The start of this year I lost my mum, Joan Stephenson, to a little-known, cruel and rare degenerative condition.

Despite many years as a journalist writing health stories I had never heard of the neurological disease that took her life — Progressive Supranuclear Palsy (PSP) — and even those in my family with a medical background were in the dark.

After the condition was diagnosed, by Huddersfield consultant neurologist Dr Badr Dafalla, we did what most people do today and went home to Google it. We learned that around 4,000 people in the UK are known to be living with the condition at any one time — although neurologists think the real figure might be more like 10,000.

What we also discovered was that PSP is caused by the destruction of brain cells, leading to a loss of speech, movement and even the ability to eat and drink. There is no cure and no treatment. And it’s thought the condition often goes undiagnosed or misdiagnosed, as some of the symptoms are similar to those of MS, Parkinson’s, stroke or a brain tumour. No-one has yet pinpointed the cause.

The comedian Dudley Moore died from PSP in 2002 at the age of 67.

In the two years following my mum’s diagnosis I often repeated this fact when asked about her condition. I felt that even if the disease was largely unknown, there was a chance that someone might remember a celebrity sufferer. It was not long before I discovered that even most health professionals knew little about PSP.

In some ways my mum was fortunate in developing the symptoms relatively late in life. She was into her eighties by the time it became clear something was wrong.

Her speech was slowing down and she was becoming unsteady on her feet. In hindsight there were other, more bizarre, signs such as inappropriate laughing, tiny handwriting and being unable to look upwards or downwards.

Unfortunately, because she suffered a suspected mini stroke while on holiday in Torquay the symptoms were put down to that. But instead of slowly improving, as many stroke patients do, she found she was getting, in her own words, “slower and slower.”

As the condition progressed, I contacted Kirklees Gateway to Care and asked how we could set up a care package. She got a Carephone, was allocated a social worker, a community physiotherapist and carers. We found a cleaner, a trusted family friend, and neighbours were alerted to her vulnerability. Bit by bit, I adopted the role of a carer.

We also joined the PSP Association (www.pspassociation.org.uk) and my mum was sent a booklet that explained how the condition would affect her. I got power of attorney over her affairs for when she eventually lost the ability to manage her financial affairs.

There is no doubt in my mind that while the PSP robbed my mum of her physical faculties, she retained her mental faculties until the end. Because of this we hid many of the unpleasant truths of the condition from her. She only knew what she could read in the PSP booklet, which has been carefully worded to avoid alarming sufferers.

One afternoon, while she was still able to talk, I broached the question of what kind of care she would want at the end of life. This is not the sort of conversation anyone wants to have with a parent, but it was becoming clear we needed to know.

Did she, for example, want to have a PEG (percutaneous endoscopic gastrostomy) feeding tube that would deliver food and fluids directly to her stomach when she lost the ability to swallow? And would she want to have heroic life-saving measures should she have a heart attack or suffer from an infection?

Her answer to both questions was ‘no’, but, as we were to discover later on, it was not that simple.

By this time last year my mum was having repeated falls at home and paramedic teams were becoming regular visitors. The Kirkwood Hospice palliative care team and a district nurse became involved in her care. If nothing else, I was learning to navigate my way around the caring services, which, thankfully, still exist.

But, finally, in May 2014 my brother and I made the decision that our mum needed residential nursing care.

She asked for a PEG to be fitted because her ability to swallow had diminished and she was continually hungry. Two months after the operation she became unable to do anything but lie in bed, propped up with pillows, a morphine driver attached to her thigh.

My mum, Joan Stephenson, Carephone user with her pendant

She suffered repeated chest infections, due to aspiration pneumonia and was brought back from the brink with antibiotics on two occasions.

The doctors who saw her thought it would be unethical to deny such treatment. At the time of her death on January 10 my mum could not speak and had been unable to keep down any food for eight weeks (the PEG was no longer of use). She literally starved to death. During this period she remained conscious much of the time because her body grew accustomed to the morphine.

In those last weeks we visited her day after day, willing her to pass peacefully away in her sleep. But her strong heart kept on pumping, while her body withered away in front of our eyes.

In years gone by I’m sure that doctors would have helped her on her way. But modern medical science kept her alive beyond the point when she had any quality of life — a matter that will grieve me and my family for the rest of our own days. And, as life expectancy increases into the 21st century, more and more of us may face an end of life that resembles hers. It is an ethical problem that needs to be addressed because, having witnessed such a death, I do not want this for myself or any more of my loved ones — but I am powerless to prevent it.

The manner of my mum’s passing caused us to think long and hard about the much-debated question of assisted suicide.

The high profile case of West Yorkshire woman Debbie Purdy, A Dignity in Dying campaigner and MS sufferer who died a few months ago, was just one of many people who have spoken out for greater choice at the end of life.

She said she felt she had no option but to starve herself to death as she could not afford to visit Dignitas in Switzerland. Like her, I’m now of the opinion that some carefully-crafted legislation — by politicians with empathy — is long overdue.

Around 30 people from the UK each year travel to the assisted-dying clinic Dignitas in Switzerland, which represents one in five of the total numbers. Reginald Crew, 74, who had motor neurone disease, became the first Briton to kill himself at the clinic back in 2003.