The University of Utah 2001
Updated February 2007
Updated September 2007
Updated September 2008
Updated September 2009
Updated September 2010
Updated November 2012
Updated September 2013
Updated December 2014
QuickTime and the QuickTime Logo are trademarks of Apple Computer, Inc., registered in the U.S. and other countries. The Get QuickTime Badge is a trademark of Apple Computer Inc., used with permission.
Pseudobulbar palsy is caused by bilateral corticobulbar tract disease (UMN
disease). The patient will have upper motor neuron signs including a positive
jaw jerk and slow side-to-side tongue movements with the jaw frequently
moving with the tongue. The patient has incomplete elevation of the palate
with excessive nasal air escape when saying "pah" or "kah" (decreased
volitional activity of CN 9 & 10) but a hyperactive gag reflex (increased
non-voluntary or reflex motor action of CN 9 & 10).
When a patient has weakness of the palatal muscles it is important to determine
if this is from UMN vs. LMN disease. Patients with bilateral LMN lesions
have both absent voluntary and reflex activity. Patients with bilateral
UMN weakness or dysfunction will lack voluntary movement of the palate but
will have a hyperactive gag reflex (just like a hyperactive DTR with UMN
disease). For UMN disease to cause palatal weakness it must be bilateral
because there is bilateral UMN innervation for the nucleus ambiguus.