The diagnosis of MLD is fairly straightforward once you know what you are looking for. Unfortunately, it is often after many misdiagnosis, and often after the disease is very progressed when the MLD sufferer is put in contact with staff that knows of MLD and performs the proper testing. Common misdiagnosis for MLD include Cerebral Palsy, Batton's Disease, and ADHD - especially with children. In adults since the presentation is often first psychological, not physical, the misdiagnosis can be a variety of psychological conditions.
MRI can indicate white matter disease (or leukodystrophy) and can suggest MLD, but a MRI alone is not a definitive diagnostic tool for MLD.
A proper diagnosis is a confirmation of the deficiency of the missing enzyme and the resulting lowered arylsulfatase A activity in the body. This diagnosis is confirmed and validated by one or more of the following procedures:
- Blood & Urine testing are complimentary to each other. Usually a blood test is done first to check for enzyme levels, followed by a urine test to confirm the presence of sulfatides.
It has been the experience of the MLD Family members that test results vary widely from lab to lab - so please talk with your doctor about this ahead of time. We recommend a particular procedure and lab for both blood & urine testing as different labs use different scales for their results and different processes to test. The results from lab to lab cannot always be compared apples to apples. The details of the Recommended Blood & Urine Labs and testing procedures can be found by clicking here.
Remember that Saposin B deficiency will show a normal enzyme level and increased sulfatides. If your blood test comes back normal but you still suspect MLD then you should have a Urine Sulfatides test done.
Likewise, the the urinary sulfatide test eliminates pseudodeficiency as a cause of false low enzyme level results.
- Imaging Studies of the brain using a CT or MRI scan will usually show an unusual loss of white matter due to demyelination. Be sure that the neurologist that reads the scans is familiar with MLD. As mentioned above, MRI can be suggestive of MLD but is generally not accepted as a formal diagnostic tool.
- Electrophysiologic Studies of the response of various limbs to a physical or electrical stimulus can show decreased nerve conduction velocities.
- Pathological studies of the white matter after staining show spherical granular masses that stain metachromatically. The stains will show strongly positive with periodic acid-Schiff (PAS) and Alcian blue or acetic acid-cresyl violet.
- Genetic counseling is sometimes used as a diagnostic tool and as a post-diagnostic tool to determine who else in your family might be a MLD carrier or be affected by MLD.