What is The Role of Frontal Intermittant Rhytmic Delta Activity (FIRDA) in The Cerebral Lesions? Evaluation of 20 Patients

Frontal intermittent rhythmic delta activity (FIRDA) is a frequent transient electroencephalographic finding in adults. Its pathophysiologic significance is unknown. So far clinical, laboratory and neuroimaging findings related to FIRDA have been reported in the literature but the relation between cerebral lesions and FIRDA is not clear. We want to discuss this EEG presentation and its related pathologies in the light of our patients' findings. All electroencephalograms (EEGs) with FIRDA, between January 2009 -December 2014 at our institution were identified. Demographic data, clinical history, laboratory results and neuroimaging studies were recorded. We identified 20 patients with this electrographic pattern. EEGs were performed because the possibility of seizures in 8 patients, altered state of consciousness in 10 patients, forgetfulness in 1 patient. In 1 patient there was no any complaint. Amongst the 20 patients with FIRDA, 6 had asymmetric pattern on EEG. Renal function impairment was present in 1 patient and 1 patient had elevated serum ammonia level. Cranial imaging was abnormal in 11 of 19. Intrahemispheric lesions, hemorrhage, encephalomalacia, tumor, were present in 5, and basal ganglia hemorrhage in 1. In 1 patient, hydrocephalus was detected. In conclusion, we observed that various etiologic factors can play an important role in the development of FIRDA and in our group, cerebral lesions are more common. Location and type of the lesions do not make any difference. But in acute cerebral lesions, asimetric pattern can be seen and this could give an idea about the location of pathology.