Overall however, EEG during episodes and other investigative methods such as brain MRI, TACs, angiographic MRIs and CFS have normal results. Non-paroxysmal symptoms
In the long term, many paroxysmal symptoms occur along with AHC, and while these symptoms vary in strength depending on the person, they are consistent features of AHC. It is thought that some of these symptoms are brought on or worsened by hemiplegic attacks, though it is not known for certain. Patients suffer persistent motor, movement (ataxia), and cognitive deficits. These deficits become more apparent over time and include developmental delays, social problems, and retardation. It is rare for someone with AHC not to have cognitive deficits, but a study in Japan did find two patients who met all of the diagnostic criteria for AHC but who were not mentally impaired. It is not known whether AHC is a progressive disease, but severe attacks are suspected to cause damage which result in permanent loss of function. 100% of children studied in the USA have had some form of mental impairment, which is usually described as mild to moderate, but varies greatly among individuals. Epilepsy
At least 50% of AHC sufferers also suffer from epilepsy, and AHC is often misdiagnosed as epilepsy because of this. These epileptic events are distinguished from other episodes by an alteration of consciousness, as well as frequent tonic or tonic-clonic activity. Epileptic episodes are generally rare, though they do increase with age. Due to the rarity of epileptic episodes, there are few EEG confirmations of them.
Some studies have found it to be very effective in reducing the duration, severity, and frequency of hemiplegic attacks. It is generally considered the best treatment available, but this drug is thought by some to be of little benefit to AHC patients. Many patients suffer adverse effects without seeing any improvement. Flunarizine also causes problems because it is difficult for patients to obtain, as it is not readily available in the United States. Sodium oxybate
In 2009 through 2011 clinical research at the University of Utah investigated whether sodium oxybate, also known as Gamma-Hydroxybutyric acid is an effective treatment for AHC. Thus far, only a small number of patients have been sampled, and no conclusive results are yet available. While some success has been had thus far with the drug, AHC patients have been known to respond well initially to other drugs, but then the effectiveness will decline over time. Currently, sodium oxybate is used as a narcolepsy-cataplexy treatment, though in the past it has been used controversially in nutritional supplements. This drug was chosen to test because of a possible link between the causes of narcolepsy-cataplexy and AHC. References
External links
Alternating Hemiplegia Information Page at NINDS
Homepage of the Alternating Hemiplegia of Childhood Foundation (AHCF).