ELECTROENCEFALOGRAFÍA: APLICACIÓN EN LOS ESTADOS DE COMA

ELECTROENCEFALOGRAFÍA : Registro de la actividad bioeléctrica de la corteza cerebral (espontánea) mediante electrodos colocados sobre el cuero cabelludo.

LAS MASA CORPORAL ESTA MAYORMENTE CONSTITUÍDA

POR SOLUCIONES IÓNICAS. LAS CORRIENTES GENERADAS POR LA ACTIVIDAD DE CÉLULAS

EXCITABLES CIRCULAN POR ESE VOLÚMEN CONDUCTOR Y PUEDEN

SER MEDIDAS EN SU SUPERFICIE.

LA MASA CORPORAL ESTA MAYORMENTE CONSTITUÍDA

POR SOLUCIONES IÓNICAS.

UNA CÉLULA EXCITABLE ACTIVADA SE COMPORTA COMO

UN DIPOLO.

IPSP

EPSP

IPSP

EPSP

SISTEMA INTERNACIONAL 10-20 FINC

A – MONTAJE REFERENCIAL

B – BIPOLAR LONGITUDINAL – DOBLE BANANA

C – BIPOLAR TRANSVERSAL

MONTAJES HABITUALES

LA ACTIVIDAD BIOELECTRICA

DE LA CORTEZA CEREBRAL ES:

-ESPONTÁNEA

-PERMANENTE

-RÍTMICA

ELECTROENCEFALOGRAFÍA : Registro de la actividad bioeléctrica de la corteza cerebral (espontánea, rítmica y permanente) mediante electrodos colocados sobre el cuero cabelludo. Variaciones de potencial eléctrico (microV) en función del tiempo. Rítmica: Frecuencias DELTA 0.5 c/s – 3.5 c/s Hz THETA 4 c/s – 7.5 c/s ALFA 8 c/s – 13 c/s BETA 13.5 c/s – 22 c/s GAMA 30 c/s - ? Transitorios Amplitud

TRANSITORIOS EPILEPTOGÉNICOS-EPILEPTIFORMES

MONITOREO EEG CONTÍNUO * VALORACIÓN CONTÍNUA DE FUNCIÓN CORTICAL * DETECCIÓN PRECOZ DE FENÓMENOS INTERCURRENTES CRISIS EPILÉPTICAS – STATUS NO CONVULSIVO * VALORACIÓN DEL TRATAMIENTO * VALORACIÓN PRONÓSTICA

ESTADO FUNCIONAL DE LA CORTEZA CEREBRAL

* MODELO FARMACOLÓGICO:

- ACTIVIDAD ALFA CON THETA MEZCLADA

- ACTIVIDAD THETA

- ACTIVIDAD THETA/DELTA

- ACTIVIDAD DELTA

- BROTES- SUPRESIÓN

- EEG DE SUPRESIÓN

* REACTIVIDAD Y VARIABILIDAD EN EL TIEMPO: EEG SERIADOS-MONITOREO

CONTINUO

CLASIFICACIONES ELECTROENCEFALOGRÁFICAS PARA EL COMA

HOCKADAY SYNEK

GRADO 1: ALFA DOMINANTE ± THETA BENIGNO: IGUAL QUE 1 Y 2,

SPINDLE COMA GRADO 2: THETA DOMINANTE± ALFA

GRADO 3: THETA DOMINANTE INCIERTO: IGUAL QUE 3, DELTA,

ALFA COMA

GRADO 4: ACTIVIDAD DELTA, ALFA/THETA

COMA, COMPLEJOS PERIÓDICOS MALIGNO: IGUAL QUE 4 Y 5,

THETA COMA, BROTES-SUPRE-

GRADO 5: EEG DE SUPRESIÓN SIÓN

EEG ICTAL

EEG INTERICTAL

TRANSITORIOS EPILEPTOGÉNICOS-EPILEPTIFORMES

EEG ICTAL

* ATENUACIÓN TRANSITORIA DE LA AMPLITUD

* ELEMENTOS EPILEPTOGÉNICOS RÍTMICOS * RITMOS PAROXÍSTICOS * DESCARGAS PERIÓDICAS (SEUDO-PERIÓDICAS) * WAXING AND WANING

“The 3 Hz cutoff used as a criterion for the frequency of repetitive epileptic discharges in NCSs is somewhat arbitrary. It is important to note that vwhen these criteria are not fulfilled, NCSE has not been excluded, it simply cannot be ruled in definitively. In other words, the criteria in the Table are specific but not sensitive. In many real-world situations the ultimate interpretation of ictal vs. non-ictal remains unclear even with expert EEG’ers and proper trials of benzodiazepines.” “NCSE cannot be definitively diagnosed simply based on the resolution of an EEG pattern without clinical improvement in the typical scenario if one large bolus of benzodiazepine is given.”

J. Jirsch, L.J. Hirsch, 2007

COMPLEJOS PERIÓDICOS:

• ONDAS TRIFÁSICAS

• CREUTZFELDT-JAKOB

• PLED - PERIODIC LATERALIZED EPILEPTIFORM DISCHARGES

BI-PLED, GPD

INFARTO CEREBRAL, LESIÓN OCUPANDO ESPACIO, INFECCIÓN

PERIODIC LATERALIZED EPILEPTIFORM DISCHARGES - PLED

“In their typical form the PLEDs consisted of sharp wave discharges repeating periodically or quasi-periodically at rates generally close to 1/sec and separated by intervals of apparent quiescence.” G.E. Chatrian, 1963

Periodic Discharges (PDs): Periodic = repetition of a waveform with relatively uniform morphology and duration with a quantifiable interdischarge interval between consecutive waveforms and recurrence of the waveform at nearly regular intervals.* Discharges: These are defined as waveforms with no more than 3 phases (i.e. crosses the baseline no more than twice) or any waveform lasting 0.5 seconds or less, regardless of number of phases. This is as opposed to bursts,defined as waveforms lasting more than 0.5 seconds and having at least 4 phases (i.e. crosses the baseline at least 3 times). * “Nearly regular intervals” is defined as having a cycle length (i.e., period) varying by <50% from one cycle to the next in the majority (>50%) of cycle pairs.

PLED = ¿CRISIS EPILÉPTICA (STATUS)?

“Several questions remain to be answered, in part because most studies of PLEDs have been retrospective. For example, what is the true incidence of PLEDs and their relationship to seizures? Should patients with PLEDs on an EEG be treated prophylactically with an anticonvulsant? ” Pohlmann-Eden, Bernd*†; Hoch, Daniel B.†; Cochius, Jeffrey I.†; Chiappa, Keith H.†, 1996

“The majority of patients with PLEDs will have seizures during the acute stage of illness and the PLEDs usually will be transiently replaced by a new pattern, often consisting of faster rhythmic activity (Fig. 7B). For this reason PLEDs are usually considered an interictal pattern, although not all agree (Assal et al., 2001; Garzon et al., 2001; Handforth et al., 1994). In several studies of NCSE, PLEDs alone were not considered an ictal pattern (Claassen et al., 2001; Jordan, 1999; Jaitly et al., 1997). Pohlmann-Eden et al. (1996) viewed PLEDs as an electrographic signature of a dynamic pathophysiological state in which unstable neurobiological processes create an ictal-interictal continuum.”

Richard P. Brenner, 2004

“Periodic discharges should clue the clinician into the high potential for seizures and status epilepticus, including nonconvulsive status epilepticus. We currently recommend conventional AED coverage to manage any occurrence of periodic discharges.” Derek J. Chong and Lawrence J. Hirsch, 2005

SIRPID: stimulus-induced rhythmic, periodic, or ictal discharges

LIDOCAINA

BENZODIAZEPINA

EJEMPLO MONITOREO CORTICAL SPRED