Adrenomyeloneuropathy (AMN) should be considered in the differential diagnosis of patients showing signs of spinal cord lesions caused by the loss of myelin, the fatty sheath that wraps around and protects nerve fibers, a case report suggests.
The report, “Adrenomyeloneuropathy Masquerading as Chronic Myelitis,” was published in the journal JAMA Neurology.
AMN is the adult-onset form of adrenoleukodystrophy (ALD), a rare neurodegenerative disorder caused by mutations in the ABCD1 gene that mainly affects men. The disease is characterized by the accumulation of fatty molecules, called very long-chain fatty acids, which can lead to myelin destruction and neuron degeneration.
Although AMN normally manifests itself with symptoms associated with myelin loss, including balance and coordination problems and bladder dysfunction, patients often do not show any signs of lesions in standard spinal cord imaging scans.
In the report, physicians described the case of a woman showing signs of spinal cord lesions and who was initially thought to have chronic myelitis, a medical condition in which the spinal cord becomes inflamed, resulting in the damage and loss of myelin.
The 70-year-old woman had a seven-year history of balance issues coupled with mild bladder dysfunction. She was also known to carry a mutation in the ABCD1 gene, because her son had been diagnosed with ALD at the age of 5.
A physical examination revealed the woman had an unstable gait, was unable to tandem walk (where the toes of the back foot touch the heel of the front foot on each step), and had a reduced sense of vibration in her legs.
She showed no signs of weakness or stiffness (spasticity) in the muscles of her legs, and her tendon reflexes were normal.
MRI scans of her brain were normal, but those of her spinal cord showed lesions at the level of her neck, suggestive of chronic myelitis. However, additional lab tests failed to confirm this diagnosis.
All screening tests for infectious and autoimmune diseases were normal, as well as those assessing the levels of several vitamins, amino acids (protein building blocks), and other compounds.
At this point, it was noted that her son, who had AMN since the age of 25, had some similar symptoms, including unsteady gait, reduced sense of vibration in his legs, and spinal cord lesions.
Both mother and son also had abnormally high levels of very long-chain fatty acids, which led physicians to diagnose the mother with AMN.
“Even though a spinal cord … signal abnormality has never been reported in AMN (to our knowledge), we concluded that [spinal MRI lesions] in these patients were likely to be associated with AMN and not chronic myelitis,” the team wrote.
“In conclusion, in cases of chronic myelopathy with [MRI] signal abnormalities, AMN can still be considered,” the researchers concluded.
We are sorry that this post was not useful for you!
Let us improve this post!
Tell us how we can improve this post?