Presentation is typically with a tonic–clonic seizure, often on wakening after a late night or sleep deprivation (common at this age). 8 The syndrome is characterised by myoclonic seizures (typically on awakening, but also at other times) in all patients, generalised tonic–clonic seizures (GTCS) in approximately 90% and brief absence seizures in approximately 60% of patients. The most common epilepsy syndrome presenting in adolescence is juvenile myoclonic epilepsy (JME). Finally, there seems to be much more focal activation of the brain in adolescence compared with early childhood, with a marked increase in the degree to which each hemisphere can process information independently. Although the precise reason for this is unknown, it is speculated that the brain is developing on the basis of experience and pertinent environmental needs-the “use it or lose it” theory. 5 The decrease in frontal grey matter volume is probably due to massive synaptic loss during this period data from primate models have estimated that up to 30 000 synapses may be lost per second over the entire cortex, particularly from the frontal regions.
A longitudinal magnetic resonance imaging (MRI) study showed that the total white matter volume continues to increase into the early 20s, frontal and parietal grey matter volume peaks at approximately 14 years of age before declining, and the grey matter in the occipital and temporal lobes continues to increase until 20 years of age.
4 Structurally, the brain continues to increase in total volume until the age of approximately 14 years. It is also not within the remit of this review to discuss in detail either the diagnostic process or the management of these disorders.Īdolescents show significant neuropsychological progress in the years leading up to adulthood, although this may lack the dramatic effect of a toddlers taking their first steps or uttering their first words. The aim of this review is to describe the common and many of the less common neurological disorders that may have an onset or are present in adolescence it is not possible to provide a comprehensive and detailed account of all the neurological disorders that may present in the teenage years-for example, head injury, brain tumour, stroke or Guillain–Barré syndrome, partly because these conditions may present throughout childhood, including adolescence. For the purposes of this review, adolescence will refer to children aged ⩾12 years. The age at which a child enters and completes adolescence is therefore difficult to characterise and depends on many variables including sex, health, sociocultural values and economic factors. 3 The Oxford dictionary defines adolescence as the process of developing from a child to an adult, and the word itself is derived from the Latin word adolescere, meaning to come to maturity. A recent review in Archives of Disease in Childhood outlined some of the major issues at this time of life, and highlighted the important differences between traditional paediatric practice and adolescent medicine. Recent medical publications, including two from the National Health Service, 1, 2 have focused on adolescent health issues, and specifically the transition from paediatric to adult services.
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