Lisbeth Regeur

Aging and the human neocortex.

Neurostereology has been applied to quantitative anatomical study of the human brain. Such studies have included the total neocortical number of neurons and glial cells, the estimated size distribution of neocortical neurons, the total myelinated fiber length in the brain white matter, the total number of synapses in the neocortex, and the effect of normal aging on these structural elements. The difference in total number of neurons was found to be less than 10% over the age range from 20 to 90 years, while the glial cell number in six elderly individuals, mean age 89.2 years, showed an average number of 36 billion glial cells, which was not statistically significantly different from the 39 billion glial cells in the neocortex of six young individuals with a mean age of 26.2 years. The total myelinated fiber length varied from 150,000 to 180,000 km in young individuals and showed a large reduction as a function of age. The total number of synapses in the human neocortex is approximately 0.15 x 10(15) (0.15 quadrillion). Although the effect of aging is seen in all estimated structural elements, the effect of sex is actually higher. The functional relevance of these differences in neuron numbers in both age and gender is not known.

Neocortical Glial Cell Numbers in Alzheimer’s Disease

Most studies agree that specific regions of the hippocampus and specific subcortical regions show neuronal loss in Alzheimer’s disease (AD). The aim of the study was to use design-based stereological methods to obtain an estimate of the total glial cell population in 14 AD cases and 20 controls to determine whether brains from AD patients have a different number of neocortical glial cells than controls. The mean total number of neocortical glial cells was 25.9 × 109 for the AD group and 29.1 × 109 for the control group, 2p = 0.18. The mean total number of neocortical neurons was 18.9 × 109 for the AD group and 21.2 × 109 for the control group, 2p = 0.059. Estimates of the sum of all glial cells and neurons in the neocortex were in the order of 50 billion cells with a glia to neuron ratio of 1.37 in both groups.

Dopa-responsive dystonia and early-onset Parkinson's disease in a patient with GTP cyclohydrolase I deficiency?

We describe a patient with a combination of dystonic and parkinsonian signs. Paraclinical studies revealed a mutation in the GTP cyclohydrolase I gene (GCH1) and a decrease in [123I]‐N‐ω‐fluoropropyl‐2β‐carbomethoxy‐3β‐(4‐iodophenyl) nortropane (123I‐FP‐CIT) binding ratios indicative of Parkinsons disease. We conclude that the patient probably suffers from a variant of dopa‐responsive dystonia (DRD) or two separate movement disorders, normally considered to be differential diagnoses, DRD and early‐onset Parkinsons disease with resulting difficulties concerning treatment and prognosis.

The utility of EMG interference pattern analysis in botulinum toxin treatment of torticollis: A randomised, controlled and blinded study

OBJECTIVE The significance of electromyography (EMG) guidance in botulinum toxin (BT) treatment has been much debated. The aim of this study was to evaluate if EMG guidance in the treatment of torticollis in BT-naive patients had a better outcome than treatment after clinical evaluation alone. METHODS Twenty-six patients with torticollis were included and treated for 1 year in this prospective, blinded study. Quantitative EMG was performed simultaneously in the four most frequently affected muscles: the sternocleidomastoid muscles and the posterior neck muscles on both sides. EMGs were analysed for turns per second. Clinical ratings were performed by an experienced neurologist (A). Injections were given by another neurologist (B), who was blinded to the ratings. In group 1, the results of the EMG were available to the treating neurologist B, whereas in group 2, neurologist B was blinded. In group 1, treatment with BT was given when turns per second were higher than 100. RESULTS In patients treated guided by EMG, clinical outcome, evaluated by objective ratings, was better than in patients treated based on clinical judgement alone (p = 0.05). In group 2, 105 muscles were treated with BT. Of these, 37 did not show dystonic EMG activity. CONCLUSIONS Treatment with BT guided by EMG results in better clinical outcome than treatment without EMG and reduces the amount of BT used. SIGNIFICANCE EMG guidance by interference pattern analysis may optimise BT treatment in torticollis by a more precise injection and may reduce side effects and the risk of development of antibodies to BT.