The attacks may last for minutes, hours or even days and are normally relieved by sleep. The attacks of hemiplegia may alternate from one side of the body to another. The causes of hemiplegic attacks differ among children. High stress activities have been know to cause attacks as well as the presence of a cold or upper respiratory problems. Children are affected by bright lights, wind, temperature changes and exposure to water.
Many attacks occur for no apparent reason.
Many children exhibit a greater degree of ability to handle the attacks or even avoid factors that cause the attacks as they age, but this is not always the case. There is no proof that the disease is fatal or shortens life expectancy is any way, but sufficient documentation is not available at this time. There is developing evidence that AHC may cause ongoing mental and neurological deficits with a progressive course. Other drugs that induce sleep have also been used to reduce the severity and length of attacks. Because the effects of AHC are thought to be cumulative in relation to damage to the brain, reducing the severity of attacks may have significant positive long term benefits.