Approach to a case of myeloneuropathy

Myeloneuropathy is a frequently encountered condition and often poses a diagnostic challenge. A variety of nutritional, toxic, metabolic, infective, inflammatory, and paraneoplastic disorders can present with myeloneuropathy. Deficiencies of vitamin B12, folic acid, copper, and vitamin E may lead to myeloneuropathy with a clinical picture of subacute combined degeneration of the spinal cord. Among infective causes, chikungunya virus has been shown to produce a syndrome similar to myeloneuropathy. Vacuolar myelopathy seen in human immunodeficiency virus (HIV) infection is clinically very similar to subacute combined degeneration. A paraneoplastic myeloneuropathy, an immune-mediated disorder associated with an underlying malignancy, may rarely be seen with breast cancer. Tropical myeloneuropathies are classified into two overlapping clinical entities - tropical ataxic neuropathy and tropical spastic paraparesis. Tropical spastic paraparesis, a chronic noncompressive myelopathy, has frequently been reported from South India. Establishing the correct diagnosis of myeloneuropathy is important because compressive myelopathies may pose diagnostic confusion. Magnetic resonance imaging (MRI) in subacute combined degeneration of the spinal cord typically reveals characteristic signal changes on T2-weighted images of the cervical spinal cord. Once the presence of myeloneuropathy is established, all these patients should be subjected to a battery of tests. Blood levels of vitamin B12, folic acid, vitamins A, D, E, and K, along with levels of iron, methylmalonic acid, homocysteine, and calcium should be assessed. The pattern of neurologic involvement and results obtained from a battery of biochemical tests often help in establishing the correct diagnosis.