Diagnosis of AHC
AHC is a "clinical" diagnosis, meaning that there isn't a specific blood test or imaging test that can definitely confirm a suspected diagnosis. The diagnosis of AHC is suspected if your child demonstrates a constellation of specific symptoms.
Diagnostic tests which can help to confirm a diagnosis of AHC and exclude other disorders which mimic AHC include:
Blood tests
Certain tests need to be obtained to rule out causes of diseases that can present in a similar fashion to AHC, including lactate levels in blood, which might indicate a mitochondrial disorder such as MELAS or PDH deficiency, which can have episodes which are similar to those seen in AHC.
Lumbar puncture
Studies of spinal fluid are often necessary to help exclude other causes of abnormal limb or eye movements, including neurotransmitter deficiency states, or to look for evidence of elevated lactic acid, as one might see in MELAS syndrome or other mitochondrial disorder.
Urine studies
Urine organic acid levels can sometimes help exclude other suspected metabolic disorders which can cause similar symptoms.
Electroencephalogram (EEG)
A test that measures the electrical activity of the brain. An EEG can detect abnormal electrical activity, and help make a diagnosis of epilepsy. Some children with AHC do have episodes with EEG abnormalities consistent with epilepsy. However, the majority of episodes they have are generally not associated with epileptiform activity. The presence of typical episodes like hemiparesis or abnormal eye movements which are not associated with epileptic activity can help to confirm a suspected diagnosis.
Muscle biopsy
A small sample of the muscle is removed and examined to determine and confirm a diagnosis or condition other than AHC, such as a mitochondrial disorder.
MRI or imaging studies
Imaging studies of the brain or spine to help rule out other conditions, such as stroke.
