Introduction. Infantile massive spasms (IMS) is an age-dependent epileptic syndrome that appears before the first year, and is characterised by delayed psychomotor development, massive spasms and hypsarrhythmia. There are classifications that only take the electroencephalogram (EEG) into account, without linking it with the IMS-associated crisis pattern which can establish a treatment to improve the recurrence of the crises in this population, according to EEG discoveries and patterns of epileptic fits. Patients and methods. We include 100 EEGs of patients diagnosed with IMS, between 2 and 12 months old, selected by using the classification of Hrachovy to identify classic and modified hypsarrhythmia, and to correlate it with the pattern of epileptic seizures associated with IMS. Results. The hypsarrhythmia found was mainly of the modified variety, and classic hypsarrhythmia only accounted for 9% of cases. The first case presented flexion IMS with generalised tonic seizures, and in the second, generalised tonic seizures and mixed IMS. Start age was between 2 and 4 months old. Conclusions. In comparison with results in other publications, in the EEG it was found that modified hypsarrhythmia with IMS-associated partial and generalised tonic seizures with was the most common, while in the classic variety mixed IMS predominated. It must be taken into account that the absence of this variety does not rule out a diagnosis of IMS, but its presence makes the prognosis worse.
