In case of a type II decompression sickness (with cerebrospinal injury), the decision on how to structure a prompt hyperbaric treatment rests on an anamnesis and the clinical investigation. In looking for an associated contingent barotrauma, one has to be satisfied with an X-ray of thorax and abdomen. The myelopathy which results from a decompression mishap with medullary involvement forms a very peculiar clinical entity defined by a fascicular injury at several levels. For several years now, clinical radiologists resort to a new medical imaging technique: Nuclear Magnetic Resonance (NMR-)Imaging. For the first time, this technique allows the imaging of intramedullary lesions due to a decompression accident. Other neuroradiological investigations (such as myelography, spinal tomodensitometry, medullary angiography, isotopic tests) are without merit for evaluating decompression accidents with medullary involvement. NMR-Imaging has the potential too, of revealing ischemic cerebral injuries, even if the clinical brain impairment is often silent and therefore overlooked. The role of NMR-Imaging for evaluating cerebrospinal aspect of decompression accidents is not yet finalized. However, NMR-Imaging will give without any doubt a boost to the pathophysiological knowledge of decompression mishaps.