A freedom of Information request found that there was very limited access to help for those in need once they turn 18.
Hospice-users and their families will meet with MSPs at Holyrood to stress the need for new facilities to be developed without delay.
Approximately 6,000 people in Scotland are affected by muscular dystrophy or a related neuromuscular condition.
Improved healthcare and support has meant that many children born with such life-limiting conditions now increasingly live well into adulthood.
But The Muscular Dystrophy Campaign argues that adult and respite care provision has not adapted to recognise this, and is now calling on the Scottish Government, local authorities and health boards to launch an urgent review of facilities for this “forgotten” age-group.
Respite care is the provision of temporary, short-term relief for carers who are often full-time. It also provides an opportunity for those with limiting conditions to take time away from their home and parents and socialise with other people.
Robert Watson, 28, from Renfrew has the life-limiting condition, Duchenne muscular dystrophy.
He said: “Adult hospice services are set up largely to cater for much older adults who have cancer and other terminal illnesses – they are just as unsuitable a place for young adults to go to as children’s respite centres are.
“Respite breaks are often the only type of holiday that people can go on, so to lose all the benefits that they bring would be devastating.
“For me and many other young adults in Scotland, a respite break is a chance to have time away from parents and from the isolation we can feel from being at home most of the time.
“It’s a great chance to socialise with other people the same age, who have the same or similar conditions.
“Equally as important is the break it gives our families, who are given the chance to recharge their batteries.”
The Children’s Hospice Association Scotland (CHAS) currently provides respite care for many young people, but has been forced to take the decision to cap the age of its users to 21 years old from 2017, following growing pressure on its services.
Jackie Baillie MSP, Chair of the Cross Party Group in the Scottish Parliament on Muscular Dystrophy, said: “This report by the Muscular Dystrophy Campaign highlights the critical role that respite facilities play in supporting and ensuring a good quality of life for many young people living with severe disabilities in Scotland.
“It is clear that there is a huge gap between the provision of respite and hospice facilities for children and older people, meaning young adults in Scotland do not have access to suitable provision.
“With life expectancy for conditions such as Duchenne muscular dystrophy increasing, this is an unsustainable situation.”