Denshi Jisho — Online Japanese dictionary

こうけい lockjaw; trismus
Noun, Obscure term 
しょけい writer's cramp
Noun 
ちんけい 1: spasmolysis;
2: (No-adjective) spasmolytic; antispasmodic; anticonvulsive
Noun 

You can also

Look up kanji details for *痙.

Try a Yahoo Jisho search for *痙 .
Try a Goo Jisho search for *痙 .
Try a Google search for *痙 .