SUMMARY Event-related potentials (ERPs) were recorded from 19 closed head injury (CHI) patients, at least 6 months after injury, and an equal number of control subjects, during a task requiring the covert counting of rare auditory "target" stimuli against a background of frequent "non-targets". In both groups, ERPs to targets contained enhanced frontal N2 and parietal P3 components. N2 was larger in amplitude in the CHI patients than in the controls, and its peak latency was delayed. P3 amplitude was smaller in the patients, but its latency was not significantly different from that of the control group. The delay in N2 latency is interpreted as evidence of an increase in the time needed to achieve stimulus categorisation in CHI patients. The larger N2s in this group are thought to reflect the additional cognitive effort required after CHI to cope with the task. The negative findings with respect to P3 latency suggest that this may be a less sensitive measure of information-processing efficiency in this task than the latency of N2.Individuals who suffer a closed head injury (CHI) often demonstrate one or more of a characteristic range of cognitive dysfunctions. These include depressed intellectual performance,1 3 poor long-term memory,4 5 and poor performance on tasks requiring speeded processing and decision making, as for example in the cases of 4-choice reaction-time6 7 and paced auditory serial addition.89 Although these sequelae are well known, there has been little attempt to relate them to indices of cerebral function such as scalprecorded event-related potentials (ERPs). ERPs are an attractive means of investigating closed head injury because of their "real-time" nature, and the fact that they are sensitive to a range of cognitive variables. They therefore offer a means of assessing information-processing efficiency independently of overt behavioural measures, and in particular, they provide a relatively direct way of investigating "early" stages of information-processing. Moreover, by determining the distribution on the scalp of ERP Address for reprint requests: M D Rugg,
Event-related potentials (ERPs) were recorded in a GO/NO-GO reaction time task from 20 closed head injury patients, at least 6 months postinjury, and from 20 controls. In this task the pitch of an initial tone (Sl) indicated whether or not a response was required to a second tone (S2) occurring 1.5 s later. In the control group both the early, frontal-maximum, and the later vertex-maximum, components of the contingent negative variation (CNV) were larger on GO than NO-GO trials. In the patients, the early frontal CNV wave did not differentiate GO and NO-GO trials, and the late CNV showed a smaller separation between these trial types than did the late CNV of the control group. These CNV abnormalities may reflect impairments in selectively orienting to salient stimuli, and in differential response preparation. Such impairments might in turn reflect the damage to the frontal lobes and/or their connections that commonly occurs as a result of closed head injury.
We report the clinical presentation and management of 34 patients with a histologically proven chordoma, treated in the neurosurgical departments in Edinburgh and Dundee, over the past 50 years. Although these tumors are commonly regarded as being locally invasive with a variable, but generally slow growth rate, they can metastasize, and this may precede surgical intervention, as in one of our patients. Our cases are compared to those in previously published series, and a comprehensive review of the treatment modalities for tumors at various sites is presented. The optimal treatment to be recommended from our own experience, and that of others, is aggressive operation and radiotherapy. A combination of hyperthermia and chemotherapy has shown some promise, but remains untested, and highlights the need for a multicenter trial with long follow-up to allow the evaluation of new therapeutic approaches.
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