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Conventional and Quantitative EEG Analyses: Normative Database and Discriminant Comparisons
| PATIENT INFORMATION | RECORDING
|
| Name: Jon Doe | Date:
|
| Exam#: 2884ec | Ref.
By: (Dr, MS, JD) |
| Age: 17.09 years | Test Site: |
| Sex: Male | Analysis Length: 3.58 Minutes |
| Handedness: |
|
| Medication: Antidepressant of unknown name. | Ave.
EEG Reliability: 0.98 (CSD) |
HISTORY:
In 1996, Mr. Doe was riding a bicycle that
was sideswiped by passing truck. He was hit by the truck's mirror
on the back of head, and a steel upright pole on corner of flatbed
hit him on back of left shoulder and elbow. He was thrown on grass,
and was unconscious for a few minutes. He walked home in a daze,
one block. Severe headache and nauseated, was taken to hospital.
Discharged from hospital later the same evening. About 2.5 months
ago, when leaving sidewalk with his bicycle to cross a side street,
he was hit by a speeding car. Mr.
Doe flew over the hood of the car and crashed through the windshield
face first. Was unconscious for 15 minutes. Drifted in and out of
consciousness the whole night. He remembers being hit by car, but
has no memory of going through windshield and going in ambulance.
Was hospitalized for 4 days. Currently, Mr. Doe has intermittent
severe headaches, depression, anxiety attacks, nightmares, dizziness,
flashbacks, fits of rage, and poor attention/concentration.
VISUAL EXAMINATION
OF EEG TRACINGS:
The
record showed excessive theta rhythms in the right parietal region
(7.77 Hz to 8.1 Hz). Laplacian remontage revealed reduced high
frequency activity in O1 and O2 at 21.22 Hz. Peak alpha activity was at 9.84Hz
and was within normal limits.
Peak-to-peak amplitudes ranged from 8 uv to 70 uv and were
within normal limits. EEG
wave morphology was within normal limits.
The spatial distribution of EEG alpha was normal with alpha
dominant in posterior regions.
Eyes open EEG demonstrated normal reactivity with alpha suppression.
However, theta rhythms in the right parietal regions persisted
in the eyes open condition.
No evidence of sharp waves and/or epileptiform events was
noted.
STATISTICAL
EXAMINATION OF EEG TRACINGS:
1- Statistically
significant elevated theta activity (P < .01) was present in
the right parietal region at 7.84 to 8.1 Hz. Right parietal region was deviant in the
delta/theta FFT power ratios.
A midline posterior deviation was noted in the Laplacian
theta/beta power ratios. Broad band relative power was within normal
limits. Diminished
power at 22Hz was present in bilateral occipital regions which was
most notable in the Laplacian montage.
2-
Intrahemispheric
Amplitude Asymmetries exhibited statistically significant deviations
from normal in left frontal-parietal regions (P < .01).
3-
Intrahemispheric
EEG coherence was within normal limits.
4- Intrahemispheric
EEG phase was deviant from normal in the left frontal-posterior
cortical regions as well as the interhemispheric temporal, parietal
and frontal regions
5- The
Mild Head Injury Discriminant Function detected a pattern in the
EEG that is associated with traumatic brain injury at the 70% confidence
level.
6- The
Traumatic Brain Injury Severity index showed was consistent with
the discriminant function and indicated a moderate level of severity.
SUMMARY:
The
visual analysis of the EEG and the power spectral EEG was mild to
moderately abnormal. The
conventional visual EEG examination was normal except for the presence
of excessive theta activity in the right parietal region.
Further power spectral analyses confirmed a focal abnormality
in the right parietal-occipital-midline region.
EEG phase and EEG amplitude asymmetries were abnormal with
a consistent pattern of left hemisphere abnormalities, especially
in left frontal and left temporal regions.
The EEG discriminant function detected a characteristic pattern
of TBI at the 70% confidence level.
The TBI severity index indicated a moderate level of severity. Overall, this is an abnormal EEG consistent
with traumatic brain injury with the 1996 back of head impact and
the 2001 face impact into a windshield producing coma for 4 hours
as, possibly, accumulative.
Evidence of a counter-coup injury
involving left frontal and the right parietal was present. The results are consistent with reduced
speed and efficiency of neuronal information processing, especially
in left frontal-temporal and right occipital-parietal regions as
well as likely white matter damage sufficient to adversely affect
conduction velocities.
Robert W. Thatcher, Ph.D., QEEG-T, BCIA, ECNS
TECHNICAL
DATA AND ANALYSES
Fig. 1 - Example of
Visual EEG and Simultaneous Relative Power Z scores 0 to 30 Hz Linked
Ears Awake Eyes
Closed
Fig. 2 - Example of
Visual EEG Current Source Density of EEG and Simultaneous Relative
Power Z Scores Laplacian Montage Awake Eyes Closed
Fig. 3 Age Matched 1 Hz Z Scores of FFT
Relative Power Linked Ears Montage
Fig. 4 - Age Matched 1 Hz Z Scores of FFT
Relative Power Current Source Density
(CSD)
Fig. 5 - Age Matched Z Scores of Complex
Demodulation Amplitude Relative Power Linked Ears Montage
Fig. 6 - Age Matched Z Scores of Complex
Demodulation Coherence Linked Ears Montage
Fig. 7 - Age Matched Z Scores of Complex
Demodulation Phase Linked Ears Montage
Fig. 8 Complex Demodulation TBI Discriminant
Function (threshold > 51% ) and a Continuous Severity Estimate
from 0 to 10 severe.
TECHNICAL CHARACTERISTICS
OF THE DIGITAL EEG
The
patient digital EEG data was recorded from 19 different scalp locations
referenced to linked ears (electrode location according to the International
10/20 Electrode Placement System) using a Lexicor NRS-24, 12 bit
A/D digital EEG machine. High
pass filter off, sample rate = 128.
Overall the quality of the data was good.
The report is based on 3.58minutes of selected samples of
digital EEG drawn from a total recording time of 10.28 minutes of
eyes closed but alert, relaxed and waking EEG.
The selection criteria were elimination of artifact and adequate
statistical levels of reliability and validity and by the judgment
by an expert review based on visual examination of the EEG.
Montage re-referencing was used to confirm or disprove the
presence of a focal deviation from normal or episodic patterns in
the EEG. The patterns of deviation in frequency
and anatomy were evaluated mathematically and statistically. No evidence of medication effects
to explain the various localized and diffuse patterns of the EEG
was present.
ARTIFACT REJECTION
AND QUALITY CONTROL:
Supervised
automatic artifact procedures were used to minimize eye movement
artifact, EMG artifact and other artifacts that were present. Split-Half reliability of the selected
artifact free segments was computed in real-time and the linked
ears montage average reliability of 0.99 which ranged from 0.97
to 0.99 for different scalp leads and the analysis was based on
an epoch length of 3.58 minutes of artifact free data.
FFT analyses of the selected EEG data were computed and compared
to age matched norms in real-time.
The back and forth visual comparisons between the FFT normative
analyses and the split-half reliable EEG samples showed that the
EEG data was not contaminated with artifact to the extent that clinical
interpretation would be compromised. No evidence of drowsiness was present
in the EEG record.