A Review of Studies Comparing Methods for Determining Transcranial Magnetic Stimulation Motor Threshold: Observation of Movement or Electromyography Assisted

Abstract

BACKGROUND: Early in the development of transcranial magnetic stimulation (TMS) as a research tool, scientists developed the concept of motor threshold (MT) as a method of quantifying dose and establishing safety. Neurophysiologists determined the MT with the aid of peripheral electromyography (EMG). More recently, clinicians started substituting the EMG with observed movements (OM) of the hand or digits. It is unclear whether the two approaches (EMG and OM) reach similar conclusions about an individual’s cortical excitability and when best to use each approach. OBJECTIVE: To review TMS studies directly comparing the EMG and OM MT methods. DESIGN: A systematic search of the literature on Medline from January 1995 through April 2008. RESULTS: Four articles directly compared the two approaches, reaching different and opposing findings. CONCLUSION S : The evidence supporting the substitution of EMG with OM is sparse and conflicting. Clinicians stimulating at or near safety guidelines should use the EMG method.

Keywords

TMS transcranial magnetic stimulation motor threshold motor evoked potentials observation of movement visualization

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References

Awiszus, F. ( 2003). TMS and threshold hunting. Supplements to Clinical Neurophysiology, 56, 13-23.

Awiszus, F. , Feistner, H. , Urbach, D. , & Bostock, H. ( 1999). Characterisation of paired-pulse transcranial magnetic stimulation conditions yielding intracortical inhibition or I-wave facilitation using a threshold-hunting paradigm. Experimental Brain Research , 129, 317-324.

Balslev, D. , Braet, W. , McAllister, C. , & Miall, R.C. ( 2007). Inter-individual variability in optimal current direction for transcranial magnetic stimulation of the motor cortex. Journal of Neuroscience Methods, 162, 309-313.

Barker, A.T. , Jalinous, R. , & Freeston, I.L. (1985). Non-invasive magnetic stimulation of the human motor cortex. Lancet, 1, 1106-1107.

Conca, A. , Konig, P. , & Hausmann, A. ( 2000). Transcranial magnetic stimulation induces "pseudoabsence seizure." Acta Psychiatrica Scandinavica, 101, 246-248.

Conforto, A.B. , Z’Graggen, W.J. , Kohl, A.S. , Rosler, K.M. , & Kaelin-Lang, A. (2004). Impact of coil position and electrophysiological monitoring on determination of motor thresholds to transcranial magnetic stimulation. Clinical Neurophysiology , 115, 812-819.

Denslow, S. , Bohning, D.E. , Bohning, P.A. , Lomarev, M.P. , & George, M.S. ( 2005). An increased precision comparison of TMS-induced motor cortex BOLD fMRI Response for image-guided versus function-guided coil placement . Cognitive and Behavioral Neurology, 18, 119-127.

Denslow, S. , Lomarev, M. , Bohning, D.E. , Mu, Q. , & George, M.S. ( 2004). A high resolution assessment of the repeatability of relative location and intensity of transcranial magnetic stimulation-induced and volitionally induced blood oxygen level-dependent response in the motor cortex. Cognitive and Behavioral Neurology, 17, 163-173.

Denslow, S. , Lomarev, M. , George, M.S. , & Bohning, D.E. ( 2005). Cortical and subcortical brain effects of transcranial magnetic stimulation (TMS)-induced movement: An interleaved TMS/ functional magnetic resonance imaging study. Biological Psychiatry, 57, 752-760.

10.

Di Lazzaro, V., Restuccia, D., Oliviero, A., Profice, P., Ferrara, L., Insola, A., et al. (1998). Effects of voluntary contraction on descending volleys evoked by transcranial stimulation in conscious humans. Journal of Physiology, 508(Part 2), 625-633. Fitzgerald, P. B., Hoy, K., McQueen, S., Herring, S., Segrave, R., Been, G., et al. (2008). Priming stimulation enhances the effectiveness of low-frequency right prefrontal cortex transcranial magnetic stimulation in major depression. Journal of Clinical Psychopharmacology, 28, 52-58.

11.

George, M.S. , Wassermann, E.M. , Williams, W.A. , Callahan, A. , Ketter, T.A. , Basser, P. , et al. (1995). Daily repetitive transcranial magnetic stimulation (rTMS) improves mood in depression. NeuroReport , 6, 1853-1856.

12.

Greenberg, B.D. , Ziemann, U. , Harmon, A. , Murphy, D.L. , & Wassermann, E.M. (1998). Reduced intracortical inhibition in obsessive-compulsive disorder on transcranial magnetic stimulation. Lancet, 352, 881-882.

13.

Greer, N. , Mosser, G. , Logan, G. , & Halaas, G.W. ( 2000). A practical approach to evidence grading. Joint Commission Journal on Quality Improvement, 26, 700-712.

14.

Hanajima, R. , Wang, R. , Nakatani-Enomoto, S. , Hamada, M. , Terao, Y. , Furubayashi, T. , et al. (2007). Comparison of different methods for estimating motor threshold with transcranial magnetic stimulation. Clinical Neurophysiology, 118, 2120-2122.

15.

Herwig, U. , Fallgatter, A.J. , Hoppner, J. , Eschweiler, G.W. , Kron, M. , Hajak, G. , et al. (2007). Antidepressant effects of augmentative transcranial magnetic stimulation: Randomised multi-centre trial. British Journal of Psychiatry, 191, 441-448.

16.

Herwig, U. , Kolbel, K. , Wunderlich, A.P. , Thielscher, A. , von Tiesenhausen, C. , Spitzer, M. , et al. (2002). Spatial congruence of neuronavigated transcranial magnetic stimulation and functional neuroimaging. Clinical Neurophysiology, 113, 462-468.

17.

Herwig, U. , Padberg, F. , Unger, J. , Spitzer, M. , & Schonfeldt-Lecuona, C. (2001). Transcranial magnetic stimulation in therapy studies: examination of the reliability of "standard" coil positioning by neuronavigation. Biological Psychiatry , 50, 58-61.

18.

Jorge, R.E. , Moser, D.J. , Acion, L. , & Robinson, R.G. (2008). Treatment of vascular depression using repetitive transcranial magnetic stimulation. Archives of General Psychiatry, 65, 268-276.

19.

Loo, C.K. , Mitchell, P.B. , McFarquhar, T.F. , Malhi, G.S. , & Sachdev, P.S. ( 2007). A sham-controlled trial of the efficacy and safety of twice-daily rTMS in major depression. Psychological Medicine , 37, 341-349.

20.

Mills, K.R. , & Nithi, K.A. ( 1997). Corticomotor threshold to magnetic stimulation: normal values and repeatability. Muscle & Nerve, 20, 570-576.

21.

Mishory, A. , Molnar, C. , Koola, J. , Li, X. , Kozel, F.A. , Myrick, H. , et al. (2004). The maximum-likelihood strategy for determining transcranial magnetic stimulation motor threshold, using parameter estimation by sequential testing is faster than conventional methods with similar precision . Journal of ExtraCorporeal Technology, 20, 160-165.

22.

Mogg, A. , Purvis, R. , Eranti, S. , Contell, F. , Taylor, J.P. , Nicholson, T. , et al. (2007). Repetitive transcranial magnetic stimulation for negative symptoms of schizophrenia: a randomized controlled pilot study . Schizophrenia Research, 93, 221-228.

23.

Nowak, D.A. , Hoffmann, U. , Connemann, B.J. , & Schonfeldt-Lecuona, C. (2006). Epileptic seizure following 1 Hz repetitive transcranial magnetic stimulation. Clinical Neurophysiology, 117, 1631-1633.

24.

O’Reardon, J.P. , Solvason, H.B. , Janicak, P.G. , Sampson, S. , Isenberg, K.E. , Nahas, Z. , et al. (2007). Efficacy and safety of transcranial magnetic stimulation in the acute treatment of major depression: A multisite randomized controlled trial. Biological Psychiatry, 62, 1208-1216.

25.

Pridmore, S. , Fernandes Filho, J.A. , Nahas, Z. , Liberatos, C. , & George, M.S. ( 1998). Motor threshold in transcranial magnetic stimulation: A comparison of a neurophysiological method and a visualization of movement method. Journal of ExtraCorporeal Technology, 14, 25-27.

26.

Rossini, P.M. , Barker, A.T. , Berardelli, A. , Caramia, M.D. , Caruso, G. , Cracco, R.Q. , et al. (1994). Non-invasive electrical and magnetic stimulation of the brain, spinal cord and roots: basic principles and procedures for routine clinical application. Report of an IFCN committee. Electroencephalography and Clinical Neurophysiology, 91, 79-92.

27.

Rossini, P.M. , Berardelli, A. , Deuschl, G. , Hallett, M. , Maertens de Noordhout, A.M. , Paulus, W. , et al. (1999). Applications of magnetic cortical stimulation. The International Federation of Clinical Neurophysiology. Electroencephalography and Clinical Neurophysiology Supplement, 52, 171-185.

28.

Rothwell, J.C. , Hallett, M. , Berardelli, A. , Eisen, A. , Rossini, P.M. , & Paulus, W. ( 1999). Magnetic Stimulation: motor evoked potentials. The Internationa Federation of Clinical Neurophysiology. Electroencephalography and Clinical Neurophysiology. Supplement, 52, 97-103.

29.

Sparing, R. , Buelte, D. , Meister, I.G. , Paus, T. , & Fink, G.R. ( 2008). Transcranial magnetic stimulation and the challenge of coil placement: a comparison of conventional and stereotaxic neuronavigational strategies. Human Brain Mapping, 29, 82-96.

30.

Tharayil, B.S. , Gangadhar, B.N. , Thirthalli, J. , & Anand, L. ( 2005). Seizure with single-pulse transcranial magnetic stimulation in a 35-year-old otherwise-healthy patient with bipolar disorder. Journal of ExtraCorporeal Technology, 21, 188-189.

31.

Wasserman, E.M. ( 2002). Variation in the response to transcranial magnetic brain stimulation in the general population. Clinical Neurophysiology , 113, 1165-1171.

32.

Wassermann, E.M. ( 1998). Risk and safety of repetitive transcranial magnetic stimulation: Report and suggested guidelines from the International Workshop in the Safety of Repetitive Transcranial Magnetic Stimulation, June 5-7, 1996. Electroencephalography and Clinical Neurophysiology, 108, 1-16.