Old Lady Myrtle  is the ghost of a senior citizen who haunted a care home and called out for her son.
Old Lady Myrtle spent her last years of life at the Arbutus Place Rest Home in Massapequa, Long Island. She waited for her son Alexander to visit and play cribbage with her but died before that happened. About a week after the Ghostbusters' case in Schenectady, the ghost of Myrtle manifested at the rest home. A little after 11:44 am, Egon Spengler and Winston Zeddemore made contact with her in the western wing. Once Egon informed Myrtle her son wasn't present, she went into an agitated state and her spectral construct Dinah the Cat attacked the duo. As Egon and Winston struggled to keep Dinah confined, Ray Stantz and Peter Venkman trapped Myrtle.
Old Lady Myrtle was able manifest a spectral construct and was stronger than normal due to the increased ambient P.K.E. in the Tri-State Area.
Old Lady Myrtle, under normal circumstances, was quite passive and a lesser manifestation. But due to the ambient P.K.E., she was much stronger.