If you or a loved one suffered from cerebellar atrophy or cerebellar degeneration while taking the anti-seizure Dilantin medication (also known by its generic name phenytoin), you are not alone. 

Research suggests that the drug may be linked to brain damage — specifically that its use may negatively affect the brain’s movement center.

The cerebellum controls voluntary movement, including speech, motor skills, and walking. When a person’s cerebellum is damaged in conditions known as cerebellar degeneration or cerebellar atrophy, their ability to speak clearly, move smoothly, or walk steadily may be affected.

In the case of cerebellar atrophy or degeneration, the cerebellum can become so damaged that it actually shrinks.

Symptoms of cerebellar atrophy or cerebellar degeneration include:

• Unsteady, lurching walk, which often includes a back and forth tremor in the main part of the body
• Slow, unsteady, jerky movements in the arms or legs
• Slow and slurred speech
• Nystagmus: small rapid movements in the eyes.
• Memory loss

The cerebellum becomes damages when the brain tissue becomes damaged, and when the neurons and the connections between them become damaged, inhibiting the brain’s ability to send messages.

Cerebellar degeneration can be caused by a range of factors, including stroke, as well as by exposure to toxins including alcohol and some medications. In fact, cerebellar degeneration can actually be caused by seizures themselves.

So, research that looked at the connection between Dilantin medication use and cerebellar degeneration had the task of separating cerebellar degeneration in epilepsy patients who were not using Dilantin versus those who were using Dilantin.

In 1994, a study was published that noted that patients who did take Dilantin medication had significantly smaller cerebella compared to epilepsy patients who had not taken Dilantin.

Then in 2003, another study was published that suggested that long term use of Dilantin was linked to moderate or severe atrophy of the cerebellum. However, the condition has also reportedly appeared even when the drug was not used for a very long time or in high doses.

Sadly, research has also shown that cerebellar atrophy and degeneration can occur in children who use Dilantin medication.

In 2017, the Journal of Epilepsy Research published a study further exploring Dilantin use and cerebellar damage. The study suggested that there may be a link, but noted a need for further research on the subject. 

In some cases, cerebellar atrophy or degeneration can be reversed. However, if the damage is severe enough, as may be the case in patients who used Dilantin in high doses or for a long time, the damage can be permanent, as will the symptoms associated with it.

Multiple Sclerosis News Today warned patients of the dangers of Dilantin use, as some patients use Dilantin to manage multiple sclerosis symptoms. The news source notes that the medication does have a black box warning about the risk of cardiovascular events associated with taking Dilantin as an injection, but does not indicate that there is a black box warning about the risk of cerebellar atrophy or degeneration.