The acronym BIH can mean dozens of things. Ball in hand (billiards), benign intracranial hypertension and bringing it home, to name a few.

these are misnomers actually,when there is no evident cause of hypertension then it is called idiopathic/benign/primary/unspecified hypertension.

http://treathypertension.blogspot.com/

It is abnormally high blood pressure within the skull

A fairly common, usually benign class of intracranial tumor affecting the meninges

Benign Nephrosclerosis