求翻译：常为PD首发症状，少数患者尤其70岁以上发病者可不出现震颤。其机制是受累肌群与拮抗肌群规律性、交替性不协调活动所致。是什么意思？

Often the first symptom of PD, a small number of patients, especially those over 70 years the incidence of tremor may occur. The mechanism involved muscles and antagonistic muscles is regularity, alternating due to uncoordinated activities.

Often the first symptoms PD a few patients, especially those over 70 years of age without a tremor onset. Its Mechanism is mistreated, and antagonist muscle groups, alternating pattern of coordination activities not.

Often is the PD first round symptom, above the minority patient 70 years old the morbidity may not appear especially trembles.Its mechanism is exhausts oneself the myo- group with to oppress the anti-myo- group regularity, not coordinated to move the result in turn.

PD often the first symptom, a small number of patients over 70 years of onset tremor may not appear. Its mechanism is involved muscle groups and antagonistic muscles, turn due to uncoordinated activities of the law.

Often firsting publish symptom for PD, a few patients, especially persons who have illness coming on do not tremble over 70. Its mechanism is given much trouble the skin group and resists a group of regularity of skin, replaces due to incongruous activity of the sex short of moneyly.