The HAT is a seven item tool developed for children/youth between 4 to 19 years old. The HAT is a seven‐item clinical assessment tool used to differentiate the various types of pediatric hypertonia, namely spasticity, dystonia, and rigidity.

The current version of the HAT consists of seven items in total: two spasticity items, two rigidity items and 3 dystonia items. Each item has to be tested and a score of 0 (negative) is assigned for the absence or 1 (positive) for the presence of the specific item.

The presence of at least one HAT item in a hypertonia subgroup confirms the presence of the specific subtype (e.g. spasticity, dystonia or rigidity). The presence of more than one subgroup item identifies the presence of mixed tone. The HAT is capable of discriminating hypertonia subtypes for upper and lower extremities.

The patient´s position is standardized prior to the administration of the assessment; all the extremities can be evaluated but it is suggested to do one limb at a time. It usually takes less than five minutes to complete the assessment on one limb and it is also advisable that the items are administered in the listed order.

See the HAT User Manual (Fehlings et al. 2010) below for detailed instructions on the assessments.