A right corticobulbar lesion causes left lower facial weakness with preserved forehead movement. A later independent lesion interrupts the left

Question

A right corticobulbar lesion causes left lower facial weakness with preserved forehead movement. A later independent lesion interrupts the left corticobulbar fibres above the facial nucleus. Under the classical corticobulbar model, which new voluntary facial pattern is most plausible?

Accepted Answer

Bilateral lower facial weakness with additional loss of the remaining cortical drive to both foreheads

Answer

Isolated right forehead weakness with recovery of the original left lower facial weakness

Answer

Complete left peripheral-pattern facial palsy with normal movement on the right

Answer

New right lower facial weakness while bilateral forehead strength remains fully preserved

Answer

Bilateral forehead weakness with preserved voluntary movement of both lower facial regions

UMN Facial Weakness – Bilateral Innervation — SCE Neurology MCQ

A right corticobulbar lesion causes left lower facial weakness with preserved forehead movement. A later independent lesion interrupts the left corticobulbar fibres above the facial nucleus. Under the classical corticobulbar model, which new voluntary facial pattern is most plausible?