Sigmoid　sinus　diverticulum　(SSD)　is　a　common　pathophysiology　of　pulsatile　tinnitus　(PT)　and　mainly　treated　by　SSD　reconstruction　surgery.　The　degree　of　reconstruction　is　an　important　indicator　of　SSD　reconstruction　surgery,　but　its　impact　on　the　effect　of　SSD　reconstruction　is　unclear.　This　study　aimed　to　clarify　the　effect　of　the　degree　of　SSD　reconstruction　on　diverticulum　reconstruction　surgical　treatment.　One　patient-specific　case　(control　subject)　was　reconstructed　based　on　the　computed　tomography　angiography　(CTA)　images　of　patients　with　PT.　The　SSD　reconstruction　degree　was　used　as　a　new　index　in　this　study.　And　the　case　of　30%　(case　1),　60%　(case　2),　and　100%　(case　3)　of　the　diverticulum　reconstruction　degree　of　control　subject　were　constructed.　Transient-state　computational　fluid　dynamics　was　performed.　Wall　pressure　distribution,　wall　average　pressure　(Pavg)　of　SSD,　flow　pattern　(velocity　streamlines　and　velocity　vector),　wall　shear　stress　(WSS)　and　averaged　WSS　(WSSavg)　were　calculated　and　used　in　evaluating　the　hemodynamic　differences　among　the　DRD　cases.　Results　demonstrated　that　change　in　SSD　pressure　was　not　linear　with　increase　in　DRD.　The　DRD　that　reached　60%　of　the　original　diverticulum　was　effective.　At　the　peak　point　of　the　inlet　boundary　condition　(T1　=　0.22s),　the　Pavg　of　SSD　had　a　nonlinear　change　(control　subject,　126.967　Pa　vs.　case　1,　126.274　Pa　vs.　case　2,　106.897　Pa　vs.　case　3,　94.116　Pa).　Flow　vorticity　decreased　gradually,　and　the　smoothness　of　the　streamlines　increased　with　DRD.　WSSavg　slightly　changed　with　increasing　DRD.　The　high-speed　flow　blood　hit　the　diverticulum　entrance　and　then　swirled　to　hit　the　area　of　the　sigmoid　sinus　wall　abnormal.　It　was　concluded　that　flow　patterns　related　to　PT　differ　with　DRD.　In　diverticulum　reconstruction　surgery,　there　is　a　threshold　value,　and　only　when　the　DRD　exceeds　this　value　(60%　or　70%　or　80%),　it　will　have　a　noticeable　effect.　In　this　study,　DRD　should　at　least　reach　60%　of　the　original　diverticulum.　When　DRD　is　insufficient,　hemodynamic　change　in　the　diverticulum　is　small,　and　the　PT　may　have　remained.　SSD　may　be　caused　by　high-speed　blood　flow.　(c)　2020　IPEM.　Published　by　Elsevier　Ltd.　All　rights　reserved.