Abstracts

Rationale:
The primary auditory cortex, or Heschl’s gyrus, lies in the medial portion of the superior temporal lobe. Studies have identified the tonotopic organization of the auditory cortex, mirroring the principle in the cochlea where there is a spatial separation of the processing of different frequencies. This is vital in the discrimination of the pitch of sounds and the processing of human speech. Less understood is the precise neural mechanism and if specific areas within Heschl’s gyrus selectively process non-speech sound patterns. In focal epilepsy, seizure related auditory phenomena as aura may suggest involvement of Heschl’s Gyrus. However, the variable presentation of these auras may lead to difficulty with identifying the clinical relevance of their sequence in the clinical semiology of seizures. Here we describe a “helicopter blade” sound as part of the auditory aura in two patients, which is reproduced during electrical stimulation of Heschl’s gyrus. 

Methods:
Two patients with refractory focal epilepsy, both with phase I evaluation suggesting left temporal onset, and both with auditory aura as part of typical seizure semiology were admitted at the University of Kentucky Epilepsy Monitoring Unit for phase II evaluation. They underwent stereotactic electroencephalography (sEEG), with primary left temporal targets, as well as electrical stimulation, which elicited the observed findings.

Results:
The first patient is a 28 year old, whose auditory aura initially consisted of random music but has evolved into a ringing sound over the years. He endorsed a “helicopter sound” heard in the right ear more than the left, upon low-voltage stimulation (1.5 mA) of left sided Heschl’s gyrus. Final sEEG results indicated a regional left neocortical temporal epileptogenic network, with independent epileptogenicity over the left amygdalohippocampal complex. The second patient is a 44 year old who complained of auditory aura, sometimes “helicopter blade-like,” as initial manifestation of her seizures. She reported hearing the helicopter sound in only her right ear upon low voltage stimulation of left sided Heschl’s gyrus. Similarly, sEEG conclusions suggested regional left neocortical temporal epileptogenic network, with independent epileptogenicity over the left amygdalohippocampal complex. Both patients underwent responsive neuro-stimulation placement with one lead stimulation targeting Heschl’s gyrus, with the latter experiencing worthwhile seizure reduction, and the former pending follow up




Conclusions:
We present two patients with a “helicopter blade sound” auditory aura evoked upon stimulation of Heschl’s gyrus, a location with early involvement in the symptomatogenic zones of their epileptogenic networks. These symptoms may be of localizing value when described as a component of aura in focal epilepsy.

Funding: None