Create table x (a varchar2(4000)); 
Insert into x values ('CT head neg (-) Pt reportedly has 20-39% stenosis of carotid arteries. EKG NSR@70bpm, Trop (-) x2 Unlikely to be cardiac in etiology. Likely ');       
Insert into x values ('Midbrain lacunar CVA+L 40-59% carotid stenosis+TIA 6/2010 (finished Stein sr center outpt PT+pt reports improving word finding.  Did reschedule fu  outpt PT');
Insert into x values ('Repeat Carotid Dopplers 12/12: <20% stenosis b/l at the bifurcation  TTE 10/2014: EF 49%  TEE: 12/15 EF 35% and fibroelastic lesion of the aortic valve  EEG');

CREATE  /*+ parallel(x 32) */    index x_idx on  x (a) indextype
        is ctxsys.context parameters ('stoplist ctxsys.empty_stoplist')
        parallel 32 
       

20-39%
40-59%
<20%
 

Select  --+ parallel(t 32)
  a 
  from   x
 where contains(a, 'near((stenosis,carotid={%}), 5)') > 0