How can fear cause un-intended urination althought sympathetic ns cause urine retention ?

Sympathetic Overload: After an overwhelming sympathetic stimulation occurs (horrific fear), the sympathetic portion may shut down temporarily. The unopposed parasympathetic system, in concert with loss of sympathetic tone, can then cause contraction of the bladder wall with relaxation of the urinary sphincter. Thus, increased sympathetic tone from meds e.g. Sudafed, can cause retention inversely to the above.