This case study describes a 54-year-old woman with recurrent epithelial ovarian cancer who was undergoing chemotherapy. After her third round of ifosfamide treatment, she developed neurological symptoms. An electroencephalogram (EEG) detected frequent low-frequency periodic waves across both hemispheres, consistent with ifosfamide-induced encephalopathy. Her chemotherapy was stopped but her condition deteriorated further with worsening encephalopathy and acute kidney injury, and she ultimately passed away within a month.

1. EEG
(ELECTROENCEPHALOGRAM)
Created & Presented By:
Shashvat
M.Sc. Neuropsychology

2. An electroencephalogram (EEG) is a test that detects electrical activity in your brain
using electrodes attached to your scalp. Your brain cells communicate via electrical
impulses and are active all the time, even when you're asleep. This activity shows up
as wavy lines on an EEG recording
Richard Caton (1875) –localization of sensory functions with monkeys
and rabbits
Hans Berger (1924) – first EEG recording done on humans

3. Why is an EEG performed?
An EEG is used to detect problems in the electrical activity of the brain that may be
associated with certain brain disorders. The measurements given by an EEG are used to
confirm or rule out various conditions, including:
• seizure disorders (such as epilepsy)
• head injury
• encephalitis (inflammation of the brain)
• brain tumor
• encephalopathy (disease that causes brain dysfunction)
• memory problems
• sleep disorders
• stroke
• Dementia
When someone is in a coma, an EEG may be performed to determine the level of brain
activity

4. EEG COMPONENTS
Active electrodes
Amplifier and ADC (Analog to
Digital Converter)
USB converter
Analog Input Box Computer storage and
display

5. BASIC ACQUISITION
• EEG signals are a measure the potential difference
between two electrodes.
• Action Potentials are caused by an exchange of ions across
the neuron membrane and an AP is a temporary change in the
membrane potential that is transmitted along the axon.
• The conduction velocity of action potentials lies between 1
and 100 m/s. APs are initiated by many different types of
stimuli; sensory nerves respond to many types of stimuli,
such as chemical, light, electricity, pressure, touch, and
stretching.

6. Brainwaves
At the root of all our thoughts, emotions and behaviours is the communication between
neurons within our brains. Brainwaves are produced by synchronised electrical pulses from
masses of neurons communicating with each other.
Types of Brainwaves:
• Delta waves (.5 to 4 Hz)
• Theta waves (4 to 8 Hz)
• Alpha waves (8 to 12 Hz)
• Beta waves (12 to 38 Hz)
• Gamma waves (38 to 42 Hz)

7. Delta Waves
 Characteristics:
-frequency: .5-4 Hz
-amplitude: 20-200µV
Meditative waves (slowest and high amplitude),
Found during periods of deep sleep in most people, Characterized by very
irregular and slow wave patterns,Also useful in detecting tumors and abnormal
brain behaviors
STUDIES
• Sleep and sleep disorders
• Alcoholism and sleep

8. Theta Waves
 Characteristics:
-frequency: 4-7Hz
-amplitude: 20-100µV
Cognitive high level thinking (correlates to mental operations, attention , info uptake ,
processing and learning or memory recall ,Frequency increases with task difficulty ,Can be
recorded from all over cortex, Carry frequency of cognitive processing , Believed to be
more common in children than adults
Walter Study (1952) found these waves to be related to displeasure, pleasure,
and drowsiness.
STUDIES
• N-Back task
• Spatial Navigation
• Brain monitoring in operational environment

9.  Characteristics:
- frequency: 8-12 Hz
-amplitude: 20-60 µV
Easily produced when quietly sitting in relaxed position with eyes closed (few people
have trouble producing alpha waves)
STUDIES
• Meditation
• Biofeedback
• Attention
Alpha Wave

10. Beta Waves
 Characteristics:
-frequency: 12-30 Hz
-amplitude: 2-20 µV
Active , busy , anxious thinking and active concentration.
Increases with motor movements that have focused attention
The most common form of brain waves. Are present during mental thought and
activity.
STUDIES
• Motor Control
• Stimulant induced alertness

11. Gamma Waves
 Characteristics:
-frequency: 30-44Hz
-amplitude: 3-5µV
Occur with sudden sensory stimuli, Gamma waves are important for learning,
memory and information processing.

12. ELECTRODE PLACEMENT
• Typically adopt an accepted placement scheme for applying electrodes to
the scalp.
• The International 10-20 placement system is the most widely adopted.
• It uses a set of measurements relative to landmarks on the head.
• Name reflects the fact that electrodes are placed at intervals that are 10%
or 20% of the distance between landmarks.

13. • Requires distance from front
to back of head and distance
from left to right.
• Front to back defined as
distance from nasion to inion.
• Nasion - intersection of the
frontal bone and two nasal
bones
• Inion - the most prominent
projection of the occipital
bone at the posterioinferior
(lower rear) part of the skull
ELECTRODE PLACEMENT

14. • Requires distance from
front to back of head and
distance from left to
right.
• Left right defined as
distance between pre-
auricular points.
• Pre-auricular point- root
of the zygomatic arch
anterior to the tragus
ELECTRODE PLACEMENT

15. EEG Recording

16. EEG AS A TIME SERIES
• The EEG signal is
recorded together
with noise that
stems from a
number of sources.
• Essentially
anything that is not
the signal of
interest is
considered noise.
• Noise amplitude is
usually larger than
the signal of
interest.

17. SOURCES OF NOISE IN EEG
• Capacitive coupling
– the electrodes and cables are coupled to signals such as lights,
computers, cell phones, etc. can induce voltage in the leads.
– Theoretically this is the same for all leads so should be removed by
common mode rejection.
– In practice, however, this is not always the case so it is best to keep
distance between leads and electrical sources.
• Induction
– Loop created between body and equipment allows for the formation
of a magnetic field that can induce current flow in wires.
– The best solution is to wrap the cables around each other so that
opposing magnetic fields will cancel each other.

18. CASE STUDY
A 54-year-old, gravid 2, para 2, married woman presented with recurrent epithelial ovarian cancer
(endometrioid adenocarcinoma). She had noninsulin dependent diabetes mellitus, diabetic retinopathy, and
hypertension. Seven years earlier, she underwent coronary artery bypass grafting due to coronary artery
disease.
Three years ago, she was transferred to our center after laparoscopic bilateral salpingo-oophorectomy
which led to a diagnosis of epithelial ovarian cancer. She underwent a debulking operation, including total
abdominal hysterectomy and pelvic and paraaortic lymph node dissection, total omentectomy,
appendectomy, peritoneal mass excision, and left ureter resection and anastomosis. The tumor was
categorized as International Federation of Obstetrics and Gynecology (FIGO) stage IIIc and cytoreductive
surgery was suboptimal. Following the surgery, she received 6 cycles of adjuvant chemotherapy with
paclitaxel/carboplatin. However, because there was disease progression in this patient, she was further
treated with 3 cycles of topotecan, followed by 3 cycles of docetaxel. An abdomino-pelvic computed
tomography (CT) scan showed aggravation of disease and her serum carbohydrate antigen 125 (CA-125)
concentration was elevated from 534 to 1,270 U/mL . In addition, brain magnetic resonance imaging (MRI)
findings were normal. An electroencephalogram showed frequent 1-1.5 Hz periodic or single triphasic
waves on both hemispheres (Fig. 1). She was diagnosed with ifosfamide -induced encephalopathy, and her
chemotherapy was discontinued immediately. Her neurologic symptoms and signs did not improve. Despite
the supportive care, her encephalopathy became aggravated, and she developed ifosfamide-induced acute
tubular necrosis. She was discharged without any hope for recovery and died within 1 month.

19. CASE STUDY
Fig.1