Although cells firing at tremor frequency, called "tremor cells" (Guiot et al., 1962), have often been recorded in the thalamus of parkinsonian patients, the extent of correlation between these spike trains and tremor has rarely been assessed quantitatively. This paper describes spectral cross-correlation functions calculated between the activity of "tremor cells" and electromyogram (EMG) signa...

BACKGROUND Resting tremor is common in Parkinson's disease (PD), but up to 47% of PD patients have action tremor, which is sometimes resistant to medications. Deep brain stimulation (DBS) of the ventral intermediate nucleus (VIM) of the thalamus or subthalamic nucleus (STN) is effective for medication-refractory tremor in PD, though it remains unclear whether STN DBS is as effective as VIM DBS ...

See Vidailhet et al. (doi:10.1093/brain/awx140) for a scientific commentary on this article.Misdiagnosis among tremor syndromes is common, and can impact on both clinical care and research. To date no validated neurophysiological technique is available that has proven to have good classification performance, and the diagnostic gold standard is the clinical evaluation made by a movement disorder...

The effect of changes in mechanical limb properties on the peak frequency of different tremor forms was analysed. Wrist tremor was recorded by an accelerometer fixed to the dorsum of the hand and demodulated surface EMG was recorded from the wrist extensors, while the extended hand was loaded with successively heavier weights. Physiological tremor was characterised by flat EMG spectra and a gra...

Postural tremor occurs when the affected body part maintains position against gravity (e.g., extending arms in front of body). Isometric tremor results from muscle contraction against stationary objects (e.g., squeezing the examiner’s fingers). Kinetic tremor, which occurs with voluntary movement, is either simple kinetic tremor or intention tremor. Simple kinetic tremor is associated with move...

Classic essential tremor is a clinical syndrome of action tremor in the upper limbs (at least 95 % of patients) and less commonly the head, face/jaw, voice, tongue, trunk, and lower limbs, in the absence of other neurologic signs. However, the longstanding notion that essential tremor is a monosymptomatic tremor disorder is being challenged by a growing literature describing associated disturba...

The speed of the ankle jerk and physiological finger tremor in patients with thyrotoxicosis and myxoedema have been compared with those in age-matched control subjects. Tremor amplitude depends on the speed of muscle contraction; the faster muscle contracts the greater is the amplitude of tremor, and vice versa. The frequency of the dominant tremor peak is not affected by the speed of contracti...

Physiological tremor is inherent in all humans. During surgeries accuracy of the hand held instrument also varies due to surgeons hand tremor and it and reduces surgeons capability to accurately manipulate instrument. This may cause irreversible damages to the small and delicate organs. Thus active cancellation of this tremor will improve manipulation accuracy in surgeries. In this paper we pro...

Adrenergic beta-receptor sensitivity of six male patients with essential tremor and six age-matched normal controls was assessed by measuring the response in the heart rate and postural tremor to incremental injections of the adrenergic beta-agonist isoprenaline. The relative increase in heart rate and tremor in essential tremor patients did not differ from that in normal controls. It is conclu...

Electrical stimulation via skin electrodes placed over human tendons results in a reflex inhibition of voluntary activity in the stimulated muscle, probably due to activation of Golgi tendon organ afferents. The characteristics of this response in the extensor digitorum communis (EDC) muscles of subjects with Parkinson's disease were compared with those in age-matched controls. The threshold of...