Spinal and Bulbar Muscular Atrophy


Spinal and bulbar muscular atrophy, also known as Kennedy disease, is caused by a mutation in the androgen receptor (AR) gene on the X-chromosome and affects the nervous system. Spinal and bulbar muscular atrophy symptoms include weakness of facial muscles, hormonal dysfunction and limb weakness.

The disease mainly affects males and impacts the body’s ability to use and transport androgens (male hormones). Women, having two X-chromosomes, are usually only carriers. When diagnosed, however, women experience milder symptoms, which may be due to having lower amounts of androgens. The symptoms usually present during adulthood, ranging from age 20 to 50.


  • Difficulty swallowing
  • Enlarged breasts
  • Facial weakness
  • Infertility
  • Muscle weakness/cramps
  • Testicle atrophy
  • Twitching


Because it is an inherited condition, spinal and bulbar muscular atrophy cannot be prevented.

Risk Factors

Spinal and bulbar muscular atrophy is caused by an inherited gene flaw in the AR gene on the X-chromosome. The flaw causes the DNA segment to repeat extra times. • When a woman carries the X-chromosome linked disease, a son has a 50% chance of inheriting the gene flaw and developing spinal and bulbar muscular atrophy. A daughter will have a 50% chance of inheriting the gene flaw and being a carrier.


  • Physical exam and review of family history. The provider can run tests to differentiate spinal and bulbar muscular atrophy from other diseases with similar symptoms, such as amyotrophic lateral sclerosis (ALS).
  • Blood test. A blood test can determine if the enzyme creatine kinase (CK) is leaking out of muscles. High levels of CK in the blood indicate muscle damage.
  • Genetic testing. Genetic testing is the most accurate way to get a diagnosis.


There is no known treatment or cure.

Follow-up Care

  • A patient may see a speech-language specialist to help with swallowing food.
  • Physical therapy may help patients maintain skills as muscle weakness progresses.
  • A cane, walker or wheelchair can be used to aid in mobility.
  • Some patients may consider breast reduction surgery if their breasts become enlarged.
  • Ventilation aids can be used to help the patient sleep.

Why Choose UK HealthCare for Neuromuscular Disorders?

If you or a loved one is living with a neuromuscular disorder, neuromuscular doctors with Kentucky Neuroscience Institute can offer the latest and most sophisticated care options. UK HealthCare’s ALS Multidisciplinary Clinic earned accreditation as a Certified Treatment Center of Excellence from the ALS Association. This honor is awarded to facilities that demonstrate competency meeting the clinical care and treatment standards set forth by the ALS Association. These facilities must also take part in ALS research and a comprehensive site review.

Additionally, the Kentucky Neuroscience Institute is ranked 44th in the country by U.S. News & World Report, and our physicians are regularly named to the Best Doctors in America List.