[Downloaded free from http://www.neurologyindia.com on Thursday, May 07, 2015, IP: 61.16.135.116]
Correspondence
Approach to diagnosis and management of optic neuropathy due to copper deficiency Sir, We read with interest the review article titled “Approach to diagnosis and management of optic neuropathy”[1] by Mustafa and Pandit. We appreciate the authors’ effort and research work. We would like to highlight a few points regarding copper deficiency. There are a few case reports of optic neuropathy in patients with low copper level,[2] presenting with reduced visual acuity and color vision, constricted visual fields, optic atrophy, and thinning of retinal nerve fibers. Scotopic and photopic electroretinograms were normal suggesting that the retinal function was normal. Copper deficiency is a rare cause for progressive optic neuropathy and myelopathy[3‑5] and hence should be considered in the differential diagnosis. It is crucial to elicit a history of gastric surgery or other risk factors for hypocupremia in patients undergoing evaluation for subacute or chronically progressive optic neuropathy or myelopathy.
Nataraja Pillai Venugopal Neuro‑Ophthalmology Clinic and Glaucoma Service, AG Eye Hospital, Puthur, Trichy, Tamil Nadu, India E‑mail: [email protected]
References 1. 2. 3.
4.
5.
Mustafa S, Pandit L. Approach to diagnosis and management of optic neuropathy. Neurol India 2014;62:599‑605. Ugarte M, Osborne NN, Brown LA, Bishop PN. Iron, zinc, and copper in retinal physiology and disease. Surv Ophthalmol 2013;58:585‑609. Pineles SL, Wilson CA, Balcer LJ, Slater R, Galetta SL. Combined optic neuropathy and myelopathy secondary to copper deficiency. Surv Ophthalmol 2010;55:386‑92. Sharma C, Nath K, Kumawat BL, Khandelwal D, Jain D. Erb’s paraplegia with primary optic atrophy: Unusual presentation of neurosyphilis: Case report and review of literature. Ann Indian Acad Neurol 2014;17:231‑3. Narayan SK, Kaveer N. CNS demyelination due to hypocupremia in Wilson’s disease from overzealous treatment. Neurol India 2006;54:110‑1. Access this article online
Website: www.neurologyindia.com DOI: 10.4103/0028-3886.156324 PMID: xxxxx
Quick Response Code
Validity versus reliability Sir, This is with reference to the article entitled “Validity of Montreal Cognitive Assessment in Non-English speaking patients with Parkinson’s disease” published in Neurol India 2015; 63: 63-7.[1] The present case-control study was designed with the aim to assess the validity of Montreal Cognitive Assessment scale for use in non-English (Malayalam) speaking patients with Parkinson's disease (PD). The authors, at the end of the study, conclude that this study establishes the reliability of cross-cultural adaptation of Montreal Cognitive Assessment for assessing cognition in Malayalam-speaking Parkinson's disease patients, for their early screening and potential future interventions for cognitive dysfunction.[1] Authors deserve appreciation for their efforts. However, I have some concerns with this study. The authors have a chosen a case-control design for the purpose of this study and as per the authors, 70 patients with Parkinson's disease and 60 age- and education-matched healthy controls were chosen for this purpose.[1] Herein lies my first concern. The authors in the first place have used a smaller number of controls that may not provide adequate power to the conclusion drawn from the study sample. But more importantly, it appears that the authors have not matched for age and education. Age and education matching of controls means that a similar proportion of cases fall into the various categories defined by the matching variable (age and education in this study). For instance, if 25% of the cases are aged 65–75 years, 25% of the controls would be taken to be of the same age. This takes me to my second concern. The authors aim to assess the validity of Montreal Cognitive Assessment but conclude with a statement on the reliability of cross-cultural adaptation of Montreal Cognitive Assessment for assessing cognition. Validity and reliability are not same. Validity of a test/assessment is the degree to which it measures what it is supposed to measure. This is not the same as reliability. Reliability is the extent to which a measurement gives results that are consistent or repeatable. Furthermore, within validity, the measurement does not always have to be similar. But in reliability, the measurements are similar. Also, the reliability of a measure does not necessarily make it valid (and vice versa). Lastly, a comment specific to this study; in psychometrics, validity has a particular application known as test validity. Test validity refers to the degree to which evidence and theory support the interpretation of test scores ("as entailed by the
Neurology India / March 2015 / Volume 63 / Issue 2
291
[Downloaded free from http://www.neurologyindia.com on Thursday, May 07, 2015, IP: 61.16.135.116]
Correspondence
proposed uses of the tests"). The validity check in this study should have looked at this aspect.
Sunil K. Raina Department of Community Medicine, DR. RPGMC, Tanda, Kangra, Himachal Pradesh, India E‑mail: [email protected]
References 1.
Krishnan S, Justus S, Meluveettil R, Menon RN, Sharma SP, Kishore A. Validity of Montreal Cognitive Assessment in Non-English speaking patients with Parkinson’s disease. Neurol India 2015;63:63-7.
Access this article online Website:
Quick Response Code
quality of our results is not compromised by the minimal difference in numbers (60 Vs 70), as the primary aims (testing the metric properties and thereby, validity and reliability of MoCA‑M for use in Parkinson’s disease patients) of the study do not rely much on the comparison between cases and controls. For the same reason, we are of the opinion that the degree of matching achieved with regard to the age and level of education, mentioned in the first paragraph under “Results” would suffice. The increased risk of cognitive dysfunction in PD patients and the increasing risk with its duration have been established by numerous earlier studies. The significantly worse performance of our PD patients in MoCA‑M (paralleling the performance in MMSE and ACE) compared to controls (who were not significantly different from them with regard to age or level of education) thus gives additional support to its validity.
www.neurologyindia.com DOI:
Dr. Syam Krishnan
10.4103/0028-3886.156326
E-mail: [email protected]
PMID:
Reference
xxxxx
1.
Authors' reply Sir, We appreciate the critical comments of the reader regarding our work “Validity of Montreal Cognitive Assessment in Non-English speaking patients with Parkinson’s disease”.[1] We welcome such healthy discussions and feel that such discussions contribute to the learning of all those who participate. We would like to answer the reader’s second concern first, as the answer to the first concern will be clearer after this. The reader has rightly pointed out the linguistic difference between validity and reliability, which we fully accept. In fact, MoCA-M is both valid and reliable for testing cognition in Malayalam-speaking patients with PD. A good correlation of MoCA-M scores with other established screening (MMSE) and more comprehensive (Addenbrooke’s Cognitive Examination‑ ACE) instruments for cognitive testing supports its validity (the degree to which it measures what it is supposed to measure). The excellent test-retest performance and internal consistency support its reliability (the extent to which it gives results that are consistent or repeatable). Regarding the reader’s first concern about the smaller number of controls-we agree that an equal number of controls would have been ideal. However, we feel that the 292
Krishnan S, Justus S, Meluveettil R, Menon RN, Sarma SP, Kishore A. validity of montreal cognitive assessment in non-english speaking patients with parkinson's disease. Neurol India 2015;63:63‑7.
Role of ocular ultrasound in idiopathic intra-cranial hypertension Sir, We came across the original article titled “Idiopathic intracranial hypertension in paediatric population: A case series from India” by Arun Roy and colleagues[1] while researching the literature for our pediatric patients with idiopathic intra‑cranial hypertension (IIH). At the outset, we would like to congratulate the authors for this large series which is probably the first from India. The reason for writing this letter is to highlight the role of an ocular B‑scan ultrasound from the neuro‑ophthalmogy point of view in evaluating IIH in children. As we all know, IIH is characterized by increased intra‑cranial pressure (ICP) with essentially normal brain magnetic resonance imaging (MRI) and magnetic resonance venography (MRV).[2] However, the presence of IIH in children offers some unique challenges. Small children may not complain of headache or diplopia. At times, it can be difficult to monitor the optic nerve function in children, especially in infants, as a formal visual acuity measurement and a visual field assessment cannot
Neurology India / March 2015 / Volume 63 / Issue 2
Copyright of Neurology India is the property of Medknow Publications & Media Pvt. Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
Correspondence
Approach to diagnosis and management of optic neuropathy due to copper deficiency Sir, We read with interest the review article titled “Approach to diagnosis and management of optic neuropathy”[1] by Mustafa and Pandit. We appreciate the authors’ effort and research work. We would like to highlight a few points regarding copper deficiency. There are a few case reports of optic neuropathy in patients with low copper level,[2] presenting with reduced visual acuity and color vision, constricted visual fields, optic atrophy, and thinning of retinal nerve fibers. Scotopic and photopic electroretinograms were normal suggesting that the retinal function was normal. Copper deficiency is a rare cause for progressive optic neuropathy and myelopathy[3‑5] and hence should be considered in the differential diagnosis. It is crucial to elicit a history of gastric surgery or other risk factors for hypocupremia in patients undergoing evaluation for subacute or chronically progressive optic neuropathy or myelopathy.
Nataraja Pillai Venugopal Neuro‑Ophthalmology Clinic and Glaucoma Service, AG Eye Hospital, Puthur, Trichy, Tamil Nadu, India E‑mail: [email protected]
References 1. 2. 3.
4.
5.
Mustafa S, Pandit L. Approach to diagnosis and management of optic neuropathy. Neurol India 2014;62:599‑605. Ugarte M, Osborne NN, Brown LA, Bishop PN. Iron, zinc, and copper in retinal physiology and disease. Surv Ophthalmol 2013;58:585‑609. Pineles SL, Wilson CA, Balcer LJ, Slater R, Galetta SL. Combined optic neuropathy and myelopathy secondary to copper deficiency. Surv Ophthalmol 2010;55:386‑92. Sharma C, Nath K, Kumawat BL, Khandelwal D, Jain D. Erb’s paraplegia with primary optic atrophy: Unusual presentation of neurosyphilis: Case report and review of literature. Ann Indian Acad Neurol 2014;17:231‑3. Narayan SK, Kaveer N. CNS demyelination due to hypocupremia in Wilson’s disease from overzealous treatment. Neurol India 2006;54:110‑1. Access this article online
Website: www.neurologyindia.com DOI: 10.4103/0028-3886.156324 PMID: xxxxx
Quick Response Code
Validity versus reliability Sir, This is with reference to the article entitled “Validity of Montreal Cognitive Assessment in Non-English speaking patients with Parkinson’s disease” published in Neurol India 2015; 63: 63-7.[1] The present case-control study was designed with the aim to assess the validity of Montreal Cognitive Assessment scale for use in non-English (Malayalam) speaking patients with Parkinson's disease (PD). The authors, at the end of the study, conclude that this study establishes the reliability of cross-cultural adaptation of Montreal Cognitive Assessment for assessing cognition in Malayalam-speaking Parkinson's disease patients, for their early screening and potential future interventions for cognitive dysfunction.[1] Authors deserve appreciation for their efforts. However, I have some concerns with this study. The authors have a chosen a case-control design for the purpose of this study and as per the authors, 70 patients with Parkinson's disease and 60 age- and education-matched healthy controls were chosen for this purpose.[1] Herein lies my first concern. The authors in the first place have used a smaller number of controls that may not provide adequate power to the conclusion drawn from the study sample. But more importantly, it appears that the authors have not matched for age and education. Age and education matching of controls means that a similar proportion of cases fall into the various categories defined by the matching variable (age and education in this study). For instance, if 25% of the cases are aged 65–75 years, 25% of the controls would be taken to be of the same age. This takes me to my second concern. The authors aim to assess the validity of Montreal Cognitive Assessment but conclude with a statement on the reliability of cross-cultural adaptation of Montreal Cognitive Assessment for assessing cognition. Validity and reliability are not same. Validity of a test/assessment is the degree to which it measures what it is supposed to measure. This is not the same as reliability. Reliability is the extent to which a measurement gives results that are consistent or repeatable. Furthermore, within validity, the measurement does not always have to be similar. But in reliability, the measurements are similar. Also, the reliability of a measure does not necessarily make it valid (and vice versa). Lastly, a comment specific to this study; in psychometrics, validity has a particular application known as test validity. Test validity refers to the degree to which evidence and theory support the interpretation of test scores ("as entailed by the
Neurology India / March 2015 / Volume 63 / Issue 2
291
[Downloaded free from http://www.neurologyindia.com on Thursday, May 07, 2015, IP: 61.16.135.116]
Correspondence
proposed uses of the tests"). The validity check in this study should have looked at this aspect.
Sunil K. Raina Department of Community Medicine, DR. RPGMC, Tanda, Kangra, Himachal Pradesh, India E‑mail: [email protected]
References 1.
Krishnan S, Justus S, Meluveettil R, Menon RN, Sharma SP, Kishore A. Validity of Montreal Cognitive Assessment in Non-English speaking patients with Parkinson’s disease. Neurol India 2015;63:63-7.
Access this article online Website:
Quick Response Code
quality of our results is not compromised by the minimal difference in numbers (60 Vs 70), as the primary aims (testing the metric properties and thereby, validity and reliability of MoCA‑M for use in Parkinson’s disease patients) of the study do not rely much on the comparison between cases and controls. For the same reason, we are of the opinion that the degree of matching achieved with regard to the age and level of education, mentioned in the first paragraph under “Results” would suffice. The increased risk of cognitive dysfunction in PD patients and the increasing risk with its duration have been established by numerous earlier studies. The significantly worse performance of our PD patients in MoCA‑M (paralleling the performance in MMSE and ACE) compared to controls (who were not significantly different from them with regard to age or level of education) thus gives additional support to its validity.
www.neurologyindia.com DOI:
Dr. Syam Krishnan
10.4103/0028-3886.156326
E-mail: [email protected]
PMID:
Reference
xxxxx
1.
Authors' reply Sir, We appreciate the critical comments of the reader regarding our work “Validity of Montreal Cognitive Assessment in Non-English speaking patients with Parkinson’s disease”.[1] We welcome such healthy discussions and feel that such discussions contribute to the learning of all those who participate. We would like to answer the reader’s second concern first, as the answer to the first concern will be clearer after this. The reader has rightly pointed out the linguistic difference between validity and reliability, which we fully accept. In fact, MoCA-M is both valid and reliable for testing cognition in Malayalam-speaking patients with PD. A good correlation of MoCA-M scores with other established screening (MMSE) and more comprehensive (Addenbrooke’s Cognitive Examination‑ ACE) instruments for cognitive testing supports its validity (the degree to which it measures what it is supposed to measure). The excellent test-retest performance and internal consistency support its reliability (the extent to which it gives results that are consistent or repeatable). Regarding the reader’s first concern about the smaller number of controls-we agree that an equal number of controls would have been ideal. However, we feel that the 292
Krishnan S, Justus S, Meluveettil R, Menon RN, Sarma SP, Kishore A. validity of montreal cognitive assessment in non-english speaking patients with parkinson's disease. Neurol India 2015;63:63‑7.
Role of ocular ultrasound in idiopathic intra-cranial hypertension Sir, We came across the original article titled “Idiopathic intracranial hypertension in paediatric population: A case series from India” by Arun Roy and colleagues[1] while researching the literature for our pediatric patients with idiopathic intra‑cranial hypertension (IIH). At the outset, we would like to congratulate the authors for this large series which is probably the first from India. The reason for writing this letter is to highlight the role of an ocular B‑scan ultrasound from the neuro‑ophthalmogy point of view in evaluating IIH in children. As we all know, IIH is characterized by increased intra‑cranial pressure (ICP) with essentially normal brain magnetic resonance imaging (MRI) and magnetic resonance venography (MRV).[2] However, the presence of IIH in children offers some unique challenges. Small children may not complain of headache or diplopia. At times, it can be difficult to monitor the optic nerve function in children, especially in infants, as a formal visual acuity measurement and a visual field assessment cannot
Neurology India / March 2015 / Volume 63 / Issue 2
Copyright of Neurology India is the property of Medknow Publications & Media Pvt. Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
