All are true about chronic SDH except:

Chronic SDH Caused bysignificant trauma, can present weeks after tril injury. Most patients are symptomatic but patient can be completely asymptomatic. Treated by burr hole/craniotomy, twist drill craniostomy with subdural drains. Clinical improvement occurs when subdural pressure is close to zero, which usually occurs after almost 20 percent of the collection has been removed. Residual subdural fluid collections are common and may take upto 6 months for complete resolution. Use of a subdural drain is associated with a decreased need for repeat surgery