"Thermoregulation-dependent component" in pathophysiology of motor disorders in Parkinson's disease?

Parkinson's disease (PD) is a neurodegenerative disorder characterised by motor symptoms (resting tremor, brady- or akinesia and muscle rigidity), and also by postural problems gait disorder and fatigue as well as behavioural and autonomic symptoms, including thermoregulatory impairment. These symptoms are strikingly similar with some motor phenomena, evoked by the whole body cooling, though the primary cause of PD and cold-induced symptoms are apparently different. The review is focused on the hypothesis that thermoregulatory mechanisms are involved in pathophysiology of motor disorders in PD.

Force control of isometric elbow flexion with visual feedback in cold with and without shivering.

Background: Exposure to cold impairs manual performance through effects on muscle tissue and control mechanisms. The purpose of this study was to assess the influence of increased muscle tone and shivering on ability to maintain required force during isometric flexion over a wide range of effort levels.

Methods: Lightly clad male subjects (n = 6) were exposed to thermoneutral air (TN, 27 degrees C) for 30 min, or to cold air (CA, 10 degrees C) for 30 min followed by a cold drink (1 L, 8 degrees C) to cause vigorous shivering (SH).

Influence of cold shivering on fine motor control in the upper limb.

The aim of the investigation was to determine the effects of cold shivering on the accuracy of force output in distal, middle and proximal muscles of the upper limb. Test of hand grip strength, elbow flexion and shoulder flexion (each done at 10% maximal voluntary contraction for 15 s) were done under three conditions: (1) thermoneutral air (27 degrees C), a condition of thermal comfort; (2) cold air (10 degrees C), a condition eliciting an increase in tonic muscle activity; (3) and cold air (10 degrees C) with a cold drink (8 degrees C), a condition that causes visible shivering. The averaged (root mean square) electromyogram (AEMG) and mean power frequency (MPF) were measured from proximal, middle and distal arm muscles during the tests and compared.

Influence of cold and hot conditions on postactivation in human skeletal muscles.

The influence of cold (+5 degrees C), room temperature (+22 degrees C) and hot (+75 degrees C) air exposures on postactivation effects (PAE) in brachial biceps (BBs) and triceps (TBs) muscles were investigated bilaterally in six male subjects. PAE were evoked by 1 min volitional isometric contraction (VIC) at submaximal level in BBs by holding an inertial weight by palms, with right-angled elbows. At room temperature, average EMG during PAE (PAEav) usually was 2-4% and the integral of EMG (PAEint) was 3-7% of that of VIC respectively.

Head and body positions affect thermoregulatory tonus in deltoid muscles.

Electromyograms (EMGs) were recorded from both deltoid muscles (DMs) when subjects were sitting, standing, and bending the head laterally at different cold sensations to clarify the role of head and body positions in the thermoregulatory tonus. At room temperature (22 degrees C), neither EMG related to thermoregulatory muscle tonus (TMT) nor were changes in EMG intensity observed during changes in posture. At a cold temperature (5 degrees C), when the subjects felt slightly cold or cold, the averaged surface EMG intensity of TMT was approximately 2-3 microV during sitting with the head held upright.