Neuronal intranuclear inclusion disease (NIID) is a disease that causes leukoencephalopathy (dementia) and peripheral neuropathy (variable manifestation including bladder dysfunction). This is the first urodynamic report to show that bladder dysfunction in NIID is a combination of detrusor overactivity, decreased bladder sensation, large post-void residual, and neurogenic changes in the sphincter electromyogram. This report will help managing bladder dysfunction in NIID.