Health Questions and Answers

MOVEMENT DISORDERS

What is Parkinson’s disease?
Parkinson’s disease is a gradual, progressive, degenerative disease of the basal ganglia (extrapyramidal) motor system.

List the four cardinal features of Parkinson’s disease.

  • Tremor
  • Rigidity
  • Bradykinesia (slowness of movement)
  • Postural instability

Describe the tremor of Parkinson’s disease.
The tremor is usually a to-and-fro, pronation-supination, resting tremor that diminishes with voluntary movement. It is coarse and slow and most prominent in the hands and head.

Describe the rigidity of Parkinson’s disease.
The rigidity is associated with a diffuse increase in muscular tone and sometimes a “cog-wheeling” property to the joints when passively moved.

How does bradykinesia manifest in Parkinson’s disease?
Patients exhibit a paucity or lack of movement and tend to show minimal axial expression. They often sit quite immobile, almost like statues.

What is the differential diagnosis of Parkinson’s disease?
A few conditions can cause parkinsonism, a symptom complex that mimics idiopathic Parkinson’s disease. The most common examples are the neuroleptic drugs. Similar symptoms also can be mimicked by multiple strokes, hydrocephalus, and degenerative conditions such as Alzheimer’s disease.

How is Parkinson’s disease treated?
The best treatment is a combination of levodopa plus carbidopa (Sinemet). The main cause for the symptoms of Parkinson’s disease is a deficiency of dopamine within the pathway running from the substantia nigra to the basal ganglia. Since dopamine cannot be given directly (because it does not cross the blood-brain barrier), it is given as levodopa. Other dopamine agonists are sometimes used to supplement Sinemet. Anticholinergic agents, which suppress the overactive cholinergic system and bring it into balance with the diminished dopamine system, can also alleviate symptoms.

What are the important types of tremors other than the resting tremor of Parkinson’s disease?
Essential tremor. This rapid, fine tremor involving the head and arms becomes more noticeable with sustained postures or intentional movement. A family history, with an autosomal dominant inheritance, is seen in about half the cases. Treatment may include a beta blocker (propranolol, 80 mg/day) or primidone (starting at 50 mg/day).
Cerebellar tremor. Damage to the cerebellum disturbs motor control by causing a tremor. The tremor is absent at rest and appears only with intentional or voluntary movements. It is a slow, coarse, dyssynergic tremor. Other evidence of cerebellar dysfunction may be present. Pharmacologic treatment is generally unsatisfactory.

What are dystonias?
Dystonias, as the name suggests, are disorders of muscle tone that result in involuntary, sustained muscle contractions. They can lead to abnormal posturing or unique repetitive movements. Examples include spasmodic torticollis, blepharospasm, and oromandibular dystonia.

How are dystonias treated?
Relief can often be obtained by injecting the muscles with botulinum toxin (Botox).

References
WEB SITES
www.neuroguide.com
www.aan.com (American Academy of Neurology)
www.medmatrix.org
www.internets.com/mednets/sneurolo.htm
www.medwebplus.com/subject/Neurology.html

BIBLIOGRAPHY

  1. Lambert D, Waters CH: Essential tremor. Curr Treat Options Neurol 1: 6-13, 1999.
  2. Aminoff M: Neurology and General Medicine, 3rd ed. Philadelphia, Churchill-Livingstone, 2001.
  3. Noseworthy JH (ed): Neurologic Therapeutics. London, Martin Dunitz, 2003.
  4. Bradley WG, Daroff RB, Fenichel GM, Jankovic J: Neurology in Clinical Practice, 4th ed. Philadelphia, Butterworth-Heinemann, 2004.
  5. Caplan LR: Stroke: A Clinical Approach, 3rd ed. New York, Butterworth-Heinemann, 2000.
  6. Samuels MA, Feske S (eds): Office Practice of Neurology, 2nd ed. Boston, Churchill-Livingstone, 2003.
  7. Johnson RT, Griffin JW: Current Therapy in Neurologic Disease, 6th ed. St. Louis, Mosby, 2002.
  8. Victor M, Ropper AH: Prinicples of Neurology, 7th ed. New York, McGraw-Hill, 2001.

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