Celine Dion’s sister has given an update on the singer's health, following her diagnosis with the rare neurological disease Stiff Person Syndrome (SPS).

Dion, 55, first shared she was living with the condition in December 2022, after having to reschedule and cancel some of her tour dates.

In a new interview, her sibling, Claudette Dion, 74, has shared a little more about the condition, praising the singer as a "strong woman" and reassuring fans she is "doing everything" she can to get better.

"It’s an illness we know so little about," she told Hello! Canada. "There are spasms – they’re impossible to control. You know who people often jump up in the night because of a cramp in the leg or the calf? It's a bit like that, but in all muscles. There's little we can do to support her, to alleviate her pain."

Read more: Celine Dion’s sister says there’s ‘little’ family can do to ‘alleviate her pain’ amid stiff person syndrome (Independent, 2-min read)

Watch: Celine Dion cancels tour due to incurable 'Stiff Person Syndrome'

When sharing her SPS diagnosis last year, Dion said it caused her spasms "affecting every aspect" of her daily life, sometimes including difficulty when she walks, and not allowing her to use her vocal cords how she's used to.

The star said she has a "great team of doctors" supporting her, as well as her children giving her hope, and a sports therapist to help her build back strength and boost her ability to perform again.

What is Stiff Person Syndrome (SPS)?

SPS is an extremely rare condition that affects the brain and nervous system and has features of an autoimmune disease, according to the National Institute of Health (NIH).

According to The Brain Charity it affects the brain and spinal cord and is defined by muscle stiffness, rigidity and body spasms which can be brought on through a heightened sensitivity to stimuli such as sudden noise or light.

Experts say the condition is associated with diseases like diabetes, thyroiditis, vitiligo and pernicious anaemia, and is often misdiagnosed as Parkinson's disease, multiple sclerosis, fibromyalgia, psychosomatic illness, or anxiety and phobia.

Patient.info says a doctor is able to confirm SPS through a blood test that checks for associated antibodies, electromyography (EMG) that tests muscle activity, and a spinal tap that looks for antibodies in your spine.

How common is SPS?

The rare neurological condition is believed to affect just one to two in every one million people. It affects twice as many women as men and those aged between 30 and 60 years of age, although it can also affect children and the elderly.

What causes SPS?

While the cause of SPS is still unknown, research suggests it may be due to an abnormal autoimmune response in the brain and spinal cord.

It is thought symptoms may be brought on by a heightened sensitivity to stimuli such as sudden noise or light.

SPS signs and symptoms

According to The Brain Charity SPS can be characterised by:

• Stiff and rigid muscles

• Muscle and body spasms

• Slouched posture

• Weight loss

Some people with SPS can be too debilitated to walk or move, and may feel scared to leave the house because street noises can trigger spasms and falls.

SPS treatment

Stiff Person Syndrome is a chronic condition, which means there is no cure. However, treatment may help to ease symptoms, improve quality of life and slow progression. It could also help to reduce the risk of experiencing other health complications.

Treatment strategies, according to Patient.info, include symptom management and disease-modifying treatment.

Certain medications could help to soothe painful muscle spasms and relax muscle stiffness. Diazepam is often used for the condition because it can help alter awry signals sent between the brain and muscles.

Muscle relaxants may also work by loosening muscles, which can help treat both muscle stiffness and spasms.

Several therapies, including physiotherapy, heat therapy, acupuncture, massage and hydrotherapy could also help to continue with everyday activities.

A recent study funded by the National Institute of National Institute of Neurological Disorders and Stroke (NINDS) demonstrated the effectiveness of intravenous immunoglobulin (antibodies produced by the body’s immune system) in reducing stiffness and lowering sensitivity to noise, touch and stress.

These types of medicines, along with pain relievers, are thought to improve SPS symptoms, but won't entirely cure the disorder. But while many people with SPS can have frequent falls, leading to severe injuries, symptoms can be well controlled with the appropriate treatment.

Speak to your GP if you have signs of SPS, and visit the Genetic Alliance for information on other support available.