The initial assessment of all patients with seizures should ideally include a complete medical history, family history, and review of systems, to determine whether the symptoms are due to neurologic or cardiac causes.
The medical history should inquire about cardiac conditions, previous cardiac testing, and medications. Inquiry about palpitations, dyspnea, chest pressure, or “heaviness” can help identify patients with atherosclerotic cardiovascular disease or valvular disease as a cause of seizure.
Risk factors for cardiac events include:
- prior events related to atherosclerotic cardiovascular disease
- diabetes mellitus
- family history of atherosclerotic cardiovascular disease at a young age
Whether apparent seizures are in fact episodes of convulsive syncope rather than a manifestation of epilepsy can often be resolved by appropriately directed questions and cardiac testing. Helpful signs of syncope (which can also be experienced in seizures) include:
- awareness as postural tone is lost during a blackout
- hemodynamic symptoms such as blurring vision and lightheadedness
- exercise-induced loss of consciousness
Medications, doses, and timing relative to onset of symptoms may reveal precipitating factors for either cardiac or neurologic events. A complete list of cardiac medications is also necessary to allow appropriate selection of antiepileptic drugs.
The screening physical examination should include respiratory rate and routine and orthostatic blood pressure with heart rate. Auscultation for cardiac murmurs, carotid bruits, and extrapulmonic sounds should be performed. Evidence of hypertension, including funduscopic vascular changes, cardiac enlargement, jugular venous distension, or peripheral edema should be noted.
If no recent laboratory evaluations are available, obtain electrolytes and a complete blood count, including platelets and coagulation parameters. Patients with suspected acute cardiac symptoms should have CPK and troponin, as well as an electrocardiogram (ECG). Children and known cardiac patients with new-onset syncope or seizures should routinely have an ECG.
Evaluation by EEG should always include at least one reliably recorded ECG channel. As in bedside telemetry, this channel is typically useful only for assessing conduction intervals and rhythm. Any suspected ischemic changes should be confirmed by performing a 12-lead ECG. For patients with possible syncope or seizure, video-EEG with an ECG channel may be necessary to document the nature of the typical clinical event.
Distinguishing syncope from seizure
Convulsive syncope may be difficult to distinguish clinically from generalized convulsive seizures. A history of exertion, micturition, or cough immediately preceding the event should argue against epilepsy. Focal symptoms associated with the event, or stereotypical semiology, argue against syncope, and may support a diagnosis of partial seizures. Simultaneous recording of clinical and EEG data is confirmatory in many cases.
In the Framingham study, over 3% of patients had at least one syncopal episode. Cardiac causes can be identified in 8% to 39% of patients.46 The major cardiac causes of syncope include:
- mechanical cardiac disease
- cardiac arrhythmias
- ventricular tachyarrhythmias
- cardioneurogenic (vasovagal) syncope
In patients studied with induced ventricular tachyarrhythmias, two-thirds had generalized tonic contraction of axial muscles, sometimes followed by irregular jerking of the extremities.47
Adapted from: Boggs J. Cardiac disorders. In: Ettinger AB and Devinsky O, eds. . Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;39-47.
With permission from Elsevier (www.elsevier.com).