And that if this were the case, then the mechanism remains unclear.Administration of nitrous oxide anesthesia can precipitate subacute combined degeneration in people with subclinical vitamin B12 deficiency, while chronic nitrous oxide exposure can cause it even in persons with normal B12 levels. Posterior column dysfunction decreases vibratory sensation and proprioception (joint sense). Lateral corticospinal tract dysfunction produces spasticity and dorsal spinocerebellar tract dysfunction causes ataxia. Cause
In general, the most common cause of this condition is a deficiency of vitamin B12. This may be due to a dietary deficiency, malabsorption in the terminal ileum, lack of intrinsic factor secreted from gastric parietal cells, or low gastric pH inhibiting attachment of intrinsic factor to ileal receptors.Vitamin E deficiency, which is associated with malabsorption disorders such as cystic fibrosis and Bassen-Kornzweig syndrome, can cause a similar presentation due to the degeneration of the dorsal columns. Diagnosis
Serum vitamin B12, methylmalonic acid, Schilling test, and a complete blood count, looking for megaloblastic anemia if there is also folic acid deficiency or macrocytic anemia. The Schilling test is no longer available in most areas.MRI-T2 images may reveal increased signal within the white matter of the spinal cord, predominantly in the posterior columns and possibly in the spinothalamic tracts. Treatment
Therapy with vitamin B12 results in partial to full recovery where SACD has been caused by vitamin B12 deficiency, depending on the duration and extent of neurodegeneration. References


== External links ==
The current standard of care for GM2 Gangliosidosis disease is limited to supportive care and aimed at providing adequate nutrition and hydration.This supportive care may substantially improve the quality of life of people affected by GM2. The therapeutic team may include specialists in neurology, pulmonology, gastroenterology, psychiatrist, orthopaedics, nutrition, physical therapy and occupational therapy. N-Acetyl-Leucine
N-Acetyl-Leucine is an orally administered, modified amino acid that is being developed as a novel treatment for multiple rare and common neurological disorders by IntraBio Inc (Oxford, United Kingdom).N-Acetyl-Leucine has been granted multiple orphan drug designations from the U.S. Food & Drug Administration (FDA)  and the European Medicines Agency (EMA) and the European Medicines Agency (EMA) for the treatment of a various genetic diseases, including GM2 Gangliosidosis (Tay-Sachs and Sandhoff). The US FDA has granted IntraBio a Rare Pediatric Disease Designation for N-Acetyl-Leucine for the treatment of GM2 Gangliosidosis.Compassionate use studies in both Tay-Sachs and Sandhoff patients have demonstrated the positive clinical effects of treatment with N-Acetyl-Leucine for GM2 Gangliosidosis  These studies further demonstrated that the treatment is well tolerated, with a good safety profile.A multinational clinical trial investigating N-Acetyl-L-Leucine for the treatment of GM2 Gangliosidosis (Tay-Sachs and Sandhoff) began in 2019 Recruitment is ongoing. IntraBio is also conducting parallel clinical trials with N-Acetyl-L-Leucine for the treatment of Niemann-Pick disease type C and Ataxia-Telangiectasia. Future opportunities to develop N-Acetyl-Leucine include Lewy body dementia, amyotrophic lateral sclerosis, restless leg syndrome, multiple sclerosis, and migraine. See also
GM2 (ganglioside)

References
External links
GeneReview/NIH/UW entry on Hexosaminidase A Deficiency