What is the meaning of an electroencephalogram (EEG) showing generalized bursts of delta waves with significant hyperventilation-induced slowing in a 33-year-old woman?

From the Guidelines

The EEG findings of generalized bursts of delta waves and strong hyperventilation-induced slowing in a 33-year-old woman are abnormal and require further neurological evaluation to determine the underlying cause and appropriate management. These findings are nonspecific but could indicate several possible conditions including epilepsy, metabolic disorders, or cerebrovascular issues. The delta bursts represent slow wave activity that is typically abnormal in adults when present during wakefulness 1. Hyperventilation normally causes mild EEG changes, but "strong" slowing suggests an exaggerated response that may indicate increased cerebral excitability or metabolic sensitivity.

Possible Conditions

• Epilepsy: Epileptiform discharges are recorded during epileptic convulsions whereas, during syncope, an EEG generally shows diffuse brainwave slowing with delta waves and a flat line pattern 1.
• Metabolic disorders: Hyperventilation syndrome may be associated with abnormal breathing patterns, respiratory alkalosis, and ECG changes resembling ischemia in subjects with normal coronary arteries 1.
• Cerebrovascular issues: Although brain structural abnormalities are rare in patients with syncope, MRI and CT of the head may be indicated if significant head injury as a result of syncope is suspected 1.

Recommended Course of Action

• Refer the patient to a neurologist for comprehensive assessment including clinical correlation with any symptoms such as seizures, headaches, or cognitive changes.
• Additional testing may be warranted, including:
  • Brain imaging (MRI) to rule out structural abnormalities.
  • Metabolic screening to identify potential metabolic disorders.
  • Possibly repeat EEG monitoring to further characterize the abnormal brain electrical activity.
• Treatment would depend on the underlying diagnosis and symptom profile.

Important Considerations

• Routine recording of an EEG is not recommended in the evaluation of patients with syncope in the absence of specific neurological features suggestive of a seizure 1.
• MRI and CT of the head are not recommended in the routine evaluation of patients with syncope in the absence of focal neurological findings or head injury that support further evaluation 1.

From the Research

EEG Findings

• Generalized burst of delta and strong hyperventilation slowing in a 33-year-old woman may be indicative of various conditions, including epilepsy or nonepileptic phenomena 2, 3.
• Hyperventilation can lead to high-amplitude rhythmic slowing on the EEG, which can be associated with altered awareness and semiological features similar to absence seizures 3.
• The presence of generalized slowing on the EEG has been associated with outcomes in patients with traumatic brain injury or subarachnoid hemorrhage, although the severity of this slowing may not be predictive of outcome in all cases 4.

Clinical Implications

• The EEG findings in this patient should be interpreted in the context of her clinical presentation and medical history, as hyperventilation-induced high-amplitude rhythmic slowing can be a nonepileptic phenomenon 3.
• Further evaluation, including video-EEG monitoring and awareness testing, may be necessary to determine the underlying cause of the patient's symptoms and to differentiate between epileptic and nonepileptic conditions 3.
• The use of antiepileptic medications, such as levetiracetam or valproate, may be considered in the treatment of epilepsy or other seizure disorders, although the efficacy and safety of these medications can vary depending on the specific condition and patient population 5, 6.