neurophysiology-eeg/SOPs/Recording-Procedures/SOP-EEG-001-Routine-EEG.md

# Standard Operating Procedure: Routine EEG Recording

| Document ID | SOP-EEG-001 |
|-------------|-------------|
| Title | Routine Electroencephalography (EEG) Recording |
| Revision | 1.0 |
| Effective Date | [DATE] |
| Author | [AUTHOR] |
| Approved By | [APPROVER] |
| Department | Neurophysiology/EEG Laboratory |

---

## 1. Purpose

To establish standardized procedures for recording routine electroencephalograms (EEG) in accordance with American Clinical Neurophysiology Society (ACNS) guidelines to ensure high-quality recordings for accurate interpretation.

## 2. Scope

This procedure applies to routine EEG recordings including:
- Routine awake EEG
- Routine EEG with sleep
- Activation procedures (hyperventilation, photic stimulation)
- Portable/bedside EEG
- Ambulatory EEG

## 3. Responsibilities

### 3.1 EEG Technologist
- Prepare patient for recording
- Apply electrodes according to 10-20 system
- Perform recording per protocol
- Monitor recording quality
- Perform activation procedures
- Document relevant observations

### 3.2 Electroneurodiagnostic Technologist (R.EEG.T or CNIM)
- Supervise EEG recordings
- Perform complex studies
- Train and mentor technologists
- Ensure quality standards

### 3.3 Interpreting Physician (Neurologist/Epileptologist)
- Review and interpret recordings
- Provide clinical correlation
- Generate diagnostic report
- Recommend follow-up studies

## 4. Definitions

| Term | Definition |
|------|------------|
| 10-20 System | International electrode placement system |
| Montage | Arrangement of electrode channels for display |
| Impedance | Resistance between electrode and scalp |
| Sensitivity | Amplitude of EEG display (µV/mm) |
| Activation | Procedures to provoke abnormalities (HV, photic) |

## 5. Equipment and Materials

- Digital EEG recording system
- Electrodes (disc, cup, or disposable)
- Electrode paste/gel (conductive)
- Skin preparation materials (abrasive gel/paste)
- Measuring tape
- Electrode placement cap or headbox
- Impedance meter
- Photic stimulator
- Video recording system
- Calibration equipment

## 6. Procedure

### 6.1 Patient Preparation

#### 6.1.1 Pre-Procedure Verification
1. Confirm patient identity (two identifiers)
2. Verify physician order and indication
3. Review relevant history:
   - Seizure history
   - Current medications (especially AEDs)
   - Sleep deprivation (if ordered)
   - Recent seizure activity

4. Patient Instructions Verified:
   - [ ] Hair clean, dry, no styling products
   - [ ] Sleep deprivation completed (if ordered)
   - [ ] Medications taken as instructed
   - [ ] No caffeine morning of test (if applicable)

#### 6.1.2 Patient Education
- Explain procedure and duration
- Describe electrode application process
- Explain activation procedures
- Discuss what to expect during recording

### 6.2 Electrode Application

#### 6.2.1 Measurement and Marking

**10-20 System Measurements:**
1. Measure nasion to inion (anterior-posterior)
2. Mark Fpz at 10% from nasion
3. Mark Fz at 30%, Cz at 50%, Pz at 70%
4. Mark Oz at 10% from inion

5. Measure preauricular points (transverse)
6. Mark T3/T4 at 10% from preauricular
7. Mark C3/C4 at 30%
8. Mark Cz at 50% (should match A-P)

9. Measure head circumference
10. Mark remaining positions per 10-20 system

#### 6.2.2 Standard Electrode Positions

| Position | Location | Hemisphere |
|----------|----------|------------|
| Fp1, Fp2 | Frontopolar | Left, Right |
| F3, F4 | Frontal | Left, Right |
| C3, C4 | Central | Left, Right |
| P3, P4 | Parietal | Left, Right |
| O1, O2 | Occipital | Left, Right |
| F7, F8 | Anterior Temporal | Left, Right |
| T3, T4 | Mid-Temporal | Left, Right |
| T5, T6 | Posterior Temporal | Left, Right |
| Fz | Frontal | Midline |
| Cz | Central | Midline |
| Pz | Parietal | Midline |
| A1, A2 | Ear/Mastoid | Reference |

#### 6.2.3 Electrode Application Process
1. Part hair at electrode site
2. Clean scalp with abrasive gel
3. Apply conductive paste to electrode
4. Affix electrode to scalp
5. Secure with tape, collodion, or cap
6. Repeat for all electrodes

#### 6.2.4 Impedance Check
- Check impedance for all electrodes
- Target: <5 kΩ
- Maximum acceptable: <10 kΩ
- Document impedance values
- Reapply electrodes if impedance excessive

### 6.3 Recording Setup

#### 6.3.1 System Configuration
| Parameter | Standard Setting |
|-----------|-----------------|
| Sensitivity | 7 µV/mm |
| Low frequency filter | 1 Hz |
| High frequency filter | 70 Hz |
| Notch filter | 60 Hz (if needed) |
| Time constant | 0.16 seconds |
| Paper speed/display | 30 mm/sec |

#### 6.3.2 Standard Montages

**Longitudinal Bipolar (Double Banana):**
- Fp1-F7, F7-T3, T3-T5, T5-O1
- Fp1-F3, F3-C3, C3-P3, P3-O1
- Fz-Cz, Cz-Pz
- Fp2-F4, F4-C4, C4-P4, P4-O2
- Fp2-F8, F8-T4, T4-T6, T6-O2

**Transverse Bipolar:**
- F7-Fp1, Fp1-Fp2, Fp2-F8
- T3-C3, C3-Cz, Cz-C4, C4-T4
- T5-P3, P3-Pz, Pz-P4, P4-T6

**Referential:**
- All electrodes referenced to average or specific electrode

#### 6.3.3 Calibration
1. Perform square wave calibration
2. Document calibration signal
3. Verify all channels responding appropriately

### 6.4 Recording Procedure

#### 6.4.1 Recording Timeline

| Phase | Duration | Activity |
|-------|----------|----------|
| Initial | 5-10 min | Eyes closed, relaxed wakefulness |
| Eyes open/closed | 2-3 cycles | Assess reactivity |
| Hyperventilation | 3-5 min | Deep breathing |
| Post-HV | 2-3 min | Recovery period |
| Photic stimulation | 5-10 min | Flashing lights |
| Drowsiness/Sleep | As able | Natural or sleep-deprived |
| Total Recording | 20-40 min | Minimum per ACNS |

#### 6.4.2 Routine Recording Protocol

1. **Resting Recording**
   - Eyes closed, relaxed
   - Minimize movement
   - Record representative sample

2. **Eyes Open/Closed**
   - Command to open eyes (10 seconds)
   - Command to close eyes
   - Document alpha reactivity
   - Repeat 2-3 times

3. **Hyperventilation (if not contraindicated)**

   **Contraindications:**
   - Recent stroke
   - Significant cardiovascular disease
   - Respiratory compromise
   - Sickle cell disease
   - Pregnancy
   - Intracranial hemorrhage

   **Procedure:**
   - Explain deep, rapid breathing
   - Patient breathes deeply for 3-5 minutes
   - Document effort level
   - Continue recording 2-3 minutes post-HV
   - Document any symptoms or findings

4. **Photic Stimulation**

   **Standard Frequencies:**
   1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18, 20, 25, 30 Hz

   **Procedure:**
   - Position photic stimulator 30 cm from face
   - Eyes closed
   - 10 seconds at each frequency
   - 10 second pause between frequencies
   - Document any clinical responses
   - Stop if clinical seizure occurs

5. **Sleep Recording (if ordered)**
   - Encourage natural drowsiness
   - Record drowsiness transition
   - Record sleep if achieved
   - Document sleep stages observed

### 6.5 Documentation During Recording

Technologist must annotate:
- [ ] Patient state (awake, drowsy, asleep)
- [ ] Eye movements and blinks
- [ ] Movement artifacts and cause
- [ ] Patient activities (talking, coughing)
- [ ] Clinical events observed
- [ ] Activation procedures (start/stop times)
- [ ] Any technical problems

### 6.6 Recording Quality Checks

Throughout recording, monitor for:
| Issue | Action |
|-------|--------|
| Electrode pop/artifact | Check connection, reapply if needed |
| Movement artifact | Reposition patient, note cause |
| Sweat artifact | Cool patient, apply antiperspirant |
| Muscle artifact | Relax jaw/neck, adjust position |
| 60 Hz interference | Check grounds, move cables |

### 6.7 Post-Recording

1. **Electrode Removal**
   - Remove electrodes carefully
   - Clean paste from scalp
   - Inspect scalp for irritation
   - Provide patient aftercare instructions

2. **Equipment Care**
   - Clean reusable electrodes
   - Disinfect equipment per protocol
   - Store equipment properly

3. **Documentation**
   Complete FRM-EEG-001 including:
   - Recording duration
   - Montages used
   - Activation procedures performed
   - Patient cooperation level
   - Technical quality assessment
   - Technologist observations

## 7. Special Considerations

### 7.1 Pediatric Patients
- May require sedation (per physician order)
- Age-appropriate electrode sizes
- Modified activation procedures
- Parent/guardian present as appropriate

### 7.2 ICU/Portable EEG
- Increased artifact sources
- Document artifact causes
- Extended recording times may be needed
- Coordinate with bedside care

## 8. Quality Control

| Metric | Target |
|--------|--------|
| Electrode impedance <5 kΩ | >90% of electrodes |
| Recording duration meets minimum | 100% |
| Activation procedures completed | 100% (unless contraindicated) |
| Technical quality adequate for interpretation | >95% |

## 9. References

- ACNS Guideline 1: Minimum Technical Requirements for Performing Clinical EEG
- ACNS Guideline 6: Recording EEG
- ASET Standards of Practice
- ABRET Certification Requirements

---

## Revision History

| Rev | Date | Description | Author |
|-----|------|-------------|--------|
| 1.0 | [DATE] | Initial release | [AUTHOR] |