ABSTRACT:

Purpose of the study:

Voluntary hyperventilation (HV) has been widely used in clinical EEG laboratories as “activation method” to enhance preexisting abnormalities and / or induce abnormal findings in an otherwise normal electroencephalogram(EEG).The present work was done to,

a. compare the incidence of epileptiform activity during hyperventilation test on the EEGs of normal and epilepitics.

b. Quantification of Changes in different seizure categories like

(a) Absent, (b) Focal and (c) Generalized.

Methods: EEGs were recorded using hyperventilation test as activation procedures in 50 patients, who were proven cases of epilepsy with different seizure categories and compared with 50 age and sex matched normal subjects. Effects of hyperventilation test on EEG were recorded and changes were analyzed statistically.

Results: Hyperventilation test had a moderately significance result in activation of Interictal epileptiform discharges (IEDs) (P=0.012).

Effect of activation was seen maximally in patients of generalized seizures especially in GTCS and Absence seizures (40%).

Interpretation and Conclusion: This work suggests that Hyperventilation test provoke epileptiform changes in EEGs Of epileptic patients and hence increase the yield of EEG recordings.

Keywords:. Electroencephalogram, Hyperventilation, Interictal Epileptiform discharges.