Section 12. Nonschedule adjustments

Notwithstanding any other provision of
  this chapter, in any case coming within the provisions of  sections  ten
  and  eleven  of  this  article,  in which the right to benefits has been
  established and benefits have been paid for not less than three  months,
  in  which  the  continuance  of  disability  cannot  be ascertained with
  reasonable certainty,  the  workers'  compensation  board  may,  in  the
  interest  of justice, approve a nonschedule adjustment agreed to between
  the claimant and the political subdivision liable  for  the  payment  of
  benefits  or its insurance carrier. The provisions of subdivision five-b
  of section fifteen of the workers' compensation law shall apply  in  any
  such case.