04/12/23 1
Digital EEG in 2000
Prof. Dr. Paulo R M de BittencourtCuritiba, Brasil
04/12/23 2
Objective
• Topics– the aging of analog EEG– the link between analog EEG and the
death of clinical neurophysiology as a specialty
– The link between digital EEG and the expansion into sleep studies, videomonitoring, spectral analysis, automatic detection of spikes and seizures
04/12/23 3
Customer Requirements
• What is the quality and value of the 20 min EEG
• Why are we so late with cardiac and carotid surgery
• Why have we lost the dementias
• Why are we so late with neonates
Customer Satisfaction
Quality Value
Service
04/12/23 4
Customer Requirements
• Why have we not taken over the intensive care units
• Continuous monitoring in coma
• Non-convulsive status
• P.O. in neurosurgery and cardiac surgery
Customer Satisfaction
Quality Value
Service
04/12/23 5
A fully digital neurophysiology unit
• Service of Neurophyisiology, Hospital Nossa Senhora das Graças
• Hospital Unit: 2 beds for sleep and videomonitoring; adults and children;
• Stellate Systems: Monitor, Rhythm, Eclipse
• 2 Medelec Discovery• Ojemann’s cortical stimulator• Amytal test: Montreal, Seattle
04/12/23 6
Meeting the Needs
• The cardiologists
• Holter for rhythm and ischaemia; doppler echocardiogram, doppler stress tests
• tilt test
20 min EEG
mapping
One hour EEG
videomonitoring
polygraphyShort sleep study: apnoea
Full night sleep study
Multiple latency
CPAP studies
neonatal
Brain death
monitoring
04/12/23 7
How the service came about
• Decision was to start epilepsy surgery program in 1990/91/92 (Palm Desert)
• Visit main Scandinavian units in January/92
• Stellate: versatile, modules, reliable, cost/ benefit
• Agreement with surgeons in 1993, difficult failure in 1992
• Acquisition of material from mid-1993
04/12/23 8
Steps
• Rhythm 9/93: 1st Amp; hardware• Monitor 2/94; Monitor 2/95: 2nd• Eclipse 2/96• Monitor 96/97: 3rd • Portable 96• Digital EcoG 97• Subdurals 98• No upgrade in 1999, 2000 (Harmonie,
Luna, Sensa)
04/12/23 9
Neurophysiology service: ideal
• 24h, 7 days a week• Same day reports• digital radical• 16-32-64 channels• Techical nursing staff• Capability in all areas, all ages• User-friendly imaging reports
04/12/23 10
Traditional EEG Services
• 20 min paper exams• Pirate mapping• Very obscure reports• Very doubtful clinical relevance• Relevance of photic stimulation,
awake and sleep studies, hyperventilation
04/12/23 11
Digital EEG in 2000
• user-friendly: kind of exam, problem-solving report
• neonatal, developmental• Awake and sleep in infancy without
sedation• Dopamine-blocking agent rather
than barbiturate• Behavioural neurology: with SPECT
04/12/23 12
Neonatal, prematures
• Sleep, awake, other states• EEG prognosis for development • video-polygraphy essential for events• Frequent repetition of exams• ICU monitoring not used• prematurity much more complex• cognitive prognosis of hypoxia,
trauma, prematurity
04/12/23 13
EEG neonatal, prematuros Kellaway, Mizrahi, Plouin, 1998
• Interictal epileptogenic patterns are not well defined in children
• Ictal patterns are similarl to adults; one is alpha and another is depressed brain seizure patterns
• EEG/video shows localization patterns in almost all secondary generalized epilepsies, including infantile spasms
04/12/23 14
Digital videopolygraphy
• Not possible with mapping packages
• ideal 1-3 h; sleep and awake• Include breathing, eye movement,
emg, ecg, oxymetry • Infantile spasms are all localized
onset• non-convulsive status is
underdiagnosed
04/12/23 15
Longterm EEG videomonitoring
• Impossible in paper• Detection of seizures and spikes
essential for subclinical seizures,focused reporting, focused recording, night and day
• Electrodes and gel imported• 32 channels; 25 used; sphenoidals• double banana, transverse, referential• Individualized drug withdrawal produces
seizures in 12-72 horas
04/12/23 16
Mapping of the background activity
• epilepsy: withdrawal of AEDs, cognitive effects of drugs and seizures
• MRIs with UWOs• encefalopathies, dementias• Behavioural syndromes in any age• Effects of sedative drugs• + SPECT + IQ + MR: dementias
04/12/23 17
Digital Real Time Eletrocorticography
• Medelec Discovery + Grass crown• Simple, reliable• Low cost, high benefit• Cortical stimulation more complex• Paper not necessary• Underused: complex original
technique• Avoids dedicated special room
04/12/23 18
The digital EEG technician
• IQ above 100• Capacity and will to learn and to
read English• Nurse technician with hospital
experience of very sick patients and children
• Training possible in 2-6 weeks• Serious legal working problems
04/12/23 19
Continuous monitoring of the EEG
• Analog record and compressed arrays
• trauma, hypoxia, hydrocephalus• Intracranial hipertension• Subaracnoid hemorrhage• Versus transcranial doppler,
monitoring of intracranial pressure• Non-convulsive status• Problem is interpretation: modem;
physician, nursing staff
04/12/23 20
Neurointensive medicineChesnut, Brock, Krieger, 1998
• Nurses and physicians control pentobarbital in status or ICH: EEG decisive in 54%, helpful 32%, not useful 14% de 200 cases
• 20% of trauma with convulsive or non-convulsive status: % alpha energy
• stroke, SAH, trauma, hypoxia, metabolic
04/12/23 21
Carotid endarterectomy
• shunt: disappearance or asymetric slowing of background fast activity
• Anesthetics provoke stable fast activity
• EEG pre-op is helpful• More necessary without
arteriography• Routine in many american centers
04/12/23 22
Carotid endarterectomy
• WAR: widespread alpha/beta anterior representation of background
• Decrease to 50-60%: shunt• or teta/delta increase of 50-60%• Risk of infarct 10% with bad EEG
without shunt• C. William Erwin, 1998, ACNS
04/12/23 23
Spectral analysis in dementias
• Posterior background, relaxed, eyes closed :13.00 >alpha>8.00Hz
• Anxiety: low amplitude• Alzheimer: below 6Hz• vascular: asymetric• Parkinson: 7-8Hz, symetric
04/12/23 24
Background activity in wakefulness
• Below 8Hz + beta: drug induced• benzos + sedatives: beta + teta• Any structural damage: slow• Demonstrated historically in any
EEG textbook• Sandmann et al 1995• Median, power, uV, 4-13Hz, 8
posterior derivations in referential montage
04/12/23 25
Problems
• Reimbursement– Low– Procedures not recognized by HMOs– US$ 120 for sleep study– US$ 20 for 20 min EEG– US$ 200 for 24h of videomonitoring– Monitoring and EcoG not specified
04/12/23 26
Problems
• Personnel– Degree of training too high for
compensation: physicians and technicians
– Recognition by customers low: patients, intensive care physicians, surgeons
– No profit, no vanity– ?The future– Probably too late and too complex
04/12/23 27
Present team
• Sleep specialist: locally trained neurologist
• Neonatal specialist: Harvard ex-fellow, PhD, pediatric neurologist
• Epileptologist: ex-Bethel fellow• General neurophysiologist
04/12/23 28
Capital + maintenance costs
• Investment: US$ 40000 per bed (3) + US$ 25000 per portable machine (2)
• Total investment: US$ 250000.00• Gross income: US$ 12500.00 per month
(5%); • 40% physicians: reporting• 25% maintenance• US$ 4375.00 (1.75% per month) net• Update systems?
04/12/23 29
Is neurophysiology doomed?
• Yes, UK; almost, Switzerland, not yet, USA
• Middle of the road, other environments
• Squeezed by imaging, doppler: intensive physicians, surgeons, neurologists
• ?Solution: subspecialty of neurology• Solution: digital, simple, cost/effective
04/12/23 30
Thank you