From the Guidelines
Adrenomyeloneuropathy (AMN) is a rare genetic disorder that is a milder, adult-onset form of adrenoleukodystrophy (ALD), primarily affecting the spinal cord and peripheral nerves, causing progressive stiffness and weakness in the legs, urinary and sexual dysfunction, and sometimes adrenal insufficiency. According to the study by 1, patients with adrenal insufficiency require lifelong hormone replacement therapy with glucocorticoids and sometimes mineralocorticoids. The recommended dosage of hydrocortisone is 15-25 mg daily in divided doses, and fludrocortisone is 0.05-0.2 mg daily 1.
Key Characteristics of AMN
- Progressive stiffness and weakness in the legs
- Urinary and sexual dysfunction
- Sometimes adrenal insufficiency
- Caused by mutations in the ABCD1 gene, leading to accumulation of very long-chain fatty acids in tissues and blood
Treatment and Management
- Lifelong hormone replacement therapy with glucocorticoids and sometimes mineralocorticoids
- Physical therapy to maintain muscle strength and mobility
- Antispasticity medications like baclofen or tizanidine to reduce muscle stiffness
- Lorenzo's oil may help stabilize very long-chain fatty acid levels, but its effect on disease progression is unclear
Monitoring and Follow-up
- Regular monitoring by a multidisciplinary team including neurologists and endocrinologists is crucial for optimal management of this progressive condition
- Patients with primary adrenal insufficiency should be reviewed at least annually, with assessment of health and well-being, measurement of weight, blood pressure, and serum electrolytes 1
From the Research
Definition and Characteristics of Adrenomyeloneuropathy
- Adrenomyeloneuropathy (AMN) is an X-linked recessive disorder characterized by myelopathy, peripheral neuropathy, and cerebral demyelination, which develop in association with the accumulation of very-long-chain fatty acids 2.
- It is a variant type of X-linked adrenoleukodystrophy, and it is a genetic metabolic disease with strong clinical heterogeneity, making it easily misdiagnosed and underdiagnosed 3.
- AMN is primarily characterized by involvements of long ascending and descending tracts of the spinal cord and peripheral neuropathy, leading to spastic paraparesis and urinary and erectile dysfunction 4.
Clinical Manifestations
- The clinical manifestations of AMN are diverse, and patients may present with adrenal insufficiency, bilateral lower extremity spastic paraplegia, and other symptoms 3, 4.
- Some patients may experience an insidious clinical onset and slow progression, while others may have a more rapid progression of symptoms 3.
- The disease can also manifest as primary adrenal failures, with increased serum very long chain fatty acid concentrations 4.
Diagnosis and Treatment
- Diagnosis of AMN is typically made through a combination of clinical evaluation, laboratory tests (including very long-chain fatty acid levels), and genetic testing 3, 4.
- Treatment for AMN may include glucocorticoid replacement therapy, as well as other therapies aimed at managing symptoms and slowing disease progression 3, 5.
- Lorenzo's oil therapy has been shown to normalize plasma very long-chain fatty acid levels, but its effectiveness in preventing or reversing neurological symptoms is still being studied 2, 5.
- A multidisciplinary approach to longitudinal care, including routine surveillance for adrenal insufficiency and onset of cerebral demyelination, is recommended for patients with AMN 6.