Gravitational Interstellar Scintillation
  Gravitation could modulate the interstellar scintillation of pulsars in a way that is analogous to refractive interstellar scintillation (RISS). While RISS occurs when a large ionized cloud crosses the pulsar line-of-sight, gravitational interstellar scintillation (GISS) occurs when a compact gravitational deflector lies very near to that line-of-sight. However, GISS differs from RISS in at least two important respects: It has a very distinctive and highly predictible time signature, and it is non-dispersive. We find two very different astronomical contexts where GISS could cause observable diffraction-pattern distortions: Highly inclined binary pulsars, and the kind of compact interstellar clouds suspected of causing extreme scattering events. 
Redouane Al Fakir