Yanny and Laurel explanation

Two days ago a BBC news announce that the computer generated word "Laurel" produced an internet debate if this is heard as "laurel" or "yanny".

The sound specialists run to explain how the humans are losing the higher frequencies listening ability with the age and this why we might listen the world with lower frequencies as is would be "laurel".
I was listening the playback and for two days since the Head of Neurology Department and one colleague told me the story and the new internet debate news, I always had listen the "yanny" word.
30 minutes ago I started to listen "laurel" word.
Yes, I know the word was created by computer and is an artificial voice the human cannot reproduce. The sounds are fake and the frequency differences are very difficult to assess by a computer voice generator. I remember the applications when you press a word text and suddenly you could listen it. This happened more than 6-7 years ago. There was no tonality, no stops or pause between words, no comma. You had to do everything.
But what happened to me? Why did I hear "laurel".
I did something before changes occurred. And I said to me, yes.
The gabaergic neurons from my cortex are weaker (the inhibitory mechanisms of my cortex were diminished by the substance intake)  and the sub-cortical areas and temporal lobe auditory cortex or let us say the auditory biological neural network is now a little bit more "awake"  and can hear the lower frequency. Or the higher frequencies are perceived with more glutamatergic (excitatory neurons) mechanisms? Is this known?
Ono et al 2017 found that responses to pure tones of both inhibitory and excitatory classes of neurons were similar in their thresholds, response latencies, rate-level functions, and frequency tuning, but GABAergic neurons may have higher spontaneous firing rates.

The auditory phantom perception biological neural network (BNN) 

involved in the subjective tinnitus perception

Conclusion:
The debate is easy: We are in front of unknown auditory perception mechanisms of a fake *artificial* sound. It seems that all is in our brain and that the gabaergic inhibitory mechanisms are involved. As much as you approach the freedom of the deeper brain structures (by forming gaps in the cortex "analytical" system) you will listen differently the word.

by Neurophysiology Plus Iceland, 18.05.2018

Cerebellopontine angle (CPA) mass IONM

by Neurophysiology Plus Iceland © 2018

IONM in 31 year-old male patient with 43/41mm right cerebello-pontine angle (CPA)  tumor

(e-Bulletin report)

We performed the following modalities:

Transcranial MEP, Corticogeniculate MEP (CoMEP), SSEP from both tibialis nerve, EEG, mapping cranial nerves (accesorius, hypoglossus, glosopharingeal, facialis ), BAEP, TOF, Blink Reflex.

Results: All modalities could be performed with exception of blink reflex which was not elicited.

Incidents: At the end of the surgery we observed decrement of right facialis (Orbicular oris muscle), CoMEP decrement of more than 80% which did not recover throughout the rest of the surgery. Surgeons explained that "there was a bleeding around the nerve". They started cooling,  irrigate and "treat" the lesion.  Mapping showed also partial decrement, but recovered after 20 minutes when stimulation was performed proximally.

Our protocol for corticobulbar MEP was double train: 1st train formed by 5 stimuli with 50 ms duration (ISI 2ms), 2nd train (single pulse 50 ms)  ITI (inter-train interval) 40 ms.

LIMIT: The assessment was possible for the right Orbicularis oris muscle and slightly for the right Orbicularis oculi muscle. No responses were obtained from the left muscles (we didn´t increase the stimulus intensity to look for the better Threshold-level ) and we consider the absence of other muscle MEP ipsilaterally (e.g. mentalis) as a serious limit of interpretation.

Right Orbicularis oris Corticogeniculate MEP decrement

Mapping with 0,3 mA baseline

Mapping with 0,86 mA (after the decrement was seen in CoMEP)

Conclusions:

Ø  All modalities with exception of  CoMEP showed similar findings at the end as at the beginning of the surgery. R1 (Trigeminofacial reflex) was not possible to elicit during this surgery.

Ø  Mapping was useful to drive the surgery moments before debulking and after the surgical removal of the tumor.  We expect partial facial nerve dysfunction (temporary deficit) in the right side.

Ø  24h after surgery, the patient showed 60% function of facial nerve preserved, Grade III (of VI) on House-Brackmann. Other VIII, IX and XII monitored cranial nerves didn´t show deficit 24 h after the surgery.

Ø  CoMEP as a measure of corticogeniculate motor tracts with different and variable assessment protocols should be considered as mandatory when trigeminofacial reflex (R1) cannot be monitored and the interpretation of the amplitude loss should be verified with anesthesist, neurosurgeons and with T-L technique (Calancie B, 2017).

Reference:

Intraoperative Neuromonitoring of CPA mass by Alba León Jorba & Ovidiu C. Banea (Oct 2014 IMGB)

Neurophysiology Plus Iceland is represented at TMS-workshop in Denmark

by Ovidiu C. Banea

Questions for TMS research scientific community in Denmark

From November 22nd to November 24th 2017, Danish Research Center for Magnetic Resonance (DRCMR) will host a new TMS workshop with special focus on multimodal combinations of TMS with other neuroimaging techniques (EEG-TMS, fMRI-TMS). 

DRCMR is located in Hvidovre Hospital, a university hospital located at 9 km from Copenhagen which is administered by the Capital Region of Denmark.

Neurophysiology Plus will be represented at this meeting but also during the 20th to 22nd period for a better understanding of the center facilities, protocols used and technical equipment. 

We look mostly to have a valuable and critical analysis input from the team leaded by Prof Dr Hartwig Roman Siebner on the Icelandic proposed study. 

In this proposed clinical applied research project members of Neurophysiology Unit and Neurosurgery department from Reykjavik University and National University Hospital of Iceland are trying to analyze if TMS-EEG modality can be used or not to assess functional cortical tissue and brain effective connectivity in patients with brain tumors. 

In Iceland, another simple technique, TMS motor evoked potentials (TMS-EMG) started to be used for preoperative mapping in 2016. We set and marked the position for the intraoperative direct stimulation (IONM) as in the nineties when this technique was described. 

On the beginning of November 2017 neurosurgery department was interested on this procedure of preoperative mapping with neuronavigation. Again we used the available devices and we were able to map motor hotspots of the upper limb and speech area in a healthy subject. On 28th of November the team will investigate and perform motor and speech mapping in two patients with brain tumors located in eloquent areas of the brain. It will be for the first time that neuronavigated mapping is applied and used for the Icelandic brain tumor patients.

And the question remains: Is there a reason to believe that TEPs (TMS-EEG evoked potentials) can be used to assess better the "non-eloquent" brain cortical tissue and give a better map of the non-affected brain areas in order to avoid new post-intervention neurological deficit in patients with brain tumors ?

TMS-EEG evoked potentials (TEPs) in Iceland

29th of Sept 2017 Reykjavik Iceland

TMS-EEG evoked potentials (TEP) were performed during a joint meeting of Clinical Neurophysiology Unit team (Neurophysiology Plus Iceland) and Icelandic Center of Clinical Neurophysiology from Reykjavik University.
The meeting was organized by Assist Prof Dr Paolo Gargiulo (Director of Institute of Biomedical and Neural Engineering, Reykjavik University & Landspitali) and had as participants Dr Magnús Kjartan Gíslason & MSc Thorsteinn Geirsson (NeckCare), Aron Dalin Jónasson MSc, Hildigunnur Katrinardóttir MSc & Ovidiu C. Banea MD (Neurophysiology Lab Landspitali and Reykjavik University) and Egill Axfjörður Friðgeirsson, PhD Student University of Amsterdam.

First TMS-EMG was performed to achieve the correct out of maximum TMS intensity necessary to evoke MEP into hand thenar muscles

Using 100% RMT TMS-EEG evoked potentials were recorded. This trial was performed on experimental basis within the expert team in a healthy subject who previously accepted the test. Another 15-20 voluntary healthy subjects will be tested on both TMS-EMG and TMS-EEG protocols in accordance with World Medical Association (WMA) Declaration of Helsinki, a statement of ethical principles for medical research involving human subjects.

The future joint applied science clinical study will be developed after two international specific trainings and meetings in Denmark (Nov 2017) and France (January 2018). The aim is to assess biological neural networks (BNN) in patients with brain tumors and symptomatic epilepsy as a preoperative safety assessment of the functional brain tissue and effective connectivity in order to improve actual procedures (motor  & speech mapping and fMRI) and avoid new neurological deficit. Main collaborators of this challenging Icelandic medical research and clinical study are Neurosurgery Department of National University Hospital of Iceland (Drs Ingvar Hakon Ólafsson & Elfar Ulfarsson) and Neurosurgery Department of del Mar Hospital Barcelona, Spain (Dr Gerard Conesa). Scientific support and research specific feedback is given by Dr Eric Wassermann (NINDS/NIH; Bethesda, United States) and Prof Dr Elías Ólafsson (Head of Neurology Department, National University Hospital of Iceland).

Guyon Type II (pure motor), who was Jean Casimir Félix Guyon?

by Neurophysiology Plus Iceland

In a 72 year-old male with suspected carpal tunnel syndrome (?) our team was able to identify a rare case of pure motor (type II) Guyon syndrome using nerve conduction studies. Case report (here). The report was corrected and split-hand index (SI) was calculated after a very good comment we received from Dr Giorgio Capoccitti (Università degli Studi di Siena, Tuscany Italy).

Preoperative Neuronavigation with TMS using operating room system in Iceland

Reykjavik, 13th of July 2017

by Neurophysiology Plus

To avoid a new neurological deficit after a brain growing tumor surgery located in or near eloquent brain areas (speech, motor, visual cortex) the surgeon uses now intraoperative neuromonitoring complementary procedures performed together with clinical neurophysiology team in the operating room.

In 1998, Sawaya et al published the tumor functional grade classification after a scheme developed at the Anderson Cancer Center in Houston Texas based on the tumor location relative to the brain function as following: Grade I non-eloquent brain: Frontal or temporal polar regions, Right parieto-occipital regions, Cerebellar hemispheres lesions; Grade II near eloquent brain: Near motor or sensory cortex, Near calcarine fissure, Near speech center, Corpus callosum, Near dentate nucleus, Near brainstem, including supplementary motor area if was investigated with preoperative magnetic resonance; Grade III eloquent brain: Motor/Sensory cortex, Visual center, Speech center, Internal capsule, Basal ganglia, Hypothalamus/thalamus, Brainstem, Dentate nucleus.

The preoperative studies used to identify the structure and the "function" of the eloquent brain are MRI, fMRI, CT, DatScan, SPECT, PET, TMS. From all these TMS-EMG and TMS-EEG modalities are used for motor mapping and speech mapping or EEG temporal related evoked potentials. The results, the identified motor hot-spots or speech area are then saved and used in operating room by neurosurgeon.

Source: Medtronic

Neuro-Navigated TMS preoperative mapping using same operating room system

13th of July 2017

If eloquent brain areas and motor cortex hot-spots with Talairach coordinates are already set on the patient MRI (structural model of the brain) before surgery the neurophysiology and neurosurgery team will use them when proposing the surgery and during the resection of tumors or abnormal (non-functional) tissues.

In Iceland, preoperative motor mapping started in January 2017 (here) and recently a team formed by Ingvar Hakón Ólafsson, Aron Björnsson, Ágúst H. Guðmundsson (Intermedica/Medtronic), David B., Aron Dalin Jónasson and Ovidiu C. Banea could prove the combination of operating room neuronavigation system (Medtronic) with TMS motor mapping and Intraoperative device (Nim Eclipse Medtronic).

The pilot study was successful and was performed in surgery room. In close future the preoperative neuro-navigated mapping will be used for the proposed patients before surgery time.