John van Swieten is well known in the field of dementia and it is his clear account on the epidemiology of fronto-temporal dementia (FTD) that forms one of our review articles in this issue. This condition - which encompasses semantic dementia and primary progressive aphasia - seems to be heterogeneous not only in its clinical presentation but its pathology and aetiology, including known genetic defects in tau and more recently in the ESCRT3 complex subunit CHMP2B. This review article clearly lays out the ambiguities of studies attempting to define the prevalence of FTD as well as delineating the heterogeneity and problems and challenges that this throws up.

For most of us (well for me, anyway) once outside the familiar ground of chronic tension type headaches, migraine and cluster headache, the diagnosis of different types of recurrent headaches becomes a little bit muzzy. What for example are hypnic headaches? In this article by Anish Bahra we are taken on a brief but thoroughly helpful review of unusual types of headache, many of which are especially responsive to indomethacin. This clearly written account by such an expert will now accompany me to clinic so that the next time I see someone with a walking headache I will know to refer them for an exercise tolerance test.

Our management series stays with headache. All in clinical practice are familiar with the headache following lumbar puncture, indeed in years gone by it was thought to be helped by not allowing the patient out of bed for several days. However, spontaneous intracranial hypotension as a cause of headache is much less common. In their article Imam and Weatherby explore the pathological basis of this condition, as well as all of its clinical features, investigations and management. This article highlights that it is CSF volume rather than pressure that is critical in the genesis of this condition which can be difficult to diagnose and treat.

Peter Tucker addresses a very interesting area of rehabilitation, namely one of the psychological sequelae and management of children/ adolescents with acquired brain injury. As he comments, "a central difference between children and adults is that while the effects of the injury are immediately obvious in adults, children's development is disordered after injury and some deficits may take a considerable time to appear". This is explored through a series of informative tables, highlighting the differences in deficits in children and adults and their functional and educational impact. This is a stimulating review which discusses an often overlooked area of rehabilitation medicine.

Microarrays are now emerging as one of the most exciting new tools in biology as they allow one to look at thousands of genes in a single experiment. Jo Jones leads us through this new technique highlighting the principles that underpin it and the differences between spotted and oligonucleotide Affymetrix gene chips. This is a clear account of an important new technique which has been criticised on the grounds that it promotes experiments which are non hypothesis- driven fishing expeditions. This is true, but fishing expeditions often identify new fishing grounds to harvest, and as such this is a powerful technique for doing just that. It does of course generate data that represents formidable bioinformatic challenges, as well as issues of which of the changes are of greatest biological significance.

The use of muscle biopsy in modern day neurological practice is explored by Dr Leslie Bridges and shown to be central in the diagnosis of many muscle disorders (see also Rakowicz). This account takes us through the practicalities of the biopsy procedure itself, through to its preparation, staining and interpretation. As with all articles in this series it boasts a plethora of wonderful illustrations.

In the visual series Stewart Shipp takes us through the complexities of the parallel visual pathways. The original scheme of organisation within the visual pathway devised by Hubel and Wiesel was conceived of as being serial-hierarchical processing, although in the mid 1960s different functional retinal ganglion cells (XYW system) were recognised, which led to the possibility that the visual system was composed of parallel pathways. This appears to have been verified over the years with three major pathways being recognised projecting from the retina to a number of targets both subcortically and cortically. Stewart Shipp takes us through this complex system highlighting what is known and not known and simplifying what is an immensely complex field into an easily digestible and illuminating article.

Don Tucker and colleagues from Oregon have also provided a very thought provoking article on the use of EEG to more accurately localise abnormalities in the CNS. This is a very technical article but nevertheless clearly written and provides insights into how old techniques can be developed and modified to provide even greater and more useful information in modern day neurological practice.

Andrew Larner takes us to one of literature's most famous epileptics, Fyodor Mikhailovich Doestoevsky. Andrew explores the origin of the epilepsy of this wonderful Russian writer, which encompasses aetiological causes ranging from psychogenic (Freud) to an onset from a left mesial temporal lobe focus (Rosetti & Bogousslavsky). This account is peppered with literary references and will hopefully enthuse you to read his novels - Doestoevsky that is, rather than Larner!!

Finally we have our usual wide range of journal, book and conference reviews. We hope you enjoy this new issue and do let us know if there aspects of neurobiology/neurology/rehabilitation that you would like to see in ACNR.

Roger Barker
Roger@acnr.co.uk