Brain : a journal of neurology
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Post-concussion syndrome (PCS) can affect up to 20%-30% of patients with mild closed head injury (mCHI), comprising incomplete recovery and debilitating persistence of post-concussional symptoms. Eye movements relate closely to the functional integrity of the injured brain and eye movement function is impaired post-acutely in mCHI. Here, we examined whether PCS patients continue to show disparities in eye movement function at 3-5 months following mCHI compared with patients with good recovery. ⋯ Poorer subconscious oculomotor function in the PCS group supports the notion that PCS is not merely a psychological entity, but also has a biological substrate. Measurement of oculomotor function may be of value in PCS cases with a high symptom load but an otherwise unremarkable assessment profile. Routine oculomotor testing should be feasible in centres with existing access to this technology.
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Case Reports
Functional definition of seizure provides new insight into post-traumatic epileptogenesis.
Experimental animals' seizures are often defined arbitrarily based on duration, which may lead to misjudgement of the syndrome and failure to develop a cure. We employed a functional definition of seizures based on the clinical practice of observing epileptiform electrocorticography and simultaneous ictal behaviour, and examined post-traumatic epilepsy induced in rats by rostral parasagittal fluid percussion injury and epilepsy patients evaluated with invasive monitoring. We showed previously that rostral parasagittal fluid percussion injury induces different types of chronic recurrent spontaneous partial seizures that worsen in frequency and duration over the months post injury. ⋯ When occurring in the motor cortex, these short EEEs were accompanied by ictal behaviour detectable with simultaneous surface electromyography. These data demonstrate that short (<2 s) focal recurrent spontaneous EEEs are seizures in both rats and humans, that they are undetectable by scalp electroencephalography, and that they are typically associated with subtle and easily missed behavioural correlates. These findings define the earliest identifiable markers of progressive post-traumatic epilepsy in the rat, with implications for mechanistic and prophylactic studies, and should prompt a re-evaluation of the concept of post-traumatic silent period in both animals and humans.
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Frontotemporal dementia (FTD) and Alzheimer's disease are sometimes difficult to differentiate clinically because of overlapping symptoms. Using diffusion tensor imaging (DTI) measurements of fractional anisotropy (FA) can be useful in distinguishing the different patterns of white matter degradation between the two dementias. In this study, we performed MRI scans in a 4 Tesla MRI machine including T1-weighted structural images and diffusion tensor images in 18 patients with FTD, 18 patients with Alzheimer's disease and 19 cognitively normal (CN) controls. ⋯ In conclusion, the regional patterns of anisotropy reduction in FTD and Alzheimer's disease compared to controls suggest a characteristic distribution of white matter degradation in each disease. Moreover, the white matter degradation seems to be more prominent in FTD than in Alzheimer's disease. Taken together, the results suggest that white matter degradation measured with DTI may improve the diagnostic differentiation between FTD and Alzheimer's disease.
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Clinical audits have highlighted the many challenges and dilemmas faced by clinicians assessing persons with disorders of consciousness (vegetative state and minimally conscious state). The diagnostic decision-making process is highly subjective, dependent upon the skills of the examiner and invariably dictated by the patients' ability to move or speak. Whilst a considerable amount has been learnt since Jennett and Plum coined the term 'vegetative state', the assessment process remains largely unchanged; conducted at the bedside, using behavioural assessment tools, which are susceptible to environmental and physiological factors. ⋯ These fMRI findings were found to have no association with the patient's behavioural presentation at the time of investigation and thus provided additional diagnostic information beyond the traditional clinical assessment. Notably, the utility of brain imaging was further underlined by the finding that the level of auditory processing revealed by functional brain imaging, correlated strongly (rs = 0.81, P < 0.001) with the patient's subsequent behavioural recovery, 6 months after the scan, suggesting that brain imaging may also provide valuable prognostic information. Although further evidence is required before consensus statements can be made regarding the use of brain imaging in clinical decision making for disorders of consciousness, the results from this study clearly highlight the potential of imaging to inform the diagnostic decision-making process for persons with disorders of consciousness.
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Inherited erythromelalgia (IEM), an autosomal dominant disorder characterized by severe burning pain in response to mild warmth, has been shown to be caused by gain-of-function mutations of sodium channel Na(v)1.7 which is preferentially expressed within dorsal root ganglion (DRG) and sympathetic ganglion neurons. Almost all physiologically characterized cases of IEM have been associated with onset in early childhood. ⋯ Using current-clamp, we show that the expression of Q10R induces hyperexcitability in DRG neurons, but produces an increase in excitability that is smaller than the change produced by I848T, an early-onset erythromelalgia mutation. Our analysis suggests a genotype-phenotype relationship at three levels (clinical, cellular and molecular/ion channel), with mutations that produce smaller effects on sodium channel activation being associated with a smaller degree of DRG neuron excitability and later onset of clinical signs.