Which EEG finding would raise concern in a 65-year-old patient?

The choice of a 7 Hz background as a concern in a 65-year-old patient is significant because a normal adult EEG typically exhibits a dominant alpha rhythm, which is usually observed in the frequency range of 8-12 Hz. Alpha rhythms are present when the patient is awake and relaxed, with eyes closed. A background of 7 Hz indicates sluggishness or the potential presence of pathological activity, especially in the context of an older patient who may be more susceptible to neurological disturbances.

In elderly patients, the absence of an alpha rhythm can suggest a variety of neurological issues, such as possible cortical impairment, advanced age-related changes, or other forms of dysfunction. If the EEG shows a dominant lower frequency, such as 7 Hz, without the expected alpha pattern, it may raise red flags for underlying conditions like dementia or other degenerative diseases. This makes the presence of a 7 Hz background a notable abnormality warranting further investigation.

Also, the normal responses to hyperventilation (HV) or the presence of beta activity in the frontal-central region can also occur in various contexts without necessarily indicating immediate concern.