Objective: To compare tremor frequency obtained by EMG and accelerometry analysis with three iPhone® applications.

Background: Frequency as a property of tremor is a vital piece of information for the differential diagnosis of tremor disorders. Assessing frequency by observation alone is approximate at best, and this is usually combined with EMG measurements and accelerometry. One study suggested that one application (iSeismometer®) through the use of the iPhone® in-built triaxial accelerometer could reliably assess tremor on the-go, since the values obtained by the application matched well with EMG analysis(1). There are several tremor-detection applications available for the iPhone but few studies have addressed them.

Methods: We selected three applications that had previously been mentioned on the literature (LiftPulse®, iSeismometer®, Studymytremor®) (2). Twenty-two patients were included (twelve with Parkinson’s disease (PD), nine with essential tremor (ET), one with Holmes tremor due to multiple sclerosis). The first author’s personal iPhone® (iPhone 5s) was strapped securely to the patient’s tremorous limb. PD patients were assessed on the rest position and ET and Holmes tremor on posture. EMG needle assessment as well as accelerometry was subsequently performed on a Nicolet Viking Select® and accelerometry analysis was performed in Viking Select Tremor Master Software v8.3.

Results: Average tremor frequency for PD was 4.5Hz and for TE 7.2Hz. Pearson correlation showed very strong correlation between the three applications, the EMG needle assessment and the accelerometry (Pearson >0.8, p<0.001). There was no statistically significant difference between the three aplications and the EMG.

Conclusions: Our data suggests that any of the applications tested – Liftpulse®, Studymytremor®, iSeismometer® – present a reliable and easy to use method for tremor frequency calculation and constitute a valid alternative to EMG analysis. 1. Joundi RA, Brittain JS, Jenkinson N, et al. Rapid tremor frequency assessment with the iPhone accelerometer. Parkinsonism and Related Disorders 17 (2011) 288-290. 2. Senova S, Querlioz D, Thiriez C, et al. Using the Accelerometers integrated in smartphones to evaluate essential tremor. Stereotact Funct Neurosurg 93 (2015) 94-101.

Portuguese National Neurology Society, Lisbon, 2015 (http://www.spneurologia.com/media/1849-ProgramaA5_4.pdf)

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MDS Abstracts - https://www.mdsabstracts.org/abstract/tremor-frequency-by-iphone-applications-correlation-with-emg-analysis/