A pseudobulbar palsy is caused by a bilateral lesion affecting the corticobulbar tracts (running from the motor cortex to the motor nuclei of cranial nerves 9, 10, and 12 in the medulla).

Note that a bilateral lesion is required as the cranial nerve motor nuclei have bilateral cortical representation (except the motor nuclei of the lower half of cranial nerve 7). A pseudobulbar palsy can be thought of as an 'upper motor neurone' lesion of speech and swallow.

Causes

• vascular causes (such as a bilateral internal capsule stroke)
• degenerative causes (such as motor neurone disease and progressive supranuclear palsy)
• neoplastic causes (such as upper brainstem tumours)
• autoimmune causes (such as multiple sclerosis)
• traumatic causes.

Clinical features

Clinical signs include a spastic tongue, a slow thick ("hot-potato") speech, a brisk jaw jerk reflex, and emotional lability. Other upper motor neurone features in the limbs may be present e.g. spastic hypertonia, pyramidal weakness, and hyper-reflexia.