3.1 By hand
***
(Smaga, 2003)
Tests ET
No specific test; rule out other problems with general chemistry profile, CBC, and thyroid function tests
(Raethjen, et al., 2004)
"We will show that robust criteria distinguishing physiologic from early stage, low amplitude pathologic tremors can be deï¬ned, whereas quantitative measures like frequency and amplitude are very sensitive to the details of the recording condition or technique and therefore need to be normalized for each individual lab."
Current diagnosis (Smaga, 2003)
3.1.1 Scheme
Figure 4 shows a scheme for evaluating tremor
Figure 4 Algorithm for evaluating tremor (Smaga, 2003)
3.1.2 No useful comparison between limb and same contralateral limb
In clinical setting it is common practice to compare a limb affected by a movement to the asymptomatic contralateral limb (ref***). By comparing the two limbs, assumptions can be made on the behavior of the symptomatic limb before the movement disorder affected the limb, and so determine the effect of the disorder. Several studies have shown that in tremor classification this method cannot be used because the tremor in two limbs are dissimilar in people without a disorder (Findley, Gresty, & Halmaygi, 1981) (Köster, et al., 1998).
3.2 Frequency analysis
***adds objective data
***different fourier transform
To transform data from the time domain to the frequency domain the Fourier transform is used. There are several forms of Fourier transforms, but the most common is the fast Fourier transform (Grimaldi & Manto, Tremor: From Pathogenesis to Treatment, 2008).
"The combination of electromyography (EMG) with kinematic sensors is widely used" (Grimaldi & Manto, Neurological Tremor: Sensors, Signal Processing and Emerging Applications, 2010)
Method used in (Timmer, Lauk, & Deuschl, Quantitative analysis of tremor time series, 1996) is applicable to accelerometer as well as to EMG data.
3.2.1 Electromyography
Electromyography (EMG) is a technique to measure electrical muscle activity and the measurement can be performed with surface electrodes and needle electrodes. Surface electrodes are applied to the skin and are considered less invasive than needle electrodes which are inserted in the muscle.
***A skeletal muscle consists of many motor units, which are all separately innervated. If they activate asynchronous smooth movements are possible, if they activate synchronous it results in a very fast motion.***
By recording the muscle activity (***actually motor unit activity) over time, an electromyogram can be produced. There is much information which can be extracted from an electromyogram, for example the burst duration of the muscle activation. Figure 5 shows burst durations in forearm muscles for several of the discussed pathological tremors (chapter***)
Figure 5 Duration of EMG bursts in forearm muscles for several pathological tremors:
PD: Parkinson's disease, ET: essential tremor, PN:
peripheral neuropathy, OT: orthostatic tremor (Grimaldi & Manto, Neurological Tremor: Sensors, Signal Processing and Emerging Applications, 2010)
