Recurrent Syncope in a 10-Year-Old Boy

Background
Figure 1. (Click to enlarge)
A 10-year-old boy is brought to an outpatient pediatric clinic by his parents with a history of multiple fainting spells. These spells are sometimes complicated by generalized tonic-clonic "seizurelike" activity. The patient first started experiencing these attacks 8 months ago. His mother has noticed that the fainting most often occurs either in the early morning, after the sounding of an alarm clock, or during some type of sports activity. The child states that the seizures occur without warning, and they are sometimes associated with urinary incontinence or vomiting. According to the patient's family, the child remains unconscious for about 1 minute, after which he awakens abruptly, with no evidence of confusion and full recall of all of the events preceding the attack.
The patient was born full-term, without any complications. He has no chronic medical conditions and is not on any medications. As a result of experiencing similar symptoms, his father was diagnosed with epilepsy and started on treatment at the age of 8 years; however, the father has been without treatment and has not had any attacks since the age of 14. The patient's paternal uncle had also been diagnosed with epilepsy at the age of 10; he died during a seizure at the age of 19. The patient has an 8-year-old brother who is well, with no history of seizures or fainting spells.
On physical examination, the patient is a well-appearing and well-developed boy whose weight and height are in the 50th and 60th percentiles, respectively. His oral temperature is 98.6°F (37.0°C). His pulse is strong at 66 bpm, with a regular rhythm. His blood pressure is 105/65 mm Hg, and his respiratory rate is 15 breaths/min. The examination of his head and neck is normal. The lungs are clear to auscultation and normal respiratory effort is noted. Cardiac auscultation reveals normal S1 and S2 heart sounds, and no audible murmurs, rubs, or gallops are heard. His abdomen is soft, with no tenderness. No organomegaly is detected. The neurologic examination reveals intact cranial nerves and intact speech. Sensory and motor functions are normal in all extremities, without any pronator drift. The deep tendon reflexes are brisk and symmetric throughout. The patient's Romberg sign is negative, and his gait is stable.
The laboratory analysis, including a complete blood cell (CBC) count and a basic metabolic panel with serum electrolytes (including calcium and magnesium), is noted as normal. A chest radiograph and a computed tomography (CT) scan of the brain are also both normal. An electrocardiogram (ECG) is obtained (see Figure 1).
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