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Amplitude/frequency characteristics of postural hand tremor in 59 patients with bilateral essential tremor of various degrees of severity were assessed using accelerometric recordings and spectral analysis. Intra-subject comparisons of tremor characteristics between the more and less affected hands were used to control for variability of tremor due to age factors and intersubject differences in amplitude and frequency. Statistical analysis distinguished three different patient groups. Some patients had low amplitude (less than 0.1-0.015 cm) tremor in the less affected limb (which tended to be 7 Hz or more in frequency in the young) and a larger amplitude tremor in the more affected hand which was 1 Hz or more lower in frequency. Other subjects had either bilaterally small or bilaterally large amplitude tremors of similar frequencies. These findings imply that there is a downwards step in frequency between symptomatic tremors of small and large amplitude. The amplitude and frequency of the small amplitude tremors were unrelated but frequency declined with age. The frequency of the large amplitude tremor was generally determined by amplitude but a wide range of amplitudes were compatible with similar frequencies. The frequency of large amplitude tremor also declined with age. It was concluded that there are two types of essential tremor, the smaller amplitude tremor probably derives from an exaggeration of some or all of the mechanisms of normal physiological tremor whereas the larger amplitude tremor probably arises from a separate "pathological" central nervous mechanism. It is not known if or how one may transform into, or be replaced by, the other during progression of the disease. [ABSTRACT FROM AUTHOR]

The supine and erect arterial blood pressure and pulse rate were measured in 13 patients with Parkinson's disease, chronically treated with levodopa and peripheral decarboxilase inhibitors presenting with or without On-Off phenomenon (end-of-dose akinesia). In the patients with dose-related response fluctuations the mean systo-diastolic blood pressure, both supine and erect, was found significantly higher during the Off phase as compared to the On phase and to that of the control group (patients with stable clinical response). The mean diurnal "excursion" of systo-diastolic supine and erect blood pressure in patients with On-Off phenomenon was significantly larger than in the control group. Although the clinical implications of such findings remain to be established, the results of this study indicate that arterial blood pressure fluctuations are a definite autonomic component of end-of-dose akinesia. [ABSTRACT FROM AUTHOR]