Authors :
Lydia Wolkiewicz, MD – Northwestern University
Stephen VanHaerents, MD – Northwestern University
Scott Adney, MD, PhD – Northwestern University
Jessica Templer, MD – Northwestern University
Yajing Xiong, MD – Northwestern University
Varun Kumar, MD – Northwestern University
Dina Ghandour, MD – Northwestern University
Presenting Author: Priya Sharma, DO – Northwestern University/Lurie Children's Hospital
Joshua Rosenow, MD – Northwestern University
Vasileios Kokkinos, PhD, PhD, PhD, CNIM, CMEG, NA-CLTM, FACNS – Northwestern University
Rationale: Ictal humming is a rare epileptic phenomenon, most often manifesting during temporal lobe epilepsy (TLE) seizures, associated with lateral temporal neocortical involvement. In this work, we investigate this unique semiology in terms of hemispheric laterality and associated ictal electrographic features in a bilateral TLE case invasively investigated by stereo-EEG (sEEG).
Methods:
A 24-year-old left-handed female with refractory TLE underwent sEEG investigation, with seizures characterized by early onset of humming and unresponsiveness, often followed by late manual automatisms. Ictal humming manifested in a stereotyped manner, with a quavering crescendo quality. Temporal lobe seizures of bilateral independent onset were captured. Invasive sEEG coverage was based on a primary right TLE+ and a secondary left TLE hypothesis. The seizure onset pattern was marked at the beginning of low-voltage fast activity (LVFA). The onset of ictal propagation activity was marked by either focal LVFA or focal rhythmic sustained alpha/theta/delta activity. The spectral profile of ictal activity for each cortical and subcortical region of interest was compiled in the time-domain using 1-sec window frequency measurements. Statistical comparisons were performed by means of two-tailed t-test.
Results:
During her sEEG, three clinical seizures were captured: SZ1 originated in the right temporal lobe and spread to the left temporal lobe, accompanied by humming (8 sec from the onset) and unresponsiveness; SZ2 originated in the left temporal lobe and spread to the right temporal lobe, accompanied by humming (10 sec from the first right temporal ictal change) and unresponsiveness; SZ3 same as SZ2 but without humming.
In SZ1, after the humming onset and up to 20 sec from the iEEG onset, the mean frequency of ictal oscillations per region was: Lateral pole: 13.46±8.12Hz (range:7-34Hz); aSTG: 7.92±1.60Hz (4-9Hz); pSTG: 9.07±2.13Hz (8-16Hz); MTG: 10.46±2.84Hz (7-16Hz); ITG: 5.07±3.45Hz (2-12Hz). In SZ2, for the same interval, the mean frequency of ictal oscillations per region were not significantly different from SZ1: Lateral pole: 8.90±1.75Hz (3-42Hz, p=0.8274); aSTG: 11.09±7.00Hz (3-31Hz, psz1=0.1894); pSTG: 10.18±3.62Hz (5-20Hz, psz1=0.3644); MTG: 11.63±3.10Hz (9-20Hz, psz1=0.3444); ITG: 5.90±3.61Hz (2-11Hz, psz1=0.5706). In SZ3, where no humming occurred, the mean frequency of ictal oscillations per region was: Lateral pole: 2.18±0.40Hz (2-3Hz, psz1< 0.00001*, psz2< 0.00001*); aSTG: 6.35±2.87Hz (3-10Hz, psz1=0.0154*, psz2=0.0306*); pSTG: 6.70±3.36Hz (2-11Hz, psz1=0.0413*, psz2=0.0348*); MTG: 4.9±3.84Hz (2-12Hz, psz1=0.0006*, psz2=0.0002*); ITG: 5.18±3.60Hz (2-12Hz, psz1=0.4669, psz2=0.3070), revealing statistically significant changes of the ictal pattern in the lateral pole, MTG and STG.