FUNCTIONAL BRAIN SCANNING WITH SPECT AFTER NEUROTOXIC CHEMICAL EXPOSURE
Article Nº AJ04-5
Government and the public have for years addressed the potential cancer causing effects of chemicals. They have neglected the fact that chemicals can be neurotoxic and at times disabling in that capacity. They have also neglected the fact that impairment of brain function can outlast neurotoxic exposure for many years.
Typical symptoms after exposure can be impairment of cognitive and memory functions, inability to perform more then one task at a time, intermittent confusion and disorientation, impairment of speech, balance and coordination, and others.
While neurotoxic impairment (toxic encephalopathy) can also be assessed with comprehensive neuropsychological evaluation, EEG and evoked response studies, functional brain scanning has in recent years become a very important investigational and clinical tool. In this context, your readers should be informed of a recent paper (1) on SPECT scanning after neurotoxic exposure. The important findings were that SPECT shows usually asymmetrical hypoperfusion in the frontal, temporal and parietal lobes. This impairment can be found years after neurotoxic exposure has ceased, i.e. at a time when the patient is still neuropsychologicaly and neurologically impaired or disabled.
Another paper (2) shows that a three-dimensional display (developed by Dr. I Mena, (3) further accentuates the usefulness of SPECT. This display makes it possible to easily see and analyze Regions Of Interest (ROI) in comparison to a control group or when comparing before and after treatment functions.
| Figure 1 shows a three-dimensional
SPECT (right and left lateral views in upper rows, anterior and posterior views below) in
a patient who continued to be severely impaired more than two years after exposure to
chlorpyrifos (Dursban) in his home. In our hands the sophistication in SPECT (as developed by Dr. I. Mena) has proved invaluable for the evaluation of patients with impairment of brain function, especially after neurotoxic exposure. Gunnar Heuser, M.D., Ph.D. |
REFERENCES:
1. Heuser, G.; Mena, I. NeuroSPECT in Neurotoxic Chemical Exposure. Demonstration of Long Term Functional Abnormalities. Toxicology and Industrial Health, 14, #6: 813-827, 1998.
2. Heuser, G.; Funktionelle Gehirn-Bildgebung mit SPECT und PET. Veranderte Gehirnaktivitaten nach neurotoxischer Exposition. Zeitschrift. Fur Umweltmedizin, 7, #26: 12-15, January 1999.
3. Prado C. and Mena I.,. Basal and frontal
activation neuroSPECT demonstrates functional brain changes in major depression. Alasbimn
Journal1(3): April 1999. http://www.alasbimnjournal.cl/revistas/3/pradoia.htm
Cita/Reference:
Gunnar Heuser, M.D., Functional Brain Scanning With SPECT After Neurotoxic Chemical Exposure. Alasbimn Journal1(4): July 1999. Article Nº AJ04-5. http://www.alasbimnjournal.cl/revistas/4/letter.htm