PubMed · 558560
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J G Millichap. 1977. Additional causes for hypocalcemia given.. https://doi.org/10.1212/wnl.27.5.500
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OBJECTIVE: The goal was to assess the safety of magnetic resonance imaging (MRI) with implanted neurostimulators, in an in vitro and in vivo study. METHODS: Two different implantable pulse generators (IPGs) (ITREL II and 3; Medtronic, Minneapolis, MN) and different leads (separately and connected to an IPG) were tested in three different MRI scanners (0.2, 0.25, and 1.5 T). Measurements of the induced voltages (using an external oscilloscope) and the induced heat (using an infrared camera) were performed in an in vitro study. Finally, 38 patients with implanted neurostimulator systems (leads and IPGs) underwent MRI in 50 examinations, with continuous monitoring by a physician with uninterrupted visual and vocal contact with the patient. Twenty-five patients were studied prospectively, with documented printouts of the parameter settings before and after MRI. RESULTS: An induced voltage of 2.4 to 5.5 V was measured in the experimental configuration with a lead connected to an IPG. The voltage was higher with the leads alone, compared with the leads connected to the IPG, and was dependent on the MRI scanner, the sequences, and the type of lead. No heat induction was observed in any part of the hardware. No change of pulse shape or change of IPG parameters was observed during MRI. No adverse effects occurred in patients with chronically implanted deep brain leads connected to an IPG. CONCLUSION: MRI can be safely performed in patients with implanted neurostimulation systems with the tested deep brain leads connected to an IPG (ITREL II and 3), with running parameters. No heat induction was detected, and the experimentally measured induced voltage did not seem to harm the patients. Only the reed switch of the IPGs was activated; the other parameters remained unchanged. Further investigations must be performed to study the local electrical effects in larger plate electrodes; these effects might cause slight discomfort. There is no danger with any type of electrode during MRI examinations if the electrodes lie outside the region of interest. These observations are restricted to the tested devices. A conscientious estimation of the risks and benefits of MRI for patients with implanted devices is recommended. If the type of device is not known to the examiner, MRI should still be considered to be contraindicated.
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Neurological disease may result in respiratory dysfunction; however the manifestations of respiratory dysfunction in such patients may be atypical because of wider effects of their underlying condition. In the present review we have considered separately acute neuromuscular respiratory disease (as well as aspects of respiratory muscle function relevant to intensive care), chronic neuromuscular respiratory disease, sleep related disorders, respiratory consequences of specific neurological diseases, and neurological features of respiratory disease. Approaches to specific clinical problems are discussed; in many instances this can be expedited by close cooperation with a respiratory physician. We suggest that management of respiratory dysfunction in neurological disease depends critically on three factors: firstly, knowledge of when respiratory dysfunction is likely to occur; secondly, maintaining a high index of clinical suspicion (specifically apparently vague symptoms should not be uncritically attributed to the underlying neurological condition); and, thirdly, the pursuing of appropriate investigations.