Unit
- EEG Basics: Electroencephalography (EEG) records electrical activity generated by cortical neurons. This non-invasive technique captures voltage fluctuations from synaptic potentials at the scalp surface. The resulting waveforms reflect brain states and are essential in diagnosing epilepsy, sleep disorders, and other neurological conditions.
- Historical Development: Hans Berger performed the first human EEG recording in 1924. Since then, technology has evolved from analog paper tracings to digital systems with high-resolution displays and automated analysis tools. Modern EEG systems integrate with hospital networks for efficient data management.
- Neurophysiological Basis: EEG signals originate from postsynaptic potentials of pyramidal neurons in the cerebral cortex. The synchronous activity of large neuronal populations generates measurable scalp potentials. Understanding this basis helps technologists recognize normal and abnormal patterns during recording.
- Clinical Applications: EEG is primarily used to evaluate seizure disorders, but also supports diagnosis of encephalopathy, brain death, and sleep disorders. It aids in monitoring during surgery and in intensive care units. The versatility of EEG makes it a cornerstone of neurodiagnostic medicine.
- Non-Invasive Nature: EEG is a painless, safe procedure that poses minimal risk to patients. Electrodes are placed on the scalp using conductive paste or gel, and no radiation is involved. This allows repeat testing and long-term monitoring without harm.
- Equipment Overview: A standard EEG system includes electrodes, amplifiers, filters, analog-to-digital converter, and a computer with display and storage. Electrode caps or individual application methods are used. Digital systems allow for montage reformatting and quantitative analysis.
- Role of EEG Technologist: The technologist is responsible for preparing the patient, applying electrodes, operating the equipment, monitoring recording quality, and ensuring patient safety. They must recognize artifacts and adjust settings to obtain optimal signals for interpretation by a neurologist.
- Integration with Healthcare: EEG findings are interpreted in the context of clinical history and other diagnostic data. Results are documented in the electronic health record and communicated to referring physicians. Effective collaboration between technologists, neurologists, and healthcare teams is critical for patient care.
- Signal Processing and Montages: EEG signals undergo amplification, filtering, and digitization to remove noise and enhance relevant brain activity. Montages such as bipolar, referential, and average allow viewing of voltage differences across electrode pairs. Understanding montage selection is critical for accurate localization of abnormal activity such as epileptiform discharges.
- Patient Safety and Infection Control: Electrodes and caps must be cleaned and disinfected between patients to prevent transmission of infections. Technologists follow standard precautions including glove use and proper disposal of supplies. Gel or paste residues are removed from skin and equipment. Routine maintenance of equipment reduces electrical hazards and ensures patient safety during long recordings.
- Electrode Application Techniques: Accurate placement according to the International 10-20 system ensures reproducible and standardised recordings. Measurements are taken from nasion to inion and preauricular points. Electrodes are applied with conductive paste or gel to achieve low impedance. Proper technique minimizes artifacts and signal distortion, especially in long-term monitoring.
Scope of Practice
Role: EEG Technologist in a Hospital Neurodiagnostic Laboratory
Within scope:
- Prepare patients for EEG procedures, including explaining the process and obtaining consent.
- Apply and remove electrodes following standard 10-20 system placement.
- Operate EEG equipment, adjust settings, and monitor recording quality.
- Recognize and correct common artifacts such as muscle tension or electrode pops.
- Maintain equipment cleanliness and perform routine checks for proper functioning.
Outside scope:
- Interpret EEG waveforms or provide clinical diagnosis based on findings.
- Prescribe or adjust antiepileptic medications.
- Perform invasive procedures such as intracranial electrode placement.
- Provide independent medical advice regarding treatment plans.
- Modify recording parameters without authorized protocol or physician direction.
Quick Revision
- EEG records cortical electrical activity via scalp electrodes, aiding diagnosis of neurological disorders.
- The technologist's role includes patient preparation, electrode application, equipment operation, and artifact recognition.
- Interpretation and diagnosis are outside the technologist's scope and reserved for licensed physicians.
- EEG is non-invasive, safe, and widely used in epilepsy, sleep, and critical care settings.