Autonomic seizures versus syncope in 18q- deletion syndrome: a case report

The 18q- deletion syndrome (18qDS) is frequently associated with cardiac anomalies. Patients with this syndrome may also have epilepsy, which presents certain diagnostic difficulties. This case report aims to illustrate these diagnostic problems, document the usefulness of heart rate-based seizure detection algorithms in this setting, and define the epilepsy syndrome associated with 18qDS.

Closed-circuit video electroencephalogram (EEG) monitoring using a heart rate-based seizure detection software was used to identify the event in question and to establish the diagnosis of epilepsy. Chromosomal analysis and magnetic resonance imaging (MRI) were used to further define the epilepsy syndrome.

We report on a patient with an atrial septal defect, enlargement of the right heart, and incomplete right bundle branch block, who developed episodes of tachycardia, loss of consciousness, and pallor, for which he was amnesic. Chromosomal analysis demonstrated karyotype 46,XY,del(18)(q21.3). ish del(18)(wcp18+,D18Z1+) with a loss of the gene for myelin basic protein. MRI revealed multifocal dysmyelination. Video-EEG monitoring using an electrocardiogram (ECG)-triggered seizure detection software proved to be indispensable in detecting an autonomic seizure and establishing the correct diagnosis; the procedure also allowed for the definition of the epilepsy syndrome. The patient was treated with carbamazepine and remained seizure-free.

Video-EEG monitoring using a heart rate-based seizure detection software can be helpful in diagnostically differentiating autonomic seizures from syncope. Dysmyelination due to loss of the myelin basic protein gene on 18q and cortical dysgenesis may be of pathogenic relevance.