Period of onset in tetanus refers to the time between
First injury to spasm
First symptom to spasm
First spasm to death
Trismus to laryngeal spasm
The interval between first symptom(dysphagia and stiffiness of jaw) to a reflex spasm is called period of onset. If this is less than 48hours,the prognosis is poor and if more than 48hours,prognosis is better. Ref:Manipal manual of surgery,4th edition,pg
General surgery