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Author Response to Letter to the Editor

Authors:

Jongmok Ha,

Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul; Neuroscience Center, Samsung Medical Center, Seoul, KR
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Boo Suk Na,

Department of Neurology, Dongshin Hospital, Seoul, KR
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Jong Hyeon Ahn,

Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul; Neuroscience Center, Samsung Medical Center, Seoul, KR
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Minkyeong Kim,

Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul; Neuroscience Center, Samsung Medical Center, Seoul, KR
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Jae Woo Kim,

Department of Neurology, Dong-A University College of Medicine, Busan, KR
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Jae Hyeok Lee,

Department of Neurology, Pusan National University Yangsan Hospital, Yangsan, KR
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Jin Whan Cho,

Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul; Neuroscience Center, Samsung Medical Center, Seoul, KR
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Ji Sun Kim,

Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul; Neuroscience Center, Samsung Medical Center, Seoul, KR
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Jinyoung Youn

Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul; Neuroscience Center, Samsung Medical Center, Seoul, KR
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Abstract

How to Cite: Ha J, Na BS, Ahn JH, Kim M, Kim JW, Lee JH, et al.. Author Response to Letter to the Editor. Tremor and Other Hyperkinetic Movements. 2019;9. DOI: http://doi.org/10.5334/tohm.501
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  Published on 02 Dec 2019
 Accepted on 04 Nov 2019            Submitted on 04 Nov 2019

Dear Editor,

This is an author response to the letter by doctors Nicholas Doher and Harsh V Gupta.

Despite the narrow indication for the dopamine transporter (DAT) scan to distinguish essential tremor from Parkinsonian syndromes, as approved by the Food and Drug Administration (FDA), (Available from: http://www.accessdata.fda.gov/drugsatfda_docs/nda/2011/022454sOrig1s000Lbl.pdf) DAT imaging is utilised for various other clinical symptoms in patients with parkinsonism: (1) to differentiate Parkinson’s disease (PD) from atypical parkinsonism (dementia with Lewy bodies (DLB), multiple system atrophy (MSA), corticobasal degeneration (CBD), etc.), vascular parkinsonism or psychogenic parkinsonism by revealing different patterns of decreased DAT uptake or the lack thereof,1,2 (2) as a marker, in PD prognostics, in that it reflects the severity of the disease,3,4 (3) as a predictor for levodopa-induced dyskinesias,5 (4) for differential diagnosis of PD from dopa-responsive dystonia6,7 or drug-induced parkinsonism8 and (5) to differentiate dystonic or psychogenic tremors from tremors due to PD.9 Additionally, false negativity or positivity, along with the advent of the novel terminology, scan without evidence of dopaminergic deficit (SWEDD) syndrome, is another compelling issue. DAT scan is the only non-invasive modality developed to assess functional integrity of the dopaminergic system currently used in clinical practice, and could give valuable clinical information for selected patients. We do think that, the approved indication of the DAT scan will be broadened to meet its versatile diagnostic potential.

Our patient exhibited definite parkinsonism after increasing the dose of the typical antipsychotic medication (haloperidol); it was therefore important to ensure whether parkinsonism resulted solely from haloperidol or if there actually was subclinical parkinsonism present and haloperidol triggered its manifestation. If the latter case was true, parkinsonism had to be considered as a symptom accompanying chorea and dystonia in the natural course of the disease, broadening the diagnostic spectrum. Although decreased DAT uptake was observed in our patient, the ‘pattern’ of decreased uptake was different from classic Parkinsonian syndromes. Moreover, we already obtained the data from magnetic resonance imaging (MRI) of the brain in advance to co-localise and compare with the DAT scan data; therefore, we were not threatened by the caveats of false-positivity.

In conclusion, we believe that in atypical, complex cases that warrant prompt diagnosis and treatment, it does not harm the patient to undergo relevant tests, if not disorienting. Our patient was in desperate need of a concrete diagnosis in order to terminate his diagnostic odyssey and the DAT scan played a crucial role in our workup.

Notes

1 In Response To: 

Doher N, Gupta HV. Reply to: Paraneoplastic Chorea Managed with Intravenous Amantadine. Tremor Other Hyperkinet Mov. 2019; 9. doi: 10.7916/tohm.v0.743

2 Original Article: 

Ha J, Na BS, Ahn JH, Kim M, Kim JW, Lee JH, et al. Anti-CV2/CRMP5 paraneoplastic chorea effectively managed with intravenous amantadine. Tremor Other Hyperkinet Mov. 2019: 9. doi: 10.7916/tohm.v0.701

3 Citation: Ha J, Na BS, Ahn JH, Kim M, Kim JW, Lee JH, et al. Author response to letter to the editor. Tremor Other Hyperkinet Mov. 2019: 9. doi: 10.7916/tohm.v0.746 

These two authors contributed equally to this work. 

5 Editor: Elan D. Louis, Yale University, USA 

6 Funding: None. 

7 Financial Disclosures: None. 

8 Conflict of Interest: The authors report no conflict of interest. 

9 Ethics Statement: Not applicable for this category of article. 

References

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  2. Scherfler, C , Schwarz, J , Antonini, A , Grosset, D , Valldeoriola, F , Marek, K , et al. Role of DAT-SPECT in the diagnostic work up of parkinsonism. Mov Disord 2007;22:1229–1238. doi: https://doi.org/10.1002/mds.2150517486648 

  3. Seibyl, JP , Marek, KL , Quinlan, D , Sheff, K , Zoghbi, S , Zea-Ponce, Y , et al. Decreased single-photon emission computed tomographic [123I]beta-CIT striatal uptake correlates with symptom severity in Parkinson’s disease. Ann Neurol 1995;38:589–598. doi: https://doi.org/10.1002/ana.4103804077574455 

  4. Asenbaum, S , Brucke, T , Pirker, W , Podreka, I , Angelberger, P , Wenger, S , et al. Imaging of dopamine transporters with iodine-123-beta-CIT and SPECT in Parkinson’s disease. J Nucl Med 1997;38:1–6.8998140 

  5. Hong, JY , Oh, JS , Lee, I , Sunwoo, MK , Ham, JH , Lee, JE , et al. Presynaptic dopamine depletion predicts levodopa-induced dyskinesia in de novo Parkinson disease. Neurology 2014;82:1597–1604. doi: https://doi.org/10.1212/WNL.000000000000038524719485 

  6. Jeon, BS , Jeong, JM , Park, SS , Kim, JM , Chang, YS , Song, HC , et al. Dopamine transporter density measured by [123I]beta-CIT single-photon emission computed tomography is normal in dopa-responsive dystonia. Ann Neurol 1998;43:792–800. doi: https://doi.org/10.1002/ana.4104306149629849 

  7. O’Sullivan, JD, , Costa, DC and , Gacinovic, S, , Lees, AJ, SPECT imaging of the dopamine transporter in juvenile-onset dystonia. Neurology 2001;56:266–267. doi: https://doi.org/10.1212/wnl.56.2.26611160970 

  8. Lorberboym, M, , Treves, TA, , Melamed, E and , Lampl, Y, , Hellmann, M, , Djaldetti, R, [123I]-FP/CIT SPECT imaging for distinguishing drug-induced parkinsonism from Parkinson’s disease. Mov Disord 2006;21:510–514. doi: https://doi.org/10.1002/mds.2074816250023 

  9. Sadasivan, S and , Friedman, JH, Experience with DaTscan at a tertiary referral center. Parkinsonism Relat Disord 2015;21:42–45. doi: https://doi.org/10.1016/j.parkreldis.2014.10.02225465746 

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