<unk>  is a rare condition that is characterized by progressive damage (-pathy) to white matter (-leuko-) in the brain (-encephalo-), particularly myelin, due to causes such as exposure to substance use, environmental<unk> s, or chemotherapeutic drugs. The prevalence of this disease is infrequent and often goes unreported, especially in cases resulting from substance use. Magnetic resonance imaging (MRI) is a popular method to study and diagnose the disease. However, even with technological advances, the exact mechanism and underlying pathophysiology of<unk>  remains unknown and is thought to vary between sources of<unk> ity. The clinical severity of<unk>  also varies among patients, exposure time, concentration, and purity of the<unk>  agent. Some reversibility of the condition has been seen in many cases when the<unk>  agent is removed.
Toxic leukoencephalopathy
Powassan encephalitis
Progressive multifocal leukoencephalopathy
Viral encephalitis
Herpesviral encephalitis
Autoimmune encephalitis
Tuberculous meningitis
Polioencephalitis