Neurophysiological bases of tremors and accelerometric parameters analysis

Physiologic tremor is causedby three different generators with two frequency peaks that act together. A mechanical-reflex slower oscillator, that resemble the viscoelastic properties of muscle-joint complex and a faster oscillator that is the compound of loop reflex-composed by the spinal loop and supraspinal reflex loop and central neurogenic oscillator. Central neurogenic tremors seem to be generated by nerve networks in the Central Nervous System (i.e. cortico-basal ganglia-cortical loops/olivocerebellar pathways). Such disorders are mainly represented by Essential tremor and Parkinson's tremor and are characterized by a frequency independent of reflex loop time, joint inertia, and joint stiffness. Even if tremor can be easily characterized describing its frequency, amplitude and relation with muscle, rest or activity, an universal method for movement disorder diagnosis and follow-up of the symptom is still missing. Among the technological tools for tremor analysis triaxial accelerometer are able to offer low invasiveness and high reliability. This paper introduces the neurophysiological substrate of tremor and offers a proof of concept of tremor evaluation for diagnostic support and drug-efficacy in Parkinsonian and subjects affected by essential tremor. It is achieved through a self-assembled wireless, low cost and wearable device, designed for operating in patient ecological environment.