Smartphone Apps Provide a Simple, Accurate Bedside Screening Tool for Orthostatic Tremor

Area of Science:

• Neurology
• Biomedical Engineering
• Medical Diagnostics

Background:

• Orthostatic Tremor (OT) presents as instability during standing, with high-frequency lower extremity tremor (13-18 Hz).
• Current diagnosis relies on surface electromyography (EMG), often requiring specialized equipment.
• A readily available clinical screening tool is needed for earlier OT detection.

Purpose of the Study:

• To assess the diagnostic accuracy of smartphone accelerometers for Orthostatic Tremor.
• To evaluate the utility of iPhone's accelerometer and specific applications as a bedside screening tool for OT.

Main Methods:

• Recordings were obtained using iPhones (Models 5, 5s, 6) with free applications: LiftPulse (App1) and iSeismometer (App2).
• Default application settings were utilized for tremor data acquisition.
• Data from 24 EMG-confirmed OT subjects and 15 age-matched controls were analyzed.

Main Results:

• App1 detected OT-range tremor in 92% of patients and 0% of controls (Specificity 100%).
• App2 detected OT-range tremor in 88% of patients and 7.7% of controls (Specificity 92%).
• Combined app usage achieved 100% sensitivity and 92% specificity in detecting OT.

Conclusions:

• Smartphone applications leveraging built-in accelerometers serve as effective bedside screening tools for OT.
• This approach offers a simple, accurate, and cost-effective method for identifying potential OT cases.
• The findings support the use of smartphone technology for earlier and more accessible OT diagnosis.