Donald M. Hadley

Face processing impairments after encephalitis: amygdala damage and recognition of fear

Face processing and facial emotion recognition were investigated in five post-encephalitic people of average or above-average intelligence. Four of these people (JC, YW, RB and SE) had extensive damage in the region of the amygdala. A fifth post-encephalitic person with predominantly hippocampal damage and relative sparing of the amygdala (RS) participated, allowing us to contrast the effects of temporal lobe damage including and excluding the amygdala region. The findings showed impaired recognition of fear following bilateral temporal lobe damage when this included the amygdala. For JC, this was part of a constellation of deficits on face processing tasks, with impaired recognition of several emotions. SE, YW and RB, however, showed relatively circumscribed deficits. Although they all had some problems in recognizing or naming famous faces, and had poor memory for faces on the Warrington Recognition Memory Test, none showed a significant impairment on the Benton Test of Facial Recognition, indicating relatively good perception of the faces physical structure. In a test of recognition of basic emotions (happiness, surprise, fear, sadness, disgust and anger), SE, YW and RB achieved normal levels of performance in comparison to our control group for all emotions except fear. Their results contrast with those of RS, with relative sparing of the amygdala region and unimpaired recognition of emotion, pointing clearly toward the importance of the amygdala in the recognition of fear.

Correlation of Parkinson's disease severity and duration with 123I-FP-CIT SPECT striatal uptake

The variability in clinical features and the masking effects of drug therapy in Parkinsons disease (PD) can affect clinical assessment of disease severity. The aim of this study was to assess the imaging of dopamine transporters using 123I‐FP‐CIT SPECT and its correlation with disease staging, severity, and duration. Differences between the clinical severity of the onset and non‐onset side and the corresponding striatal uptake ratios were also examined. Forty‐one patients with PD (nine unilateral, 32 bilateral clinical features) were studied. Clinical severity was determined by using the Unified Parkinsons Disease Rating Score (UPDRS). Unilateral UPDRS was calculated from unilateral arm and leg resting and action tremor, rigidity, finger taps, hand movements, alternating movements, and leg agility. 123I‐FP‐CIT striatal uptake was expressed as the ratio of specific:nonspecific (SP:NS) uptake for defined brain areas. Patients with PD who had unilateral symptoms showed a significant difference between the ipsilateral and contralateral SP:NS ratios in both the caudate and putamen, but there was a considerable overlap between between the two sides. This result was repeated in patients with bilateral symptoms and there was overlap of SP:NS ratios between the two groups. For the whole group of patients with PD, striatum, caudate, and putamen SP:NS ratios correlated with disease severity assessed by UPDRS and duration of disease. The SP:NS ratios correlated with the bradykinesia subscore but not with rigidity or tremor subscore. In conclusion, this study provides further evidence that the SP:NS ratio is a robust measure of disease severity correlating with duration of PD. However, variability in uptake values suggest that factors other than nigrostriatal degeneration may contribute to disease severity. Correlation with bradykinesia but not with tremor may indicate an origin for tremor outwith the dopamine transporter system. 123I‐FP‐CIT SPECT offers significant potential in defining the nigrostriatal changes in PD.

Investigation of the factors responsible for burns during MRI

Numerous reported burn injuries have been sustained during clinical MRI procedures. The aim of this study was to investigate the possible factors that may be responsible for such burns. Experiments were performed to investigate three possible mechanisms for causing heating in copper wire during MRI: direct electromagnetic induction in a conductive loop, induction in a resonant conducting loop, and electric field resonant coupling with a wire (the antenna effect). Maximum recorded temperature rises were 0.6°C for the loop, 61.1°C for the resonant loop, and 63.5°C for the resonant antenna. These experimental findings suggest that, contrary to common belief, it is unlikely that direct induction in a conductive loop will result in thermal injury. Burn incidents are more likely to occur due to the formation of resonant conducting loops and from extended wires forming resonant antenna. The characteristics of resonance should be considered when formulating safety guidelines. J. Magn. Reson. Imaging 2001;13:627–631.

Parkinson's disease is overdiagnosed clinically at baseline in diagnostically uncertain cases: a 3-year European multicenter study with repeat [123I]FP-CIT SPECT

Overdiagnosis of Parkinsons disease (PD) is suggested by specialist review of community diagnosis, and in postmortem studies. In specialist centers 4 to 15% of patients entered into clinical trials as early PD do not have functional imaging support for a PD diagnosis. In a European multicenter, prospective, longitudinal study, we compared clinical diagnosis with functional SPECT imaging using [123I]FP‐CIT (DaTSCAN™, GE Healthcare). Repeat observations were performed over 3 years in patients with tremor and/or parkinsonism in whom there was initial diagnostic uncertainty between degenerative parkinsonism and nondegenerative tremor disorders. Video‐recording of clinical features was scored independently of functional imaging results by two blinded clinicians at 36 months (= gold standard clinical diagnosis). Three readers, unaware of the clinical diagnosis, classified the images as normal or abnormal by visual inspection. The main endpoint was the sensitivity and specificity of SPECT imaging at baseline compared with the gold standard. In 99 patients completing the three serial assessments, on‐site clinical diagnosis overdiagnosed degenerative parkinsonism at baseline in diagnostically uncertain cases compared with the gold standard clinical diagnosis (at 36 months), the latter giving a sensitivity of 93% and specificity of 46%. The corresponding baseline [123I]FP‐CIT SPECT results showed a mean sensitivity of 78% and a specificity of 97%. Inter‐reader agreement for rating scans as normal or abnormal was high (Cohens

Ictal/postictal SPECT in the pre-surgical localisation of complex partial seizures.

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Prospective study of presynaptic dopaminergic imaging in patients with mild parkinsonism and tremor disorders: Part 1. Baseline and 3-month observations

= 0.94–0.97).

Early and late magnetic resonance imaging and neuropsychological outcome after head injury.

Single photon emission computed tomography (SPECT) used in conjunction with HM-PAO (Ceretec-Amersham International) was used to image regional cerebral blood flow (rCBF) in 28 patients with medically intractable complex partial seizures during or soon after a seizure, and interictally. Changes from interictal rCBF were seen in 26/28 (93%) patients. The main findings were; 1) During the seizure--hyperperfusion of the whole temporal lobe; 2) Up to 2m postically--hyperperfusion of the hippocampus with hypoperfusion of lateral temporal structures; 3) From 2-15m postically--hypoperfusion of the whole temporal lobe. When compared with EEG and MRI data, correct localisation to one temporal lobe was obtained in 23 patients. In one further patient bilateral temporal foci, and in a further two patients frontal foci, were correctly identified. There were no disagreements between EEG and SPECT localisation. Temporal lobe surgery was successful (by the criterion of at least 90% reduction in seizure frequency) in all but one of the 23 patients operated on. It is concluded that ictal/postictal SPECT is a reliable technique for the presurgical localisation of complex partial seizures. The data indicate a likely sequence of changes in rCBF during and after complex partial seizures of temporal lobe origin.

Randomized, controlled trial of insulin for acute poststroke hyperglycemia

To record prospectively, from early presentation, the clinical features of parkinsonism and tremor disorders, in relation to evidence of dopaminergic deficit shown with [123I]‐FP‐CIT (DaTSCAN, Amersham Health) single photon emission computerised tomography (SPECT). Clinical signs were recorded in 62 patients, of whom 24 failed standard Parkinsons disease (PD) and essential tremor criteria, and 38 fulfilled UK Brain Bank step 1 PD criteria. Striatal radioligand uptake was graded visually as normal or abnormal, and specific:nonspecific ratios were calculated. Bradykinesia and rigidity showed significant overall association with abnormal scans (P ≤ 0.003), but rest tremor did not (P = NS). In the 24 patients not fulfilling specific criteria (mean age 63 [SD 9] years, disease duration 3 [SD 4] years), 10 (42%) had abnormal visual SPECT assessment and 14 (58%) had normal scans. Of 38 patients with early PD by clinical criteria (mean age 60 [SD 9] years, disease duration 3 [SD 1.7] years), 33 (87%) were visually abnormal. Baseline clinical diagnosis corresponded with SPECT imaging results in 51 of 62 cases (82%), which increased to 56 of 62 cases (90%) with amendment of seven clinical diagnoses at 3 months (blind to SPECT results). Akinetic–rigid cardinal diagnostic features of parkinsonism associate well with dopaminergic deficit in patients with early and mild clinical features. When these clinical features are uncertain, or the patient fails clinical diagnostic criteria, testing for dopaminergic deficit with [123I]‐FP‐CIT SPECT may assist the diagnostic process.

MRI Safety Review

Twenty five adults with closed head injury who had early magnetic resonance imaging (MRI) and computed tomography (CT) were followed up 5 to 18 months after injury. Patients were given a repeat MRI and performed a series of neuropsychological tests. They were classified by the deepest abnormality detectable on scanning. Classifications derived from early and late MRI scanning were significantly correlated. However, measures of neuropsychological outcome showed a strong correlation only with late MRI, and little or no relationship with either early MRI or early CT. Deeper abnormalities detected by late MRI were associated with poorer neuropsychological test performance; late ventricular enlargement was particularly associated with poor outcome. It is concluded that the lesions visualised by MRI are important for neuropsychological outcome, and that functionally significant abnormalities may only be fully apparent on late scanning.

Two-year follow-up in 150 consecutive cases with normal dopamine transporter imaging.

Poststroke hyperglycemia is common and is associated with increased risk of death and dependence, but appropriate management remains uncertain. Glucose potassium insulin (GKI) infusion did not benefit patients with moderate poststroke hyperglycemia in a recent trial. Using magnetic resonance imaging (MRI), previous studies identified a relationship between recruitment of ischemic tissue to the final infarct and hyperglycemia, possibly mediated by brain lactic acidosis.