Rev Neurol France
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Brain abscesses occur in 5 to 13 % of patients with pulmonary arteriovenous malformation (PAVM), more often present in Rendu-Osler-Weber disease or hereditary hemorrhagic telangiectasia (HHT). ⋯ Combining different MRI techniques (in particular diffusion and proton MR spectroscopy) provides invaluable data for the diagnosis of brain abscess. Careful search for PAVM must be undertaken, particularly in adults with cryptogenic abscess, to avoid further abscess formation or stroke.
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Standard neurophysiological techniques evaluate exclusively large myelinated fibers, but are not useful to explore sensory small fibers. Quantitative sensory tests have been developed to explore the thermal nociceptive function but this exploration is only subjective. Laser evoked potentials (LEPs) represent a noninvasive and objective test to explore thermal and nociceptive pathways. ⋯ In routine, the determination of detection and nociceptive thresholds, the analysis of N2P2 latencies and amplitudes enable demonstration of a dysfunction of A delta nerve fibers, to quantify these lesions and to determine whether the neuropathies are length-dependent or not. The LEP amplitude is negatively correlated to deafferentation. The interest of LEPs remained to be studied compared to skin biopsy.
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Botulinum toxin type A (BTX-A) is a potent neurotoxin that blocks acetylcholine release from presynaptic nerve terminals by cleaving the SNARE complex. BTX-A has been reported to have analgesic effects independent of its action on muscle tone. The most robust results have been observed in patients with neuropathic pain. ⋯ Further studies are needed to assess some important issues, i.e. BTX-A efficacy in patients with small fiber neuropathies and the relevance of early and repeated injections. Future studies could also provide valuable insights into pathophysiology of neuropathic pain.