Ictal Dysprosodia: Documentation by Fourier Spectral Analysis

Introduction: Dysprosodia in the literal sense is the disturbance of the speech melody which usually transports emotional contents of language. It accompanies sometimes aphasias but appears typically without aphasic symptoms in lesions of the non-dominant right hemisphere. Dysprosodia as an ictal phenomenon, however, is reported rarely. Methods: We report on a patient with dysprosodia during ictal speech. Ten seizures were documented by video EEG monitoring. The sound track of the video was then analyzed by Fourier spectral analysis. Results: The 22-year-old woman had suffered from epilepsy since age 13 years, she reported an abdominal aura and psychomotor seizures. As a possible precipitating event there had been febrile seizures at the age of 13 months. MRI showed a right-sided hippocampal sclerosis. Interictal epileptiform discharges had their maximum on the right sphenoidal electrode and, rarely, the right temporal anterior one. We recorded 2 isolated auras without EEG seizure pattern and 8 psychomotor seizures, in all of them we recorded a right temporal EEG seizure pattern. During the psychomotor seizures with mainly oral automatisms the patient remained responsive and could name objects and talk to the EEG assistants, but the speech melody was severely disturbed and sounded unnaturally monotone. The characterization of the dysprosodia by Fourier spectral analysis revealed that the monotone character of the speech was produced by superposition of a „wrong“ speech melody and not simply by reducing the pitch range. There was an increasing glissando over an interval of up to a fifth over most of the ictal utterances instead of the falling of the tone in a declarative sentence. In the end of the seizures the normal speech melody gradually reappeared, but the modulation of the pitch was diminished. Another feature in this patient was an increase of the pitch level of about a third. Conclusions: Dysprosodia can be a prominent feature of epileptic seizures. We documented this symptom in a classical mesial temporal lobe epilepsy of the non-dominant hemisphere. Dysprosodias may often be unrecognized as they are difficult to describe and prove objectively. Fourier spectral analysis may help in the documentation and description of ictal prosodic changes.