Metabolic CNS disease means disease caused by some problem with metabolism such as an endocrine (gland) problem or some sort of vitamin deficiency
. If i understand the question correctly, you are asking this because of an MRI scan
that showed some abnormality in the cervical spinal cord and on the report of the scan there was something about "rule out metabolic CNS disease." one possible cause for a metabolic disease that involves the cervical spine and that might be seen on an MRI scan is vitamin B12 deficiency
. There is a blood test for b12. Of course, there are many other causes of abnormal signal intensities on MRI scans that are not caused by metabolic causes.