The common antiepileptic drug Dilantin may be associated with cerebellar atrophy, a condition that can impose its own set of motor symptoms on patients who are already living with epilepsy.

Dilantin is Pfizer Inc.’s brand name for the drug phenytoin. This drug was originally discovered in the early 1900s and used then as a treatment for the convulsionsthat sometimes resulted from electroshock therapy.

Today Dilantin is FDA-approved to treat epileptic seizures and the seizures that happen during or after neurosurgery. It is one of the most widely used of all drugs, as well as one of the most commonly prescribed treatments for epilepsy.

Dilantin and Cerebellar Atrophy

Despite Dilantin’s long history and widespread use, in rare cases the drug has been associated with a condition known as cerebellar atrophy. Cerebellar atrophy is a type of focal cerebral atrophy that consists of a reduction in volume of the cerebellum, a part of the brain that handles coordination of movement. Degeneration of the cerebellum can inhibit a person’s balance, coordination and refined movements.

A few years ago, scientists weren’t fully in agreement as to the cause of cerebellar atrophy in epilepsy patients who took phenytoin. Some thought the condition was caused by the phenytoin, but others believed it was caused by the seizures themselves.

A 1994 study reviewed magnetic resonance imaging of patients with partial epilepsy and long-term phenytoin exposure.

The researchers found significantly pronounced cerebellar atrophy in the epilepsy patients as compared to healthy persons. However, they were unable to determine whether that cerebellar atrophy was caused by phenytoin or by the seizures themselves, or whether it was a synergistic effect of both phenytoin and seizures.

In a 2003 study, researchers found a frequent association of cerebellar atrophy with long-term use of phenytoin.

Researchers in that study concluded that while the duration of the patients’ epilepsy could have had some effect on their cerebral atrophy, that factor was not as important than how long the patient had been exposed to phenytoin.

Some case studies have also suggested a link between phenytoin and cerebellar atrophy. In a 2000 study, reasearchers told the story of a woman who suffered signs of cerebellar dysfunction soon after receiving an overdose of phenytoin.

Her condition improved rapidly after discontinuation of phenytoin, and imaging studies conducted months later showed evidence of cerebellar atrophy. The study noted this finding could indicate that even short-term use of phenytoin could result in cerebellar atrophy.

Because cerebellar atrophy affects a person’s ability to coordinate movement, it can make many aspects of everyday life difficult or impossible. Patients may have difficulty walking or grasping objects, and simple actions like speaking or swallowing can become unusually difficult. These symptoms in turn can have significant effects on the patient’s personal and professional lives.