Which finding is consistent with a diagnosis of non-convulsive status epilepticus?

A diagnosis of non-convulsive status epilepticus is characterized by a persistent altered mental status and continuous seizure activity that may not involve convulsions, making the findings on an EEG critical for diagnosis. Prolonged theta activity is commonly associated with this condition as it reflects an abnormal EEG pattern seen in prolonged seizure states. In non-convulsive status epilepticus, the brain may exhibit a sustained theta frequency due to the prolonged nature of the seizure activity, which is less than the expected frequency of normal wakefulness (alpha rhythm).

This sustained theta activity, especially when bilateral and widespread, can provide conclusive evidence of non-convulsive seizure activity occurring without the overt manifestations typically associated with generalized tonic-clonic seizures. In contrast, the other choices do not comprehensively represent the specific EEG findings associated with non-convulsive status epilepticus.