A multiple-sclerosis-like syndrome associated with glue-sniffing

Transient receptor potential Ankyrin-1 (TRPA1) agonists suppress myelination and induce demyelination in organotypic cortical slices

Oligodendrocytes are highly specialized glial cells characterized by their production of multilayer myelin sheaths that wrap axons to speed up action potential propagation. It is due to their specific role in supporting axons that impairment of myelin structure and function leads to debilitating symptoms in a wide range of degenerative diseases, including Multiple Sclerosis and Leukodystrophies. It is known that myelin damage can be receptor-mediated and recently oligodendrocytes have been shown to express Ca2+ -permeable Transient Receptor Potential Ankyrin-1 (TRPA1) channels, whose activation can result in myelin damage in ischemia. Here, we show, using organotypic cortical slice cultures, that TRPA1 activation, by TRPA1 agonists JT010 and Carvacrol for varying lengths of time, induces myelin damage. Although TRPA1 activation does not appear to affect oligodendrocyte progenitor cell number or proliferation, it prevents myelin formation and after myelination causes internodal shrinking and significant myelin degradation. This does not occur when the TRPA1 antagonist, A967079, is also applied. Of note is that when TRPA1 agonists are applied for either 24 h, 3 days or 7 days, axon integrity appears to be preserved while mature myelinated oligodendrocytes remain but with significantly shortened internodes. These results provide further evidence that TRPA1 inhibition could be protective in demyelination diseases and a promising therapy to prevent demyelination and promote remyelination.

[Imaging in acute toxic encephalopathy]

Neuroimaging, particularly MR imaging, plays a major role for the diagnosis of many acute toxic encephalopathies. Toxic disorders are related to drugs (immunosuppressive agents, chemotherapeutic agents, anti-epileptic drugs, heroin...), to metals (lead, manganese, mercury...), and to industrial and environmental chemicals (solvent, carbon monoxide...). MR imaging with diffusion and perfusion imaging provides information regarding brain lesions induced by the toxic agents (vasogenic edema, cytotoxic edema, infarction, hemorrhage, demyelination...).

Substance Use Disorders and Neurologic Illness

Because of the high rates of substance use disorders among the general and clinical populations, and the abuse potential of many medications commonly used in the treatment of neurologic illnesses, the treating neurologist must deal with drug misuse and abuse in practice. The most important tool neurologists must have in their arsenal is the ability to assess for and recognize substance use disorders in their patients. Any treatment plan developed for such patients must include ongoing management of substance abuse issues. After a substance use disorder is diagnosed, the neurologist must make proper referrals to adjunctive support interventions (Alcoholics Anonymous or Narcotics Anonymous) and chemical dependency specialists, and work closely and in collaboration with these components of the patient's overall treatment. The treating neurologist should be aware of the myriad neurologic sequelae of drug use, because most drugs of abuse, including alcohol, can have neurologic manifestations resulting from acute intoxication, acute withdrawal, or chronic use. Drug use (past and present) should be included in the differential diagnosis for any patient with an atypical constellation of symptoms or with isolated neurologic deficits. If the treatment of a neurologic condition requires the use of a potentially addictive substance, particularly when the patient has a history of substance use disorders, then the clinician must minimize the risk of addiction by giving the least addictive substances and developing a plan to manage the use of the drug throughout the treatment period.