Intravenous immunoglobulins (IVIg) have been used successfully as an immunomodulating treatment for patients with inflammatory diseases of the central nervous system (CNS) including multiple sclerosis (MS). It was shown previously that IVIg could modulate the functions of microglia, the main immune cell in the CNS. We have compared five commercially available IVIg preparations on their capacity to modulate tumor necrosis factor (TNF)-alpha secretion and nitric oxide production in cultured microglia. All preparations induced a dose-dependent stimulation of TNF-alpha secretion as measured by ELISA. There were some small differences between preparations consisting of IgG, while the preparation enriched for IgM and IgA induced a considerably higher TNF-alpha production at 1 mg/mL and 10 mg/mL. Similar results were seen for nitric oxide production as measured indirectly by the Griess reaction. These results indicate that IgM/IgA-enriched IVIg may be a more potent immunomodulator than pure IgG preparations on inflammatory reactions in the CNS.

OBJECTIVE:A measurement protocol for magnetoneurography (MNG) is established which allows the non-invasive localization and tracing of evoked compound action currents propagating along cervical nerve roots in man. METHODS:Inside a magnetically shielded room either both median or both ulnar nerves of healthy subjects were conventionally electrostimulated in alternation. Evoked magnetic responses were recorded using a multichannel SQUID-detector with a planar measuring area centered over the neck. Simultaneously, electric surface potentials were recorded using cervical bipolar electrode montages. RESULTS:Upon median (ulnar) nerve stimulation somatosensory evoked magnetic fields up to 20 fT (10 fT) amplitude were detected propagating over the cervical transforaminal root entry zone, with corresponding electrical surface potentials of 1.5 microV (0.5 microV). Furthermore, the signal-to-noise ratio of the spatiotemporal magnetic field mappings in median nerve stimulation experiments allowed dipolar source reconstructions and tracing of the propagation of the compound action currents along nerve root fibers. CONCLUSION:Magnetoneurography allows tracing of the propagation of evoked compound action currents along cervical roots in healthy subjects with millisecond temporal and high spatial resolution. Thus, MNG offers a sensitivity appropriate to serve as a clinical diagnostic tool for localizing focal neuropathies of cervical nerve roots.

Using a low-noise 49-channel dc-SQUID system spinal somatosensory evoked fields (SEF) were recorded which were generated by compound action currents evoked upon posterior tibial nerve stimulation. The SEF mapping showed the action current propagation along the sciatic nerve, lumbosacral plexus and cauda equina in parallel to simultaneously recorded electrical potentials (SEP). For a reliable intraindividual side-to-side comparison of spinal SEFs the right and left tibial nerves were stimulated in alternating order; this procedure minimizes artifactual inter-nerve SEF map differences due to eventual patient-to-sensor displacements which might occur in serial measurements. These large-area lumbar SEF mappings open up several clinical perspectives for magnetoneurography, in particular with respect to the 3D-localization of proximal conduction blocks.

Article Nachweis DC-naher biomagnetischer Felder von Muskelverletzungsströmen in vivo was published on January 1, 1997 in the journal Biomedical Engineering / Biomedizinische Technik (volume 42, issue s2).

Based on low-noise superconducting quantum interference devices (SQUIDs) magnetoencephalography allows the non-invasive detection of low-amplitude high-frequency brain responses evoked about 20 ms after electric hand nerve stimulation. The main spectral energy of these brief oscillatory bursts (near 600 Hz) is in the range typical for rapidly repeated action potentials. Here, the magnetic fields of median and ulnar nerve evoked 600 Hz bursts are shown to exhibit a somatotopic arrangement at the primary somatosensory hand cortex closely resembling that of the concomitant postsynaptic primary cortical response (¿N20m'). Two possible burst generators are discussed: (1) repetitive spike volleys conducted along the terminal segments of somatotopically arranged thalamocortical axons, and (2) early intracortical spike activity in nerve-specific subterritories of the 3b hand area.