A comparative study of brain perfusion single-photon emission computed tomography and magnetic resonance imaging in patients with post-traumatic anosmia

Shahid Sadughi Hospital, Yazd, Iran.
American journal of rhinology & allergy (Impact Factor: 1.81). 07/2009; 23(4):409-12. DOI: 10.2500/ajra.2009.23.3345
Source: PubMed


Loss of smell is a problem that can occur in up to 30% of patients with head trauma. The olfactory function investigation methods so far in use have mostly relied on subjective responses given by patients. Recently, some studies have used magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT) to evaluate patients with post-traumatic anosmia. The present study seeks to detect post-traumatic anosmia and the areas in the brain that are related to olfactory impairment by using SPECT and MRI as imaging techniques.
The study was conducted on 21 patients suffering from head injury and consequently anosmia as defined by an olfactory identification test. Two control groups (traumatic normosmic and nontraumatic healthy individuals) were selected. Brain MRI, qualitative and semiquantitative SPECT with 99mtc-ethyl-cysteinate-dimer were taken from all the patients. Then the brain SPECT and MRI were compared with each other.
Semi-quantitative assessment of the brain perfusion SPECT revealed frontal, left parietal, and left temporal hypoperfusion as compared with the two control groups. Eighty-five percent of the anosmic patients had abnormal brain MRI. Regarding the MRI, the main abnormality proved to be in the anterior inferior region of the frontal lobes and olfactory bulbs.
The findings of this study suggest that damage to the frontal lobes and olfactory bulbs as shown in the brain MRI and hypoperfusion in the frontal, left parietal, and left temporal lobes in the semiquantitative SPECT corresponds to post-traumatic anosmia. Further neurophysiological and imaging studies are definitely needed to set the idea completely.

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    • "The lower BOLD signal observed in the mOFC of our COI participants is in accordance with structural and metabolic changes within this region following the loss of smell perception. These changes include grey matter volume reductions (Bitter, Bruderle, Gudziol, Burmeister, & Guntinas-Lichius, 2010; Bitter, Gudziol et al., 2010), increased grey matter thickness (Frasnelli, Fark, Lehmann, Gerber, & Hummel, 2013), hypometabolism (Varney, Pinkston, & Wu, 2001) and hypoperfusion (Eftekhari et al., 2006; Atighechi et al., 2009). Two previous studies reported a positive correlation between olfactory performance and grey matter thickness in the mOFC in healthy individuals (Frasnelli et al., 2010; Seubert, Freiherr, Frasnelli, Hummel, & Lundstrom, 2012). "
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