Physical Examination to Diagnose and Monitor Progression

Spinal muscular atrophy (SMA) must be diagnosed with a genetic test. Before suspecting SMA, doctors often use physical exams to help distinguish it from other similar neuromuscular disorders.

A diverse team of doctors will also perform regular physical tests to monitor the progression of SMA. This team includes experts in breathing, motor function, and nutrition. Doctors will use tests to determine how to treat or manage symptoms.

What exams are used to diagnose SMA?

Once doctors suspect SMA, people can be easily diagnosed using a genetic test. However, families often experience delays in diagnosis. This is because SMA is one of many neuromuscular conditions with similar symptoms. People may undergo many tests and referrals as doctors come to an SMA diagnosis.1

The combination of symptoms and age when they begin helps doctors narrow down the diagnosis. Many neuromuscular conditions show low muscle mass and weakness. Physical signs that help distinguish SMA from other similar conditions include:1

  • Abnormal breathing and heart rate
  • Tongue twitches
  • Absent reflexes
  • Weak cry and cough
  • Bell-shaped chest
  • Slow feeding and swallowing problems

Doctors may also perform physical exams for other conditions to rule them out. Signs of other disorders that are not present in SMA include:1

  • Eye muscle weakness. This is a possible sign of congenital muscular dystrophies and congenital myasthenic syndromes.
  • High “creatine kinase” levels in the blood indicating muscle damage. This is a potential sign of Duchenne muscular dystrophy.
  • Involvement of other organs, such as the heart. This is a potential sign of Pompe disease.

What exams are done to monitor the progression?

A diverse team will use many different physical exams to monitor the progression of SMA. This team is often led by a pediatric neurologist. It will also include other specialists who can evaluate motor, breathing, and nutritional status.2,3

The tests they perform depend on the type and severity of SMA. People with more severe types of SMA may need to be monitored more often. However, every person with SMA is different and requires a custom set of routine tests.2,3

For example, orthopedic doctors are specialists in skeletal conditions. They can perform tests for joint and motor function and suggest physical therapy interventions. Some tests for skeletal and motor function include:2

  • Measuring spine curvature to diagnose scoliosis
  • Measuring range of motion to diagnose joint contractures
  • Checking tolerance for sitting or other postures
  • Tests for hip dislocation and chest and foot deformities
  • Assessing muscle weakness using antigravity movements or strength tests
  • Assessing movement on functional scales (such as CHOP INTEND in type 1 SMA)
  • Checking mobility with timed tests and measures of endurance

Nutritionists may also be involved in the care of SMA. They can monitor nutrient intake and suggest diets to fix deficiencies. Some nutritional tests include:2

  • Videofluoroscopic swallowing studies to diagnose aspiration or swallowing problems
  • Checking height, weight, and bone density
  • Analyzing nutritional quality of foods
  • Monitoring vitamin D levels and glucose metabolism

Pulmonologists will also be part of the team managing SMA. These are doctors who specialize in lung conditions. They will perform tests for lung function and suggest ways to support breathing. Some pulmonary tests include:3

  • Pulse oximetry and other tests for shallow or slow breathing
  • Sleep study recordings to monitor sleep disordered breathing or respiratory failure
  • Tests for cough function
  • Spirometry to assess how well lungs inhale and exhale
  • Checking acid reflux

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Written by: Matt Zajac | Last reviewed: August 2021