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Genetic and Rare Diseases Information Center (GARD)

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Primary lateral sclerosis


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Overview

What is primary lateral sclerosis?

What are the signs and symptoms of primary lateral sclerosis?

How is primary lateral sclerosis diagnosed?

What is primary lateral sclerosis?

Primary lateral sclerosis is a type of motor neuron disease, where nerve cells that control voluntary muscle movement breakdown and die. In primary lateral sclerosis only the upper motor neurons in the brain are affected. Symptoms often begin with problems in the legs (e.g., weakness, stiffness, spasticity, and balance problems), but may also start with hand clumsiness and changes in speech. The symptoms worsen gradually over time, however people with this condition have a normal life expectancy. Progression of symptoms varies from person to person, some people retain the ability to walk without assistance, others eventually require assistive devices such as canes or wheelchairs. Diagnosis requires extensive testing to exclude other diseases. Treatment may include baclofen and tizanidine to reduce spasticity, quinine or phenytoin to reduce cramps, as well as physical and speech therapy as required.[1]
Last updated: 1/22/2010

What are the signs and symptoms of primary lateral sclerosis?

Primary lateral sclerosis (PLS) causes weakness in the voluntary muscles, such as those used to control the legs, arms and tongue. PLS can happen at any age, but it is more common after age 40. A subtype of PLS, known as juvenile primary lateral sclerosis, begins in early childhood. PLS is often mistaken for another, more common motor neuron disease called amyotrophic lateral sclerosis (ALS). However, primary lateral sclerosis progresses more slowly than ALS, and in most cases is not considered fatal.[2]

Signs and symptoms of PLS typically take years to progress.[2] The hallmark of PLS is progressive weakness and spasticity of voluntary muscles. The first symptoms are often tripping or difficulty lifting the legs. Other people may be the first to notice a change in the affected person's gait. Occasionally, speaking (dysarthria) and swallowing (dysphasia) difficulties, or arm weakness are the first symptoms. Speech problems can begin with hoarseness, a reduced rate of speaking, excessive clearing of the throat, or slurred speech when a person is tired. In some cases, speech becomes so slurred that others cannot understand it. Drooling can be a problem as well due to weakened bulbar muscles.[3] Many people report painful muscle spasms and other pain. Other common symptoms may include hyperactive reflexes and Babinkski's sign. Wherever symptoms originate, the legs, arms, hands, and speech and swallowing muscles are eventually affected. As the disease progresses, assistive devices such as canes, walkers or wheelchairs are typically needed.[3]
Last updated: 3/30/2011

How is primary lateral sclerosis diagnosed?

There is no single test that confirms a diagnosis of primary lateral sclerosis (PLS). Because the disease can mimic signs and symptoms of other neurological diseases such as multiple sclerosis and amyotrophic lateral sclerosis (ALS), several tests are done to rule out other diseases. After taking a careful record of an individual's medical history and performing a complete neurological examination, a doctor may order the following tests:
  • Blood work. Blood tests are done to check for infections or other possible causes of muscle weakness.
  • Magnetic resonance imaging (MRI) of the brain and spine. An MRI or other imaging tests may reveal signs of nerve cell degeneration and look for other causes of symptoms, such as structural abnormalities, spinal cord compression, multiple sclerosis and spinal cord tumors.
  • Motor and sensory nerve conduction studies. These tests use a low amount of electrical current to test how quickly the nerves carry impulses through the body, and can indicate damage to nerve cells.
  • Electromyogram (EMG). During this test, the doctor inserts a needle electrode through the skin into various muscles. The electrical activity of the muscles is evaluated when they contract and when they're at rest. This test can measure the involvement of lower motor neurons, which can help to differentiate between PLS and ALS.
  • Cerebrospinal fluid (CSF) analysis. An analysis of the CSF, which is taken during a lumbar puncture in the lower back, can help to rule out multiple sclerosis and other causes of spasticity.[2]
After other diseases are ruled out, a doctor may make a preliminary diagnosis of PLS. Sometimes doctors wait three to four years before being sure of the diagnosis, because early ALS can look just like PLS until additional symptoms surface a few years later.[2]
Last updated: 6/6/2011

References
  1. NINDS Primary Lateral Sclerosis Information Page. National Institute of Neurological Disorders and Stroke. 2009; http://www.ninds.nih.gov/disorders/primary_lateral_sclerosis/primary_lateral_sclerosis.htm. Accessed 1/21/2010.
  2. Primary lateral sclerosis (PLS). Mayo Clinic. October 16, 2010; http://www.mayoclinic.com/health/primary-lateral-sclerosis/DS01115. Accessed 3/30/2011.
  3. John Fink. About PLS (Primary Lateral Sclerosis). Spastic Paraplegia Foundation. 2011; http://www.sp-foundation.org/pls.html. Accessed 3/30/2011.


See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.