These disorders are characterized by the degeneration of motor neurons in the cerebral cortex, spinal cord, brain stem, and pyramidal tracts.
[5] Patients with early cases of PBP have difficulty with pronunciations, particularly lateral consonants (linguals) and velars, and may show problems with drooling saliva.
[citation needed] About twenty-five percent of patients with PBP eventually develop the widespread symptoms common to ALS.
It is not currently known if and how the decreased SOD1 activity contributes to Progressive Bulbar Palsy or FALS, and studies are being done in patients and transgenic mice to help further understand the impact of this gene on the disease.
[citation needed] A case study was done on a 42-year-old woman who complained of muscle weakness 10 months prior to admission in the hospital.
Upon neurological examination, the patient showed muscle atrophy, fasciculation in all limbs and decreased deep tendon reflexes.
In 1869, Charcot studied the involvement of the corticospinal tracts and with Joffroy, who noted the loss of the bulbar motor nuclei, discovered the similarities to amyotrophic lateral sclerosis (ALS).
[8] It was observed that a distinction from ALS was fatigue that predominated in muscles innervated by lower cranial nerve nuclei, rather than the upper motor neurons.