BOSTON — Just as epilepsy is a disease of those at the start of their lives, it can present for the first time in those whose lives are beginning to draw to a close. Unlike the generalized clonic seizures of children, this treatable condition in the elderly is subtle and may be misdiagnosed as dementia or confusion.
In fact, because the presenting feature of new-onset epilepsy in the elderly is complex partial seizures, the clinical picture may resemble that of sudden-onset dementia, A. James Rowan, M.D., said at a meeting on epilepsy in the elderly sponsored by Boston University.
The incidence of new-onset seizures begins to climb when patients are in their 50s after a decline that begins in childhood and reaches a nadir around age 30 years, said Dr. Rowan, professor of neurology at the Mount Sinai School of Medicine in New York. By age 60, the incidence of epilepsy reaches 40 new cases per 100,000 per year, Dr. Rowan said, citing data from W. Allen Hauser, M.D., professor of neurology and neuroepidemiology at Columbia University, New York. The incidence begins an almost exponential climb to age 75, when it hits 139 new cases per 100,000 per year, which is higher than the incidence of epilepsy in infants and children up to age 3.
“Epilepsy is, in fact, a disease of the very young and the very old,” Dr. Rowan said. Yet epilepsy in elderly patients is often quite different from that in children, who typically have generalized tonic-clonic seizures. In the elderly, complex partial seizures are the norm.
Dr. Rowan described the case of a 72-year-old woman whose treatable epilepsy was misdiagnosed as worsening dementia. She was about to be sent to a nursing home.
The woman was admitted to the hospital for a dementia evaluation. She reported having “fuzzy” periods. Her past medical history was unremarkable. A CT scan showed atrophy. ECG and lab results were negative. But in a neurologic consult, she said the “fuzzy” periods were intermittent. She kept asking, “What am I doing here?”
The neurologist felt that something did not fit, Dr. Rowan said.
A video EEG revealed a complex partial seizure. In the elderly the postictal state following a complex partial seizure may last up to 2 weeks. When she was treated with phenytoin, the symptoms resolved, and she went home. “It was a remarkable turnaround,” he said.
If such patients are recognized as having seizures, they can be treated and may enjoy a vastly improved quality of life. Often, he added, they are misdiagnosed with altered mental status, confusion, dizziness, syncope, memory disturbance, or dementia.
Dr. Rowan noted that 50% of all new-onset seizures occur in patients 60 years or older. Although in younger patients the diagnosis of epilepsy is reserved for those who have had at least two seizures, the diagnosis can be made in the elderly after just one seizure; 90% of elderly patients who have had one seizure will have a second unless they are treated.
Among the other differences between epilepsy in the young and the elderly, he added, is that epilepsy in the elderly, while extremely common, is manifested by a low rate of seizures. Yet in the elderly the postical state after complex partial seizures tends to be prolonged. The period of confusion can last up to 2 weeks, compared with a minute or so in infants and youngsters.
In most cases, epilepsy in the elderly develops secondary to cerebrovascular disease, said Dr. Rowan.
Cerebral infarctions account for nearly 40% of cases of new onset epilepsy. Multivessel atherosclerosis, cerebral hemorrhage, and subarachnoid hemorrhage make up another 10%. Approximately 30% of cases are of unknown etiology. About 20% of cases were Alzheimer's patients. Drugs such as theophylline lower the seizure threshold.