Emergent EEG is helpful in neurology critical care practice

Emergent EEG (eEEG) is increasingly used in critical care practice related to neurological disorders although it involves considerable reorganization in the neurophysiology department at high cost. There is little data regarding the usefulness of eEEG in acute care situations. Our objective was to audit the practice and utility of eEEG in critical care practice in a developing country.

This study was carried out in a tertiary care neurological center situated in a developing country. We had defined eEEG as any EEG performed on a non-elective basis upon request from a clinician for a seemingly emergency indication. All eEEGs performed in the neurophysiology service between October 2002 and September 2003 were reviewed. Referral diagnosis, delay in execution, final diagnosis and outcome were analyzed. eEEG was classified as useful if it clinched a diagnosis, excluded a specific diagnosis or helped in management. Statistical analysis was performed using the chi2 test or Fisher's exact test when indicated. The referral diagnosis and eEEG characteristics were correlated with the utility of the eEEG. Those with P-value <0.05 were considered significant.

There were 286 eEEGs (males 160, mean age 40.6 +/- 23.5 years) among 2798 EEGs (10.2%) performed in the service. eEEG was performed within 24 h in 241 instances and the mean interval from request to formal reporting was 1.13 days. In 62.1% instances eEEG was classified as useful. Usefulness varied according to the referral diagnosis: status epilepticus (n = 41, 100% useful; P = 0.000), brain death (n = 28, 100% useful; P = 0.000), nonconvulsive status (n = 54, 96.3% useful; P = 0.000), recurrent seizures (n = 42, 81% useful; P = 0.006), hypoxic encephalopathy (n = 36, 80.6% useful; P = 0.016), encephalitis (n = 63, 42.9% useful; P = 0.001), metabolic encephalopathy (n=64, 37.4% useful; P = 0.000) and acute demyelination (n = 20, 25% useful; P = 0.001). eEEG findings included epileptiform discharges (n=58), periodic lateralized epileptiform discharges (n=27), discrete seizures (n = 28), nonconvulsive status (n = 12), status epilepticus (n = 8), triphasic waves (n = 15), generalized suppression (n = 22), burst suppression (n = 9), alpha-theta coma (n = 7), electro cerebral silence (n = 2), focal and generalized slowing (n = 172), focal and generalized nonspecific dysfunction (n = 87), and no abnormalities (n = 24). Only discrete seizures (P = 0.000), nonconvulsive status (P = 0.004), generalized suppression (P = 0.004) epileptiform discharges (P = 0.047), and alpha-theta coma pattern (P = 0.047) were significantly correlated with usefulness.

eEEG provided data that influenced clinical decision-making in the setting of epilepsy related situations, hypoxic encephalopathy and brain death examination.

eEEG can provide useful information in selected clinical situations in neurological critical care. The service needs to be called upon judiciously in order to improve the efficacy of this service.