A comparison of relative-frequency and threshold-hunting methods to determine stimulus intensity in transcranial magnetic stimulation

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• 作者：B.I. Silbert ; H.I. Patterson ; D.D. Pevcic ; K.A. Windnagel ; G.W. Thickbroom ; ^{gary.thickbroom@gmail.com}
• 关键词：Transcranial magnetic stimulation ; Threshold ; IFCN ; Rossini&ndash ; Rothwell ; PEST
• 刊名：Clinical Neurophysiology
• 出版年：2013
• 出版时间：April, 2013
• 年：2013
• 卷：124
• 期：4
• 页码：708-712
• 全文大小：427 K

文摘

Objective

Stimulation intensity (SI) in transcranial magnetic stimulation is commonly set in relation to motor threshold (MT), or to achieve a motor-evoked potential (MEP) of predefined amplitude (usually 1 mV). Recently, IFCN recommended adaptive threshold-hunting over the previously endorsed relative-frequency method. We compared the Rossini-Rothwell (R-R) relative-frequency method to an adaptive threshold-hunting method based on parameter estimation by sequential testing (PEST) for determining MT and the SI to target a MEP amplitude of 1 mV (I_1 mV).

Methods

In 10 healthy controls we determined MT and I_1 mV with R-R and PEST using a blinded crossover design, and performed within-session serial PEST measurements of MT.

Results

There was no significant difference between methods for MT (52.6 ¡À 2.6 % vs. 53.7 ¡À 3.1 % ; p = 0.302; % maximum stimulator output; R-R vs. PEST, respectively) or I_1 mV (66.7 ¡À 3.0 % vs. 68.8 ¡À 3.8 % ; p = 0.146). There was strong correlation between R-R and PEST estimates for both MT and I_1 mV. R-R required significantly more stimuli than PEST. Serial measurements of MT with PEST were reproducible.

Conclusions

PEST has the advantage of speed without sacrificing precision when compared to the R-R method, and is adaptable to other SI targets.

Significance

Our results in healthy controls add to increasing evidence in favour of adaptive threshold-hunting methods for determining SI.