patterns

Parkinsonism Disease or Not?

This last year we lost an old friend, Bill Hudspeth…. William J Hudspeth, PhD. He scientifically contributed to understanding the EEG of maturation, and his multivariate connectivity eigenvector work is still ahead of many others in modeling brain function. We lost a real contributor.

In his later years he was treated for hypertension with Reserpine. I recall Bill’s dehydration in Arizona at an ISNR meeting when I carried him out of the hall during a syncopal spell. He was not well conmtrolled on his diuretic. Reserpine is rarely used in the management of hypertension today, as it is a second-line adjunct agent for patients who are poorly controlled on a diuretic, when cost is an issue. It is an inexpensive and effective antihypertensive, though not without a substantial potential for side-effects, which has it banned in England.   

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Epilepsy and EEG

Epilepsy and EEG have been inextricably linked since the 1930s, when Frederick and Erna Gibbs discovered that epileptic events were visible in the EEG.  The evolution of other medical imaging in the 1970s and 1980s provided a better way to localize tumors, and the clinical use tapered off in areas other than epilepsy and encephalopathies.  Even with the multiplicity of other methods, the EEG remains the gold standard for identification of epilepsy.

In modern neuroscience centers, the EEG is still the tool of choice in evaluation of convulsive epilepsy, as well as some other non-convulsive forms, such as staring episodes seen in “absence epilepsy” typically as a 3/second spike and wave dominant anteriorly, or temporal lobe epilepsy, which is seen as a “notched” slow wave discharge fronto-temporally.

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Three Sets of Data from the Same EEG

This is three sets of data from the same underlying EEG, all with varying coherence results, and with the weighted average showing the alpha hypercoherent pattern with better fidelity than any other for this data.

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qEEG Artifacting

The qEEG represents the statistical manipulation of the raw EEG, so an understanding of these manipulations should precede any discussion of the qEEGs clinical indications for protocols. Without such knowledge any given finding may be misinterpreted.

Following the careful recording of the EEG, the quantitative analysis is begun with the sampling of the data to be used in the analysis by the Fourier transform. The Fourier analysis assumes there are no transients (epileptic discharges, episodic voltage changes etc.) or state changes (light sleep, drug effect, mental task, etc.), so these must be avoided when selecting data for analysis in qEEG for eyes closed resting database comparison. There are some eyes open and task databases available more recently (Hudspeth, Sterman, Duffy etc.)

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Patterns seen in the qEEG and their indicated interventions

Diffuse slowing, with slower alpha

The ascending reticular activating system stimulates the diffuse thalamic projection system and sets the general arousal level of the brain. With an increase in the CNS arousal level, there is an increase in the mean frequency of alpha and a decreased slowing. With decreases in arousal there is a slowing of the alpha, as well as eventually an increase in diffusely distributed slowing ( a mixture of diffuse lower voltage delta and theta, usually with a weak vertex prominence in linked ear montages).

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