Normal-pressure hydrocephalus-1 (HYDNP1) is an autosomal dominant neurologic disorder characterized by the clinical triad of slowly progressive gait instability, urinary incontinence, and cognitive decline associated with ventricular enlargement on brain imaging with normal pressure of the cerebrospinal fluid (CSF). The onset of symptoms is usually in late adulthood; the symptoms are responsive to shunting. The disorder has been associated with recurrent respiratory infections and possible infertility issues, but the latter has not been confirmed (summary by Takahashi et al., 2011 and Morimoto et al., 2019).

An unintentional, oscillating to-and-fro muscle movement about a joint axis.

The term gait disturbance can refer to any disruption of the ability to walk. In general, this can refer to neurological diseases but also fractures or other sources of pain that is triggered upon walking. However, in the current context gait disturbance refers to difficulty walking on the basis of a neurological or muscular disease.

An increase in size of the ventricular system of the brain.

Tremor that occurs during any voluntary movement. It may include visually or non-visually guided movements. Tremor during target directed movement is called intention tremor.

Occipitofrontal (head) circumference greater than 97th centile compared to appropriate, age matched, sex-matched normal standards. Alternatively, a apparently increased size of the cranium.