Effects of medial temporal lobe degeneration on brain perfusion in amnestic MCI of AD type: deafferentation and functional compensation?

PURPOSE: Cortical atrophy is correlated with the progression of neuropathological lesions within the medial temporal lobes (MTL) in Alzheimer's disease (AD). Our aim was to determine which local and remote functional changes result from MTL volume loss at the predementia stage. METHODS: We studied the relationship between entorhinal and hippocampal MR volumes and whole-brain SPECT perfusion via a voxel-based correlative analysis in 19 patients with amnestic mild cognitive impairment with a memory profile suggestive of early AD. RESULTS: Right MTL volumes were positively correlated with remote posterior perfusion of the posterior cingulate cortex, and negatively correlated with remote anterior perfusion of the right medial and dorsolateral prefrontal cortex. There was no local correlation between volumes and perfusion within the MTL. CONCLUSION: These findings provide further insight into functional changes that result from MTL volume loss during the predementia stage of AD. The positive correlation between MTL volumes and posterior cingulate perfusion may reflect the deafferentation of a temporocingulate network due to mediotemporal degeneration. The paradoxical negative correlation between MTL volumes and prefrontal perfusion may result from recruitment of an alternative anterior temporofrontal network. It remains to be investigated how the "net sum" of this perfusion modulation affects memory and other cognitive domains through a possible compensatory perspective.

Predictive value of brain perfusion SPECT for ketamine response in hyperalgesic fibromyalgia.

PURPOSE: Ketamine has been used successfully in various proportions of fibromyalgia (FM) patients. However, the response to this specific treatment remains largely unpredictable. We evaluated brain SPECT perfusion before treatment with ketamine, using voxel-based analysis. The objective was to determine the predictive value of brain SPECT for ketamine response. METHODS: Seventeen women with FM (48 +/- 11 years; ACR criteria) were enrolled in the study. Brain SPECT was performed before any change was made in therapy in the pain care unit. We considered that a patient was a good responder to ketamine if the VAS score for pain decreased by at least 50% after treatment. A voxel-by-voxel group analysis was performed using SPM2, in comparison to a group of ten healthy women matched for age. RESULTS: The VAS score for pain was 81.8 +/- 4.2 before ketamine and 31.8 +/- 27.1 after ketamine. Eleven patients were considered "good responders" to ketamine. Responder and non-responder subgroups were similar in terms of pain intensity before ketamine. In comparison to responding patients and healthy subjects, non-responding patients exhibited a significant reduction in bilateral perfusion of the medial frontal gyrus. This cluster of hypoperfusion was highly predictive of non-response to ketamine (positive predictive value 100%, negative predictive value 91%). CONCLUSION: Brain perfusion SPECT may predict response to ketamine in hyperalgesic FM patients.

99mTc-ECD brain perfusion SPECT in hyperalgesic fibromyalgia.

PURPOSE: Neuro-imaging studies with (99m)Tc-HMPAO SPECT in fibromyalgia (FM) patients have reported only limited subcortical hypoperfusion. (99m)Tc-ECD SPECT is known to provide better evaluation of areas of high cerebral blood flow and regional metabolic rate. We evaluated a homogeneous group of hyperalgesic patients with FM using (99m)Tc-ECD SPECT. The aim of this study was to investigate brain processing associated with spontaneous pain in FM patients. METHODS: Eighteen hyperalgesic FM women (mean age 49 years, range 25-63 years; American College of Rheumatology criteria) and ten healthy women matched for age were enrolled in the study. A voxel-by-voxel group analysis was performed using SPM2 (p<0.05, corrected for multiple comparisons). Visual Analogue Scale score for pain was 82+/-4 at the time of the SPECT study. RESULTS: Compared with control subjects, we observed individual brain SPECT abnormalities in FM patients, confirmed by SPM2 analysis, with hyperperfusion of the somatosensory cortex and hypoperfusion of the frontal, cingulate, medial temporal and cerebellar cortices. CONCLUSION: In the present study, performed without noxious stimuli in hyperalgesic FM patients, we found significant hyperperfusion in regions of the brain known to be involved in the sensory dimension of pain processing and significant hypoperfusion in areas assumed to be associated with the affective-attentional dimension. As current pharmacological and non-pharmacological therapies act differently on the two components of pain, we hypothesise that SPECT could be a valuable and readily available tool to guide individual therapeutic strategy and provide objective follow-up of pain processing recovery under treatment.

Follow-up of pain processing recovery after ketamine in hyperalgesic fibromyalgia patients using brain perfusion ECD-SPECT.

PURPOSE: The aim of this study was to determine whether the follow-up of pain processing recovery in hyperalgesic fibromyalgia (FM) could be objectively evaluated with brain perfusion ethyl cysteinate dimer single photon computerized tomography (ECD-SPECT) after administration of ketamine. MATERIALS AND METHODS: We enrolled 17 hyperalgesic FM women patients (48.5 +/- 11 years, range 25-63). After treatment with subcutaneous ketamine, 11 patients were considered as "good responders", with a decrease in pain intensity, evaluated by visual analog scale (VAS), greater than 50%. On the other hand, six patients were considered as "poor responders". A voxel-based analysis of regional cerebral blood flow (rCBF) was conducted (p (voxel) < 0.001uc), in the two subgroups of patients, before and after treatment, in comparison to a group of ten healthy subjects, matched for age and gender. RESULTS: In comparison to baseline brain SPECT, midbrain rCBF showed a greater increase after ketamine in the responder group than in the nonresponder group (p (cluster) = 0.016c). In agreement with the clinical response, the change in midbrain rCBF after ketamine was highly correlated with the reduction of VAS pain score (r = 0.7182; p = 0.0041). CONCLUSION: This prospective study suggests that blockade of facilitatory descending modulation of pain with ketamine can be evaluated in the periaqueductal grey with brain perfusion SPECT.

Neural network underlying ictal humming demonstrated by very early SPECT: a case report.

We report the case of a 49-year-old right-handed woman with brief partial seizures in which the clinical semiology was marked by an early humming automatism. MRI fusion of the registered ictal and interictal single-photon emission computed tomography (SPECT) substraction exhibited a left neural network involving lateral temporal, inferior frontal, and inferior parietal cortices.