Chapter 14: Basal Ganglia Disorders: Parkinson's and Huntington's Diseases

OBJECTIVES

• 1) Discuss the demographics and etiology of idiopathic Parkinson’s (PD) and Huntington’s diseases (HD)

• 2) Compare and contrast the pathological features and pathogenesis of idiopathic PD, PD plus syndromes, and HD

• 3) Differentiate between the diagnosis of idiopathic PD and HD

• 4) Compare and contrast typical signs and symptoms of idiopathic PD and HD

• 5) Describe the clinical course, prognosis, and medical and surgical treatment of idiopathic PD and HD

• 6) Discuss evidence-based examination of the client with PD and HD

• 7) Discuss evidence-based management of the client with PD and HD

• 8) Compare and contrast examination and management of early, middle, and late stage PD and HD

WHAT ARE PARKINSON’S AND HUNTINGTON’S DISEASES?

Parkinson’s disease and Huntington’s disease are progressive neurodegenerative disorders of the basal ganglia and its connections that profoundly impact motor, cognitive, and psychiatric functions of affected individuals. Parkinson’s disease was named for James Parkinson, an English physician, whose work “An Essay on the Shaking Palsy” published in 1817 described six individuals with symptoms of the disease. Huntington’s disease was named for George Huntington, an American physician, who published an article entitled “On Chorea” in 1872 that described the disease.

EPIDEMIOLOGY

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, after Alzheimer’s disease, with an estimated 1 million Americans and 7–10 million people worldwide affected by the disease. There are approximately 60,000 new cases annually of PD in the United States.¹ The average age of onset is 60, and prevalence and incidence rates are very low in individuals under 40 years, increasing with age and peaking by age 80.² The disease is approximately 1.5 times more common in men than women. The incidence of PD was reported to be highest among Hispanics, followed by non-Hispanic whites, Asians, and Blacks in one study conducted in a multi-ethnic population in California.³

ETIOLOGY AND RISK FACTORS FOR PARKINSON’S DISEASE

Parkinsonism refers to a group of disorders with a variety of different underlying pathologies that can cause Parkinson’s-like symptoms, including slowing movement (bradykinesia), tremor, rigidity or stiffness, and balance problems. PD, or idiopathic parkinsonism, is the most common disorder, affecting about 78% of individuals. Secondary parkinsonism results from identifiable causes such as toxins, trauma, multiple strokes, infections, metabolic disorders, and drugs. There are also conditions, called parkinson-plus syndromes that mimic PD in some ways but are caused by other neurodegenerative disorders.

IDIOPATHIC PARKINSON’S DISEASE

The exact cause of Parkinson’s disease remains unknown,⁴ but most scientists believe that it is caused by an interaction between genetic and environmental factors. Family history has been shown to be a strong risk factor for PD with a person’s risk of developing PD 2.9 times greater if a first-degree relative had PD.⁵ Twin studies have reported either no difference ...