Consensus neuropathological diagnosis of common dementia syndromes: testing and standardising the use of multiple diagnostic criteria

The aim of this study was to assess the variation between neuropathologists in the diagnosis of common dementia syndromes when multiple published protocols are applied. Fourteen out of 18 Australian neuropathologists participated in diagnosing 20 cases (16 cases of dementia, 4 age-matched controls) using consensus diagnostic methods. Diagnostic criteria, clinical synopses and slides from multiple brain regions were sent to participants who were asked for case diagnoses. Diagnostic sensitivity, specificity, predictive value, accuracy and variability were determined using percentage agreement and kappa statistics. Using CERAD criteria, there was a high inter-rater agreement for cases with probable and definite Alzheimer's disease but low agreement for cases with possible Alzheimer's disease. Braak staging and the application of criteria for dementia with Lewy bodies also resulted in high inter-rater agreement. There was poor agreement for the diagnosis of frontotemporal dementia and for identifying small vessel disease. Participants rarely diagnosed more than one disease in any case. To improve efficiency when applying multiple diagnostic criteria, several simplifications were proposed and tested on 5 of the original 20 cases. Inter-rater reliability for the diagnosis of Alzheimer's disease and dementia with Lewy bodies significantly improved. Further development of simple and accurate methods to identify small vessel lesions and diagnose frontotemporal dementia is warranted.

Reduced BDNF mRNA expression in the Parkinson's disease substantia nigra

Brain-derived neurotrophic factor (BDNF) has potent effects on survival and morphology of dopaminergic neurons and thus its loss could contribute to death of these cells in Parkinson's disease (PD). In situ hybridization revealed that BDNF mRNA is strongly expressed by dopaminergic neurons in control substantia nigra pars compacta (SNpc). In clinically and neuropathologically typical PD, SNpc BDNF mRNA expression is reduced by 70% (P = 0.001). This reduction is due, in part, to loss of dopaminergic neurons which express BDNF. However, surviving dopaminergic neurons in the PD SNpc also expressed less BDNF mRNA (20%, P = 0.02) than their normal counterparts. Moreover, while 15% of control neurons had BDNF mRNA expression >1 SD below the control mean, twice as many (28%) of the surviving PD SNpc dopaminergic neurons had BDNF mRNA expression below this value. This 13% difference in proportions (95% CI 8-17%, P < or = 0.000001) indicates the presence of a subset of neurons in PD with particularly low BDNF mRNA expression. Moreover, both control and PD neurons displayed a direct relationship between the density of BDNF mRNA expression per square micrometer of cell surface and neuronal size (r(2) = 0.93, P </= 0.00001) which was lost only in PD neurons expressing the lowest levels of BDNF mRNA. If BDNF is an autocrine/paracrine factor for SNpc dopaminergic neurons, loss of BDNF-expressing neurons may compromise the well-being of their surviving neighbors. Moreover, neurons expressing particularly low levels of BDNF mRNA may be those at greatest risk of injury in PD and possibly the trigger for the degeneration itself.

New dopaminergic neurons in Parkinson's disease striatum

A new population of dopaminergic neurons has been identified in Parkinson's disease striatum. These neurons are sufficiently numerous to have an important effect on dopaminergic function in the striatum.

Hemicranial volume deficits in patients with temporal lobe epilepsy with and without hippocampal sclerosis

PURPOSE

In patients with refractory temporal lobe epilepsy, studies have suggested volume deficits measured by MRI of brain structures outside the epileptogenic hippocampus. Hippocampal sclerosis (HS) is a frequent, but not obligate, finding in such patients. The present study examines the influence of the presence of HS on quantitative magnetic resonance imaging (MRI) measurements.

METHODS

We analyzed 47 patients and 30 controls by quantitative MRI, including intracranial volume (ICV), hemicranial volume, hippocampal volume (HCV), and T2 relaxometry. MRI results were compared with histological findings in the resected temporal lobe.

RESULTS

Histology documented HS in 35 patients (HS group) and other findings in 12 patients (no-HS group). In both groups, the hemicranial volume ipsilateral to the epileptogenic focus was significantly smaller than on the contralateral side (p < 0.004). The HCV on both sides was smaller in the HS group compared with patients without HS (p < or = 0.004). Unilateral hippocampal atrophy and increased T2 value were found in 71% of patients with HS, and bilaterally normal HCV and T2 value were found in 67% of patients without HS.

CONCLUSIONS

The smaller hemicranial volume on the focus side, irrespective of the presence or absence of HS suggests a different pathogenic mechanism for the additional hemicranial volume deficit, compared to HS itself. The contralateral HCV deficit depends on the presence of HS, indicating a pathogenic connection between damage to both hippocampi.

Lipomatous meningioma: characteristic computed tomographic appearance

A case of lipomatous meningioma is reported. This is a rare variant of meningioma in which metaplasia of meningoepithelial cells occurs and mature adipocytes are present within the tumour. The heterogeneous attenuation and heterogeneous enhancement visualized on computed tomography (CT) can mimic necrotic malignant tumours. However, the demonstration of fat attenuation within the tumour explains the heterogeneity and suggests a benign process. The differential diagnosis of an extra-axial fat-containing tumour should include lipomatous meningioma.

Life-threatening focal status epilepticus due to occult cortical dysplasia

OBJECTIVE

Neuronal migration disorders are usually, but not necessarily, demonstrated by magnetic resonance imaging. Preoperative suspicion of these anomalies in the presence of normal magnetic resonance studies has important practical implications. This study delineates some clinical features that permit early suspicion of focal cortical dysplasia localized in the central and precentral regions.

DESIGN

In a retrospective case series, we studied the clinical presentation of four consecutive patients with normal preoperative magnetic resonance images in whom focal cortical dysplasia was found in the surgical specimen.

SETTING

Patients were seen in three referral centers specializing in epilepsy surgery.

PATIENTS

Four patients (three female), between the ages of 4 and 21 years, had intractable partial seizures leading to resective brain surgery.

INTERVENTION

Three patients had corticectomies in the central (two patients) or frontal (one patient) regions. One underwent an en bloc resection of the central area after two unsuccessful corticectomies and cortical transection.

RESULTS

Three patients presented with life-threatening focal motor status epilepticus necessitating intubation, and one had epilepsia partialis continua. All had had seizures previously, and the attacks progressed to intractability after 1 1/2 to 3 years. Surgery led to control of the seizures, but only two patients became seizure free (mean follow-up, 15.7 months). All but one developed a postoperative deficit, which eventually improved.

CONCLUSIONS

Focal cortical dysplasia should be suspected when life-threatening focal motor status epilepticus or epilepsia partialis continua occur in children or young persons without another obvious cause. Normal magnetic resonance studies do not exclude neuronal migration disorders.

Angiotensin II receptor binding associated with nigrostriatal dopaminergic neurons in human basal ganglia

In the human brain, receptor binding sites for angiotensin are found in the striatum and in the substantia nigra pars compacta overlying dopamine-containing cell bodies. In contrast, angiotensin-converting enzyme occurs in the substantia nigra pars reticulata and is enriched in the striosomes of the striatum. In this study, using quantitative in vitro autoradiography, we demonstrate decreased angiotensin receptor binding in the substantia nigra and striatum of postmortem brains from patients with Parkinson's disease. In the same brains the density of binding to angiotensin-converting enzyme shows no consistent change. We propose, from these results, that angiotensin receptors in the striatum are located presynaptically on dopaminergic terminals projecting from the substantia nigra. In contrast, the results support previous studies in rats demonstrating that angiotensin-converting enzyme is associated with striatal neurons projecting to the substantia nigra pars reticulata. These findings raise the possibility that newly emerging drugs that interact with the angiotensin system, particularly converting enzyme inhibitors and new nonpeptide angiotensin receptor blockers, may modulate the brain dopamine system.

Surgical risk of hemorrhage in cerebral amyloid angiopathy

Cerebral amyloid angiopathy is increasingly recognized as a cause of lobar cerebral hemorrhage in normotensive elderly individuals. Isolated reports have suggested that neurosurgical intervention entails a high risk of precipitated hemorrhage. We identified 16 pathologically confirmed cases of cerebral amyloid angiopathy. Fourteen of these patients presented with lobar cerebral hemorrhage. Fifteen neurosurgical procedures in eight patients included eight clot evacuations, three abscess drainage procedures, two ventriculoperitoneal shunts, one biopsy, and one lobectomy. Recurrent postoperative cerebral hemorrhage was seen in four patients at 2 days, 9 days, 6 weeks, and 10 months, but surgery was thought to have precipitated the cerebral hemorrhage in only one patient. Recurrent cerebral hemorrhage also was seen in two of the eight nonoperated cases. Recurrent cerebral hemorrhage is characteristic of cerebral amyloid angiopathy, but we conclude that neurosurgical intervention, particularly evacuation of hematomas, is not associated with major risk of precipitated hemorrhage.

The development of Cushing's syndrome from a previously silent pituitary tumour

A 60 year old woman originally presented with headache. Investigations revealed a pituitary tumour and endocrine investigations at that time showed normal plasma cortisol levels. Seven years after removal of this tumour, the patient developed the clinical and biochemical features of Cushing's disease. Immunoperoxidase staining of the original tumour was positive for adrenocorticotrophic hormone. This report suggests that immunocytochemistry may have an important role in the routine evaluation of pituitary tumours.

Watery diarrhea-hypokalemia-achlorhydria syndrome and carcinoma of the esophagus

The watery diarrhea-hypokalemia-achlorhydria syndrome associated with ectopic secretion of vasoactive intestinal peptide has only been conclusively documented with tumors originating in the pancreas or sympathetic chain. We report here the case of a 50-yr-old woman who developed this syndrome 3 wk after an apparently effective course of radiotherapy for an obstructing, mixed-cell carcinoma of the esophagus. High concentrations of vasoactive intestinal peptide were found in plasma (100-200 pmol/L; normal less than 20 pmol/L) and in the metastatic skin nodules (750 pmol/g) that later developed and that contained one of the two cell types from the original tumor. Stool volumes reached a plateau of 15-20 L/day, and potassium requirements were greater than 1000 mmol/day. Symptoms failed to respond to any of the regimens previously described as effective in this syndrome. After 14 wk of massive fecal fluid and electrolyte losses, symptoms resolved dramatically with the first dose of 5-fluorouracil. Plasma vasoactive intestinal peptide concentration returned to normal, where it remained despite subsequent evidence of renewed tumor spread. This case illustrates the unpredictability of the response of this syndrome to medical treatment, and suggests that vasoactive intestinal peptide secretion may occur in a wider range of tumors than has so far been described.

Gerstmann-Sträussler-Scheinker disease with coincidental familial onset

A family with Gerstmann-Sträussler-Scheinker disease had coincidental clinical onset in three members of two generations, a phenomenon suggesting a common source of a transmissible agent. A regular dietary supplement in this family was home-bred rabbit. The clinical picture, although generally similar to that in previous accounts, included the unusual findings of visual loss (one patient) and sensory loss (one patient), and dementia was not apparent until late in the illness in two patients. Pathological examination of a cerebellar cortical biopsy specimen from one patient and postmortem tissue from two patients revealed multicentric amyloid plaques located in cerebral and cerebellar cortex, basal ganglia, and white matter with degeneration of corticospinal, dorsal spinocerebellar, dentatorubral, and geniculocalcarine tracts and dorsal columns. Spongiform change was focal and confined to the superficial cerebral cortical layers.