medical Imaging and Computing, University College London, London, United Kingdom) suite will fulfill this purpose, and we will be pleased to share this with interested centers. DISCLOSURE I have no conflicts of interest to disclose. I confirm that I have read the Journal’s position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.
Mark Nowell [email protected] National Hospital for Neurology and Neurosurgery, London, United Kingdom REFERENCES 1. Nowell M, Rodionov R, Zombori G, et al. Utility of 3D multimodality imaging in the implantation of intracranial electrodes in epilepsy. Epilepsia 2015;56, 3:403–413, March 2015. 2. Hogan RE, Lowe VJ, Bucholz RD. Triple-technique (MR imaging, single-photon emission CT, and CT) coregistration for image-guided surgical evaluation of patients with intractable epilepsy. AJNR Am J Neuroradiol 1999;20:1054–1058. 3. Murphy M, O’Brien TJ, Morris K, et al. Multimodality image-guided epilepsy surgery. J Clin Neurosci 2001;8:534–538. 4. Murphy MA, O’Brien TJ, Morris K, et al. Multimodality imageguided surgery for the treatment of medically refractory epilepsy. J Neurosurg 2004;100:452–462. 5. Cardinale F, Cossu M, Castana L, et al. Stereoelectroencephalography: surgical methodology, safety, and stereotactic application accuracy in 500 procedures. Neurosurgery 2013;72:353–366; discussion 66. 6. Cossu M, Cardinale F, Castana L, et al. Stereoelectroencephalography in the presurgical evaluation of focal epilepsy: a retrospective analysis of 215 procedures. Neurosurgery 2005;57:706–718; discussion -18. Epilepsia, 56(6):973–982, 2015
7. Cossu M, Cardinale F, Castana L, et al. Stereo-EEG in children. Childs Nerv Syst 2006;22:766–778. 8. Wellmer J, Parpaley Y, Von Lehe M, et al. Integrating magnetic resonance imaging postprocessing results into neuronavigation for electrode implantation and resection of subtle focal cortical dysplasia in previously cryptogenic epilepsy. Neurosurgery 2010;66:187–194; discussion 94–95. 9. Harput MV, Gonzalez-Lopez P, Ture U. Three-dimensional reconstruction of the topographical cerebral surface anatomy for presurgical planning with free OsiriX Software. Neurosurgery 2014;10(Suppl. 3):426–435; discussion 35.
The terminology of psychogenic nonepileptic seizures: a historical perspective To the editors, We read with interest the recent paper by Brigo et al.1 on the prevalence of various phrases used to describe the syndrome now most commonly known as psychogenic nonepileptic seizures (PNES). The authors aim to quantify the popularity of several terms by measuring the number of results retrieved (“hits”) for each term in PubMed and Google. Although this approach provides a measure of the current popularity of each phrase, it cannot reveal changes over time, something we suspect may be important in a field in which novel terms emerge and older phrases may develop pejorative connotations over time. Furthermore, the choice of PubMed and Google limits the users of the terms to the authors of scientific articles (for PubMed) and to website developers (for Google), although it would be of value to know the use of each phrase by all parties involved: researchers, caregivers, and patients. Google’s N-gram viewer (https://books.google.com/ ngrams) allows the quantification of the prevalence of a word or combination of words in the entire literature of various languages up to 2008. This corpus includes both scientific and lay books. We entered a number of labels related to PNES in English to quantify their occurrence from 1860 to 2008 (Fig. 1). For readability, only a selection of terms studied by Brigo et al. are shown, and data have been smoothed for a period of 2 years. This analysis shows that the phrase “psychogenic nonepileptic seizures” has become dramatically more prevalent in recent decades. However, “psychogenic seizures,” a term less common in the study by Brigo et al., remained more common in the English-language literature until 2008. This finding is in agreement with the results of a survey of the American Epilepsy Society, which also found that “psychogenic seizures” is the most commonly used denominator to explain the condition to patients, although PNES was not included as an option in this survey.2
978
GRAY MATTERS
Figure 1. The prevalence of various labels for psychogenic nonepileptic seizures (PNES) in the English language literature. The use of PNES has increased dramatically in recent years, but is still lower than the use of “psychogenic seizures.” PNES has only recently surpassed historical, now discredited labels such as “hystero-epilepsy” and “hysterical seizures” in popularity. Data have been smoothed for a period of 2 years. Epilepsia ILAE
We also compared these terms to older descriptors of psychogenic attacks. Of interest, this analysis shows that PNES has only recently surpassed the phrase “hysterical seizures,” a description that was considered highly offensive by patients in one British study.3 The original description by Charcot for this condition was “hysteroepilepsie.”4 Surprisingly, PNES has overtaken the English version of this phrase only recently and is still far less prevalent in English than “hystero-epilepsy” was at the height of its popularity. Our analysis complements the results of Brigo et al. by showing that it can take some time for older, discredited terms to disappear and newer phrases to become commonplace. The use of these phrases in the English literature seems to lag behind their appearance in PubMed-indexed articles and websites. It goes without saying that the prevalence of a term is not a measure of its accuracy. We agree with Brigo et al. that PNES remains a precise way to describe this condition. Quality of care will benefit from consistent and unequivocal use of accurate terminology. This is especially true for patients with PNES, who are often misdiagnosed before receiving their diagnosis and who struggle to incorporate this new diagnosis in their own terms.5 We hope that the observed increase in use of the phrase “psychogenic nonepileptic seizures” will continue and will eventually lead to its universal adoption as a neutral denominator by researchers, caregivers, and patients alike. However, our analysis suggests that it may take a long time before this becomes a reality.
DISCLOSURE We confirm that we have read the Journal’s position on issues involved in ethical publication and affirm that this report is consistent with those guidelines. Neither of the authors has any conflict of interest to disclose.
Martijn R. Tannemaat [email protected] J. Gert van Dijk Department of Neurology and Clinical Neurophysiology, Leiden University Medical Center, Leiden, The Netherlands REFERENCES 1. Brigo F, Igwe SC, Ausserer H, et al. Terminology of psychogenic nonepileptic seizures. Epilepsia 2015;56:e21–e25. 2. LaFrance WC, Rusch MD, Machan JT. What is “treatment as usual” for nonepileptic seizures? Epilepsy Behav 2008;12:388–394. 3. Stone J, Campbell K, Sharma N, et al. What should we call pseudo seizures? The patient’s perspective. Seizure Seizure Eur J Epilepsy 2003;12:568–572. 4. Bogousslavsky J, Walusinski O, Veyrunes D. Crime, hysteria and belle epoque hypnotism: the path traced by Jean-Martin Charcot and Georges Gilles de la Tourette. Eur Neurol 2009;62:193–199. 5. Thompson R, Isaac CL, Rowse G, et al. What is it like to receive a diagnosis of nonepileptic seizures? Epilepsy Behav 2009;14:508–515.
In response: Terminology of PNES over time—the terms they are a-changin’ Dear Editors, We thank Dr. Martijn Tannemaat and Gert van Dijk for their kind interest in our work. Their analysis of changes
979
Epilepsia, 56(6):973–982, 2015
Mark Nowell [email protected] National Hospital for Neurology and Neurosurgery, London, United Kingdom REFERENCES 1. Nowell M, Rodionov R, Zombori G, et al. Utility of 3D multimodality imaging in the implantation of intracranial electrodes in epilepsy. Epilepsia 2015;56, 3:403–413, March 2015. 2. Hogan RE, Lowe VJ, Bucholz RD. Triple-technique (MR imaging, single-photon emission CT, and CT) coregistration for image-guided surgical evaluation of patients with intractable epilepsy. AJNR Am J Neuroradiol 1999;20:1054–1058. 3. Murphy M, O’Brien TJ, Morris K, et al. Multimodality image-guided epilepsy surgery. J Clin Neurosci 2001;8:534–538. 4. Murphy MA, O’Brien TJ, Morris K, et al. Multimodality imageguided surgery for the treatment of medically refractory epilepsy. J Neurosurg 2004;100:452–462. 5. Cardinale F, Cossu M, Castana L, et al. Stereoelectroencephalography: surgical methodology, safety, and stereotactic application accuracy in 500 procedures. Neurosurgery 2013;72:353–366; discussion 66. 6. Cossu M, Cardinale F, Castana L, et al. Stereoelectroencephalography in the presurgical evaluation of focal epilepsy: a retrospective analysis of 215 procedures. Neurosurgery 2005;57:706–718; discussion -18. Epilepsia, 56(6):973–982, 2015
7. Cossu M, Cardinale F, Castana L, et al. Stereo-EEG in children. Childs Nerv Syst 2006;22:766–778. 8. Wellmer J, Parpaley Y, Von Lehe M, et al. Integrating magnetic resonance imaging postprocessing results into neuronavigation for electrode implantation and resection of subtle focal cortical dysplasia in previously cryptogenic epilepsy. Neurosurgery 2010;66:187–194; discussion 94–95. 9. Harput MV, Gonzalez-Lopez P, Ture U. Three-dimensional reconstruction of the topographical cerebral surface anatomy for presurgical planning with free OsiriX Software. Neurosurgery 2014;10(Suppl. 3):426–435; discussion 35.
The terminology of psychogenic nonepileptic seizures: a historical perspective To the editors, We read with interest the recent paper by Brigo et al.1 on the prevalence of various phrases used to describe the syndrome now most commonly known as psychogenic nonepileptic seizures (PNES). The authors aim to quantify the popularity of several terms by measuring the number of results retrieved (“hits”) for each term in PubMed and Google. Although this approach provides a measure of the current popularity of each phrase, it cannot reveal changes over time, something we suspect may be important in a field in which novel terms emerge and older phrases may develop pejorative connotations over time. Furthermore, the choice of PubMed and Google limits the users of the terms to the authors of scientific articles (for PubMed) and to website developers (for Google), although it would be of value to know the use of each phrase by all parties involved: researchers, caregivers, and patients. Google’s N-gram viewer (https://books.google.com/ ngrams) allows the quantification of the prevalence of a word or combination of words in the entire literature of various languages up to 2008. This corpus includes both scientific and lay books. We entered a number of labels related to PNES in English to quantify their occurrence from 1860 to 2008 (Fig. 1). For readability, only a selection of terms studied by Brigo et al. are shown, and data have been smoothed for a period of 2 years. This analysis shows that the phrase “psychogenic nonepileptic seizures” has become dramatically more prevalent in recent decades. However, “psychogenic seizures,” a term less common in the study by Brigo et al., remained more common in the English-language literature until 2008. This finding is in agreement with the results of a survey of the American Epilepsy Society, which also found that “psychogenic seizures” is the most commonly used denominator to explain the condition to patients, although PNES was not included as an option in this survey.2
978
GRAY MATTERS
Figure 1. The prevalence of various labels for psychogenic nonepileptic seizures (PNES) in the English language literature. The use of PNES has increased dramatically in recent years, but is still lower than the use of “psychogenic seizures.” PNES has only recently surpassed historical, now discredited labels such as “hystero-epilepsy” and “hysterical seizures” in popularity. Data have been smoothed for a period of 2 years. Epilepsia ILAE
We also compared these terms to older descriptors of psychogenic attacks. Of interest, this analysis shows that PNES has only recently surpassed the phrase “hysterical seizures,” a description that was considered highly offensive by patients in one British study.3 The original description by Charcot for this condition was “hysteroepilepsie.”4 Surprisingly, PNES has overtaken the English version of this phrase only recently and is still far less prevalent in English than “hystero-epilepsy” was at the height of its popularity. Our analysis complements the results of Brigo et al. by showing that it can take some time for older, discredited terms to disappear and newer phrases to become commonplace. The use of these phrases in the English literature seems to lag behind their appearance in PubMed-indexed articles and websites. It goes without saying that the prevalence of a term is not a measure of its accuracy. We agree with Brigo et al. that PNES remains a precise way to describe this condition. Quality of care will benefit from consistent and unequivocal use of accurate terminology. This is especially true for patients with PNES, who are often misdiagnosed before receiving their diagnosis and who struggle to incorporate this new diagnosis in their own terms.5 We hope that the observed increase in use of the phrase “psychogenic nonepileptic seizures” will continue and will eventually lead to its universal adoption as a neutral denominator by researchers, caregivers, and patients alike. However, our analysis suggests that it may take a long time before this becomes a reality.
DISCLOSURE We confirm that we have read the Journal’s position on issues involved in ethical publication and affirm that this report is consistent with those guidelines. Neither of the authors has any conflict of interest to disclose.
Martijn R. Tannemaat [email protected] J. Gert van Dijk Department of Neurology and Clinical Neurophysiology, Leiden University Medical Center, Leiden, The Netherlands REFERENCES 1. Brigo F, Igwe SC, Ausserer H, et al. Terminology of psychogenic nonepileptic seizures. Epilepsia 2015;56:e21–e25. 2. LaFrance WC, Rusch MD, Machan JT. What is “treatment as usual” for nonepileptic seizures? Epilepsy Behav 2008;12:388–394. 3. Stone J, Campbell K, Sharma N, et al. What should we call pseudo seizures? The patient’s perspective. Seizure Seizure Eur J Epilepsy 2003;12:568–572. 4. Bogousslavsky J, Walusinski O, Veyrunes D. Crime, hysteria and belle epoque hypnotism: the path traced by Jean-Martin Charcot and Georges Gilles de la Tourette. Eur Neurol 2009;62:193–199. 5. Thompson R, Isaac CL, Rowse G, et al. What is it like to receive a diagnosis of nonepileptic seizures? Epilepsy Behav 2009;14:508–515.
In response: Terminology of PNES over time—the terms they are a-changin’ Dear Editors, We thank Dr. Martijn Tannemaat and Gert van Dijk for their kind interest in our work. Their analysis of changes
979
Epilepsia, 56(6):973–982, 2015
