Head CT negative. .
 History of head trauma
(ROOT (S (VP (VB Head) (S (NNP CT) (ADJP (JJ negative)) (. .))) (. .)))
(ROOT (NP (NP (NN History)) (PP (IN of) (NP (NN head) (NN trauma)))))
( ( Head ( CT ( negative . ) ) ) . )
( History ( of ( head trauma ) ) )