A MAN has been sentenced after pleading guilty to the manslaughter of his vulnerable grandfather in a 'violent and unprovoked attack'. Brian Cullen, 73, died two weeks after being assaulted in his Liverpool home earlier this year by his grandson, Ryan Cullen. The 34-year-old was sentenced at Liverpool Crown Court on Friday to a five-year Section 45a Hybrid Order. The ruling means he will be sent to a hospital until he is deemed fit to serve the remainder of his sentence in prison. "This is an absolutely tragic case which has devastated the family and although Ryan Cullen has today faced justice, we know that such an outcome cannot provide much comfort or healing," said Detective Chief Inspector Andy McCourt. Assault At around 5.40pm on Saturday, February 10, officers were called to an address on Midghall Street in Liverpool to reports of a domestic assault. The Liverpool Echo reports that Ryan Cullen, who had suffered with mental health issues, attacked his grandfather because he wouldn't give him money for drugs.…