Classic PKAN is characterized by early onset (usually before 6 years) and rapid progression. Common initial symptoms include gaits changes with falling and speech delay. Dystonia, dysarthria and spasticity usually progress during periods of decline that are interspersed with periods of stability that may last for months or years. Dystonia is particularly challenging to manage, leading to complications that include difficulty with eating, severe tongue-biting, loss of ambulation, and episodes of status dystonicus. Retinal degeneration occurs in 2/3 of classic cases, manifested as poor night vision and loss of peripheral vision.
Atypical PKAN is more variable in age of onset, usually within the first three decades. The first symptom is often a change in speech, such as dysarthria, palilalia, or tachylalia. Verbal and motor tics are also common. Neuropsychiatric changes, such as depression, anxiety, impulsivity, and emotional lability are common. Parkinsonism is more frequent in this group, and corresponding treatments may be indicated that are not typically helpful in classic cases.
PANK2