Brain : a journal of neurology
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To investigate postoperative changes in the cerebral glucose metabolism of patients with mesial temporal lobe epilepsy (MTLE), statistical parametric mapping (SPM) analysis was performed on pre- and postoperative (18)F-fluorodeoxyglucose PET (FDG-PET) images. We included 28 patients with MTLE who had undergone surgery and had been seizure-free postoperatively (16 had left MTLE and 12 right MTLE). All patients showed hippocampal sclerosis by pathology or brain MRI. ⋯ Subtraction between pre- and postoperative FDG-PET images in individual patients produced similar findings to the SPM results, and additionally showed that postoperative glucose metabolism increased in the anterior thalamus in 12/28 patients (42.8%). SISCOM (subtraction ictal-interictal SPECT co-registered to MRI) performed in 17 patients showed ictal hyperperfusion in the ipsilateral temporal lobe, including the temporal stem white matter, midbrain, insular cortex and cingulate gyrus, bilateral basal ganglia and thalami, and multiple small regions in the frontoparietal lobes during seizures. This study suggests that brain regions showing a postoperative increase in glucose metabolism appear to represent the propagation pathways of ictal and interictal epileptic discharges in MTLE, whereas the postoperative decrease in glucose metabolism may be related to a permanent loss of afferents from resected anterior-mesial temporal structures.
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Gain-of-function mutation in Nav1.7 in familial erythromelalgia induces bursting of sensory neurons.
Erythromelalgia is an autosomal dominant disorder characterized by burning pain in response to warm stimuli or moderate exercise. We describe a novel mutation in a family with erythromelalgia in SCN9A, the gene that encodes the Na(v)1.7 sodium channel. ⋯ We demonstrate that this mutation, which produces a hyperpolarizing shift in activation and a depolarizing shift in steady-state inactivation, lowers thresholds for single action potentials and high frequency firing in dorsal root ganglion neurons. Erythromelalgia is the first inherited pain disorder in which it is possible to link a mutation with an abnormality in ion channel function and with altered firing of pain signalling neurons.
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Cerebral ischaemia appears to be an important mechanism of secondary neuronal injury in traumatic brain injury (TBI) and is an important predictor of outcome. To date, the thresholds of cerebral blood flow (CBF) and cerebral oxygen utilization (CMRO(2)) for irreversible tissue damage used in TBI studies have been adopted from experimental and clinical ischaemic stroke studies. Identification of irreversibly damaged tissue in the acute phase following TBI could have considerable therapeutic and prognostic implications. ⋯ We conclude that, in TBI, the threshold of CBF below which irreversible tissue damage consistently occurs differs from the classical CBF threshold for stroke (where similar methodology is used to define such thresholds). The CMRO(2) threshold is comparable to that reported in the stroke literature. At a voxel-based level, however (and in common with ischaemic stroke), the extent of irreversible tissue damage cannot be accurately predicted by early abnormalities of any single physiological variable.
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We report seven patients, six from a single institution, who developed subacute limbic encephalitis initially considered of uncertain aetiology. Four patients presented with symptoms of hippocampal dysfunction (i.e. severe short-term memory loss) and three with extensive limbic dysfunction (i.e. confusion, seizures and suspected psychosis). Brain MRI and [(18)F]fluorodeoxyglucose (FDG)-PET complemented each other but did not overlap in 50% of the patients. ⋯ Overall, the phenotype associated with the novel neuropil antibodies includes dominant behavioural and psychiatric symptoms and seizures that often interfere with the evaluation of cognition and memory, and brain MRI or FDG-PET abnormalities less frequently restricted to the medial temporal lobes than in patients with classical paraneoplastic or VGKC antibodies. When compared with patients with VGKC antibodies, patients with these novel antibodies are more likely to have CSF inflammatory abnormalities and systemic tumours (teratoma and thymoma), and they do not develop SIADH-like hyponatraemia. Although most autoantigens await characterization, all share intense expression by the neuropil of hippocampus, with patterns of immunolabelling characteristic enough to suggest the diagnosis of these disorders and predict response to treatment.
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We have developed a dual-component artificial nerve graft comprising an outer microporous conduit of chitosan and internal oriented filaments of polyglycolic acid (PGA). The novel graft was used for bridging sciatic nerve across a 30-mm defect in six Beagle dogs, which were used as a chitosan/PGA graft group. The other Beagle dogs were divided into an autograft group (n = 6) as the positive control and a non-grafted group (n = 5) as the negative control. ⋯ Six months post-operatively, a combination of electrophysiological examination, FluoroGold retrograde tracing, histological assessment including light microscopy and transmission electron microscopy, immunohistochemistry as well as morphometric analyses to both regenerated nerves and target muscles was utilized to investigate the nerve repair effects of our artificial nerve graft. The results demonstrated that, in the chitosan/PGA graft group, the dog sciatic nerve trunk had been reconstructed with restoration of nerve continuity and functional recovery, and its target skeletal muscle had been re-innervated, improving locomotion activities of the operated limb. This study proves the feasibility of the chitosan/PGA artificial nerve graft for peripheral nerve regeneration by bridging a longer defect in a large animal model.