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Stiff Person Syndrome: Understanding a Rare Neurological Condition

Stiff Person Syndrome (SPS) is a rare, progressive autoimmune neurological disorder that causes muscle stiffness, rigidity, and painful muscle spasms. Although awareness has increased following the diagnosis of singer Céline Dion, SPS remains poorly understood and is frequently misdiagnosed.

SPS affects approximately 1–2 people per million people and is more common in women, typically developing between the ages of 30 and 60 years. The condition sits within a broader group of disorders known as Stiff Person Spectrum Disorders (SPSD), which can vary significantly in severity and presentation.

What Causes Stiff Person Syndrome?

SPS is believed to occur when the immune system mistakenly attacks parts of the nervous system responsible for controlling muscle activity.

Key features include:

  • Most commonly associated with anti-GAD65 antibodies

  • Reduced activity of GABA, an important neurotransmitter that helps regulate muscle movement

  • Continuous overactivity of muscles, resulting in stiffness and spasms

  • May be associated with other autoimmune conditions, including:

    • Type 1 Diabetes

    • Thyroid disorders

    • Pernicious anaemia

  • Rarely, SPS can occur as part of a cancer-related (paraneoplastic) syndrome

Common Signs and Symptoms

People with SPS may experience:

  • Progressive muscle stiffness and rigidity

  • Stiffness affecting the trunk and proximal limbs

  • Difficulty walking and reduced mobility

  • Painful muscle spasms that may cause falls

  • Changes in posture, including increased arching of the lower back

  • Difficulty with balance and functional activities

  • Anxiety and fear related to the unpredictability of symptoms

  • Depression and reduced participation in daily activities

Common triggers include:

  • Sudden loud noises

  • Unexpected touch

  • Emotional stress

  • Overstimulation

Diagnosis and Treatment

SPS is often difficult to diagnose because symptoms can resemble many other neurological and musculoskeletal conditions. Diagnosis is based on a combination of clinical assessment, specialised testing such as EMG, antibody testing, and investigations to rule out other causes.

While there is currently no cure, treatment aims to reduce symptoms and slow disease progression. Management may include immunotherapy treatments such as IVIg, corticosteroids, plasma exchange or rituximab, alongside medications that help reduce muscle stiffness and spasms, including baclofen and benzodiazepines.

The Role of Physiotherapy

Physiotherapy can play an important role in helping people maintain mobility, function, and quality of life.

Physiotherapy goals

  • Maintain mobility and independence

  • Reduce pain and stiffness

  • Improve safety and reduce falls risk

  • Prevent deconditioning and secondary complications

Physiotherapy interventions

  • Gentle stretching

  • Passive range of movement exercises

  • Heat therapy and hydrotherapy

  • Relaxation and breathing techniques

  • Functional mobility training

  • Transfer and stair practice

  • Individualised exercise programs

Important considerations

To minimise symptom flare-ups, physiotherapists should:

  • Identify individual triggers before treatment

  • Use slow, predictable handling techniques

  • Allow adequate rest periods

  • Monitor closely for spasm onset

  • Avoid rapid movements, high-intensity strengthening, cold therapy, and overstimulating environments

The Role of Occupational Therapy

Occupational therapists support people with SPS to remain independent and engaged in meaningful daily activities.

Interventions may include:

  • Energy conservation and pacing strategies

  • Task simplification

  • Prescription of adaptive equipment

  • Home modifications and falls prevention

  • Education regarding trigger management

  • Support for anxiety and confidence with daily activities

A Multidisciplinary Approach is Essential

Because SPS symptoms can fluctuate and affect multiple aspects of a person's life, management is most effective when delivered by a multidisciplinary team. Early diagnosis, appropriate medical treatment, and individualised rehabilitation can help people with SPS maintain function, improve safety, and maximise their quality of life.

At Physio Express, our team of neurological physiotherapists and occupational therapists work closely with clients living with complex neurological conditions to provide evidence-based, person-centred care that supports their goals and independence.

Rachel Dool