New-onset seizures in the elderly patient

The incidence of seizures in older adults is often underestimated. A recent Veterans Administration study showed that for elderly patients who ultimately received a diagnosis of epilepsy, only 73.3% of primary care physicians or internists considered a seizure disorder in their initial differential diagnosis.¹ Seizures are less likely to be witnessed in the elderly, who frequently live alone and may have limited social interactions.² They are more likely to suffer debilitating fractures, subdural hematomas,³ and prolonged postictal states than are younger people with a seizure disorder.⁴ Psychologically, seniors with epilepsy may lose confidence and independence,⁵ and they are at increased risk for depression,⁶ already a problem in that population.

The highest incidence of epilepsy occurs in adults who are older than 65 years.⁷ Nationwide, approximately 300,000 seniors have the disease,⁸ and by the year 2030 people older than 65 years will comprise nearly 20% of the US population.⁹ Elderly patients have an increased risk of stroke, more metabolic derangement, and a higher rate of comorbid illness, all of which may explain the higher prevalence of epilepsy in this population.¹⁰

Older patients are also at an increased risk for adverse drug effects. Both advanced age and the use of multiple medications make these patients more susceptible to drug toxicities.^4,11 Seniors who are already experiencing compromised cognitive function can be significantly impaired by even brief seizures.¹² Neurologic disabilities such as hemiparesis and aphasia may be exacerbated during prolonged postictal states.¹³ Having uncontrolled seizures also puts people at risk for falls, burns, intracerebral hemorrhage, subdural hematoma, postictal confusion, and decreased cognitive function.^12,13

Pathophysiology

A seizure is a series of aberrant, hypersynchronous electrical discharges of a group of cortical neurons that result in abnormal behaviors or sensory experiences. These electrical impulses are caused by dysregulation of excitatory and inhibitory neuronal effects, resulting in an excess of excitatory activity.¹⁴ Seizures appear in many different forms. An elderly patient having seizures may present with episodes of confusion, memory loss, or delirium.⁷ Family members or other caregivers may report periods of staring or disorientation. Table 1 lists classifications and descriptions for various seizure types.

Partial seizures, the most common type in older adults, arise from focal, unilateral electrical discharges, while generalized seizures originate through diffuse, bilateral electrical discharges. The pathogenesis of partial seizures reflects focal areas of neuron damage secondary to cerebrovascular disease. Indeed, the most commonly identified comorbidities in a recent study of new-onset epilepsy in the elderly are strongly associated with cerebrovascular disease: hypertension, stroke, cardiac disease, and diabetes.¹⁵

Complex partial seizures are the most common seizure type in adults of all ages. These often have activity centered in the frontal or parietal lobes, resulting in complaints such as dizziness, paresthesias, and memory disturbances.^1,16 Diagnosis is usually easy in patients who present with generalized tonic-clonic seizures, but the manifestations of simple partial and complex partial seizures are often subtle and easily overlooked. Frequencies of the various seizure types in the elderly are shown in Table 21.

History and physical examination

Obtaining an accurate history of the paroxysmal event from the patient may be difficult or impossible. Thus, it is critical to obtain a reliable firsthand observer's complete account of the events leading up to, during, and following the seizure. Ask about initial changes in speech or behavior, whether the onset was sudden or gradual, about the existence of pallor or cyanosis, and about abnormal motor activity, urinary incontinence, tongue-biting, lateralization of symptoms, or alteration in the patient's level of consciousness.¹⁷ Historical features of the spell that are suggestive of syncope include episodes that are precipitated by pain, anxiety, or a change in position, are associated with diaphoresis and pallor, and involve a rapid recovery of neurologic function after the event.⁷ Prodromal neurologic symptoms (unusual tastes, smell, thoughts), postevent focal motor weakness or focal sensory deficits (Todd's phenomenon), or a prolonged postictal period suggest seizure as the probable diagnosis.¹⁸

Ask the patient or the family about any systemic illnesses, current medications (including nutritional supplements or herbal compounds), recent stress or illnesses, sleep problems, history of head trauma, and family history of neurologic disorders. Table 3 lists drugs that are commonly implicated in provoked seizure. Table 4 lists other known triggers of seizures.