**2. Methods**

This clinical study was performed according to the Good Clinical Practice (GCP) guidelines. Approval was obtained from Hamad Medical Corporation Ethical Committee and Institutional Review Board (IRB). All subjects/relative(s) (caregivers) provided consent before participating.

**47**

*Nonconvulsive Status Epilepticus in Patients with Altered Mental Status Admitted to Hamad…*

NCSE was defined as an AMS with diminished responsiveness, a positive EEG. and a response to anti-seizure drug (ASD) therapy; as a status, NCSE should be present for a minimum of 30 minutes of continuous nonconvulsive seizure activity or after repeated seizures without recovery of consciousness between events [1];

Young's criteria [27] of electrographic SE and modified criteria of Chong and Hirsch [28] were used to diagnose NCSE; In addition, the International League against Epilepsy (ILAE) definition and classification of Status Epilepticus [29] and EEG Salzburg Consensus Criteria for NCSE [30] were used to recognize NCSE; NCSE was diagnosed in the presence of continuous generalized spike wave discharges with changes in intensity or frequency, epileptiform activity with ictal patterns that wax and wane, rhythmic and periodic discharges, and subtle and discrete electrographic seizures, when lasting for 30 minutes [10, 13, 15]. In comatose patients, epileptiform discharges faster than 2.5 Hz or generalized periodic discharges (GPDs), lateralized periodic discharges (LPDs) and continuous 2/s GPDs with triphasic morphology [31] of less than 2.5 Hz, as well as rhythmic discharges (RDs) faster than 0.5 Hz were also taken into consideration as NCSE if they responded to benzodiazepine treatment with

Two EEG specialists agreed independently that the patient condition and EEG findings represent NCSE particularly when an EEG pattern did not meet above criteria; finally NCSE was considered if the EEG/or level of consciousness responded

Unexplained confusional state, change in behavior, mild to moderate obtundation, alteration in cognition and behavior from baseline, and unexplained decrease in level of consciousness including after convulsive status epilepticus treatment [2, 33] were considered AMS; in elderly patients, delirium (altered level of consciousness, with a fluctuating course, disorganized thinking, and inattention) was also included [15].

All patients with AMS, from the Emergency Department and from ICUs, aged 12 years or above, had a cEEG monitoring [2, 33]. Not included were patients with open head injury, those whose relatives did not sign the consent form and patients with suspected brain death and an isoelectric EEG. In addition, patients treated for convulsive status epilepticus (CSE) who did not develop later NCSs/NCSE on cEEG

Patients with AMS and those whose EEG was not compatible with NCSE during 3 days of cEEG monitoring recording were taken as controls. The NCSE and control groups were compared: this included the clinical presentation and medical condition, AMS etiology, neuroimaging, laboratory findings, length of stay, recovery, and outcome

The following EEG recording system was used: international 10/20 system with 21 silver/silver chloride cup electrodes. Digital EEG signal stored electronically was filtered for display. High-pass filter and low-pass filter were 0.5–1 and 70 Hz. For

improvement in the EEG or in patient mental status [13, 15, 29, 32].

*DOI: http://dx.doi.org/10.5772/intechopen.83580*

recently shorter durations have been reported.

**2.2 Patient selection for cEEG monitoring**

**2.3 Patients with NCSE and control group**

**2.4 cEEG monitoring and duration**

*2.4.1 cEEG recording*

monitoring were excluded.

**2.1 Definition of NCSE and AMS**

to an ASD trial.

*Nonconvulsive Status Epilepticus in Patients with Altered Mental Status Admitted to Hamad… DOI: http://dx.doi.org/10.5772/intechopen.83580*
