Progressive Supranuclear Palsy (PSP) and Parkinson’s Disease research by Cori and Justin

The motor system

The motor system is the part of the central nervous system that is involved with movement. It consists of the pyramidal and extrapyramidal system. The motor pathway also called pyramidal tract or the corticospinal tract start in the motor center of the cerebral cortex. There are upper and lower motor neurons in the corticospinal tract. The motor impulses originates in the Giant pyramidal cells or Betz cells of the motor area i.e precentral gyrus of cerebral cortex. These are the upper motor neurons (UMN) of the corticospinal tract. The axons of these cells pass in the depth of the cerebral cortex to the Corona radiata and then to the Internal Capsule passing through the posterior branch of internal capsule and continue to descend in the Midbrain and the Medulla Oblongata. In the lower part of Medulla oblongata 80 to 85% of these fibers decussate (pass to the opposite side) and descend in the White Matter of the Lateral funiculus of the spinal cord on the opposite side. The remaining 15 to 20% pass to the same side. Fibers for the extremities (limbs) pass 100% to the opposite side. The fibers of the corticospinal tract terminate at different levels in the Anterior horn of the Grey Matter of the spinal cord. Here the Lower Motor Neurons (LMN) of the corticospinal cord are located. Peripheral motor nerves carry the motor impulses from the anterior horn to the voluntary muscles.

Progressive Supranuclear Palsy

Progressive supranuclear palsy (PSP) is a rare degenerative disease of the brain. The disease impairs movements and balance. Many people with PSP also experience changes in mood, behavior, and personality. A decline in cognitive mental processes, such as thinking, memory, attention, and speech, balance, swallowing- and eye sight is not uncommon. When these mental changes are severe enough to interfere with everyday activities, they are called dementia.

The name progressive supranuclear palsy seems like a mouthful, but it accurately describes the disease. PSP is progressive, meaning that it gets worse over time. The disease affects the part of the brain above the nuclei (“supranuclear”), which are pea-sized structures in the part of the nervous system that controls eye movements. Palsy means weakness, and it is this characteristic weakness in eye movements for which the disease is named. PSP is sometimes called Steele-Richardson-Olszewski syndrome, after the 3 scientists who first described it in 1963.

About 20,000 people in the United States have PSP. The disease usually develops in people aged 60 years or older. Symptoms typically become noticeable in the early 60s, although the disease sometimes affects people in their 40s or 50s. PSP is slightly more common in men than in women.

Because PSP mainly affects older people and has somewhat similar symptoms, it is often mistaken for Parkinson disease a much more common movement disorder. The distinction is important, because treatments that help many people with Parkinson disease do not help those with PSP. Unfortunately, we do not yet have an effective treatment for PSP.

Parkinson's disease

Parkinson's disease (also known as Parkinson's, Parkinson disease or PD) is a degenerative disorder of the central nervous system that often impairs the sufferer's motor skills, speech, and other functions.

Parkinson's disease belongs to a group of conditions called movement disorders. It is characterized by muscle rigidity, tremor, postural abnormalities, gait abnormalities, a slowing of physical movemen (bradykinesia) and a loss of physical movement (akinesia) in extreme cases. The primary symptoms are the results of decreased stimulation of the motor cortex by the basal ganglia. Normally this involves insufficient formation and thus action of dopamine produced in the dopaminergic of the midbrain (specifically the substantia nigra). Secondary symptoms may include high level cognitive dysfunction and subtle language problems. PD is both chronic and progressive.

PD is the most common cause of chronic progressive parkinsonism, a term which refers to the syndrome of tremor, rigidity, bradykinesia and postural instability. PD is also called "primary parkinsonism" or "idiopathic PD" (classically meaning having no known cause). While many forms of parkinsonism are idiopathic, "secondary" cases may result from toxicity most notably of drugs, head trauma, or other medical disorders. The disease is named after English apothecary James Parkinson, who made a detailed description of the disease in his essay: "An Essay on the Shaking Palsy" (1817)

What other conditions resemble Parkinson's disease?

In its early stages, Parkinson's disease can resemble a number of other conditions with Parkinson-like symptoms known as Parkinsonism. These conditions include multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, Lewy body dementia, stroke, encephalitis (inflammation of the brain), and head trauma. Alzheimer's disease and primary lateral sclerosis can also be mistaken for Parkinson's disease. Other similar conditions include essential tremor, dystonic tremor, vascular Parkinsonism, and drug-induced Parkinsonism.