A comparative study of brain perfusion single-photon emission computed tomography and magnetic resonance imaging in patients with post-traumatic anosmia
ABSTRACT 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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ABSTRACT: Olfaction and gustation contribute both to the appreciation of food flavours. Although acquired loss of smell has profound consequences on the pleasure of eating, food habits and body weight, less is known about the impact of congenital olfactory impairment on gustatory processing. Here we examined taste identification accuracy and its neural correlates using functional magnetic resonance imaging (fMRI) in 12 congenitally olfactory impaired individuals and 8 normosmic controls. Results showed that taste identification was worse in congenitally olfactory impaired compared to control subjects. The fMRI results demonstrated that olfactory impaired individuals had reduced activation in medial orbitofrontal cortex (mOFC) relative to normosmic subjects while tasting. In addition, olfactory performance as measured with the Sniffin' Sticks correlated positively with taste-induced BOLD signal increases in bilateral mOFC and anterior insula. Our data provide a neurological underpinning for the reduced taste perception in congenitally olfactory impaired individuals.Neuropsychologia 09/2014; 62. DOI:10.1016/j.neuropsychologia.2014.07.018 · 3.45 Impact Factor
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ABSTRACT: To study the acute relationship between olfactory function and traumatic brain injury (TBI), cognitive functions and outcome. Sixty-two patients with TBI were evaluated within the first 2 weeks following TBI. The Sniffin'Sticks identification test was used to assess olfaction. A neuropsychological evaluation was carried out to assess attention, verbal fluency, naming, memory, problem-solving and mental flexibility. The extended Glasgow Outcome Scale (GOSE) and the Disability Rating Scale (DRS) were rated at discharge from acute care. Traumatic lesions located in the basal frontal area resulted in odour identification scores that were significantly lower than when lesions were elsewhere (p < 0.001). A significant positive correlation was shown between odour identification scores and mental flexibility scores (p = 0.004) and patients with hyposmia had worse performances on executive tests measuring problem-solving, verbal fluency and mental flexibility (p < 0.01). Moreover, the odour identification score and the DRS total score were related (p = 0.019). These findings add information regarding acute olfactory status following TBI and provide evidence on the importance of assessing olfaction very early post-TBI in order to plan intervention and determine what accident prevention advice will be required for home or work re-integration.Brain Injury 03/2015; DOI:10.3109/02699052.2015.1004748 · 1.86 Impact Factor