Dr. Joon Faii Ong is an expert on essential tremor (ET) and Parkinson’s disease (PD). Dr. Ong was kind enough to lend his expertise to help us better understand these conditions.

What is Essential Tremor?

Essential tremor is a common neurological movement disorder that causes oscillatory, tremulous motion of the hands at rest. The problem usually appears in adulthood without any apparent cause, but it can also be inherited. When ET begins during childhood or adolescence, doctors typically notice signs of the condition before age ten. Tremor is most likely to affect the hands and arms when it first appears, but the tremor may affect the head and voice over time.

The essential feature of ET is a three-cycle per second (3Hz) tremor in the setting of rest and, in some cases, action. Essential means that no other neurologic condition can explain the tremor, such as drugs, alcohol, head injury, or metabolic disorder. ET is the most common of all tremor disorders; it occurs in 5% of people over age 40 and rises to 20-30% of people over 70 years old.

What Causes Essential Tremor?

The cause for essential tremor (ET) remains unknown; however, there are several theories. One theory is that damage to the cerebellum can cause oscillation of nerve cell connections, which leads to tremors. Another theory is that the problem originates in a part of the brain called the basal ganglia, which controls smooth movement. This theory explains why tremor often gets worse at rest and lessen with action.

Is There Any Treatment for Essential Tremor?

The first line of treatment is beta-blockers such as propranolol or Inderal and primidone to reduce the tremor. Sedatives and antidepressants can also be helpful, especially if anxiety makes the tremor worse. Stimulants such as caffeine, alcohol, and nicotine can make the tremor worse.

What is Parkinson’s Disease?

Parkinson’s disease (PD) is a progressive neurodegenerative disorder in which the major features are tremor, rigidity, and bradykinesia. It sometimes causes people to freeze when they try to take a step; this condition is called akinesia. PD often develops gradually but can get worse rapidly over time. People with PD experience symptoms by the time they are 50-60 years old, although it can affect younger adults or children under age 30. Parkinson’s disease is not fatal, but it often restricts patients’ ability to do certain activities and may require nursing care.

What Causes Parkinson’s Disease?

The cause of Parkinson’s Disease is not fully understood and remains a bit of a mystery. However, it is known that neurons in several parts of the brain die off or become impaired, leading to the symptoms of Parkinson’s Disease. This destruction may be due to overactivity by naturally occurring substances such as dopamine, glutamate, and glycine in part of the brain called the substantia nigra.

What are the Symptoms of Parkinson’s Disease?

Symptoms of Parkinson’s Disease vary from patient to patient. Generally, patients experience less movement than usual, especially when they move their arms or legs in a particular direction. They also experience stiffness and slowing down of movements that make it difficult to get up from a chair or exit from a car. Other common symptoms include tremors, slowness of movement that may affect the face and limbs, problems with posture, reduced sense of smell, depression, anxiety, cognitive impairment (deficits in memory), muscle cramps, and pain.