Many relatively uncommon disorders may have symptoms that overlap with the symptoms of Parkinson’s disease. These disorders are often referred to as atypical Parkinsonian syndromes or Parkinson’s plus syndromes. Like Parkinson’s, they often have tremors, stiffness and slowness and may even respond to the same anti-Parkinson’s medications. They usually have additional features that allow movement disorder specialists to distinguish them from typical Parkinson’s. Some of these disorders include:

• Progressive supranuclear palsy — Parkinson's-like symptoms along with eye movement abnormalities and trouble with balance and mood
• Multiple systems atrophy — Parkinson's-like symptoms with additional difficulties with balance or trouble regulating blood pressure and urine control
• Corticobasal ganglionic degeneration — Parkinson's-like symptoms along with trouble controlling hand movements and performing certain tasks
• Diffuse Lewy body disease — Parkinson's-like symptoms with significant memory trouble

Causes

Parkinson’s disease is believed to be caused by the degeneration of nerve cells in a part of the brain known as the substantia nigra pars compacta. These nerve cells produce a substance known as dopamine. Dopamine is a neurotransmitter—a chemical signal sent from one nerve cell to another during normal brain activity, such as movement. Reduction of the amount of dopamine in the brain interferes with the normal brain circuitry involved in movement; in particular, areas of the brain known as the basal ganglia, thalamus, subthalamic nucleus and motor cortex. An abnormality in the circuitry is believed to result in the symptoms of Parkinson’s disease.

Symptoms

The four primary symptoms of Parkinson’s disease are tremor, or trembling in hands, arms, legs, jaw and face; rigidity, or stiffness of the limbs and trunk; bradykinesia, or slowness of movement; and postural instability, or impaired balance and coordination. As these symptoms become more pronounced, patients may have difficulty walking, talking or completing other simple tasks.

Diagnosis

The diagnosis of most movement disorders are made based on the clinical exam and history. A neurological examination assesses motor and sensory skills, the functioning of one or more cranial nerves, hearing and speech, vision, coordination and balance, mental status and changes in mood or behavior, among other abilities.  A movement disorder exam often focuses on additional features like tremor analysis, muscle tone, posture and balance. Movement disorder neurologists have the experience to more readily identify rarer subtypes of Parkinsonism and other, sometimes uncommon, movement disorders based on the clinical exam.

However, in many cases, additional screening tests are useful to clarify the diagnosis. Laboratory screening tests of blood, urine or other substances are used to help diagnose disease, better understand the disease process and monitor levels of therapeutic drugs. Certain tests provide general information, while others are used to identify specific health concerns.

Genetic testing or counseling can help parents who have a family history of a neurological disease determine if they are carrying one of the known genes that cause the disorder or find out if their child is affected. Some movement disorders, especially those affecting young patients, have a known genetic component that can be detected with a blood test.