What Are Upper Motor Neuron Lesions?

If you have upper motor neuron lesions, you have damage to certain nerve cells that help you move. Medicines and therapy can help control symptoms like muscle spasms and help you walk and talk more easily.

Motor neurons are nerve cells in your brain and spinal cord that control movement. They tell your muscles to squeeze (or "contract") so you can walk, talk, and move your body.

You have two types of motor neurons:

Upper motor neurons are located in your brain and spinal cord. They send signals to lower motor neurons.

Lower motor neurons are in your brain stem and spinal cord. When they get a signal from the upper motor neurons, they send another signal to your muscles to make them contract.

Lesions are areas of damage to motor neurons. Damage to upper motor neurons stops the signals your muscles need to move.

When your muscles don't move for a long time, they become weak and stiff. Over time, it can become harder to walk and control your movements. Your doctor will do tests to find out which condition you have so you can get the right treatment.

Causes

Conditions that damage upper motor neurons include:

Symptoms

Upper motor neuron lesions prevent signals from traveling from your brain and spinal cord to your muscles. Your muscles can't move without these signals and become stiff and weak.

Damage to upper motor neurons leads to a group of symptoms called upper motor neuron syndrome:

Muscle weakness. The weakness can range from mild to severe.

Overactive reflexes. Your muscles tense when they shouldn't. For example, just rubbing your hand over your belly might cause your abdominal muscles to tighten up.

Tight muscles. The muscles become rigid and hard to move.

Clonus. This is muscular spasm that involve repeated, often rhythmic, contractions.

The Babinski response. Young children have a reflex called the Babinski reflex. If you stroke the bottom of their foot, their big toe will pull back and their other toes will spread out. This reflex usually disappears after age 2. In adults, the Babinski response is a sign of damage to the nervous system.

Upper motor neuron lesions can get worse over time. Over time, you can have trouble controlling your muscles.

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Diagnosis

Motor neuron diseases can be tricky to diagnose. Their symptoms are often very similar to those of other diseases.

Your doctor can do blood and urine tests to check for infections, muscle diseases, and other conditions that have symptoms similar to those of motor neuron diseases.

During an exam, your doctor will look for signs of a nervous system problem by checking your:

  • Balance and coordination
  • Movement
  • Hearing, speech, and vision
  • Memory and concentration

A few other tests can help your doctor diagnose upper motor neuron lesions:

MRI, or magnetic resonance imaging. It uses powerful magnets and radio waves to make pictures of structures inside your body. An MRI can show damage to upper motor neurons.

EMG, or electromyogram. It uses a thin needle to check the activity in your muscles when they contract and when they're at rest. An EMG can check for problems with your lower motor neurons and help diagnose ALS and PLS.

Nerve conduction study. This test measures how quickly an electrical current moves through your nerve. It can show how well your nerves are sending signals to your muscles and if you have nerve damage.

Spinal tap or lumbar puncture. It removes a small amount of fluid from your spine to show whether MS or an infection is causing your symptoms.

Nerve biopsy. It removes a small sample of the nerve to check for damage. It’s not likely that you’ll have this done. Doctors hardly ever use this method when trying to diagnose an upper motor neuron disease.

Treatment

Which treatment you get depends on what disease caused your upper motor neuron lesions.

Medicines won't stop diseases like ALS or PLS, but they can help you manage symptoms. Some of the drugs used to treat upper motor neuron symptoms include:

Muscle relaxants. Baclofen, clonazepam (Klonopin), and tizanidine (Zanaflex) control muscle spasms in PLS. Doctors may also use Botox to treat tightness and stiffness of muscles.

ALS drugs. Edaravone (Radicava) and riluzole (Rilutek) slow the progression of ALS.

MS drugs. Beta interferons, dimethyl fumarate (Tecfidera), fingolimod (Gilenya), glatiramer acetate (Copaxone), and ocrelizumab (Ocrevus) can slow MS damage to nerve cells.

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Along with medicine, these treatments can help you live better and more comfortably:

Physical therapy. A physical therapist can teach you exercises to help maintain your muscle strength and movement.

Speech therapy. Weak muscles in your face can make it harder to talk. A speech therapist will teach you techniques to help you communicate.

Occupational therapy. This type of therapist teaches you how to perform daily activities more easily. They can recommend special devices to help you get dressed, eat, and bathe.

Assistive devices. A brace, cane, walker, or wheelchair can help you get around safely.

Social support. A psychologist or social worker can talk you through some of the emotional stresses of living with a motor neuron disease.

WebMD Medical Reference Reviewed by Neil Lava, MD on May 11, 2018

Sources

SOURCES:

ALS Association: "Ask the Doc: Q&A With Edward Kasarskis, MD, PhD."

Bennetti, Susan E. Neurological Disabilities: Assessment and Treatment.

Case Western Reserve University School of Medicine: "Upper Motor Neuron Lesions."

Columbia Motor Neuron Center: "About Motor Neurons."

Mayo Clinic: "Amyotrophic Lateral Sclerosis (ALS): Diagnosis & Treatment." "Multiple sclerosis: Diagnosis." "Primary lateral sclerosis (PLS): Diagnosis & Treatment."

National Institute of Neurological Disorders and Stroke: "Motor Neuron Diseases Fact Sheet."

Neuroscience. 2nd edition: "Damage to Descending Motor Pathways: The Upper Motor Neuron Syndrome."

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