Question Title: Adrenomyeloneuropathy -vs- Primary Progressive MS

I am wondering if it is possible to distinguish between adrenomyeloneuropathy (AMN) and primary progressive MS (PP-MS) using an MRI scan.

Also, what other methods might be used to distinguish between the two disorders.

I believe there is a genetic test for Adrenoleukodystophy (ALD), but I'm not sure if the test can be used to assess the adult version of the disorder(AMN). Also, I am familar with the blood serum test for VLCFA's (in ALD), but I recently read an article that claims blood serum levels of VLCFA's can be influenced by diet. Assuming that a person is on a VERY low fat diet, how else might a doctor make a firm diagnosis between Adrenomyloneuropathy and Primary Progressive MS.

Much thanks!
Brett

Dear Brett:

Adrenomyeloneuropathy (AMN) is a rare, but indeed an important entity in the differential diagnosis of a progressive myelopathy (and primary progressive MS), both in males as well as in females (as many as 20-30% of heterozygotes may have signs).

MRI of the brain may show characteristic findings in about half of the cases with AMN, and thus may be useful diagnostically. I do not think there are any characteristic features on spine MRI that are useful. EMG examination shows evidence of an axonopathy in about half of the cases of AMN, while such abnormality is not seen with MS.

VLCFA levels are not substantially lowered just by a low fat diet, since such fatty acids are endogenously synthesized. Lorenzo's oil (a mixture of triglycerides of oleic and erucic acids), however, can normalize VLCFA levels - I guess you are not on such a diet!

I do not know the details of commercially available genetic tests and their sensitivity for diagnosing AMN. Most individuals with AMN have been found to have identifiable mutations of the ABC gene on the X chromosome.

Although there are descriptions of characteristic lamellar bodies on electron microscopy of brain and/or peripheral nerve in AMN, I do not think these abnormalities are of any clinical relevance today.

If AMN is a serious consideration, a consultation with Dr. Hugo Moser at the Kennedy Krieger Institute, Baltimore is most appropriate.