Brain : a journal of neurology
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Guillain-Barré syndrome (GBS) is traditionally considered to be a large-fibre neuropathy. However, the presence of hypo-aesthesia, dysaesthesia and dysautonomia in GBS patients raises the possibility that small-diameter sensory and autonomic nerves may also be affected. To investigate small-fibre neuropathy in GBS, we performed a skin biopsy from the distal leg of 20 patients with the demyelinating form of GBS. ⋯ Patho logically, sudomotor innervation of the skin was reduced in five of 17 (29.4%) GBS patients in whom sweat glands could be recognized. These findings suggest that small-fibre sensory and autonomic neuropathies exist in a significant proportion of GBS patients, and that END values are correlated with functional disabilities. In summary, GBS should be considered a global neuropathy instead of a pure large-fibre neuropathy.
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We report the response properties of the suprasylvian opercular and insular cortices to a painful stimulation delivered by a CO(2) laser recorded by depth intracerebral electrodes in epileptic patients. We defined two cortical areas of activation in the operculo-insular cortex in response to a painful laser stimulation: a suprasylvian opercular area, where we recorded responses peaking 140-170 ms after a painful stimulation (N140-P170), and a deeper insular area, where responses with a similar pattern peaked 180-230 ms after the stimulus (N180-P230). The average delay of 50 ms measured between the opercular and insular responses may reflect either sequential activation of the suprasylvian cortex then of the insula via corticocortical connections, or direct activation of the insula by inputs conveyed via thalamocortical projections through distinct fibres with different conduction times. ⋯ We were able to distinguish the suprasylvian opercular and insular cortices in terms of response latencies evoked by a painful stimulus and in terms of stereotactic coordinates of the sources of these responses. The sequential timing of activation of the suprasylvian and insular cortices shown in this study thus complements in the time domain the spatial information provided by neuroimaging studies of the cortical processing of pain. It strongly suggests that these cortical areas are those responding with the shortest latency to peripheral pain inputs in the human brain.
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Besides the common distal symmetrical sensory-motor polyneuropathy (DSP) that is often associated with autonomic dysfunction, diabetic patients may develop multifocal sensory-motor deficits (MDN) secondary to roots, plexus and nerve trunk involvement. Nerve ischaemia has been suggested as a common mechanism for the different patterns of diabetic neuropathies, yet the important clinical differences that exist between DSP and MDN suggest concurrent factors. In order to learn more on the subject, we prospectively studied 22 consecutive diabetic patients with MDN, for which other causes of neuropathy were excluded by appropriate investigations, including biopsy of a recently affected sensory nerve. ⋯ Perivascular mononuclear cell infiltrates were present in the nerve specimens of 21 out of 22 patients, prominently in four patients. In comparison, nerve biopsy specimens of 30 patients with severe distal symmetrical diabetic polyneuropathy showed mild epineurial mononuclear cell infiltrate in one patient and endoneurial seepage of red cells in another. We conclude that MDN is related to pre-capillary blood vessel involvement in elderly diabetic patients with a secondary inflammatory response.
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Changes in the cerebral metabolism and the excitability of brain areas remote from an ischaemic brain lesion have been reported in animals and humans and implicated as a mechanism relevant to functional recovery. The aim of the present study was to determine whether changes in the inhibitory and excitatory activity in motor cortex of the non-affected hemisphere are present in stroke patients, and whether these changes are related to the extent of the patients' recovery of function. Transcranial magnetic stimulation (TMS) was used to study the first dorsal interosseus muscle (FDI) of the non-affected hand in 13 patients with good recovery of hand function after stroke, and was compared with left hemispheric stimulation in 13 healthy age-matched volunteers. ⋯ The similarity of the inhibitory effect at low CS intensities in the patients with good recovery and healthy subjects, and the steeper increase of conditioned MEP amplitude at higher CS intensities in the recovering patients suggest that in the patients' contralesional motor cortex the balance of excitatory and inhibitory activity was shifted towards an increase of excitatory activity in the neuronal circuits tested at ISIs of 2 and 3 ms. This shares similarities to mechanisms implicated as relevant for reorganizational processes after experimental brain injury and may be relevant for functional recovery after stroke. The absence of changes in cortical excitability in patients with poor recovery supports the relevance of our findings for recovery.