Neurophysiologie clinique = Clinical neurophysiology
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Occipital nerve stimulation (ONS) is a surgical approach to treat patients with medically intractable chronic headache disorders. However, no preoperative test has been yet validated to allow candidates to be selected for implantation. In this study, the analgesic efficacy of transcutaneous electrical nerve stimulation (TENS) was tested for 1 to 3 months in 41 patients with pharmacologically intractable headache disorders of various origins, using a new technique of electrode placement over the occipital nerve. ⋯ Implanted ONS may be a valuable therapeutic option in the long term for patients with pharmacologically intractable chronic headache. Although we cannot conclude in patients with poor or no response to TENS, a good or very good response to TENS can support the indication of ONS therapy. This preoperative test could particularly be useful in patients with chronic migraine, in whom it may be difficult to indicate an invasive technique of cranial neurostimulation.
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Laser-evoked potential (LEP) habituation was investigated under the influence of capsaicin-induced peripheral and central sensitization. ⋯ Capsaicin-induced central sensitization does not alter LEP habituation. The physiological habituation of LEP amplitudes is reduced due to peripheral mechanisms after applying capsaicin topically. These findings form a basis for future studies, which use the habituation paradigm to investigate pain conditions promoted by sensitization phenomena.
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Comparative Study
Diagnosis of small fiber neuropathy: A comparative study of five neurophysiological tests.
The diagnosis of small fiber neuropathy (SFN) is a challenge for clinical neurophysiology. Conventional nerve conduction studies are inappropriate for this purpose and therefore various neurophysiological tests have been proposed. In this study, we compared the diagnostic value of five of these tests in 87 patients with clinically definite (n=33) or possible (n=54) SFN related to amyloid neuropathy secondary to transthyretin gene mutation or monoclonal gammopathy (n=30), primary Sjögren's syndrome (n=20), Fabry's disease (n=2), or unknown cause (n=35). ⋯ The LEP was the most sensitive test (altered in 79% of the patients with at least one abnormal test), followed by ESC (61%), WDT (55%), SSR (41%), and CDT (32%). The combination of LEP, assessing A-delta sensory fibers, WDT, assessing sensory C fibers, and ESC, assessing autonomic C fibers, appears a relevant approach for the diagnosis of SFN. Compared to SSR and CDT, these three tests, LEP, WDT, and ESC, had a significantly better diagnostic sensitivity and their combination further improved diagnostic accuracy.
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Deep brain stimulation (DBS) of the subthalamic nucleus (STN) and internal globus pallidus (GPi) deep brain stimulation (DBS) provides an efficient treatment for the alleviation of motor signs in patients with Parkinson's disease. The effects of DBS on gait and balance disorders are less successful and may even lead to an aggravation of freezing of gait and imbalance. The identification of a substantia nigra pars reticulata (SNr)-mesencephalic locomotor region (MLR) network in the control of locomotion and postural control and of its dysfunction/lesion in PD patients with gait and balance disorders led to suggestion that DBS should be targeting the SNr and the pedunculopontine nucleus (part of the MLR) for PD patients with these disabling axial motor signs. ⋯ In this review, we discuss the effects of DBS of these basal ganglia and brainstem structures on the neurophysiological parameters of gait and balance control in PD patients. Overall, the data suggest that both STN and GPi-DBS improve gait parameters and quiet standing postural control in PD patients, but have no effect or may even aggravate dynamic postural control, in particular with STN-DBS. Conversely, DBS of the SNr and PPN has no effect on gait parameters but improves anticipatory postural adjustments and gait postural control.
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Review Meta Analysis
Repetitive peripheral magnetic stimulation to reduce pain or improve sensorimotor impairments: A literature review on parameters of application and afferents recruitment.
Repetitive peripheral magnetic stimulation (rPMS over spinal root, nerve or muscle belly) is a promising technology in physiopathology research. As compared to electrical stimulation, rPMS is deemed to activate deep conductive structures and produce strong muscle contractions and massive proprioceptive afferents with minimal cutaneous recruitment. RPMS may thus act differently on neural plasticity involved in pain reduction and motor recovery in musculoskeletal or neurological conditions. However, literature is very scant and still controversial concerning afferents recruited by rPMS, thus no consensus is reached yet for its clinical use. ⋯ The review proposed recommendations to improve rPMS application in clinical research. However, the development of guidelines still requires methodological and clinical studies enrolling larger samples and with randomized sham-controlled designs.