Electroretinogram by Donnell J Creel

Figure Reference: Med.Utah.edu (linked, pl click)

In general, intraopertive neurophysiological monitoring teams do not conduct ERG or EOG in the Operating room set up, it is rather cumbersome and difficult to get a reliable readings combined with the difficulty of placing the recording electrode and risks that are associated with the procedure.  However, Donnell in its Chapter on"The electroretinogram" presents the latest developments that record the status of retinal function using skin electrodes and he also sheds light on the recent advancement in ERG the multifocal retiongram. Whether you are going to conduct this test or not, if you are interested in all the evoked potentials and the basics, this is an excellent reading material. Enjoy.

 The Electroretinogram: Clinical Applications by Donnell J. Creel

Electrophysiological testing of patients with retinal disease began in clinical departments in the late nineteen forties. Under the influence of the Swedish pioneers, Holmgren (1865) and Granit (1933), the electroretinogram was being dissected into component parts and early intraretinal electrode studies were beginning to tell which cells or cell layers gave rise to the various components. A detailed discussion of the electroretinogram, or ERG as it is commonly abbreviated, is found in the accompanying chapter by Ido Perlman. A little after the introduction of the ERG as a test of the state of the patient’s retina, another diagnostic test called the electrooculogram (EOG) was introduced to the clinic (Arden et al., 1962). The EOG had advantages over the ERG in that electrodes did not touch the surface of the eye. The changes in the standing potential across the eyeball were recorded by skin electrodes during simple eye movements and after exposure to periods of light and dark. Over the years ERG recording techniques have become progressively more sophisticated in the clinical setting. With the advent of perimetry, optical coherence tomography (OCT) and pattern ERG techniques, more precise mapping of dysfunctional areas of the retina is now possible. The most recent advance in ERG technology is the multifocal electroretinogram (mfERG). The mfERG provides a detailed assessment of the health of the central retina.

ABRET changes the Eligibility Requirement for All Exams?

ABRET has announced a major change in the eligibility requirement for exams like CNIM, Long Term Monitoring, EEG and EP technologists.  These news changes will be effective for some exams from Jan 2009 and for others from 2012. The change will apply to all the exams conducted by ABRET.  

The new requirements for CNIM exam is the candidate should undergo prior EEG credentialing???

There are two major requirements, of which the second one is already known to the folks in this area, but the first requirement:

1.An electroneurodiagnostic credential; R. EEG T. or R. EP T. or Canadian equivalent. A copy of current registration must accompany the Application.

For someone with a graduate degree or PhD or MD, if they wanted to be neuromonitoring specialist, they must undergo EEG or EP credentialing through ABRET?, does this makes any sense to those advanced degree holders?. It simply sounds to be ridiculous that ABRET is bent on making such changes as this would drive the PhDs and other advanced degree holders, there are already lots of shortage in neuromonitoring, it is difficult for companies to hire graduates with specialization in neurophysiology or neuroscience, with this new requirements, it is going to get worst to find someone with a credentialing in EEG or EP. 

As of January 1, 2010 the following eligibility requirements will be in effect for the CNIM Examination

The Certification Examination in Neurophysiologic Intraoperative Monitoring is designed and written for the advanced level electroneurodiagnostic professional who is currently practicing in an intraoperative environment.

All candidates must meet the following requirements by the application deadline. There are no alternative routes.

1. An electroneurodiagnostic credential; R. EEG T. or R. EP T. or Canadian equivalent. A copy of current registration must accompany the Application.

How to Calculate Frequency, Duration & Amplitude in EEG?

Bill Byrum writes about how to analyse and evaluate EEG inorder to calculate the frequency, duration etc., in the following article that appeared in the latest ASET newsletter.

Calculating Frequency, Duration, Amplitude, and Voltage Using a Legend
By Bill Byrum, MBA, R. EEG/EP T., CNIM

In this article I want to review with you
how simple it is to use a Legend. You will
need a measurement ruler graduated into
one mm segments. It would also be handy
to have a calculator that can be set to divide
to 3 decimal places. If you perform division
by hand, please be sure to carry the results
to 3 decimal places when calculating
waveform duration.
I strongly recommend whenever you
are doing calculation utilizing a Legend
that you use a referential montage and the
reference is not contaminated with EEG
activity. This is because in a bipolar
montage the waveforms are the result of
two inputs active with EEG activity. The
same can be said of a referential montage if
the reference is contaminated. For complete article, click the linked title?.

Some Stats about CNIM Exam

CNIM Written Exam 2003-2006
One of the following must be met and verified for candidates

to be eligible to take the CNIM Exam:

Health care credential plus documentation of 100 cases monitored
Bachelor’s degree plus documentation of 100 cases monitored
68% passed on their first attempt. The pass rate for repeaters was 46%.
39% had another health care credential. Their pass rate was 50%.
61% of candidates had a bachelor’s degree or higher and a 61% pass rate.
Some of the candidates with bachelor’s or advanced degrees, also documented they had another health care credential.
Procedures Performed in the OR Totals
Totals Percentage
Spinal Nerve EMG 911 83%
Motor Pathway 783 71%
Intraop Scalp EEG 719 65%
BAEP 661 60%
Cranial Nerve EMG 619 56%
Cortical mapping 337 31%
ECOG 197 18%
VEP 139 13%

41% of candidates stated CNIM was a Job Requirement. This was the most common reason stated for taking the exam. The second most common response was Professional Advancement (34%) and the third reason selected was Personal Goal (18%).