Diagnosis

To diagnose myoclonus, your doctor will review your medical history and symptoms and conduct a physical examination.

To determine the cause of myoclonus and rule out other potential causes of your condition, your doctor may recommend several tests, including:

Electroencephalography (EEG)

This procedure records the electrical activity of your brain and may help determine where in your brain the myoclonus originates. In this procedure, doctors attach small electrodes to your scalp. You may be asked to breathe deeply and steadily and look at bright lights or listen to sounds, as these actions may uncover abnormal electrical activity.

Electromyography (EMG)

In this procedure, doctors put EMG surface electrodes on multiple muscles, especially on those muscles that are involved in the jerking.

An instrument records the electrical activity from your muscle at rest and as you contract the muscle, such as by bending your arm. These signals help determine the pattern and origin of the myoclonus.

Evoked potential studies

These tests measure the electrical activity of the brain, brainstem and spinal cord that is triggered by touch, sound, sight and other stimuli.

Magnetic resonance imaging (MRI)

An MRI scan may be used to check for structural problems or tumors inside your brain or spinal cord, which may cause your myoclonus symptoms. An MRI scan uses a magnetic field and radio waves to produce detailed images of your brain, spinal cord and other areas of your body.

Laboratory tests

Your doctor may suggest genetic testing to help identify possible causes of myoclonus. He or she may also test your blood or urine to check for:

• Metabolic disorders
• Autoimmune disease
• Diabetes
• Kidney or liver disease
• Drugs or toxins