Numerous recent scientific studies have found associations between Dilantin toxicity and cerebellar atrophy, or degeneration of the cerebellum.

Also known by its generic name phenytoin, Dilantin has been used for more than six decades for the treatment of seizures, primarily in epileptic patients. Less often, it is given to patients who have suffered from head injuries and may be predisposed to seizures as a result.

In 2008, the U.S. Food and Drug Administration placed Dilantin on its list of medications with Potential Signals of Serious Risks. While the medication has been linked to several side effects, cerebellar atrophy is one of the most serious and is presently of greatest concern to scientists and drug safety advocates.

The Dilantin Story

The chemical compound phenytoin was first developed by a German chemist before the First World War. The patent was sold to Parke-Davis (today a division of Pfizer); however, it was not until 1938 that its usefulness as an anti-seizure medication was identified. The FDA granted Dilantin approval for this condition in 1953.

Over the next several decades, there were efforts to find additional uses for Dilantin, including the treatment of depression and anxiety disorders. However, the holder of the patent at the time, Parke-Davis, was not inclined to invest more resources in a medication because the patent on it was set to expire.

Studies involving the drug were also inconclusive. Nonetheless, in addition to controlling seizures, Dilantin may also be prescribed for heart problems such as arrhythmia and tachycardia, digoxin overdose, and as a second-line treatment for facial pain due to trigeminal neuralgia.

Dilantin Toxicity and Cerebellar Atrophy

Studies dating back more than fifty years have found links between Dilantin and cerebellar atrophy. One study published in the Archives of Neurology in 1994 noted the condition in patients who had been exposed to Dilantin for an extended period.

However, it was unclear to researchers as to whether cerebellar atrophy was caused by Dilantin, or was the result of seizures. A later study, led by a U.K. radiologist, confirmed that cerebellar atrophy was more common in patients who had long-term exposure to Dilantin.

All researchers who have explored this problem have noted that cerebellar atrophy can be caused by other factors in addition to epilepsy itself. Among these are normal aging, alcohol abuse, brain inflammation and a more generalized disorder known as multiple system atrophy. Medical tests can help to rule out factors other than Dilantin toxicity.

Signs of Cerebellar Atrophy

If you or a family member has been under long-term Dilantin therapy for seizures, there are a number of symptoms to be aware of. The most obvious is loss of motor control; victims tend to have an unsteady, lurching gait along with tremors in the waist and abdomen. Other signs include:

• slow, unsteady and/or sudden uncontrolled movement in the extremities
• verbal communication difficulties
• rapid, uncontrollable eye movement (nystagmus)
• cognitive difficulty and loss of memory

If the disorder is diagnosed early and is still localized, it is possible to stop its progress and even reverse it by withdrawing from Dilantin. However, if the symptoms have been going on for a longer period of time, injuries due to Dilantin toxicity are usually permanent and irreversible.