Paroxysmal hyperventilation responses in the adult electroencephalogram

Area of Science:

• Clinical Neurophysiology
• Neurology

Background:

• Hyperventilation (HV) is a standard EEG activation technique.
• Paroxysmal HV slowing is linked to hypoglycemia in children and cerebral instability in adults.
• The clinical significance of paroxysmal HV slowing in adults requires further investigation.

Purpose of the Study:

• To investigate the clinical correlates of paroxysmal HV slowing in non-hypoglycemic adults.
• To compare the prevalence of neurological and psychiatric conditions in patients with paroxysmal HV slowing versus controls.

Main Methods:

• Retrospective analysis of 100 consecutive EEGs with paroxysmal HV slowing (recorded in 1984).
• Comparison with 100 age-matched control EEGs (recorded since 1982).
• Clinical data review for neurological disorders, syncope, headaches, and psychiatric conditions.

Main Results:

• 28% of patients over 15 with paroxysmal HV slowing (not due to hypoglycemia) reported headaches, 80% vascular.
• 10% experienced syncope, 15% acute behavioral changes, and 20% had definite seizures.
• Fewer patients with HV paroxysms had epilepsy compared to controls (p<0.05).
• Neurologic disorders, excluding epilepsy, were more common in the HV paroxysm group (p<0.025).

Conclusions:

• Paroxysmal HV responses in non-hypoglycemic adults may indicate a predisposition to syncope, vascular headaches, and autonomic dysfunction.
• These HV responses are not correlated with epilepsy and should not be considered abnormal.
• Further research into the link between HV responses and autonomic dysfunction is warranted.