Potential risk of Brain Ischemia (blood insufficiency)

 

qEEG screening

Service code s9016

Please note that screening does NOT result in a medical diagnosis; it gives a probabilistic estimate of risk. In other words, the screening gives information on the presence of a pattern in the qEEG that is often – but not always – found in persons with a history of a particular condition.

Short description

Ischemic processes (localized reduction of blood flow to brain tissue) may be functional or due to arterial obstruction or systemic hypo-perfusion. This frequently occurs in conjunction with brain hypoxia (inadequate supply level of oxygen to the brain).

Ischemic processes do not necessarily mean the blockage of vessels. Instead, they are usually functional – the result of (a) increased or decreased tonus of brain vessels, (b) arterial stiffness, (c) endothelial dysfunction, or (d) circulatory distress in the vertebrobasilar system due to tension or compression. Additionally, altered cerebral autoregulation may result in the situation where more arterial oxygen is transmitted to the venous circulation as a result of microvascular dysfunction in which the brain tissue is less able to extract oxygen from arterial blood.

Prolonged ischemia may be associated with brain infarction and stroke.

Usefulness of qEEG screening in objective detection of ischemic processes have been demonstrated in scientific research(1,2,3,4,5).

X-ray, CT and conventional MRI do not show ischemic tissue which is still viable for rescue, but only dead tissue in the infracted core. qEEG in contrast is able to detect the signs of brain ischemic tissue due to the fact that ischemic tissue generates pathological oscillations which can be seen in the scalp EEG.

The qEEG has been shown to be a reliable marker of the decline in neuronal integrity associated with a decline in blood flow(1,2,3,4,5). The scientific studies show a sensitivity greater than 80%, false-positive rates below 5%-10%, and correlations of 70% between qEEG and blood flow in ischemic and non-ischemic regions. Thus, qEEG can detect reliable focal features that are missed using routine EEG and can be quite abnormal even when the CT or MRI are still normal(6). Early detection gives scope for earlier and potentially more effective intervention measures.

Results

By performing this qEEG screening you will get the information on:

  • whether you have a qEEG pattern typical for brain ischemia and
  • the potential degree of severity.

Notes:

  • The results of qEEG analysis are put in context of published scientific studies, the individual’s health history, complaints, symptoms and psychometric and other evaluations (if available).
  • Present psychotropic medication use may affect the results.

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References

  1. Blume WT, Ferguson GG, McNeill DK. Significance of EEG changes at carotid endarterectomy. Stroke 1985; 17: 891–897.
  2. Nagata K. Topographic EEG in brain ischemia: correlation with blood flow and metabolism. Brain Topogr 1988; 1: 97–106.
  3. Jonkman EJ, Poortvliet DCJ, Veering MM, et al: The use of neurometrics in the study of patients with cerebral ischemia. Electroencephalogr Clin Neurophysiol 1985; 61: 333-341.
  4. Ingvar DH, Sjolund B, Ardo A: Correlation between dominant EEG frequency, cerebral oxygen uptake and blood flow. Electroencephalogr Clin Neurophysiol 1976; 41: 268-276.
  5. Nagata K, Tagwa K, Hiroi S, et al. Electroencephalographic correlates of blood flow and oxygen metabolism provided by positron emission tomography in patients with cerebral infarction. Electroencephalogr Clin Neurophysiol 1989; 72: 16-30.
  6. Hughes JR, E. John ER. Conventional and quantitative electroencephalography in psychiatry. The Journal of Neuropsychiatry and Clinical Neurosciences 1999; 11:190-208.