Dilantin is a common anti-epileptic (anti-seizure) drug that is used to treat seizures. Dilantin is the brand name for the drug phenytoin.

Though this drug has been used to improve the quality of life for those who suffer from seizures, the drug may have some serious side effects that could negatively impact a person’s quality of life, including cerebellar atrophy and cerebellar degeneration.

Medline Plus notes that Dilantin can be taken in a number of forms, and different forms of the drug are used in different cases. Dilantin can be taken as an extended-release capsule, a chewable tablet, and a liquid taken orally. It’s used commonly in both adults and children. 

What are the Side Effects of Taking Dilantin?

Research has shown that Dilantin use has been linked to the development of cerebellar atrophy, or cerebellar degeneration. Cerebellar degeneration and atrophy are conditions in which the movement center of the brain becomes damaged, and even shrinks in size. This can result in a patient having decreased control over voluntary movement.

What are Symptoms of Cerebellar Degeneration and Cerebellar Atrophy?

Because the cerebellum is the movement center of the brain, when it suffers damage, a person’s ability to walk, speak, and use precise movements is affected.

Symptoms of cerebellar atrophy 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

What Causes Cerebellar Atrophy?

Damage to the cerebellum causes cerebellar atrophy, and damage can come in a number of forms. When the brain is exposed to toxins, like ethanol, chemotherapy drugs, or other medications, cerebellar atrophy can occur.

Cerebellar atrophy’s connection with Dilantin use is complex because seizures themselves can result in cerebellar atrophy and cerebellar degeneration. So, researchers examining the connection between cerebellar atrophy and Dilantin toxicity had to make sure to not confuse this link with the link between epilepsy and cerebellar degeneration.

Even when considering this connection, epilepsy patients taking Dilantin were seen to have notably smaller cerebella than those not taking Dilantin.

What Happens When you Take too Much Dilantin?

Research indicates that patients who have taken Dilantin for a long time or who have taken a high dosage of Dilantin, especially a dosage above the recommended therapeutic range, are at a higher risk of developing cerebellar degeneration. Taking Dilantin for a long time can result in Dilantin toxicity.

A 2003 study linked moderate to severe cerebellar atrophy with long term use of Dilantin. The Epilepsy Foundation notes that the symptoms listed above, linked with cerebellar degeneration, are most often seen in epilepsy patients whose doses of Dilantin are too high. This can be an indication that Dilantin toxicity is at play.

Is Cerebellar Atrophy Permanent?

When cerebellar degeneration is linked to Dilantin toxicity, it can be reversed in some cases. If Dilantin use is stopped, some cases of this kind of degeneration may be reversible and symptoms may stop. However, in some cases, these symptoms may be permanent, especially if the cerebellar damage was severe.