Journal of Clinical Neurology (Seoul, Korea) | 2021
Nondominant Temporal Lobe Epilepsy With Dysprosody: Qualitative and Quantitative Acoustic Analysis
Abstract
Dear Editor, Prosody refers to the important features of intonation, accent pattern, and rhythm in language. Dysprosody is defined as the loss of language melody, and has been reported in various neurological diseases including cerebrovascular disease, epilepsy, Parkinson’s disease, and Huntington’s disease. Ictal dysprosody is easily recognized in patients with epilepsy, but its incidence has been underestimated and it is rarely reported. A 26-year-old, right-handed male college graduate was admitted to our epilepsy clinic for a presurgical evaluation. He reported seizures consisting of focal impaired awareness automatisms several times per month, which evolved to bilateral tonic-clonic seizures once yearly while on valproate, zonisamide, levetiracetam, and carbamazepine. Caregivers reported that he said random words or sentences during the seizures. Brain MRI showed communicating hydrocephalus and right hippocampal sclerosis (Fig. 1A). Brain 18F-fludeoxyglucose PET showed hypometabolism in the right anterior to posterior temporal regions, especially involving the mesial temporal area. An intracarotid amobarbital test demonstrated that he had a left-sided language center. Video-EEG monitoring for 3 days recorded six seizures. Interictal EEG showed frequent epileptiform activity localized to the right anterior temporal region. Seizure semiology was an unclassified aura that evolved to automotor seizures with lip smacking and right-hand fumbling, followed by random speech. Ictal speech utterances consisted of repetitions of typical Korean expressions such as “mama” and “where am I?” Ictal EEG showed all six seizures with a maximum amplitude over the right frontotemporal electrodes (Fig. 1B and C). Subtracted ictal-interictal SPECT coregistered with MRI revealed hyperperfusion at the right temporal pole and anterior temporal region. A high-quality recording of involuntary speech utterances during the ictal state revealed that the ictally registered words were repeated interictally. Qualitative and quantitative analyses were applied to the ictal and interictal speech samples. Qualitative analysis by speech-language pathologists of the ictal speech revealed high pitch and intensity. The quantitative analysis was performed using Computerized Speech Lab Model 4150 software, which reveals the frequency peaks and loudness of a sound. The pitch of the sounds was 217.7±26.1 Hz (mean±SD) ictally and 145.1±18.3 Hz interictally, while their loudness was 77.8±5.6 dB and 74.1±3.0 dB, respectively. A quantitative analysis showed that the ictal sounds had a higher pitch and were louder than the interictal sounds (Fig. 1D and E). The brain network responsible for prosodic processing is still controversial. From the aspect of functional properties of prosody, affective prosody plays a predominant role in the right hemisphere, whereas linguistic prosody is preferentially processed in the left hemisphere.1 On the other hand, the processing of affective and linguistic prosody involves both hemispheres based on interhemispheric crosstalk. With respect to the characteristic properties of prosody, the right hemisphere is dominant for pitch information, while the left hemisphere may be reKyoung Jin Hwang Jiyoung Kim Dae-Won Seo