Patients with serious brain injuries are being let down by poor care, the BBC's Newsnight programme has learned.
Secretly-filmed footage passed to Newsnight shows examples of patient neglect and ignored safety procedures.
Incidents include one healthcare worker cleaning a feeding and medicine tube with a pen nib and one patient marked as nil-by-mouth being given drinks.
NHS England told the BBC it is working to improve specialist rehabilitation for patients with such complex needs.
However, one leading expert told Newsnight that some patients were not recovering as fully as they might because of these problems with their care.
Professor Michael Barnes, a specialist in neurological rehabilitation medicine who chairs the UK Acquired Brain Injury Forum, said: "There are some very good rehabilitation centres in this country, but equally I'm afraid there are units in this country that really don't provide proper co-ordinated rehabilitation at all.
"And yet that's what they are called. And that, I think, is a sad reflection and something needs to be done about that."
Every 90 seconds someone in the UK suffers a brain injury. There can be many causes, such as a bleed to the brain, a fall, an assault - often it is the result of a road accident.
Following an injury of this sort, the brain has to rebuild pathways to allow the person who has suffered the injury to re-learn the things they once took for granted, and that is why specialist rehabilitation and good care are so vital.
Grant Clarke had a massive brain haemorrhage last year, at the age of 43. He was left severely disabled, but during 12 weeks in hospital he made steady progress.
His family believed with the right help he would be home within four months.
But they say his recovery was undermined by poor care and a lack of appropriate rehabilitation when he was transferred to the West Kent Neuro-rehabilitation Unit in Sevenoaks.
"He didn't have his teeth brushed," Mr Clarke's partner Binny told us.
"He didn't have his armpits washed. He was left in urine, all the time. Every time I went to see him he was wet to his armpits, and cold."
After raising her concerns on a number of occasions she decided to take the extreme action of installing a secret camera in his room. She was shocked by the footage it recorded.
Mr Clarke's injuries had left him unable to swallow, and so a tube was inserted to bring food, liquids and medication straight to his stomach.
The tube had to be cleaned with care to avoid infection, but the secret filming shows a healthcare worker cleaning the top of it with the nib of a pen.
Despite him being nil-by-mouth, another healthcare assistant was seen giving Mr Clarke drinks of water five times over two nights.
And though he can barely speak, his call bell was removed three times in 10 days.
Binny later discovered that only one of the nursing staff at the unit had training in brain injuries, even though it was described as a specialist unit.
Following a complaint made by the family the healthcare worker who gave Grant the drinks was interviewed by police, but they decided not to take action against him.
The worker gave a letter to the police in which he expressed his regret for his actions. He no longer works for the West Kent Neuro-rehabilitation Unit.
Mr Clarke's family made 26 complaints to the Kent and Medway NHS and Social Care Partnership Trust. Most were upheld - including the removal of the call bell and the use of a pen to clean the top of Mr Clarke's feeding tube.
In a statement to BBC Newsnight the Trust said: "We remain appalled by what happened."
It continues: "We subsequently created a robust action plan to address all concerns," and adds that compulsory, specialist training for all staff has now been introduced.
Failings in basic care
Mr Clarke, who is now in another rehabilitation unit that is providing him with the care and support he needs, is making progress and starting to spend time at home with his family.
But concerns of a similar nature have been raised by the family of Mark Courtney.
He had a severe asthma attack in March 2007 that left him severely brain damaged. His family say they have experienced failings in basic care ever since.
"He has been in four different placements in the last six-and-a-half-years and I have found that not any of the placements are ideal," his wife Chammelle told BBC Newsnight.
Mrs Courtney's concerns about her husband's care include unexplained cuts and bruises, medication errors and a failure to position him correctly.
She believes patients in all of the facilities where he has been treated are at serious risk of harm.
Professor Michael Barnes says that investment in brain injury rehabilitation could save the state money in the longer term.
"There is good evidence that although rehabilitation costs more money clearly than someone going home, or going to a nursing home, that money is recouped over two to three years by that person requiring less support from the state, getting back to work and earning money."
Dr John Etherington is the National Clinical Director for Rehabilitation and Recovering in the Community at NHS England.
He told BBC Newsnight: "This role bolsters a number of initiatives already underway which will start to enhance provision. These include the establishment of a Clinical Reference Group to examine the commissioning of specialised rehabilitation services, the development of regional trauma networks to review services - which has already led to service improvements - and a review of funding for long term conditions which is underway through the 'Year of Care' initiative that will enable a more flexible and patient centred distribution of funding.
"We have also for the first time, put in place a national specification for specialised rehabilitation to combat variation in services and ensure more equitable access across the country. This work is vital to improving outcomes for patients."