There were failings in the care and treatment given to a man with severe learning difficulties who broke his neck in a fall at a residential home, an inquest jury has concluded.

Heddwyn Hughes, 67, was living at the Bro Myrddin residential unit in Carmarthen, west Wales, when he fell in May 2015 but his broken neck was not diagnosed until 10 days later. He died in October 2015.

Recording a narrative verdict, the jury at Milford Haven town hall said it believed Hughes suffered the injury in his bedroom after returning from the bathroom.

Asked whether he received appropriate care and treatment on 6 May 2015, the jury said: “We believe staff followed the set protocol, but we think the protocol is inadequate and needs to be reviewed as we believe this is what failed Mr Hughes.”

It added that health board staff did not respond appropriately or with sufficient urgency and said communication between the care home staff and a GP was not adequate.

During the three-day inquest the jury heard that Hughes began having seizures when he was about 10 months old. He had poor communication skills and spoke few words but communicated with staff by smiling or slapping the table or his legs. He could feed himself and “shuffle” around the home.

A doctor who visited Hughes after the fall told the inquest he had not been told that Hughes had fallen and believed he had had a stroke. Hughes was taken to the Glangwili general hospital, but his neck break was not diagnosed until more than a week later.

In a statement, his family said: “Heddwyn was particularly fond of music and, even after his injury, he would greet us with that lovely smile of his, unaware of the gravity of his situation. It has been a long three years since Heddwyn’s death.”

Hughes needed full-time care and was detained under a deprivation of liberty safeguard (DOL), which is designed to protect the rights of people judged to need to be held in a hospital or care home in England and Wales.

The inquest heard that on the day of the fall, Hughes suddenly lost the use of all four of his limbs after collapsing to the floor while being lifted by staff.

It took around four hours for him to be seen by a medical professional. A spinal expert told the jury that Hughes was likely to have become quadriplegic at the point of injury.

Hughes’s sister, Moelwen Gwyndaf, said: “At the centre of all this is my brother, Heddwyn, who was much loved and whose life required so much support. His legacy will be that other such vulnerable adults in the care of the state and who cannot say what has happened to them will have protocols and procedures in place that will ensure their safety and care. I would like to thank the coroner and jury for their thorough investigation.”

Clare Richardson, of the law firm Deighton Pierce Glynn, who represented the family, said: “This conclusion is the result of three years of remarkable courage and determination by Heddwyn’s family who have overcome significant obstacles in their search for the truth.”

Deborah Coles, the director of the charity Inquest, said: “This inquest has identified an insufficient and inappropriate response by healthcare staff to Heddwyn. These failures are all too familiar in the cases of people with learning disabilities, whose premature deaths are endemic in our health and care systems. More must be done to ensure there are sufficient and caring homes for those who need them, and society is better equipped to appropriately support people with learning disabilities.”

Dr Warren Lloyd, the associate medical director and clinical director for mental health and learning disabilities services at Hywel Dda University health board, said: “We wish to offer our sincere condolences to Mr Hughes’s family for their loss.

“The health board accepts the inquest findings and we wish to reassure Mr Hughes’s family that we have taken this matter extremely seriously. We have undertaken significant work over the past three years to improve our compliance with expected standards and a protocol issued to staff will be further developed in consultation with Mr Hughes’s family following the conclusion of the inquest verdict and recommendations.

“The health board continues to invest in improving awareness of the needs of patients with a learning disability and have recently recruited dedicated nursing support to provide advice and assistance in understanding the needs of people with a learning disability, who may be under the care of our general hospital wards and community settings.”

Following the death of her son 18-year-old son, Oliver McGowan, Paula McGowan set up a petition to parliament calling for training in autism and learning disability to be made mandatory for staff in healthcare settings. The petition, which has more than 51,000 signatures, will be debated in parliament on Monday.