Progressive Spinal Muscular Atrophy (PSMA)

Progressive Spinal Muscular Atrophy (PSMA) is a neuromuscular disorder affecting the peripheral nervous system. It leads to the insufficient or complete loss of muscle function. PSMA is a progressive condition, meaning patients deteriorate over time, though the rate of progression varies and cannot be predicted with certainty.

Prevalence

There are approximately 100 to 200 people with PSMA in the Netherlands. The cause of PSMA is unknown. While it is generally not hereditary, genetic factors may play a role in certain forms of the disease.

Breakdown of the Name:

• Progressive: The disease worsens over time.
• Spinal: Involves the spinal cord.
• Muscular: Affects the muscles.
• Atrophy: Refers to the thinning or wasting away of tissue.

PSMA, therefore, describes the progressive thinning of muscle tissue caused by damage to the nerve pathways in the spinal cord.

Disease Course

Patients with PSMA experience increasing muscle weakness, making walking and movement progressively more difficult. In advanced stages, nearly all muscles in the arms and legs may be affected, leading to significant paralysis.

PSMA shares many symptoms with ALS, such as:

• Fasciculations (small muscle twitches under the skin)
• Respiratory difficulties caused by weakness of the breathing muscles

However, unlike ALS, PSMA does not involve spasticity. Sensory nerves also remain unaffected, similar to ALS.

PSMA can present in two forms:

1. Slowly Progressive PSMA:
   • Characterized by a more stable disease progression over months or years, as observed through neurological examinations and lung function tests.
   • Patients may eventually become severely paralyzed, but the progression is slower.
2. Rapidly Progressive PSMA:
   • Deterioration occurs faster, and in some cases, PSMA may transition into ALS after months or years.

Treatment

Patients are referred by a neurologist to a specialized care team experienced in PLS, ALS, and PSMA, typically located in a nearby rehabilitation center. This multidisciplinary team includes:

• A rehabilitation physician
• An occupational therapist
• A physical therapist
• A speech therapist
• A dietitian
• A social worker

This approach ensures comprehensive care tailored to the patient’s evolving needs.

Key Takeaways:

• PSMA primarily causes progressive muscle weakness and paralysis.
• It can resemble ALS in symptoms but lacks spasticity and involves intact sensory nerves.
• A multidisciplinary care team is essential for managing the condition effectively.
• The disease progression varies significantly between individuals, with some experiencing a slower decline and others a more rapid progression.