In March, 2010, a 65-year-old woman presented to our clinic with refractory epileptic seizures that had started 4 years earlier. Carbamazepine made these episodes worse, and she was put on levetiracetam 2·0 g per day. In the week before presentation, seizures recurred daily. She also had a history of hypertension treated with ramipril 5 mg per day. The seizures lasted up to 30 s, and they began with a feeling of fear and epigastric discomfort that was often followed by impairment of consciousness, a facial expression of fear, lip automatisms, and left upward eye-deviation, but without pallor. Subsequently, she felt mentally confused for a few minutes. No precipitating factor was identifi ed, and she also experienced events during sleep that woke her. During her seizures she never fell or had diaphoresis, visual changes, or incontinence. Neurological examination, electroencephalogram (EEG), 12-lead electrocardiogram (ECG), echo cardiogram, brain MRI, and blood tests were normal. Although the key clinical features pointed to epilepsy, in our opinion two factors argued against this diagnosis. The fi rst was the drug-resistance, because prognosis of new-onset seizures in elderly patients is good, especially if seizures are not symptomatic. The second factor was the normal EEG, because the yield of epileptiform EEGs is high if the recording is made during a period of increased seizure frequency. Video-EEG/ECG monitoring was used to capture one of our patient’s seizures while she was awake and sitting in bed with her eyes open. ECG recording revealed an abrupt asystole that spontaneously resolved after 16 s with reappearance of normal sinus rhythm. The EEG showed the characteristic “slow-fl at-slow” pattern of syncope, which started 7 s after the asystole onset and lasted 17 s. The aura of fear coincided with the EEG slowing, and loss of consciousness with the fl at EEG. During a 12-lead ECG recording, another spontaneous paroxysmal asystole was stopped by temporary trans-cutaneous pacing stimulation, which also prevented the electroclinical features. During continuous cardiac monitoring, occasional episodes of sudden change from normal 1:1 atrio-ventricular conduction to complete heart block were recorded and treated by temporary pacing in the right ventricle until normal sinus rhythm was restored (fi gure). Further investigations identifi ed no cardiac disease. A diagnosis of paroxysmal atrioventricular block (PAVB) was made, and a dual-chamber pacemaker device was implanted. At her last outpatient visit, in December, 2010, she had remained seizure-free. PAVB is a poorly-recognised condition that consists of the abrupt occurrence of repetitive block of the atrial impulse, with a relatively long (>2 s) ventricular asystole, leading to potential sudden cardiac death. Patients reported with PAVB usually have unambiguous syncopes, but unlike our patient, most of them have concomitant cardiac disease or defi nite triggering factors. In our patient, the key clinical features, the spontaneous occurrence of episodes even at night, and the lack of evidence for atrioventricular conduction disease between episodes, were less likely to raise suspicion of cardiac syncope and thus more prone to misdiagnosis. Detailed history-taking and careful examination led us to the appropriate diagnosis of PAVB. In exceptional cases, asystole can be the consequence of focal epileptic seizures and a likely cause of sudden unexplained death in epilepsy. However, unlike PAVB, epileptic asystole always occurs several seconds after the EEG seizure activity. Our patient reinforces the diffi culty that exists in diagnosing seizure and syncope, and emphasises the need to consider cardiac causes in patients with drugresistant epilepsy.
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Sep 7, 2023
I A Kovalyov + 4
Open Access
