10/18/10 1 Digital EEG in 2000

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

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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

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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

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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

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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

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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

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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)

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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Present team

• Sleep specialist: locally trained neurologist

• Neonatal specialist: Harvard ex-fellow, PhD, pediatric neurologist

• Epileptologist: ex-Bethel fellow• General neurophysiologist

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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?

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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

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Thank you