Michael M. Saling

Functional connectivity networks are disrupted in left temporal lobe epilepsy

Functional connectivity maps the distributed network of brain regions fluctuating synchronously during a continuous brain state. This study sought to investigate whether patients with left temporal lobe epilepsy (TLE) differ from controls in their resting‐state functional connectivity between typical language regions.

The assessment of orientation following concussion in athletes

The purpose of this study was to investigate the sensitivity of orientation and recent memory questions in the diagnosis of concussion. In a prospective study over 7 consecutive years (1985-1991), all players at a professional Australian Rules Football club who sustained a concussive injury (n = 28) were administered a set of questions evaluating orientation and recent memory. Concussion was diagnosed independently on the basis of loss or disturbance of consciousness and clinical symptoms. A control group of age-matched nonconcussed players was administered the same set of questions. The results showed that items evaluating recently acquired information were more sensitive in the assessment of concussion than standard orientation items. The relative sensitivity of orientation questions must be considered when they are used in the clinical diagnosis of concussion in sport.

Paired associate performance in the early detection of DAT.

Subjects underwent longitudinal neuropsychological assessment in order to retrospectively determine which measures of cognitive function best predicted later development of dementia of the Alzheimer type (DAT). Three groups of subjects were studied: normal controls, patients with early DAT, and questionable dementia subjects (QD). All subjects were assessed using a battery of standard neuropsychological measures and two subtests from the Cambridge Neuropsychological Test Automated Battery (CANTAB), paired associate learning and delayed matching to sample. A structured interview was also used to elicit a profile of the subjects daily functioning. Subjects were assessed every 6 months for 2 years. At the 6 month assessment, almost half of the QD group exhibited significant deterioration in scores on the computerized paired associate learning subtest, while maintaining their scores on standard measures. At the conclusion of the study, all of this QD subgroup fulfilled the NINCDS-ADRDA criteria for probable DAT pertaining to significant cognitive and functional deterioration. Performance on the C

Lateralization of verbal memory and unilateral hippocampal sclerosis : evidence of task-specific effects

This study retrospectively investigated the effect of left (LHS) versus right (RHS) hippocampal sclerosis on verbal memory, measured by means of the Paired Associate Learning and Logical Memory subtests of the Wechsler Memory Scale (WMS) administered as part of a routine preoperative assessment. Patients were selected for the presence of unilateral hippocampal sclerosis by means of preoperative magnetic resonance imaging (MRI) and postoperative neuropathology. The LHS patients (n = 20) were significantly worse on paired associate learning than RHS patients (n = 18), the performance of RHS patients being consistent with normative standards. In contrast, no laterality effect was seen on the immediate and delayed recall of passages; the evidence suggests that both groups performed at a mildly impaired level. It was suggested that the laterality of verbal memory is conditional upon specific task demands in patients with damage to mesial temporal structures.

Verbal memory in mesial temporal lobe epilepsy: beyond material specificity

The idea that verbal and non-verbal forms of memory are segregated in their entirety, and localized to the left and right hippocampi, is arguably the most influential concept in the neuropsychology of temporal lobe epilepsy, forming a cornerstone of pre-surgical decision making, and a frame for interpreting postoperative outcome. This critical review begins by examining some of the unexpressed but inescapable assumptions of the material-specificity model: (i) verbal and non-verbal memory are unitary and internally homogenous constructs; and (ii) left and right memory systems are assumed to be independent, self-contained modules. The next section traces the origins of an alternative view, emanating largely from three challenges to these assumptions: (i) verbal memory is systematically fractionated by left mesial temporal foci; (ii) the resulting components are differentially localized within the left temporal lobe; and (iii) verbal and non-verbal memory functions are not entirely lateralized. It is argued here that the perirhinal cortex is a key node in a more extensive network mediating protosemantic associative memory. Impairment of this fundamental memory system is a proximal neurocognitive marker of mesial temporal epileptogenesis.

Anterior temporal abnormality in temporal lobe epilepsy: a quantitative MRI and histopathologic study.

Objective: To examine the nature and frequency of anterior temporal lobe (AT) abnormalities that occur in intractable temporal lobe epilepsy (TLE). Methods: We reviewed the MR scans and clinical histories of 50 consecutive patients with intractable TLE. Histopathology was available in 42 surgically treated cases. Results: MRI demonstrated loss of the gray-white matter differentiation and decreased T1- and increased T2-weighted signal in the ipsilateral AT in 58% of the 50 patients. This appearance was observed in 64% of the 36 patients with hippocampal sclerosis (HS) but was also seen in patients without HS. These changes were associated with temporal lobe atrophy, a higher hippocampal T2 relaxation time, and a history of febrile convulsions. Pathologic examination showed that the MRI appearances were not caused by dysplasia, degenerative abnormalities, or inflammatory change. Histologic quantitation showed increased glial cell nuclei counts in the intractable TLE cases compared with controls. There was no difference in glial cell numbers between cases with AT abnormality and those without this appearance. Presence or absence of changes was not predictive of preoperative neuropsychology, postoperative change in neuropsychology, or seizure outcome after surgery. Conclusions: These frequently seen ipsilateral changes are not caused by gliosis and may reflect a nonspecific increase in water content in the temporal lobe. This may be due to myelin abnormalities or some other as yet unidentified pathologic factor.

Pattern and significance of cerebral microemboli during coronary artery bypass grafting

BACKGROUND Strokes that occur during coronary artery bypass grafting are often caused by embolism. Intraoperative transcranial Doppler monitoring can detect cerebral microemboli. The aims of this study were to identify the pattern of microembolic phenomena during various stages of coronary artery bypass grafting, to verify whether numbers of high-intensity transient signals correlated with early neuropsychologic deficits, and to identify, using magnetic resonance imaging scans, whether radiologic evidence of cerebral infarction correlated with microembolic numbers during the bypass period. METHODS Forty-one consecutive patients undergoing coronary bypass grafting with transcranial Doppler monitoring were enrolled in this study. All had preoperative and postoperative magnetic resonance imaging brain scans. A subgroup of 32 patients were studied by comparing microembolic load and early neuropsychological outcomes. RESULTS Transcranial Doppler monitoring confirmed that most microemboli occurred during cardiopulmonary bypass. A significant early neuropsychological deficit after coronary artery bypass grafting did correspond to the total microembolic load during bypass (p = 0.008). However, patients with cerebral infarction on magnetic resonance imaging had significantly more microembolic signal during the preincision phases and not during the bypass period. CONCLUSIONS Microembolic load during bypass is associated with early neuropsychologic deficits. In contrast, patients who show evidence of strokes during coronary artery bypass grafting have a higher microembolic load during the preincision phase than those without cerebral infarction. Differing mechanisms may be responsible for these different outcomes.

The 18F-FDG PET Cingulate Island Sign and Comparison to 123I-β-CIT SPECT for Diagnosis of Dementia with Lewy Bodies

Neuroimaging is increasingly used to supplement the clinical diagnosis of dementia with Lewy bodies (DLB) by showing reduced occipital metabolism and perfusion and reduced striatal dopaminergic innervation. We aimed to optimize the interpretation of 18F-FDG PET images for differentiating DLB from Alzheimer disease (AD) and to compare the results with dopamine transporter imaging using 123I-β-carbomethoxy-3ß-(4-iodophenyl)tropane (123I-β-CIT) SPECT. Methods: Fourteen subjects with a clinical diagnosis of DLB and 10 with AD underwent both 18F-FDG PET and 123I-β-CIT SPECT. Four DLB and 1 AD diagnoses were subsequently confirmed at autopsy. Diagnostic accuracy was calculated for visual interpretation by 3 readers of standard 3-plane and stereotactic surface projection 18F-FDG PET images, receiver-operating-characteristic analysis of regional 18F-FDG uptake, and a cutoff value for the striatal-to-occipital binding ratio of β-CIT defined by receiver-operating-characteristic analysis. Results: Visual interpretation of 3-plane 18F-FDG PET images had a sensitivity of 83% and specificity of 93% for DLB, slightly higher than the results with the stereotactic surface projection images. Regionally, hypometabolism in the lateral occipital cortex had the highest sensitivity (88%), but relative preservation of the mid or posterior cingulate gyrus (cingulate island sign) had the highest specificity (100%). Region-of-interest analysis revealed that occipital hypometabolism and relative preservation of the posterior cingulate both had a sensitivity of 77% and specificity of 80%. β-CIT achieved 100% accuracy and greater effect size than did 18F-FDG PET (Cohen d = 4.1 vs. 1.9). Conclusion: Both 18F-FDG PET and 123I-β-CIT SPECT appear useful for the diagnosis of DLB, although the latter provides more robust results. The cingulate island sign may enhance the specificity of 18F-FDG PET.

Patient Expectations of Temporal Lobe Surgery

Summary: Purpose: The purpose of this study was to examine expectations of postoperative quality of life expressed by patients undergoing anterior temporal lobectomy (ATL) for the control of intractable seizures. An important component of this study was an exploration of the relationship between preoperative expectations and perceived success of the operation.

The “burden of normality”: concepts of adjustment after surgery for seizures

OBJECTIVES To conceptualise the process of adjustment provoked by the sudden alleviation of chronic epilepsy by temporal lobectomy. On being rendered seizure free, the process of adjustment primarily depends on the patients capacity to discard roles associated with chronic epilepsy and to learn to become well. This can involve a reconceptualisation of the patients identity from chronically ill to “cured”, and can give rise to a constellation of psychological, affective, behavioural, and sociological features characterised as the “burden of normality”. METHODS This is a theoretical inquiry that documents the clinical phenomenology of the burden of normality by classifying its key psychological and psychosocial features. The model of adjustment is presented in the context of previous outcome research on surgery for seizures, providing a conceptual link between practice based rehabilitation measures of outcome and multidimensional constructs, such as health related quality of life. RESULTS The model represents a process oriented, theoretical framework for comprehensively measuring outcome after life changing medical interventions. It has implications for clinical practice, including the identification of preoperative predictors of outcome and informing appropriate management and rehabilitation of patients. CONCLUSION This model of outcome after temporal lobectomy may ultimately be applicable to the treatment of other chronic conditions.